The Current Paradigm: Unbounded Silliness
JohnEB
mockan1
And why do you call it unbounded silliness?
> This Week’s Hypehttp://www.math.columbia.edu/~woit/wordpress/?p=3515
JohnEB
What do you think is the currecnt paradigm? And why do you call it unbounded silliness?
kmarinas86
nonexistent dimensions?
mockan1
If a scientist makes a hypothesis about dimensions or universes that
cannot be observed,
and then sets up an experiment to try to obtain more data, how can the
scientist not talk
about it? And since the purpose of the experiment is to obtain data,
how can one reach
any conclusions about the hypothesis before the experiment is
completed, and
the data obtained and analyzed? I am not trying to be funny or
offending. My question is
sincere. You said you can think of nothing sillier than talking about
"dimensions" or
"universes" that cannot be observed. On what do you base your opinion?
JohnEB
kmarinas86
of 5 stars] (102 users) More options Mar 19, 2:22 am"
"JohnEB View profile Translate to Translated (View Original) [1 out
of 5 stars] (33 users) More options Mar 19, 2:33 pm"
Someone can't handle the truth. Who could it be?
> This Week’s Hypehttp://www.math.columbia.edu/~woit/wordpress/?p=3515
JohnEB
JohnEB
Quantum probe beats Heisenberg limit
A group of physicists in Spain has shown how to make a quantum
measurement that overcomes a limit related to Werner Heisenberg's
uncertainty principle. The researchers confirmed a theoretical
prediction of how to beat the Heisenberg limit by using interacting
photons to measure atomic spin, and they say that their approach could
lead to more sensitive searches for the ripples in space–time known as
gravitational waves and perhaps also to improved brain imaging.
http://physicsworld.com/cws/article/news/45535
JohnEB
Multiverse is far more of a belief system than it is a hypothesis:
2011 Templeton Prize
http://www.math.columbia.edu/~woit/wordpress/?p=3598
JohnEB
The Higgs Particle the Standard Model and the Emperor’s New Clothes
http://mendelsachs.com/the-higgs-particle-rhe-standard-model-and-the-emporers-new-clothes/#more-347
JohnEB
A commenter points to the long-awaited release of a preprint from the
XENON100 experiment giving results from a 100-day run last year. This
is the most sensitive dark matter experiment that has released data.
The result: with an expected background of 1.8 +/- .6 events, they see
3 events (i.e. about what you’d expect if there’s nothing there). For
a WIMP mass of 50 GeV, this allows them to exclude certain WIMP cross-
sections at the level of 7.0 x 10-45cm2. This pretty conclusively
kills off some other claims by dark matter experiments to have seen
something, especially the CDMS result from late 2009 (see here).
http://www.math.columbia.edu/~woit/wordpress/?p=3624
JohnEB
JohnEB
The Alice experiment may soon be able to make experimental measurements which, for the first time, can be modelled using the techniques of string theory.
Although the experimental results will not prove string theory to be correct, an accurate prediction would certainly show that the techniques work, could distinguish between different versions of the theory, and perhaps even show whether the theory is going in the right direction.
Given this kind of quote, one can see why the writer completely mixes up string theory unification and string theory as approximate calculational method in heavy-ion physics:
The researchers, at Cern, the European centre for particle physics near Geneva, say results from the Large Hadron Collider suggest it could offer the first experimental test for some aspects of string theory.
Formulated in the 1960s, this theory attempts to describe how all the fundamental forces of nature, such as gravity and electromagnetism, interact with matter.
On paper, the theory has been highly successful, resolving many mathematical problems.
In practice, however, there is no experimental evidence to support its predictions, including the idea that there could be as many as 11 dimensions – the three physical dimensions, time and seven others as yet undiscovered.
At Cern, there are now hopes the LHC may be able to break this impasse.
Then, as usual, the headline writer takes things a step further:
SCIENTISTS have devised the first experiment capable of giving insight into one of the universe’s greatest mysteries: could there be more dimensions than we know about?
So, out-of-control promotional efforts for ALICE are at the bottom of this one.
JohnEB
Compared to AMS-02, the Multiverse is like 'Alice in Wonderland':
Cosmological Interpretations of Quantum Mechanics
http://www.math.columbia.edu/~woit/wordpress/?p=3723
JohnEB
A large fraction of the physics community has abandoned trying to explain our world as unique, as mathematically the only possible world. Right now the multiverse is the only game in town. Not everybody is working on it, but there is no coherent, sharp argument against it.
In 1974 I had an interesting experience about how scientific consensus forms. People were working on the as yet untested theory of hadrons [subatomic particles such as protons and neutrons], which is called quantum chromodynamics, or QCD. At a physics conference I asked, “You people, I want to know your belief about the probability that QCD is the right theory of hadrons.” I took a poll. Nobody gave it more than 5 percent. Then I asked, “What are you working on?” QCD, QCD, QCD. They were all working on QCD. The consensus was formed, but for some odd reason, people wanted to show their skeptical side. They wanted to be hard-nosed. There’s an element of the same thing around the multiverse idea. A lot of physicists don’t want to simply fess up and say, “Look, we don’t know any other alternative.”
JohnEB
The following is from Leonard Susskind's SciAm article and it is a startling admission of the failure of the current QM based paradigm:
"We may never be able to grasp that reality. The universe and its ingredients may be impossible to describe unambiguously."
The fact of the matter is that our ONE UNIQUE 4-SPACE UNIVERSE is totally unambiguous and coherent when viewed with CLASSICAL PHYSICS.
JohnEB
"Susskind worries that reality might be beyond our limited capacity to visualize it. He is not the first to express such a concern. In the 1920s and 1930s the founders of quantum mechanics split into realist and anti-realist camps. Albert Einstein and other realists held that the whole point of physics is to come up with some mental picture, however imperfect, of what objective reality is. Antirealists such as Niels Bohr said those mental images are fraught with peril; scientists should confine themselves to making and testing empirical predictions. Susskind thinks the contradictions and paradoxes of modern physics vindicate Bohr's wariness."
and
"A large fraction of the physics community has abandoned trying to explain our world as unique, as mathematically the only possible world. Right now the multiverse is the only game in town. Not everybody is working on it, but there is no coherent, sharp argument against it."
Susskind doesn't seem to realize that the "contradictions and paradoxes" were CAUSED by Bohr. Here is Susskind's SciAm article:
IN BRIEF
WHO
LEONARD SUSSKIND
VOCATION I AVOCATION
Theoretical physicist, known especially for pioneering string theory, black hole physics and the multiverse
WHERE
Stanford University
RESEARCH FOCUS
What is the deep nature of physical reality?
BIG PICTURE
We may never be able to grasp that reality. The universe and its ingredients may be impossible to describe unambiguously.
____________________________________
COSMOLOGY
Bad Boy of Physics
Leonard Susskind rebelled as a teen and never stopped. Today he insists that reality may forever be beyond reach of our understanding
Interview by Peter Byrne
STANFORD UNIVERSITY PHYSICIST LEONARD SUSSKIND REVELS IN DISCOVERING IDEAS that transform the status quo in physics. Forty years ago he co-founded string theory, which was initially derided but eventually became the leading candidate for a unified theory of nature. For years he disputed Stephen Hawking's conjecture that black holes do not merely swallow objects but grind them up beyond recovery, in violation of quantum mechanics. Hawking eventually conceded. And he helped to develop the modern conception of parallel universes, based on what he dubbed the "landscape" of string theory. It spoiled physicists' dream to explain the universe as the unique outcome of basic principles.
Physicists seeking to understand the deepest levels of reality now work within a frame-work largely of Susskind's making. But a funny thing has happened along the way. Susskind now wonders whether physicists can understand reality.
Susskind worries that reality might be beyond our limited capacity to visualize it. He is not the first to express such a concern. In the 1920s and 1930s the founders of quantum mechanics split into realist and anti-realist camps. Albert Einstein and other realists held that the whole point of physics is to come up with some mental picture, however imperfect, of what objective reality is. Antirealists such as Niels Bohr said those mental images are fraught with peril; scientists should confine themselves to making and testing empirical predictions. Susskind thinks the contradictions and paradoxes of modern physics vindicate Bohr's wariness.
One thing that led Susskind to this conclusion is his principle of black hole complementarity, which holds that there is an inherent ambiguity in the fate of objects that fall into a black hole. From the point of view of the falling object itself, it passes without incident through the hole's perimeter, or horizon, and is destroyed when it reaches the hole's center, or singularity. But from the vantage point of an external observer, the falling object is incinerated at the horizon. So what really happens? The question, according to the principle of black hole complementarity, is meaningless: both interpretations are valid.
A related idea favoring antirealism is the holographic principle that Susskind and Nobel laureate Gerard 't Hooft of Utrecht University formulated in the mid-1990s. It holds that what happens in any volume of spacetime can be explained by what happens on its boundary. Although we usually think of objects as zipping around three-dimensional space, we can equally well think of them as flattened blobs sliding across a two-dimensional surface. So which is the true reality: the boundary or the interior? The theory does not say. Reality, in this holographic conjecture, is perspectival.
Hoping to better understand how the tension between hard evidence and unproved conjecture works at the frontier of physics, we asked Susskind to explain how his ideas have evolved.
SCIENTIFIC AMERICAN: How did the son of a Bronx plumber end up questioning the nature of reality?
LEONARD SUSSKIND: I was a bad high school student. I was very good in mathematics, but I was a bad boy, and I got in trouble a lot. The effect of that is I wasn't allowed to take regular physics. I was told I had to take automotive physics. But then in college, which was an engineering school, I took my first physics course. I was just so much better than anybody else, including the professor. And fortunately, it was not a source of contention between us that I could do the things he couldn't. But then I was actually told by one of the engineering professors that he didn't think I was cut out to be an engineer, which was correct. I asked him, "What should I do?" He said, "Well, you're exceptionally smart. You should become a scientist."
SCIENTIFIC AMERICAN: Did you take any philosophy courses?
LEONARD SUSSKIND: Yeah, I did in college. I was quite fascinated by some of the concepts. My interest in it lapsed when I really got hooked by physics.
SCIENTIFIC AMERICAN: Are there any philosophers of science whom you like?
I'm one of the few physicists I know who likes Thomas Kuhn. He was partly a historian of science, partly a sociologist. He got the basic idea right of what happens when the scientific paradigm shifts. A radical change of perspective suddenly occurs. Wholly new ideas, concepts, abstractions and pictures become relevant. Relativity was a big paradigm shift. Quantum mechanics was a big paradigm shift. So we keep on inventing new realisms. They never completely replace the old ideas, but they do largely replace them with concepts that work better, that describe nature better, that are often very unfamiliar, that make people question what is meant by "reality." Then the next thing comes along and turns that on its head. And we are always surprised that the old ways of thinking, the wiring that we have or the mathematical wiring that we may have created, simply fail us.
SCIENTIFIC AMERICAN: In the midst of all this remodeling, is there room for such a thing as an objective reality?
LEONARD SUSSKIND: Every physicist must have some sense that there are objective things in the world and that it's our job to go and find out what those objective things are. I don't think you could do that without having a sense that there is an objective reality. The evidence for objectivity is that experiments are reproducible. If you kick a rock once, you'll hurt your toe. If you kick a rock twice, you'll hurt your toe twice. Do the same experiment over and over with a rock, and you'll reproduce the same effect.
That said, physicists almost never talk about reality. The problem is that what people tend to mean by "reality" has more to do with biology and evolution and with our hardwiring and our neural architecture than it has to do with physics itself. We're prisoners of our own neural architecture. We can visualize some things. We can't visualize other things.
Einstein's abstract, four-dimensional geometry was hard to concretely visualize. It became visualizable through mathematical relations. When relativity suddenly appeared, it must have seemed to many people: What happened to "real" time? What happened to "real" space? It just got mixed up into this funny thing, but there were rules. The point was there were clear and precise mathematical rules that had been abstracted out of it, and these survived, and the old notions of reality went away.
So I say, let's get rid of the word "reality." Let's have our whole discussion without the word "reality." It gets in the way. It conjures up things that are rarely helpful. The word "reproducible" is a more useful word than "real."
SCIENTIFIC AMERICAN: What about quantum mechanics? According to that theory, kicking the same rock the same way can actually give different results.
LEONARD SUSSKIND: That's the big one, isn't it? There are two things that were discovered in quantum mechanics that upset our classical sense of reality. One was entanglement. What entanglement said was something very bizarre: that you can know everything there is to know about a composite system and yet not know everything about the individual constituents. It is a good example of how we're simply not biologically equipped for abstraction and how our sense of reality gets upset [see "Living in a Quantum World," by Vlatko Vedral; SCIENTIFIC AMERICAN, June].
The other thing that really hit hard on the idea of classical reality was the Heisenberg uncertainty principle. If you try to describe an object as having both a position and a momentum, you'll run into trouble. You should think of it as having a position or a momentum. Don't try to do both.
SCIENTIFIC AMERICAN: This is what physicists mean by "complementary"?
LEONARD SUSSKIND: Exactly. It turns out that the mathematics of the event horizon of a black hole is very similar to the uncertainty principle. Again, it's a question of "or" versus "and" At a completely classical level something falls into a black hole, something doesn't fall into a black hole, whatever. There are things outside the black hole, and there are things inside the black hole. What we learned is that's the wrong way to think. Don't try to think of things happening outside the horizon and things happening inside the horizon. They're redundant descriptions of the same thing. You describe it one way, or you describe it the other way. This means we have to give up the old idea that a bit of information is in a definite place [see "Black Holes and the Information Paradox;' by Leonard Susskind; SCIENTIFIC AMERICAN, April 1997].
SCIENTIFIC AMERICAN: If I get you correctly, the holographic principle extends the complementary model of a black hole to the universe.
LEONARD SUSSKIND: Yes. Suppose we want to describe some system with enormous precision. To probe with great precision, you need high energy. What's eventually going to happen as you try to get more and more precise is you're going to start creating black holes. The information in a black hole is all on the surface of the black hole. So the more and more refined description you make of a system, you will wind up placing the information at a boundary.
There are two descriptions of reality: either reality is the bulk of spacetime surrounded by the boundary, or reality is the area of the boundary. So which description is real? There is no way to answer that. We can either think of an object as an object in the bulk space or think of it as a complicated, scrambled collection of information on the boundary that surrounds it. Not both. One or the other. It's an incredibly scrambled mapping of one thing to the other thing.
SCIENTIFIC AMERICAN: The original goal of string theory was to provide a unique explanation of reality. Now it gives us multiple universes. What happened?
LEONARD SUSSKIND: A large fraction of the physics community has abandoned trying to explain our world as unique, as mathematically the only possible world. Right now the multi-verse is the only game in town. Not everybody is working on it, but there is no coherent, sharp argument against it.
In 1974 I had an interesting experience about how scientific consensus forms. People were working on the as yet untested theory of hadrons [subatomic particles such as protons and neutrons], which is called quantum chromodynamics, or QCD. At a physics conference I asked, "You people, I want to know your belief about the probability that QCD is the right theory of hadrons." I took a poll. Nobody gave it more than 5 percent. Then I asked, "What are you working on?" QCD, QCD, QCD. They were all working on QCD. The consensus was formed, but for some odd reason, people wanted to show their skeptical side. They wanted to be hard-nosed. There's an element of the same thing around the multiverse idea. A lot of physicists don't want to simply fess up and say, "Look, we don't know any other alternative."
The universe is very, very big. Empirically we know it's at least 1,000 times bigger in volume than the portion that we can ever see. The success of the concept of cosmic inflation opens the possibility that the universe is varied on big-enough scales. String theory provides Tinkertoy elements that can be put together in an enormous number of ways. So there's no point in looking for explanations of why our piece of the world is exactly the way it is because there are other pieces of the world that are not exactly the same as ours. There can't be a universal explanation of everything that it is any more than there can be a theorem that says the average temperature of a planet is 60 degrees Fahrenheit. Anyone who tried to make a calculation to prove that planets have a temperature of 60 degrees would be foolish because there are lots of planets out there that don't have that temperature.
But nobody knows the underlying rules for multiverses. It's a picture. Nobody knows how to use this predictively. This process of eternal inflation just produces bubble after bubble after bubble and produces any number of them of every kind. So that means that the probability for one versus the other is infinity over infinity. We would like to have a probability distribution that would say one is more probable than the other and then make a prediction. So we've gone from what looks like a very compelling picture on the one hand to absurdly trying to measure an infinity of probabilities. If it's going to go down, it's going to go down because of that [see "The Inflation Debate," by Paul J. Steinhardt; SCIENTIFIC AMERICAN, April].
SCIENTIFIC AMERICAN: Is it possible to do theoretical physics and not have philosophical thoughts?
LEONARD SUSSKIND: Most great physicists have had a fairly strong philosophical side. My friend Dick Feynman hated philosophy and hated philosophers, but I knew him well, and there was a deep philosophical side to him. The problems that you choose to think about are conditioned by your philosophical predispositions. But I also have a strong sense that surprises happen and put your philosophical prejudices on their head. People have the idea that there are cut-and-dried rules of science: you do experiments, you get results, you interpret them; in the end, you have something. But the actual process of science is as human and as chaotic and as contentious as anything else.
____________________________________
Peter Byme is author of "The Many Worlds of Hugh Everett" in the December 2007 issue of Scientific American, which developed into the book The Many Worlds of Hugh Everett III: Multiple Universes, Mutual Assured Destruction and the Meltdown of a Nuclear Family (Oxford University Press, 2010).
____________________________________
MORE TO EXPLORE
Farewell to Reason. Paul Feyerabend. Verso,1988.
The Cosmic Landscape: String Theory and the Illusion of Intelligent Design. Leonard Susskind. Back Bay Books, 2006.
The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics. Leonard Susskind. Back Bay Books, 2009.
ScientificAmerican Online
Do you think we can grasp reality? Join the discussion at ScientificAmerican.com/jul2011/susskind
JohnEB
"Susskind worries that reality might be beyond our limited capacity to visualize it. He is not the first to express such a concern. In the 1920s and 1930s the founders of quantum mechanics split into realist and anti-realist camps. Albert Einstein and other realists held that the whole point of physics is to come up with some mental picture, however imperfect, of what objective reality is. Antirealists such as Niels Bohr said those mental images are fraught with peril; scientists should confine themselves to making and testing empirical predictions. Susskind thinks the contradictions and paradoxes of modern physics vindicate Bohr's wariness."
But it was Niels Bohr who put the "contradictions and paradoxes" into physics. Before her death in 2004, Mara Beller was one of the world's greatest experts on Bohr. She wrote a book titled "Quantum Dialogue: the making of a revolution" that shows the massively confused thinking of Bohr (and others).
Mara Beller, in chapter 1 of "Quantum Dialogue: the making of a revolution", explains her incredible book:
Note: AHQP = Archive for the History of Quantum Physics
Mara Beller - http://mothersday2005.org/MaraBeller.htm
CHAPTER 1
Novelty and Dogma
I believe that to solve any problem that has never been solved before, you have to leave the door to the unknown ajar. You have to permit the possibility that you do not have it exactly right. - Richard Feynman 1998, 26-27
A dialogue can be among any number of people, not just two. Even one person can leave a sense of dialogue within himself, if the spirit of the dialogue is present. The picture or image that this derivation suggests is of a stream of meaning flowing among and through us and between us. - David Bohm 1996, 6
Dialogical Creativity
"Science is rooted in conversations." These words were written by Werner Heisenberg, a great physicist of the twentieth century and a founder of the quantum revolution (1971, vii). How exactly is science rooted in conversations? And how did an extended conversation among scientists result in the quantum revolution? These are the major issues of this book.
Science is also rooted in doubt and uncertainty. "And it is of paramount importance, in order to make progress, that we recognize this ignorance and this doubt.... what we call scientific knowledge today is a body of statements of varying degrees of certainty. Some of them one most unsure; some of them are nearly sure; but none is absolutely certain. Scientists are used to this. "These words belong to another great scientist of the twentieth century, the quantum physicist Richard Feynman (1998, 3, 27). "We know that it is consistent to be able to live and not know," continued Feynman: "I always live without knowing. That is easy. How you get to know is what I want to know" (1998, 27-28).
How is the presence of uncertainty and doubt built into scientific theorizing at its most basic level? How do scientists live without knowing? And how do they get to know? I argue throughout this book that the question of how scientists live in uncertainty, the question of how they create their knowlege, and the question of how science is rooted in conversations are, in fact, one and the same. I elaborate an answer to this question for the case of the quantum revolution.
This book examines the fluid, open-ended, and often ambiguous process of scientific creativity, treating it as being rooted in, and perhaps indistinguishable from, an ongoing scientific conversation about theories, experiments, and instruments. I address the central issue of how theoretical knowledge is achieved, articulated, and legitimated. I also deal with another major issue: the conceptual and emotional turmoil created by attempts to interpret the potent quantum formalism.
I describe and analyze the intricate flux of dialogues among quantum physicists—dialogues that resulted in scientific breakthroughs of unprecedented scope and in a radical quantum philosophy. These dialogues underlay both the open-minded foundational research and the erection of the orthodox interpretation of quantum physics: the Copenhagen interpretation. Tracing the web of dialogues reveals a story about the workings of free scientific imagination and about the consolidation of scientific dogma.
One of the major puzzles in the history of quantum physics is the existence of numerous contradictions in the Copenhagen interpretation. What is the source of these contradictions? And why are they impotent to detract from the spectacular power of quantum physics? A large part of this book constitutes an answer to these questions.
The analysis and the narrative in this work are permeated with the notion of communicability. I argue that dialogue underlies scientific creativity and that the emergence of scientific novelty cannot be understood without scrutinizing the ways scientists respond to and address each other. This book analyzes the complex, multidirectional dialogical nature of scientific theorizing (part 1) and the strategies by which this dialogical flux is flattened into a monological narrative (part 2).
This book is based on a close study of primary sources—correspondence between the participants, notebooks, original papers. Historians of quantum physics are fortunate to have access to the Archive for the History of Quantum Physics (AHQP), where correspondence and original manuscripts are collected. Thus I had the opportunity to study in detail the intricate paths along which ideas emerged as the founders of quantum physics addressed each other in their letters. I gradually realized that dialogical addressivity permeates not only scientific correspondence but also published scientific papers, and more generally, I came to the realization that scientific creativity is fundamentally dialogical in the sense elaborated in this book.
The dialogical approach to the history of science is "bottom up"—it searches for the most basic details in order to conceptualize the process through which knowlege grows. A dialogical analysis, by closely following ideas as they gradually form in numerous dialogues between scientists, deals primarily with the cognitive content of science. It requires painstaking attention lo every nuance of the primary sources. In fact, it demands closer attention to the minutia of scientific reasoning than the older, "internal" (evolutionary) history of science and than "rational reconstruction" accounts.
My exposition differs from the usual accounts by describing the flux of ideas without presupposing underlying conceptual frameworks, schemes, or paradigms. In fact, these notions, whether on a global or a more restricted scale, are not easily compatible with the dynamics of ceaseless scientific change. Living in doubt and uncertainty is not compatible with the accepted historiographical notions of "beliefs" and "commitments." Nor are Kuhnian and post-Kuhnian "agreement" and "consensus" suitable to describe the dynamics of living without knowing. Doubt and uncertainty should be incorporated into the basic terms used to describe the growth of knowledge. From the dialogical perspective, it is "creative disagreement"—with oneself (doubt) or with others (lack of consensus)—that plays the crucial role in the advance of knowledge. The privilege to be unsure, to theorize freely, to explore different options at the same time, is incorporated into the notion of creative dialogical flux. I will elaborate on the philosophical, historiographical, and wiological advantages of such a dialogical approach in the concluding chapter of the book.
This book simultaneously revises the story of the quantum revolution and outlines a tentative program for a dialogical historiography of science. My work began with a revision of the history of matrix mechanics (Beller 1983) and progressed to revisions of other major episodes in the history of quantum physics, such as the emergence of Born's probabilistic interpretation (Beller 1990) and the birth of Bohr's complementarity (Beller 1992a). It gradually became clear to me that the need for ongoing revision has a fundamental historiographical cause. This cause is intimately connected with the complex dialogical nature oI thought and with the strategies used to flatten it into linear monological narratives.
I begin my description of the quantum revolution with an analysis of matrix theory in flux (chapter 2), arguing against the received story of the existence of two totally distinct theoretical frameworks—the matrix and the wave theoretical. In chapters 2 and 3 I describe how a strong distinction between the matrix and wave approaches crystallized as the end result of a conceptually fascinating and emotionally intense confrontation among quantum physicists. In the fruitful ambiguity of the newly created knowledge, there was no place for strong "beliefs" in indeterminism or "commitments" to positivism. Nor is it correct to see the matrix theoreticians as committed to a particle ontology, as opposed to Schroedinger's wave approach. We will see that Heisenberg's, Born's, and Pauli's pronouncements on foundational and interpretive issues were all fluid and uncommitted. Similarly, I will argue, Born's probabilistic interpretation did not stem from his "belief" in particles and "commitment" to indeterminism, as the received history of quantum physics implies (chapter 2).
The flux of ideas in the emergence of matrix theory and in the formation of Born's probabilistic interpretation demonstrates the primacy of mathematical tools over fundamental interpretive ideas. These tools can be borrowed, developed, and successfully applied without a clear-cut stand on basic interpretive issues. It was on the efficiency of the mathematical tools, and not on metaphysical "paradigmatic" issues, that there was agreement in the community of quantum physicists. And on this point the orthodox and the opposition were united; agreement on the potency of these tools prevented scientific practice from disintegrating, be the philosophical disagreements as large as they may.
Theoretical tools (equations, methods of solution, and approximations) have their own momentum, while philosophical ideas are adapted aposteriori (chapter 3). The fact that theoretical tools have some autonomy allows scientists to theorize without taking an interpretive stand. The English physicist Charles Darwin wrote to Niels Bohr: "It is apart of my doctrine that the details of a physicist's philosophy do not matter much" (Darwin to Bohr, December 1926, AHQP). This belief in the primacy of mathematical tools was especially strong in Gottingen, inspiring Born's and Heisenberg's search for a new quantum theory. "Mathematics knows better than our intuition" was Born's motto (interview with Born, AHQP).
The neutrality of a mathematical formalism with respect to possible interpretations has another far-reaching consequence: scientists may give all authority in interpretive matters to a few leaders, whose philosophy they are willing to accept. Such humble resignation from philosophical exploration is often nothing but a convenient choice not to deal with confusing and perhaps irrelevant matters.1 It is this attitude that creates room for an authoritative and privileged interpretation, such as the Copenhagen orthodoxy.
The dispensability of paradigmatic interpretive agreement also explains what Steven Weinberg, not without a touch of disdain, called "the unreasonable ineffectiveness of philosophy" in scientific practice (Weinberg 1992, 169). The application of theoretical tools involves flexibility and conceptual opportunism—no system of philosophical preconceptions can survive in such a fluid environment (chapter 3). Philosophical "influence" indeed cannot determine a scientific knowledge claim. Yet philosophy can be suggestive in a limited way, as inspiration along some path in the dialogical web of creativity. In chapter 4 I argue that the ideas of the German philosopher Fichte were important for Heisenberg's treatment of measurement in the uncertainty paper. This treatment, or "reduction of wave packets," became the source of the major conceptual hurdle of quantum physics—the notorious measurement problem.
Scientific creativity as a dialogical flux is exemplified by the emergence of Heisenberg's uncertainty principle, which I describe in chapter 4. We can see how Heisenberg theorized without a clearly delineated conceptual framework, without "beliefs" and "commitments." Instead, we observe the indispensability of open-ended disagreement and ongoing doubt for achieving a theoretical breakthrough. The existing historiography presents one-dimensional pictures: Jammer described the uncertainty formula as emerging naturally from the imperative to adapt the new mathematical formalism to the possibilities of measurement (Jammer 1966).2 The perspective offered by social historians similarly focuses only on a single aspect: a predilection for acausality among quantum physicists determined their efforts to interpret the new quantum mechanics along probabilistic lines (Forman 1971; Feuer 1963).
I describe Heisenberg's discovery of the uncertainty relations as a multidirectional process, which took place in a communicative network with many interlocutors, including such prominent names as Einstein, Schrodinger, Pauli, Dirac, Bohr, Born, and Jordan. Less known, yet no less important for Heisenberg's discovery, are the names Campbell, Duane, Zernike, and Sentfleben. In chapter 4 we follow the process of discovery and observe how fragments of insight gradually emerge, how ideas clash, change, disappear, or survive. The gradual forming of a preference, of choosing one intellectual option over another, of defining what the options are—all occur in a coalescence of insights, arrived at in different dialogues and at different times.
Heisenberg's discovery of the uncertainty principle was a complex process of disagreements, qualifications, elaborations, supplementations, and borrowings. He had no foundational commitments, even on such basic issues as discontinuity and indeterminism; rather his preference for discontinuity and acausality took shape gradually in many fruitful dialogues. Though immersed in interpretive efforts, Heisenberg was uncertain even about what the word "interpretation' means (chapter 5). Disagreements with interlocutors—a militant one with Schrodinger, a subdued yet painful one with Bohr, a restrained one with Jordan and Born—were triggers for Heisenberg's reasoning. Agreement too played a part, in the form of Heisenberg's partial, often only temporary, acceptance of the ideas of others, especially those of Dirac, Campbell, and Duane. Heisenberg's case demonstrates how genuine novelty emerges through dialogical creativity. Dialogical creativity is not an instantaneous "eureka" experience; it is rather a patiently sustained process of responsiveness and addressivity to the ideas of others, both actual and imagined.
One might expect that in a published scientific paper, all previous cognitive tensions would be resolved and a coherent unequivocal message expressed. Yet an analysis of Heisenberg's uncertainty paper finds clear traces of past struggles, conflicting voices on the same issue, and unresolved tensions (chapter 5). The polyphony of the creative act echoes in the paper itself. Similarly, at least two conflicting, in fact incompatible, voices can be heard in Bohr's response to Einstein-PodolskyRosen's challenge to the Copenhagen interpretation (chapter 7).
One might object, then, that such unresolved tensions perhaps characterize scientific papers written during revolutionary upheavals, but when things settle down and the revolution is over, a new paradigm triumphs and the foundational debate is closed. There is, the argument might continue, at the present time only one correct, agreed-upon meaning of the uncertainty principle and of wave-particle complementarity. But is there? One can find a "correct' meaning in textbooks, or in some philosophical writings on the quantum theory—in short, in the graveyards of science. On the research frontier nothing is immune to reappraisal—be it uncertainty, complementarity, or even the determinism of classical physics (chaos theories) and the indeterminism of quantum physics (Bohm's theory and Bohmian alternatives, such as Darr, Goldstein, and Zanghi 1992a, 1992b, 1996). Numerous meanings of the uncertainty formulas are proposed in current research papers (Home and Whitaker 1992; Valentini 1996). The same is true of Born's probabilistic interpretation and his solution of the collision problem (Daumer 1996). Similarly, there is no agreement about the meaning or even the validity of wave-particle complementarity (chapter 11). Even such basic formulas as Schrodinger's equation are open to modification (Ghirardi, Rimini and Weber 1986). The flux of creative research cannot be forced into an unequivocal, final conceptual scheme.
The description of Heisenberg's creative theorizing calls fora reevaluation of the role of "lesser" scientists in the growth of scientific knowledge (chapter 4). We will see that some of the most important insights pertaining to Heisenberg's formulation of the uncertainty principle belonged to scientists whose names do not appear in the received history of quantum mechanics—Sentfleben and Campbell. The issue is not one of priority, even though the distribution of credit is often unfair. Neither Campbell nor Sentfleben, from their positions in the communicative web, could have accomplished exactly what Heisenberg did. Yet neither could Heisenberg have developed his ideas had he not been responding creatively to Campbell's and Sentfleben's insights. Heisenberg's discovery is organically linked to the ideas of the "lesser" scientists. From the epistemological point of view, the notion of a scientific collective is intrinsic to the dialogical approach.
We can reevaluate the prevalent idea of a lonely creative individual, and of solitude as a precondition of creativity. Conventional opinion holds that "the spark of creativity burns most brightly in a mind working in solitude" (Storr 1988). When Heisenberg "fabricated" the new quantum mechanics (his expression, van der Waerden 1967, 15), he was isolated on the island of Helgoland. After their stormy debates on the interpretation of quantum mechanics in the fateful year of 1926, Heisenberg and Bohr needed to get away from each other. Separated, Heisenberg wrote the essentials of his uncertainty paper and Bohr elaborated his complementarity. Yet solitude does not imply cognitive isolation. If Heisenberg needed time away from Bohr, it was in order to strike a proper, uncoerced balance in his own communicative network of cognitive responses (chapters 4 and 6).
The dialogical perspective provides a new way to read published scientific texts. Concealed doubt becomes visible, and a paper becomes a fascinating scientific and human document, resounding with conflicting inner voices, populated by many "virtual" interlocutors (chapters 5 and 6). We will see in chapter 5 that Heisenberg's uncertainty paper is permeated with doubts and indecision on such central issues as indeterminism, realism, visualizability, and the status of classical concepts in the quantum domain. A comparison of the (seemingly) confident published paper with the almost identical draft (in a letter to Pauli) filled with doubt regarding all the basic interpretive issues reveals how misleading it is to ascribe any "beliefs" or "commitments" to Heisenberg. My analysis applies to the issues of acausality and positivism that according to the accepted history of quantum physics, are the two central pillars of Heisenberg's uncertainty paper.
My examination of Heisenberg's uncertainty paper reveals the argumentative strategies by which interpretive freedom is concealed, and the illusion created that the orthodox interpretation is "inevitable" the issue to which the bulk of part 2 of this book is devoted. Tension between the conceptual freedom experienced by the Copenhagen physicists and their desire to advocate one privileged interpretation is one of the major sources, I argue, of the numerous contradictions and inconsistencies in the Copenhagen interpretation of quantum physics.
Yet the dialogical analysis of a published paper does more than reveal the inconclusive nature of scientific theorizing. Such an analysis can also substantially modify our understanding of the content of a published paper. A dialogical reading is a potent tool for deciphering especially obscure and opaque texts. Chapter 6 is devoted to a dialogical analysis of Bohr's Como lecture, in which Bohr announced his principle of complementarity.
The Como lecture is considered one of the most incomprehensible texts in twentieth-century physics. My dialogical reading constitutes a basic revision of the accepted reading of this text, by presenting the Como lecture, not as the unfolding of a single argumentative structure, but as the juxtaposition of several simultaneously coexisting arguments, addressed to different quantum theorists about different issues. A dialogical analysis reveals that the central message of Bohr's paper was not the resolution of wave-particle duality by the complementarity principle, as usually assumed, but rather Bohr's extensive defense of his concepts of stationary states and discontinuous energy changes (quantum jumps) against Schrodinger's competitive endeavors.
A dialogical reading allows the reevaluation of some central events in the history of quantum physics, such as the famous clash between Heisenberg and Bohr over the uncertainty paper. This reevaluation merges "motives" and "reasons," connecting "conceptual" and "anecdotal" history into one meaningful, comprehensible story. This story throws new light on Einstein's and Schrodinger's initial reservations about the early interpretive attempts of Bohr and Heisenberg—reservations due to difficulties and contradictions in the emerging Copenhagen interpretation rather than to Einstein's and Schrodinger's "conservatism."
My analysis of the initial efforts of Bohr and Heisenberg to unveil the physical meaning of the quantum formalism demonstrates the vast freedom of interpretive endeavors. Yet this freedom is not arbitrary. We will see the great extent to which the formulations of Born's probabilistic interpretation, Heisenberg's uncertainty, and Bohr's complementarity were woven around detailed analyses of experimental situations (a fact not sufficiently apparent in the existing histories of quantum
mechanics). These first attempts at interpretation revolved around pivotal experiments by Franck and. Hertz (1913), Bothe and Geiger (1925a, I925b), and Compton (1923), as well as around experimental work by the lesser known Moll and Burger (1925). There is a crucial difference between evidence-based interpretive efforts and closed dogmatic systems, although the first can degenerate into the second, as with Bohr's, Heisenberg's, and Pauli's later philosophical writings, which came close to preaching a rigid ideology (part 2).
Chapter 7 (the last chapter of part 1) analyzes the process by which sincere and open-minded, though interest-laden, interpretive attempts hardened into an ideological stand intended to protect quantum theory from challenge and criticism. This chapter, partly based on my paper with Arthur Fine (Beller and Fine 1994), is devoted to an analysis of Bohr's reply to the Einstein-Podolsky-Rosen (EPR) challenge. This chapter is located, so to speak, on a "cut" between parts 1 and 2 and can be moved from the end of part 1 to the beginning of part 2 without distorting the argument of my book. This means that dialogical emergence and rhetorical consolidation are not completely distinct processes. Consolidation was already present in the initial interpretive attempts of the Gottingen-Copenhagen camp, and limited dialogical responsiveness accompanied later elaborations of the Copenhagen interpretation. Still, chapter 7 reveals a vast difference between Bohr's reasoning in his Como lecture and his reply to the EPR challenge. My analysis uncovers a transition from legitimate, though often confused, arguments for the consistency of quantum theory, to argumentative strategies promoting the inevitability of the orthodox stand. This transition naturally contains both old insights and new conquests, and it is not surprising that two different, often incompatible voices permeate Bohr's response to EPR. The voices correspond to Bohr's two different answers to EPR: one relying on the concept of disturbance, the other dispensing with it. In contrast to the received story, which, following the orthodox narrative, affirms Bohr's "victory" in this confrontation, the analysis in chapter 7 reveals that none of Bohr's answers can be considered satisfactory.
I further analyze Bohr's about-face on the central interpretive issues—the problems of reality, acausality, and measurement—raised by the EPR challenge. I extend this analysis in chapter 8, arguing that the Copenhagen interpretation is in fact a compilation of various philosophical strands, given a public presentation that often hid shifting disagreements between its main architects. The Copenhagen interpretation of quantum physics did not originate from a disinterested search for philosophical foundations—from the very beginning it was constructed in the heat of a fierce confrontation. As the nature of the opposition's challenge changed, so did the local responses of the orthodox. It is not surprising therefore that what is called the Copenhagen interpretation is so riddled with vacillations, about-faces, and inconsistencies (chapter 8). The orthodox aimed to present a united front to the opposition, concealing the substantial differences of approach among its members. I analyze some of the strategies by which such differences were suppressed by relying on a distinction between what scientists "must not" and what scientists "need not" do (chapter 8).
Rhetorical Strategies
How does one construct from among these numerous contradictory arguments a narrative that seems to irrevocably imply the pillars of the Copenhagen dogma? How does one reconstruct history so that the central tenets of the Copenhagen interpretation, such as indeterminism and the impossibility of an objective, observer-independent description, seem not merely highly persuasive but outright inevitable?
In part 2 of the book I contend that all the Copenhagen arguments of "inevitability" are in fact fallacious—they rely either on circular reasoning or on highly appealing but misleading metaphorical imagery (chapters 9 and 12). They are strongly supported by falsified history, which renders certain developments as dictated by the inner logic of the development of ideas (chapters 10 and 11). Discrediting the opposition and caricaturing the opposition's criticism of the Copenhagen stand is yet another potent rhetorical device to strengthen the orthodoxy (chapter 13). These chapters reveal how fruitfully ambiguous and wisely uncommitted interpretive efforts are concealed by rigid reconstructed stories. Complex, many-voiced, multidirectional theorizing is thus conflated into an orthodox, one-dimensional narrative.
"History is written by winners"—this cliche finds powerful confirmation in the case of the quantum revolution. We have numerous reminiscences by the winners—Bohr, Heisenberg, Born, Jordan, and others. There are hardly any reminiscences by Einstein and Schrodinger about the same events—we do not hear the opposition's side of the story. In the quantum revolution, the orthodox constructed the narrative, eliminating dissident voices and largely suppressing the crucial contributions of the opposition and of lesser scientists. In part 2 I describe the strategies by which the past is manipulated in order to make the winners look naturally right. By such a reconstruction of the past, the cornerstones of the Copenhagen interpretation—quantum jumps, the impossibility of causal space-time models, indeterminism, and wave-particle complementarity—were even more firmly entrenched (chapters 10 and 11).
I describe how the opposition's stand is delegitimated and trivialized. In their fabricated narratives, the winners construct the profile of the opposition the description of past science concurrently. The ideas of the opposition are projected as most characteristic of the overthrown past, and thus the opposition naturally appears reactionary—disposing of the old and discrediting the opposition are, in fact, one and the same process. As a result, not only is the opposition caricatured but past science is trivialized. Hero worship of the winners further delegitimates the opposition and prevents criticism of the orthodox stand (chapter 13).
Historians of science rarely question the narrative of the winners: Jammer (1966) and Mehra and Rechenberg (1982), for example, closely follow the orthodox line. Jammer, in the preface to his classic book, quotes Einstein's penetrating warning not to rely on the recollections of the participants: "To the discoverer in this field the products of his imagination appear so necessary and natural that he regards them .. . not as creations of thought but as given realities." Yet Jammer "felt entitled to ignore this warning," and he "discussed the subject with quite a number of prominent physicists who contributed decisively to the development of the theory" (1966, viii). Pais's recent book (1991) is written exclusively from Bohr's perspective. This is not to say that these accounts do not use primary sources; in fact, Jammer, Mehra and Rechenberg, and Pais use the sources extensively. Yet what they see in those sources, and more important, what they ignore therein, is dictated by the overwhelming authority of the winner's perspective. A notable exception in this respect is Cushing's (1994b) important book about Bohmian mechanics as a viable alternative to the Copenhagen hegemony.
The "naturalness" and even "finality" of the orthodox point of view is advanced through powerful strategies of persuasion, which I refer to as the "rhetoric of inevitability" (chapter 9). The ingenious technique was to disguise arguments of consistency as those of inevitability. What is taken as objective quantum philosophy (and "inevitable" at that) turns out to be ideology—where by ideology I mean a system of assertions that imply, from within, their own justice, truth, and self-evidence. With respect to the entrenchment of the Copenhagen dogma, epistemology and sociology often merge—considerations of epistemic warrant and of social legitimacy are, at times, indistinguishable. The foundations of the Copenhagen paradigm were chosen and elaborated indirect contrast to the opposition's stand. The construction of the winner's narrative and philosophical arguments of inevitability serve the same end.
In chapter 11, I contrast the dramatic narrative of the "inevitability" of wave-particle complementarity with the freedom and plurality of theoretical approaches to the wave-particle issue. The "logical" arguments for the inevitability of wave-particle complementarity are built on Bohr's peculiar doctrine of the "indispensability" of classical concepts-a doctrine that few theorists, including Bohr's closest collaborators, found persuasive (chapter 8). 'I'hutie mathematical physicists who gave up this rigid doctrine suggested a rich variety of solutions to the wave-particle dilemma (chapter 11). The discussion in chapter 11 demonstrates that there is a fundamental ambiguity, and therefore a lack of "paradigmatic" agreement, concerning even such basic physical terms as "wave" and "particle" (scientists hold different opinions, each from his own theoretical viewpoint, of what are to be considered necessary or sufficient attributes of those terms). Despite this lack of clarity, or perhaps because of it, conversation on this issue continued, and new theoretical breakthroughs occurred.
The same freedom that created room for open-ended creative theorizing allowed the construction of a variety of ad hoc strategies for the legitimation of the Copenhagen stand. The proliferation of such ad hoc moves is yet another source of the inconsistencies that still plague the Copenhagen interpretation today. Both Heisenberg and Pauli supported Bohr's philosophy of wave-particle complementarity in public, while often expressing, behind closed doors, views that were contrary to Bohr's. Heisenberg, Born, and Pauli, as well as Bohr himself, exploited wave-particle complementarity for pedagogical and ideological reasons. The simple thought experiments that supposedly demonstrated the necessity of both the wave and particle descriptions were especially effective for promoting the philosophical "lessons" of quantum theory to wider audiences. From the analysis of these experiments, supported by Bohr's doctrine of the indispensability of classical concepts, both the "finality" of indeterminism and the "impossibility" of unified objective description followed, leaving seemingly no possibility of other interpretive options.
The accessibility of the explanatory strategies fed the illusion that no technical understanding of the quantum mechanical formalism is needed in order to grasp the essence of the quantum revolution.3 This illusion was most vigorously sustained by Bohr himself. "Philosophy is but a sophisticated poetry"—this view of philosophy aptly characterizes Bohr's voluminous improvisations on the theme of complementarity, filled with affective analogies, subjective associations, and allusions to "harmonies," expressed in "common language." In chapter 12, I argue that Bohr's philosophy is best characterized as a richly imaginative, yet ultimately misleading attempt to comprehend the quantum mystery without recourse to the mathematical formalism of quantum theory. There is, in this sense, a vast difference between the complementarity principle and Bohr's correspondence principle, which guided the search for the new theory in the early I920s, and with which the complementtarity principle is sometimes confused. The metaphors of the complementarity principle are vague and arbitrary, in contrast to the more rigorous use of analogies between the macro- and microdomains guided by the correspondence principle. While the correspondence principle was a potent heuristic that led to the discovery of the rigorous quantum formalism, the complementarity principle was a device of legitimation—it led to no new physical knowledge.
In chapter 12, I analyze the ways Bohr, Pauli, and Heisenberg, by their imprecise allusions to quantum "wholeness," spun a metaphorical web of associations that disguise, rather than reveal, quantum entanglement and nonlocality. I argue that these allusions and analogies are fed by classical intuitions and contain nothing quantum about them. Not surprisingly, Bohm's version of quantum theory and its recent variants, which fundamentally incorporate quantum wholeness as a basic principle, are compatible with deterministic description. Bohr's numerous opaque allusions to quantum wholeness contribute to the illusion that his philosophical views were stable, despite the fact that he used this notion differently in different contexts. The notion of wholeness undergoes especially drastic change between Bohr's pre-1935 and his post-1935 writings (as a result of EPR). This ingenious and misleading improvisation on the idea of quantum holism contributes to the deception that awell-defined philosophical framework exists, thus further entrenching the Copenhagen orthodoxy.
Support for the orthodox view comes not only from historians but from philosophers of science as well. The strongest support came from Norwood Hanson and, after him, Thomas Kuhn, who incorporated the Copenhagen ideology into an overarching theory of the growth of scientific knowledge (chapter 14). Hanson and Kuhn canonized the concepts of paradigm and incommensurability into objectified philosophical notions that exclude, in principle, diversity of opinion and legitimate disagreement. Thus opposition is discredited and eliminated in the most radical way—by definition. Kuhn and sociologists of science who follow Kuhn's approach talk in terms of "deviance" and "impermissible aberration" rather than acknowledging reasonable disagreement. Kuhn's theory of incommensurable paradigms and the orthodox narrative of the quantum revolution reinforce each other—the quantum revolution is cited as a prime example supporting Kuhnian philosophy,4 and the orthodox narrative of the quantum revolution is objectified by a Kuhnian theory of the growth of knowledge (chapter 14). By such circular argumentation, the orthodox perspective is made to appear unassailable.
By incorporating addressivity and disagreement as fundamental notions, the dialogical approach, developed here, presents an alternative to current approaches to the study of science. Dialogical analysis incorporates conversation and communicability both as social realities and as epistemological presuppositions. From the dialogical perspective, a creative scientist cannot, in principle, be isolated—he, or she, is linked fundamentally to the efforts and concerns of others. In the dialogical approach, the notorious question of whether science is "rational" or "social" in nature becomes a pseudoproblem. Science is simultaneously rational and social—the rationality of science is dialogical and communicative.
The view of scientific activity as an ever-changing, open-ended communicative flux fits well scientists' own image of their work. Theoretical physicist David Finkelstein (1987), describing the state of his discipline today, chose the Heraclitean "All is flux" for the title of his paper. David Bohm emphasized the essential communicability of scientific doing: "Communication plays an essential role in the very act of scientific perception.... They [scientists] constantly engage in a form of internal dialogue with the whole structure of their particular discipline.... When insight occurs, it emerges out of this overall structure of communication and must then be unfolded so that it obtains its full meaning within it" (Bohm and Peat 1987, 67).
In the concluding chapter of this book I provide a tentative outline for a dialogical historiography and philosophy of science. Dialogical historiography reestablishes scientific individuality as the focus for studies of the growth of knowledge. Dialogical analysis demonstrates that scientific theorizing can be both free and nonarbitrary, and that theoretical achievements can be simultaneously well grounded and imaginatively beautiful.
We constantly conduct conversations with others—with living people, with the dead, and even with the yet unborn. The Russian poet Marina Tsvetaeva, in one of her poems, addressed a reader one hundred years in the future—the one who will truly love and understand her, and who will prefer her remains to the flesh of the living. Without unceasing addressivity and communicability, existence and thought, artistic imagination and scientific creativity are inconceivable.
1. This position was taken by Darwin: "I'm quite ready in advance to believe that your criticisms are quite right, but I feel that perhaps this does not matter much. Because the best sort of contribution that peop1e like me can make to the subject is working out of problems, leaving the questions of principles to you. In fact even if the ideas on which the work was done are wrong from the beginning to end, it is hardly possible that the work itself is wrong in that it can easily be taken over by any revised fundamental ideas that you may make" (Darwin to Bohr December 1926, AHQP).
2. Jammer described the controversy between Bohr and Heisenberg with respect to the uncertainty paper as a tool for elucidating Bohr's and Heisenberg's respective positions and as anecdotal history. From Jammer's analysis it is not clear how the disagreements contributed to the creation of uncertainty and complementarity.
3. Many postmodernist critics of science fell prey to the temptations of this strategy of argumentation (Beller 1998).
4. Even historians whouestion the adequacy of Kuhnian notions to describe other historical developments (Westman 1994, discussing the Copernican-Newtonian revolution assume that Kuhn philosophy adequately describes the case of the quantum revolution.
JohnEB
The following is from Mara Beller's 'Quantum Dialog: The Making of a Revolution':
"Chapter 13
Hero Worship, Construction of Paradigms, and Opposition
'Even to the big shots, Bohr was the great God' -- Richard Feynman, 1980
"Los Alamos from Below" In Badash, Hirshfelder, and Broida, 105-32
'Scientists are inclined to take their own outlook for the natural way of looking at things, while the outlook of others, inasmuch as
they differ from theirs, are adulterated by preconceived and unwarranted philosophical tenets, which unprejudiced science must
avoid.' -- Erwin Schroedinger, 1955 "The Philosophy of Experiment" *Nuovo Cimento* 1:5-15
In our times, the dethroning of heroes is commonplace. We are reassured to learn that our cultural and scientific heroes --the
overpowering Newton and the incomparable Mozart--are in fact flesh and blood, endowed with the frailties, ambitions, and vices of simple mortals. In the history of science we have also come to recognize hero worship as a major distortion of the past.
Yet hero worship is not merely a historiographical sin. It is a powerful tool for legitimating orthodoxy. Hero
worship does not merely deify and mystify the hero. Hero worship errects psychological barriers against criticism and delegitimates opposition. Hero worship effectively conceals the dialogical network in the emergence of novelty by centralizing insights, dispersed among many participants, into the hands of a few great scientists. In this way, the 'lesser' figures are painlessly eliminated from history. If, in the evolutionary narrative, the scientific community becomes superfluous, in the revolutionary account, the scientific collective is no more than a dutiful army of puzzle solvers. The communicative, interactional nature of scientific creativity is as alien to the revolutionary as to the evolutionary narrative (see chapter 15).
In this chapter I describe what can be called the hero worship of Bohr, and I indicate how Bohr's authority promoted uncritical acceptance of the Copenhagen philosophy. I also describe the strategies by which the orthodox portrayed their insights as revolutionary by discrediting the opposition and constructing a simplistic notion of past science.
Bohr and Hero Worship
One cannot overestimate the impact of the authority figure in the evaluation and acceptance of ideas. Bohr's unprecedented authority not only promoted the widespread, uncritical acceptance of the Copenhagen philosophy but obtained a favorable reception for his dubious and poorly developed ideas outside of his area of competence (Heilbron 1987 'The Earliest Missionaries of the Copenhagen Spirit' - In Ullman-Margalit, 201-33 ). Bohr's deliberations on complimentarity in biology, psychology, and anthropology are good examples. [1]
Bohr's authority was based on his outstanding scientific achievements in the past, his formidable institutional power, and his unique personal charisma. Bohr could provide simultaneously intellectual stimulation and help in advancing careers, spiritual fulfillment and down to earth fun, material benefits and psychological counsel. [2] Bohr became a father figure whose unique status many young scientists were eager to honor and whose authority not many dared to challenge.
Many physicists, among them Pauli and Jordan, used the words 'father figure' when referring to Bohr. Pais ('Niels Bohr 's Times, in Physics, Philosophy, and Polity', Oxford: Clarendon, 1991) calls Bohr a 'father figure extrodinary.' Jordan referred to Bohr as 'the father of the great world-wide family of quantum physicists.' (1972, 214) Bohr was a father figure for 'physicists belonging to several generations.' Pais('Niels Bohr 's Times, in Physics, Philosophy, and Polity', Oxford: Clarendon, 1991,3) Bohr's assistant Kalckar called Bohr a 'fatherly friend' Pais ('Reminiscences from the Post-War Years' In Rosental, 1967, 227).
Scientific heros are often described as being endowed not only with supernatural reasoning faculties but also with superhuman personal qualities. Any event or trait, no matter how irrelevant, or even discrediting, is construed as reinforcement of the hero's unique stature. Often such a construction is accompanied by genuine affection, as in Pais's (1991) depiction of Bohr. Pais presents Bohr's ignorance as formidable intuition-Bohr did not know what an isomer was but knew that the arguments of a lecturer pertaining to isomers were 'all wrong' Pais(1991,7). Reminiscences, irrelevant to the scientific problems at hand, Pais presents as 'warming up exercises,' while Bohr's inability to deliver a coherent public lecture Pais interprets as an 'unrelenting struggle for truth' (1991,11).
To a certain extent, Bohr was a tragic figure. He laid the foundations of the quantum theory of an atom and inspired and
supervised the erection of the new quantum theory. Yet he was unable, with his heavy administrative duties and limited
mathematical knowledge, to participate actively in further developments when the field became too mathematical (chapter 12).
While Bohr presented himself as a dilettante who had to approach 'every new question from a starting point of total
ignorance,' Pais graciously remarks that 'Bohr's strength lies in formidable intuition and insight rather than erudition' (1991,7).
Bohr's 'formidable intuition' and 'subtle reasoning' were often used by the orthodox to certify the Copenhagen interpretation as final and to disarm those who sought an alternative. The legend that Bohr had some sort of access to nature's secrets, qualitatively different from that of other mortals, directly discouraged critical dialog. This legend is supported by another, peculiar claim--unlike other theoretical physicists, Bohr did not need to calculate in order to obtain 'the truth.' Blaedel's is a typical statement: 'Perhaps his intuition allowed him to grasp things when others needed calculations ('Harmony and Unity: The Life of Niels Bohr', 1988,11). Bohr's personal limitation is thus uncritically transformed into a strength. At the same time, strong legitimation is given to Bohr's metaphorical presentation of complimentarity by singling out his associations as privileged (chapter 12). Needless to say, none of the cases in which Bohr turned out to be wrong--the Bohr-Slaters-Kramer theory, the existence of spin and the neutrino, complimentarity between 'vitalism' and 'mechanism' [3] are mentioned when Bohr's intuition is being worshipped or used as a weapon against dissent.
It became almost obligatory, when writing about Bohr, to write about the 'sublety' of his thinking. Followers and opponents alike
characterized Bohr's thought as subtle. Yet, peculiarly, it is rarely a specific argument that is singled out for this description. Rather, the word 'Subtle' is used when the author encounters a difficulty in understanding Bohr, failing to penetrate the structure of the argument, to achieve a clear and coherent reading of Bohr's writings. Thus Sklar, characterizing Bohr's philosophy as 'exciting and subtle' simultaneously complains that 'his so-called Copenhagen interpretation is not easy to summarize neatly (1992,172) and that 'complimentarity is a difficult notion to fully pin down' (173). Hailing Bohr's philosophy as 'extrodinarily ingenious,' Sklar calls it 'not a view of the world easy to understand ('Philosophy of Physics', Oxford: Oxford University Press, 1992,175).
Even Bohr's opponents felt the pressure. Thus Bohm and Hiley, describing 'Bohr's very subtle thought,' mentioned that his ideas 'do not appear to be well understood by the majority of physicists' (1993,15). It seems that the more one feels at a loss to extract a clear and coherent message from Bohr's philosophy, the more often one calls it 'subtle' and 'ingenious.' This terminology creates a qualitative gap between oneself and the hero, excusing inability to understand and simultaneously preventing criticism of the hero's authority. No wonder Bohr's notion of 'deep truth' was used to disarm those young visitors to Bohr's institute who thought they had found contradictions in his reasoning. [4] Any doubts physicists had about Copenhagen wisdom were silenced by an appeal to Bohr's unreachable depth of discourse, beyond the usual 'simplistic' cannons of argumentation. When the 'simple' truth seemed to contradict the orthodoxy, the inaccessible 'deep' truth prevented further questioning.
This is not to deny Bohr's reasoning on complimentarity, in which arguments of consistency are subtly disguised as those of
inevitability. Some of the consistency arguments are very clever; other arguments owe their sublety to skillful ad hoc maneuvering. [5] One can easily criticize the lack of rigor in such arguments, for Bohr and his followers often transended the framework of nonrelativistic quantum mechanics while attempting to demonstrate its consistency. In the case of the Bohr-Einstein argument about the time-energy uncertainty relation (see Bohr 1949 'Discussion with Einstein on Epistemological Problems in Atomic Physics' In Schilpp 1970,201-41, 224-28), Bohr was forced to invoke ad hoc a formula from general relativity theory. In the case of Heisenberg's gamma-ray thought experiment, Bohr used the formulas of classical wave theory while simultaneously denying that theory's validity by appeal to the photon concept. No wonder Einstein was not swayed by such arguments--it is an illegitimate mixture of classical and quantum concepts similar to the setup he found so unsatisfactory in Planck's initial derivation of the distribution law. Some physicists, such as Heisenberg and Bopp, understood that the frivolous mixing of classical and quantum concepts in the analysis of thought experiments was inconsistant, Bohr's ideology of complimentarity notwithstanding. Yet Bohr's arguments were accepted uncritically by many physicists, historians, and philosophers; these arguments were construed as the 'triumphant victory' of Bohr, heroically countering the theatening moves of the opposition.
The fact that many physicists were willing to accept Bohr's authority on fundamental issues of quantum theory is not entirely surprising. Bohr's arguments for the consistency of quantum mechanics (his response to EPR) and of quantum electrodynamics (1933 Bohr and Rosenfeld 'Light and Life', Nature 131: 421-23, 457-59) [6] were perceived by physicists as a vindication of the powers and consistency of their tools, as a green light to go on confidently (Beller and Fine; Pais 1991). Few bothered to carefully study either the EPR paper or Bohr's response to it. [7]
More striking are testimonies of blind acceptance of Bohr's authority even in such matters as the physics of the atomic bomb.
According to Feynman's reminiscences about Bohr's visit to Los Alamos, nobody there dared to subject Bohr's proposal for improving the bomb to critical scrutiny. Feynman, who was unaware at the time he was talking to the great Bohr himself, criticized Bohr's ideas freely. After the meeting Bohr told his son Aage that "Feynman had been the only person at the meeting who had been willing to say that an idea of his was 'crazy'" Schweber (1994, 'QED and the Men Who Made It: Dyson, Feynman, Schwinger and Tomonaga' Princeton, N.J.: Princeton University Press, 403). According to Feynman, Bohr said "Next time when we want to discuss ideas, we are not going to do it with these [big shots] . . . who say everything is yes, yes Dr. Bohr (Feynman 1976, "Los Alamos from Below: Reminiscences of 1943-1945" *Engineering and 'Science* 29)"
Hero worship, and the associated suppression of criticism, need not always be sober and serious. [8] Thus Hendrik Casimir, a physicist from Bohr's circle, wrote a comical poem for Bohr's fiftieth birthday. He described Bohr's famous theory that a defensive, as opposed to aggressive, shooter has an advantage because supposedly making a voluntary decision takes more time than reacting in a purely mechanical way. The poem concludes with an attempt to give Bohr a gun so he can prove his theory "experimentally" by defending himself:
So the three of us went to the center of townAnd there at a gunshop spent many a crownOn pistols and lead, and now Bohr had to proveThat in fact the defendant is quickest to move.Bohr accepted the challenge without ever a frown;He drew when we drew ... and shot each of us down.This tale has a moral, but we knew it before:It's foolish to question the wisdom of Bohr.Casimir's translation (Casimir 1983, 98-99); original German (Casimir 1967,113)
The moral of the story is clear. Nothing positive awaits those who challenge Bohr's authority. But is not such an interpretation inconclusive and tendentious, misrepresenting the joyful and humorous atmosphere in Copenhagen? Clearly not, for let us quote Casimir's own sober reading of his poem: "The moral of the story that one should not doubt the wisdom of Bohr applies to more important things than shooting gunmen in Westerns" (1967,113;1983, 98-99).
The exuberant celebrations at Bohr's institute, such as a feast held by the graduate students' club on the occasion of the twenty-fifth anniversary of the institute, are also instructive about the nature of Bohr's authority. Students, standing on chairs, beer in hand (with Bohr similarly on a chair), sang the hymn "Fathers of Selena," which hailed the "noble Bohr" who "knows the way amidst all false tracks" (Pais 1991, 6). Those false tracks no doubt referred to directions of thought at odds with the Copenhagen orthodoxy.
Bohr's unpublished correspondence discloses the overwhelming guilt experienced by those physicists who dared to challenge him. Thus Bopp argued in a letter to Bohr that one cannot obtain a contradiction-free interpretation of quantum theory by relying on thought experiments that explicitly use the concepts of classical particle mechanics—exactly the concepts that the new physics gave up. Bopp's contention strikes, of course, at the very heart of Bohr's lifelong enterprise. Bopp prefaces his argument with the following words: "A young Japanese colleague said once: we must do something, that our parents do not understand, and this is very painful" (Bopp to Bohr, 4 February 1962, AHQP). [9] These words, again, reveal the enormous parental authority of Bohr.
Many of Bohr's correspondents could not transgress the psychological barrier of even beginning to criticize Bohr. Thus Jesse Du Mond wrote to Bohr of his numerous unsuccessful attempts to grasp the meaning of Bohr's writings: "This is of course not the first time I have read and tried to grasp your point of view.... regarding your viewpoint I have never been able to get a clear answer from others. I hasten to say that I do not mean to imply any shortcomings in your own written exposition and am very ready to admit that the difficulty is entirely the fault of my own slowness and dullness" (Du Mond to Bohr, 7 March 1961, AHQP).
Yet Weizsacker's reminiscences about his first encounter with Bohr constitute perhaps the best evidence for the overpowering, almost disabling impact of Bohr's authority. After the meeting with Bohr, Weizsdcker asked himself: "What had Bohr meant? What must I understand to be able to tell what he meant and why was he right. I tortured myself on endless solitary walks" (Weizsacker 1985,185, my italics). The question was not; Was Bohr right? or To what an extent was Bohr right? or On what issues was Bohr right? but, quite incredibly, What must one assume and in what way must one argue in order to render Bohr right?
The Issue of Consistency
Scholars of Bohr's thought are bewildered by the number of contradictions in his writings. As I have argued, the inconsistencies are genuine, stemming from many conflicting voices, from confusion between consistency and inevitability arguments, from a mixture of metaphorical and model theoretical argumentation, and from a mixture of classical and quantum concepts. Moreover, unbridgeable gaps exist between Bohr's pre-1935 and post-1935 philosophies.
Encountering these inconsistencies, scholars respond in ingenious ways and develop different interpretations of Bohr's thought—anything short of admitting the contradictions. The unshakable belief in his consistency more often than not follows directly from explicit hero worship: Bohr's mind is too "sublime," "subtle," "too relentless," or "too scrupulous" to produce inconsistencies (Honner 1987, 12). And even a historically sensitive philosopher, Don Howard, who insists on applying "the critical tools of a historian" in order to understand Bohr, defines understanding Bohr as reconstructing "from Bohr's words a coherent philosophy of physics" (1994, 201). Howard's imaginative reconstruction, as he does not fail to realize, transcends Bohr's words significantly. [10]
Even the most competent and friendly readers find Bohr's philosophy obscure and inconsistent. Physicist and philosopher Abner Shimony admits: "I must confess that after 25 years of attentive—and even reverent—reading of Bohr, I have not found a consistent and comprehensive framework for the interpretation of quantum mechanics" (1985, 109). We might wonder what reason he has to remain "reverent" after repeatedly (for twenty-five years!) finding Bohr's writings unsatisfactory and whether anybody but a "hero" would receive such charity. Yet perhaps the most extreme expression of the passion to save Bohr's consistency by any means comes from Honner: "If Bohr's thought is not found to provide a consistent framework for the interpretation of quantum mechanics, then perhaps one's expectations of 'interpretation' should be revised" (1987, 23). Clearly, the soundness of Bohr's reasoning is not judged by objective standards, rather Bohr's authority defines what the legitimate standards of reasoning should be.
Philosophers often apply double standards when judging the orthodox and the opposition. A weakness in the opposition's stand might be a reason for total dismissal. A similar deficiency in the case of the winners is downplayed and rationalized. Hooker, one of the most sympathetic and penetrating commentators on Bohr's thought, after (reluctantly) criticizing Bohr's doctrine of the indispensability of classical concepts, defends him: "Bohr was only driven to adopt indispensability [of classical concepts] by his efforts to understand the conceptual significance of quantum theory." Moreover, while there is no evidence that Bohr ever considered abandoning this peculiar, untenable doctrine, Hooker feels compelled to ascribe such open-mindedness to him: "Though Bohr held strongly to BC15 [the doctrine of the indispensability of classical concepts], he would in principle give it up [!] had circumstances demanded it" (1991, 491).
Opposition, Paradigms, and Past Science
There are numerous ways to delegitimate the opposition and to discredit its stand. When skillful rhetorical techniques, disguised as a disinterested search for truth, are used by powerful authority figures, their effect is potent. It is difficult enough to produce a well-developed alternative to the deeply entrenched and elaborated quantum orthodoxy; it is intimidating, if not paralyzing, when all such alternatives are confidently ruled out by the "unbearable weight" of Bohr's authority and by such scientific heroes as Heisenberg and Pauli.
The orthodox exaggerated the difficulties of the opposition stand while ignoring their own. As the opponents realized, not without some bitterness, their criticism of the Copenhagen interpretation was simply "brushed off" with accusations of not "understanding Bohr" (Lande 1965, 123). As in politics, so in science, the orthodox misrepresented, trivialized, and caricatured the opposition's stand.
Perceiving threats from the technically sophisticated and proficient theoretical explorations of Einstein, Schrodinger, Lande, and Bohm, the orthodox translated them into "simple" language. This tactic ensured that few would bother to look into the original arguments, learning about the opposition stand through a presentation by the orthodox. Such translation not only distorted the original arguments, hiding their strengths, but also tailored them for the upcoming attack. Bohr's simple exposition of the EPR argument misrepresented its original structure and hid its radical message about either the incompleteness or the nonseparability of quantum mechanics (chapter 7 and Beller and Fine 1994). Diverting the issue from the focus of the opposition's criticism to a position on which the opponent may be weaker is a strategy often used. Thus, in a controversy between Born and Schroedinger, Born (1953b) advanced arguments against Schroedinger's (1952a) attempts to eliminate particlehood, when the bulk of Schroedinger's paper was directed against quantum jumps.
Orthodox quantum physicists often used the argument that ift-waves are not real—Schroedinger was amazed by it: "Something that influences the physical behavior of something else must not in any respect be called less real than the something it influences—whatever meaning we may give to the dangerous epithet 'real' " (1950, 110).
The G6ttingen-Copenhagen physicists discredited Schroedinger's interpretive aspirations by pointing out that classical waves propagate in the usual three-dimensional space, rather than in a 3N-dimensional space (Born 1953b,142-43). Yet this criticism was misleading and outdated. Since 1927, Schroedinger had replaced his original "naive" wave interpretation with that of the "second quantization approach" (according to this approach, one can translate any statement about N-particles in 3N-dimensional space into a statement about N-level excitations of the three-dimensional vacuum state). In fact, Schroedinger's own work (even before the advent of wave mechanics) foreshadowed the modern concept of quantized fields (Darrigol 1986). And though he had some reservations about the very "abstract" character of these "waves," Schroedinger's preference for this scheme over the orthodox model was unequivocal: "I believe the discrete scheme of proper frequencies of second quantization to be powerful enough to embrace all the actually observed discontinuities in nature" (1952b, 27).
The orthodox delegitimated the opposition by presenting it as "conservative" and "dogmatic." Heisenberg, intimating that Einstein "had difficulty" understanding the Copenhagen interpretation, labeled him a "dogmatic" realist, as opposed to Heisenberg's own, "nondogmatic" brand of realism (1958, 81). According to Heisenberg, those who questioned the Copenhagen orthodoxy were dealing with "cracks in old bottles instead of rejoicing over the new wine" (1958, 139). The orthodox often discredited the opposition by accusing it of incompetence, indulgence in wishful thinking, or even personality disorders. Those who did not agree with the orthodoxy were "unable to face the facts." Those who allowed the possibility of hidden variables were presented as dreamers who had lost touch with reality: "To hope for hidden variables is as ridiculous as hoping that 2 x 2 = 5" (Heisenberg 1958, 132). Those who seek an alternative to the Copenhagen interpretation are simply outdated "grumblers": "This group of distinguished men .. . may be called philosophical objectors, or, to use a less respectful expression, general grumblers" (Born 1953a,129). [12]
It is tempting, of course, to present one's own contributions as revolutionary, where "revolutionary" is synonymous with novel, bold, original, radically new. [13] Intensely ambitious individuals are especially prone to using revolutionary rhetoric. Heisenberg hoped that his own contributions to quantum physics would "revolutionize" the twentieth century as Copernican ideas had transformed the Renaissance (1979, 21). Bohr, who wished "to realize his wishes as to the future of physics," expected that his complementarity would be taught in elementary school alongside Copernicus's ideas (interview with Bohr, AHQP; Rosenfeld, quoted in French and Kennedy 1985, 323). Yet originators of new theories and the judgment of posterity do not always agree about what exactly was revolutionary in their work. Planck, for example, considered his discovery of the numerical value of h, rather than discreteness of the quantum of action, as constituting a "revs lution." [14]
Exactly where one chooses to demarcate between the old and the new depends on the local theoretical and sociopolitical context. While in the 1930s Heisenberg presented relativity theory and quantum theory as together opening a new era in physics (the quantum overthrow of Kantian causality is a direct continuation of the Einsteinian overthrow of Kantian space-time), both Einstein and relativity disappeared from Heisenberg's speeches and writings during the Third Reich (see the collection of his essays, Heisenberg 1979). In the postwar years, when Einstein was perceived as the most prominent opponent of the Copenhagen interpretation, the line again was drawn differently—relativity, which still preserves the notions of causality and of an invariant objective reality, belongs to the prerevolutionary past—it is quantum theory that opened a genuinely new age.
Whether one chooses to present a contribution as revolutionary, and what feature one singles out as the "most revolutionary," also depends on local theoretical and sociopolitical circumstances. Heisenberg's reinterpretation paper (1925) is usually accepted today as the basis of the new quantum theory and as the inauguration of the conceptual revolution in physics. Yet initially neither Heisenberg nor Born and Jordan, who extended Heisenberg's ideas (Born and Jordan 1925a; Born, Heisenberg, and Jordan 1926), presented the new quantum theory as revolutionary. Quite the contrary—because of the highly abstract character of the new quantum formalism, they preferred to emphasize its connection with the past and with cherished classical ideas (the identical form of the canonical equations, the identity of the perturbation methods, energy conservation). No indeterministic conclusions were initially deduced from the formalism (chapter 2). The rhetoric of a return to classical purity and beauty was abruptly silenced when something still more classically pure and beautiful appeared—Schroedinger's competitive wave theory. I have argued that Heisenberg and other orthodox physicists developed the arguments for a revolutionary overthrow of causality as a response to Schroedinger's competing theory of quantum mechanics—a continuous, causal alternative. This example indicates how the choice is made of which ideas to label "conservative."
This analysis also suggests why some elements, rather than others, are chosen to serve as foundational pillars for a new paradigm. It also points out the intimate connection between a challenge from the opposition and the construction of the scientific past. It was because of Schrodinger's challenge and Einstein's critique in the late 1920s and early 1930s that the Gottingen-Copenhagen physicists chose acausality and indeterminism as the focal points of their emerging quantum paradigm (rather than the more recently proposed nonlocality).
As this new paradigm emerged, its founders constructed a profile of the opposition and a description of past science simultaneously. The ideas of the opposition were projected as most characteristic of the overthrown past—in this way opponents were automatically presented as conservatives; disposing of the old and discrediting the opposition went hand in hand. The opposition became simpleminded and reactionary; the past became monolithic. The diversity, ingenuity, fluidity, and epistemological resilience of past science was thus forced into a few rigid, simplistic categories. In this way classical physics became uniformly deterministic. Yet probabilistic ideas were introduced into classical physics as early as the beginning of the nineteenth century (see the papers in Kruger, Gingerenzer, and Morgan 1987). Statistical methods were the mainstream in quantum physics since Planck's and Einstein's work at the turn of the century, before the new quantum theory. This was the reason Born did not initially regard his probabilistic interpretation of the wave function as signifying a revolutionary departure, the way it was later construed by the Copenhagen physicists (interview with Born, AHQP).
Nor were classical physicists naive about the possibility of exact predictability. Since Poincare's work at the turn of the century, physicists were aware of the existence of chaotic systems—nonlinear dynamical systems with sensitive dependence on initial conditions.15 Born himself was cognizant of this phenomenon—he wrote a paper with an unequivocal title: "Is Classical Mechanics in Fact Deterministic?" (Born 1955a). The prominent orthodox argument that quantum physics gives up causality in principle, while classical physics gave it up only in practice, was itself crystallized in this tendentious construction of the past. It is the very meaningfulness of this distinction between indeterminism in principle and indeterminism in practice that chaos theorists challenge today.
In the simultaneous construction of the opposition and the past, the opponents—such as Einstein, Schrodinger, Bohm, and Lande—were presented as conservatives, unable to digest the revolutionary novelties. I have not been able to find any common criteria by which their stand was characterized as conservative—their conservatism consisting merely in their disagreement with the orthodoxy. We are all familiar with the caricatures of the opponents—the image of aging Einstein, stubbornly mumbling "God does not play dice." We are also familiar with Galileo's construal of the fictional Peripatetic Simplicio. As Galileo's brilliant caricature distorts and disguises the complexity and resilience of Aristotelian thought (Schmitt 1983), so too the G6ttingenCopenhagen physicists trivialized and distorted the ideas of Einstein, Schroedinger, and Bohm. Recent scholarship, notably Arthur Fine's and Don Howard's work, reveals that Einstein was neither a simpleminded determinist (he did not hope for a completion of quantum physics by hidden variables, but for a radically new theory that would subsume the current quantum physics—Fine 1986), nor was he an unsophisticated realist—in fact, his philosophy had prominent conventionalist strands (Howard 1990, 1993). Far from holding a correspondence theory of truth, Einstein considered the concept of independent physical reality meaningless (Fine 1986; Beller, forthcoming). Nor was Einstein a dogmatic adherent to causal, continuous field theories—there was "another Einstein," and the debate between Einstein's two conflicting voices lasted to the end of his life (Stachel 1993).
Recent scholarship has also refuted the picture of Schroedinger as an adherent to realism. As did Einstein, so too did Schroedinger deny the meaningfulness of the concept of independent reality, regarding the idea of reality rather as a regulative construct (Ben-Menahem 1992; Bitbo11996; Beller, forthcoming).
Schroedinger's defense of a comprehensive wave ontology, as well as the persistent Copenhagen caricature of Schroedinger's position, has resulted in an image of Schroedinger as a conservative, simpleminded, classical realist, unwilling and unable to sacrifice traditional concepts and accept new ones. Yet an analysis of Schroedinger's writings reveals instead a very sophisticated position, along neo-Kantian lines: the concept of reality "as such," as it objectively exists independent of all human observers, is indefensible, if not downright meaningless. Similarly, Schroedinger fully understood that the correspondence theory of truth can hardly be sustained. Still, the concept of reality, held Schroedinger, is as indispensable in science as it is in everyday life. There is no distinction in principle between a layman's and a scientist's conception of reality—both are regulative constructs, indispensable for mental (and physical) activity.
Schroedinger, no fan of duplications and divisions, dismissed those dichotomies on which representative realism rests—the dichotomy between primary and secondary qualities, between mind and matter, between theory and experiment. The division into experimental and theoretical physics is artificial—it is "mostly caused by the fact that the two kinds of activity require, each of them, such elaborated special training and skill, that they are seldom commended by the same person" (Schrodinger 1954, 124).
The objectification of measurements, the intersubjective agreement about the results of experiments, is primarily based on geometric and kinematic statements. For it is in the assessment of a geometric coincidence between the marks on the scale and the pointer that the discrepancy between the judgments of two different observers is the least possible. In this sense, empirical statements about geometric and kinematic relations clearly have a privileged epistemological status. Yet this state of affairs contributes to the fallacious naive realist view that "something is distributed in space in a definite arrangement and well defined order," this "something" is changing according to objective laws, and "this changing something" constitutes so-called objective reality (Schrodinger 1954,144 – 45).
Positing this objective reality leads, according to Schrodinger, to a very awkward philosophical situation. Since "secondary" sensory experiences (sensations of color, taste, smell, sound) are removed from "objective reality," one invents a new realm for them—the mind (!), forgetting that "all that we have been talking about till now is also in the mind and nowhere else." This division creates philosophical pseudoproblems, such as how mind and matter act on each other, and the like (Schrodinger 1954, 145).
Schrodinger's draft for the James lectures (1954) allows us to form a clearer view of his aversion to the strong positivist elements of the Copenhagen interpretation—an aversion that the Gottingen-Copenhagen physicists mistakenly characterized as a form of simpleminded realism. An analysis of these lectures reveals why Schrodinger fundamentally rejected another dichotomy—Bohr's notorious division between the micro- and macrodomains, between classical "reality" that is close to common sense and the quantum mechanical "abstract formalism" that is a tool for description and prediction of measurement results. Schrodinger rejected this division not because he extended the naive realism of the macrodomain into the microdomain. Quite the opposite: he denied to the macrodomain a realistic status that the Copenhagen philosophy regarded as a self-evident fact.
Schrodinger was fully aware of the pitfalls, deficiencies, and ideological power of positivism. He called the legitimating positivist stratagems of the Copenhagen orthodoxy "unfair subterfuge" (1952d, 83), a "supreme protector" (1935, 157). The positivist approach entrenches the basic assumptions of the Copenhagen interpretation and endows controversial assertions with an aura of inevitability. The Copenhagen claim that quantum mechanics is complete is among such assertions, prohibiting further questioning. Completeness seems to arise as a straightforward deduction from positivism: "It must be impossible to add onto it additional correct statements, without otherwise changing it; else one would not have the right to call meaningless all questions extending beyond it" (Schroedinger 1935, 159).
Schroedinger was no less a philosophical "opportunist" than his Gottingen-Copenhagen opponents (compare chapter 3). He did not shy away from positivist arguments when they suited his purposes. In fact, it seems that Schroedinger was no less skillful in positivist analysis when criticizing the orthodox camp than the Gottingen-Copenhagen physicists were when fending off the challenges of the opposition. In such criticisms, Schrodinger often presupposed the verificationist meaning of quantum formulas: the uncertainty relations, for example, are not merely limits on the possible measurement values of physical variables—uncertainty restricts the very definability of the concepts used (see his criticism in chapter 6). Similarly, Schrodinger used positivist arguments when "deconstructing" the concept of a particle: "We are not experimenting with single particles, any more than we can raise Ichthyosauria in the zoo. We are scrutinizing records of events long after they have happened" (Schroedinger 1952a, 240). As Born noted shrewdly, refusing to go from an experimental event to an underlying substratum (particle matter) is a positivist argument (1953b,144).
A letter from Schrodinger to Eddington (written in 1940, reprinted in Bitbol 1995, 121-22) reveals that Schrodinger indeed considered himself simultaneously an heir to Machean positivism and a follower of Boltzmann's descriptive tradition. The approaches of Boltzmann and Mach, at first sight irreconcilable, were in fact directed toward the same goal: avoiding doubtful presuppositions, excluding contradictory assumptions, clearing obstacles on the path to truth. While "Boltzmann's idea consisted in forming absolutely clear, almost naively clear and detailed `pictures'—mainly in order to be quite sure of avoiding contradictory assumptions"—Mach "was most anxious not to contaminate this absolute reliable timber [an economical summary of the observed facts] with any other one of a more doubtful origin" (Bitbol 1995, 121). Thus Schrodinger wrote to Eddington that he could hardly be impressed by the "brave new world" of the Copenhagen positivism—a rather crude and naive version of an approach he was always familiar with. While one may and even must use pictures, one has to do so with one's eyes open to their limitations, revealed by an analysis of the experimental possibilities (Bitbol 1995, 122). It is the relative weight of positivist and model-descriptive elements in Schroedinger's arguments that changed, one can conclude, according to the theoretical challenges that he encountered.
Philosophically sophisticated and technically ingenious are also Bohmian alternatives to the Copenhagen interpretation (Cushing 1994a; Bohm and Hiley 1993). And Anthony Valentini has recently argued that de Broglie's scientific contributions have also been misconstrued in a grotesque way— de Broglie was not some cranky outsider, or second-rate theorist, but a deep thinker and an outstanding physicist, who in fact as early as 1927 (twenty-five years before Bohm) had derived all the correct "pilot wave" dynamics for a multiparticle system. [16]
As to the claim that the opponents did not have a deep working knowledge of quantum physics, anyone who is even superficially familiar with Einstein's and Schroedinger's publications immediately sees how ridiculous it is. It was the opposition—Einstein and Schroedinger who in the mid-1930s discovered and mathematically elaborated the basic nonseparability of quantum systems (Einstein, Podolsky, and Rosen 1935; Schrodinger 1935). It was the orthodoxy, as I have argued, who diffused these arguments by operational stratagems, preventing serious exploration of nonseparability until Bell's seminal work. Einstein's characterization of Bohr as a "Talmudic philosopher" referred precisely to Bohr's circumventing, rather than directly confronting, the most fundamental problem of quantum theory. This deep physical challenge was met with the rhetoric of "sacrifice." [17] The "sacrifice" primarily meant elimination of the opposition's ideas.
____________________________________
[1] As Lande commented: 'It is a matter of social psychology how people perceive the ideas uttered by great men outside of their
field of expertise' (interview with Lande, Archive for the History of Quantum Physics (AHQP))
[2] All this was offered at Bohr's institute in Copenhagen. As early as the 1920s, Bohr could support Heisenberg's and Pauli's visits to Copenhagen much better than the young German physicists could expect to be financed in Germany. About Bohr's connection with funding agencies, including the Rockefeller Foundation, as well as about the institute as a place of fun (sports, the opposite sex) see Pais (1991) Bohr's expertise in securing funding is explored in Kojevnikov (1997). Many recollections Bohr's colleagues and disciples reveal a unique, powerful charismatic personality.
[3] Bohr avoided this terminology after the discovery in 1953 of the DNA structure by Watson and Crick.
[4] According to a saying of Bohr's there is a 'simple truth,' the opposite of which is falsity; and the 'deep truth,' the opposite of which is also a truth (1949,240)
[5] Bohr's uses of correspondence arguments in his early creative years display an outstanding ingenuity and skillfulness. My criticism here refers to the philosophical legitimation of the Copenhagen ideology.
[6] See Schweber (1994) for an excellent discussion of Freeman Dyson's use of the Bohr and Rosenfeld paper.
[7] 'When I asked George Uhlenbeck, who was an active physicist in his mid thirties when EPR appeared, what he recalled about
physicists' reactions, he replied that no one he knew paid any attention' (Pais 1991,430)."
[8] I discuss the humorous critique of complementarit in my "Jocular Commemorations: The Copenhagen Spirit" (Beller 1999).
[9] "Ein junger japanischer Kollege hat einmal gesagt: wir mussen etwas tun, was unsere Eltern nicht verstehen, and das schmerzt uns sehr."
[10] In fact, Howard uses von Neumann's analysis based on pure cases and mixtures, which Bohr himself considered superfluous, and which cannot be construed as a natural extension of Bohr's deliberations.
[11] The discreteness is deduced because the vibrating field, enclosed in a finite volume, can have only discrete proper modes.
[12] The opposition did not spare the sharp words either, though these found expression more often in private correspondence than in published writings. Einstein called the Copenhagen philosophy a "tranquilizer" for an uncritical follower, and Schrodinger defined it as "philosophical extravaganza dictated by despair" (Lande 1965, 124). More eloquently, Schrodinger referred to believers in the Copenhagen philosophy as "asses": "With very few exceptions (such as Einstein and Laue) all the rest of the theoretical physicists were unadulterated asses and I was the only sane person left" (Schrodinger to Synge, quoted in Moore 1989, 472).
[13] In classical times one used the word mutatio for novelty. In the sixteenth and seventeenth centuries one used the word "new" rather than "revolutionary."
[14] His idea was that h, together with other fundamental constants—e (electron charge), k (Boltzmann's constant, and c (the speed of light)—would provide absolute universal units of measurement, independent of the "accident" of human life on Earth. For details, see Klein (1977).
[15] An error in the determination of the initial conditions quickly becomes large enough to preclude the possibility of predicting the future state of the system.
[16] This assessment of de Broglie's work is opposed to the received view that de Broglie developed only a primitive case, treating as some classical field in three-dimensional space. Valentini also challenges the accepted story that at the fifth Solvay conference de Broglie was unable to reply to Pauli's penetrating criticism and he therefore abandoned his efforts for an alternative to the Copenhagen orthodoxy. I am grateful to Valentini who shared with me his reinterpretation of de Broglie's work in private communication before publication. This subject is treated in Valentini (1998). It must be noted that Valentini s interpretation is controversial. Scholars disagree about where de Broglie stood conceptually in 1927, and about the success with which he countered Pauli's objections at the Solvay conference (James Cushing, private communication).
[17] Bohr, Heisenberg, and Born talked repeatedly about a "sacrifice" of the old. The following statement is typical: "All progress has been achieved by sacrifice" (Heisenberg 1979, 27). The rhetoric of sacrifice is noted in Heilbron (1987, 219).
JohnEB
The Quantum Muddle
Mara Beller, in "Quantum Dialogue: the making of a revolution", shows that the Copenhagen interpretation is essentially nonsense. At no time was a consistent, coherent structure presented to the physics community for analysis. If it had been attempted, the quantum muddle would have been shown to be exactly that--the quantum muddle. Even Bell was never able to make any sense of Bohr's ideas concerning quantum mechanics.
Note: AHQP = Archive for the History of Quantum Physics
"CHAPTER 7
The Challenge of Einstein-Podolsky-Rosen and the Two Voices of Bohr's Response
position of his principal opponent, Bohr. Yet most contemporary theorists have the impression that Bohr got the better of Einstein
Two Voices in Bohr's Response to Einstein-Podolsky-Rosen
The strongest challenge ever posed to the orthodox philosophy of
quantum physics is the Einstein-Podolsky-Rosen argument (Einstein,
Podolsky, and Rosen 1935, hereafter EPR). 1 The argument, if one
accepts some intuitive and, at the time, widely accepted notions of
physical description (reality), pointed out that something peculiar,
and perhaps unacceptable, is implied by the quantum formalism:
Quantum theory is either incomplete, or inconsistent, or both
(Beller and Fine 1994). In particular, the conjunction of the
completeness of quantum theory and the separability of states of
distant systems cannot be maintained. The argument came as a "bolt
from the blue," and its effect was "remarkable" not only on Bohr
but also on other quantum physicists (Rosenfeld 1967,128-29).
Dirac initially considered the argument devastating: "Paul Dirac
said: 'Now we have to start all over again, because Einstein proved
that it does not work'" (interview with Bohr, 17 November 1962,
AHQP).
Bohr's pre-1935 philosophy contained as an intrinsic part the
concept of a robust physical disturbance. The challenge of EPR
undercut Bohr's idea of a direct physical disturbance. Einstein,
Podolsky, and Rosen discussed a system of two particles that
interacted initially and then moved apart. If one directly measures
the value of either of two conjugate variables for one system, one
can predict with certainty the (unmeasured) value of the same
quantity in the other system. 2 The authors of EPR investigated
the state function of a two-particle system and its "reduction" to
the state functions of the component systems during measurement.
They reached the puzzling conclusion that as a consequence of two
different measurements, "without in any way disturbing" the second,
distant system, two different functions can be assigned "to the same
reality." The unmeasured particle has a reality that is
simultaneously describable by an eigenfunction of position and an
eigenfunction of momentum--using a standard eigenstate-eigenvalue
rule, the authors concluded that both position and momentum can,
with certainty, be ascribed to the second particle. As quantum
mechanics forbids assignment of definite values to two conjugate
variables simultaneously, the authors concluded that quantum
mechanics was incomplete. 3
During the course of their argumentation, the authors proposed
a "criterion of reality": "If, without in any way disturbing a
system, we can predict with certainty the value of a physical
quantity, then there exists an element of physical reality
corresponding to this physical quantity" (EPR, 778).4 Bohr did not
challenge their definition, finding only an "ambiguity" in the
expression "without in any way disturbing a system." Bohr's answer
to EPR centered on the idea of disturbance. Two different, even
incompatible, answers are concurrently present in Bohr's response
to EPR. One is tempted to assume that Bohr must have presented
only one unequivocal answer and the difficulty is that of the
reader. Yet such an assumption renders much of Bohr's text
superfluous or incomprehensible. The two voices in the paper are
real, with one voice rooted in the past (before 1935), the other
emerging into the future (after 1935).
Bohr's response (or responses) to EPR was built on the "physical
actualization" of EPR's mathematical reasoning, rather than dealing
directly with the consequences of the formalism. Bohr proposed for
the measurement arrangement a diaphragm with two parallel slits
through which both particles pass simultaneously. If such a
diaphragm is suspended by weak springs, we can know Qsub(1) - Qsub
(2) and Psub(1) + Psub(2). Because Qsub(1) - Qsub(2) commutes with
Psub(1) + Psub(2), we can by measuring Qsub(1) calculate Qsub(2) or
by measuring Psub(1) calculate Psub(2). What is the reason that
contra Einstein, we cannot do both simultaneously?
Let us consider Bohr's first answer-the operational one: 5 In
addition to the first two-slit diaphragm, we employ a second
diaphragm suspended by weak springs or rigidly bolted, depending on
whether we intend to measure the position or momentum of the first
particle (see diagram on next page). We can measure Psub(1) of the
first particle by using the second diaphragm, and deduce Psub(2) --
the momentum of .the second particle. For the measurement of Psub
(1) we use the movable diaphragm, so we exclude in principle the
possibility of measuring Qsub(1), and thus we exclude in principle
the possibility of predicting Qsub(2) --the position of the second
particle. This answer accords well with Bohr's statement that
measurements on the first particle imply "an influence on the very
conditions which define the possible types of predictions regarding
the future behavior of the system" (1935a, 700). 6 If,
operationally, we equate measurement, and associated predictions,
with definability, we see that there is no possibility of
simultaneous prediction, and therefore definability, of the position
and momentum of the second particle.
This answer is both too short and too long. Too short, because there
are many sentences in Bohr's text (in addition to his repetition of
some "simple, and in substance well-known," examples of measurement
arrangements) that seem to be either superfluous or irrelevant
(they find, as I will shortly demonstrate, a natural place from the
perspective of Bohr's second answer). Yet the first answer is also
too long, because the operational reply does not require
the "physical actualization" of the EPR argument-the operational
reply is a general one, independent of the specifics of the
experimental arrangement. Indeed, when Bohr summarized his response
to EPR in 1949, instead of two particles, he considered "for the
two parts of the system. . . a particle and a diaphragm." The
operational answer is thus compressed into a few lines: "After the
particle has passed through the diaphragm, we have in principle the
choice of measuring either the position of the diaphragm or its
momentum and, in each case, to make predictions as to subsequent
observations pertaining to the particle. As repeatedly stressed,
the principal point is here that such measurements demand mutually
exclusive experimental arrangements" (Bohr 1949, 233). A
simultaneous reality, according to the operational approach, can be
ascribed to two variables only if they are simultaneously measured.
Let us note that this simple answer was provided before Bohr by
Arthur E. Ruark (1935). 7 His crisp reply does not leave much
ground for the Bohr-Einstein dialogue--the opponents can only
acknowledge a fundamental difference between their metaphysical
presuppositions. Einstein envisaged such a simple (and for him,
deeply unsatisfactory) countermove calling such a
reply "unreasonable" (EPR, 780). Bohr's aim was not confined to
amicably stating the metaphysical disagreements between Einstein and
himself--Bohr wanted to "convince" Einstein, and to emerge "a
victor" from this confrontation. If the operational reply is indeed
what Bohr offered, it is not clear why he needed six weeks
of "utmost concentration and unrelenting efforts" to fashion such a
response (which was suggested, before Bohr, by Ruark and even
Einstein himself!). Where in the operational reading do we find
the "painstaking scrutiny of every detail" (Rosenfeld 1967, 131)?
There clearly must be something more in the text than this simple
operational countermove.
Another reading of Bohr's reply finds his second answer, which deals
with the "ambiguity" in the concept of disturbance in a more direct
way (Beller and Fine 1994). 8 It is this reading that makes good
sense of Bohr's discussion of the details of the specific physical
actualization that he proposes (details that do not make sense
under the operational reading).
The measurement of momentum is similar to that outlined in the first
answer--we measure Psub(1) + Psub(2) with the help of the two-slit
diaphragm (through which both particles pass simultaneously). The
two-slit diaphragm must be movable (suspended by weak springs or
the like). We can subsequently measure the momentum of the first
particle, using a second movable diaphragm, spatially separated from
the first. Knowing Psub(1) + Psub(2), and measuring Psub(1), we can
easily predict Psub(2) (because of the law of conservation of
momentum, the two diaphragms can indeed be at any distance from
each other).
The position measurement, however, presents a totally different
conceptual situation. In fact, Bohr's physical actualization of
the position measurement violates the EPR case. In Bohr's setup, as
opposed to the EPR setup, Qsub(1) - Qsub(2) has a definite value
at one instant only--when the two particles pass through the two
slits of the first diaphragm. At any other point, the value Qsub
(1) - Qsub(2) becomes indefinite, according to Schrodinger's
equation. Yet this means that if we use a second diaphragm,
spatially separated from the first (the two-slit diaphragm), to
measure Qsub(1), we cannot predict Qsub(2) (We have lost our
knowledge of Qsub(1) - Qsub(2).) In order to be able to predict
Qsub(2) from the measurement of Qsub(1), we must measure Qsub(1) at
the very moment the two particles pass through the two-slit
diaphragm! This means either that the second diaphragm must be
infinitely close to the first or that the two diaphragms (the two-
slit one and the one for measurement of Qsub(1) actually merge into
a single arrangement.
This reading accords well with certain passages in Bohr's reply to
EPR, which seem to be strangely out of place under an operational
reading. For example, if we measure the position Qsub(1) of the
first particle, we lose the possibility of knowing Psub(1) + Psub
(2). This loss of knowledge occurs only because the common
diaphragm (which includes the two-slit one for the measurement of
Psub(1) + Psub(2)) must now be rigidly bolted and cannot serve for
momentum measurement: "We have by this procedure cut ourselves off
from any future possibility of applying the law of conservation of
momentum to the system consisting of the diaphragm and the two
particles" (1935a, 697). There are other sentences that seem to
make sense only under the specific condition of merged diaphragms
(Beller and Fine 1994, 14).
Clearly, the realization of position measurement introduces
restrictions and physical effects not present in the EPR paper. In
the EPR case both Qsub(1) - Qsub(2) and Psub(1) + Psub(2) are
determinable simultaneously with either the position QI or the
momentum PI of the first particle, while Bohr's double-slit
arrangement does not satisfy this requirement. In Bohr's example
only one of Qsub(1) - Qsub(2) or Psub(1) + Psub(2) could be
determined simultaneously with the variable one chooses to measure
on the first particle. In addition, the EPR condition that "no real
change can take place in the second system in consequence of
anything that may be done to the first system" is violated in
Bohr's arrangement. Bohr's physical realization contains an indirect
mechanical disturbance, because changing the measurement from Qsub
(1) to Psub(1) of the first particle demands a change in the
mechanical arrangement of the two-slit diaphragm, through which both
particles pass (and, consequently, in the second diaphragm, which
must be attached to the first).
We can see now why Bohr does not challenge the EPR conception of
reality and only finds an "ambiguity" in the expression "without in
any way disturbing a system." A real physical disturbance does
exist in Bohr's (incorrect) realization of the case proposed by
EPR! Bohr's second reply is a veritable failure. No wonder Bohr
never repeated this intricate, yet fundamentally flawed argument.
Refusing (or unable) to explore quantum "wholeness" in terms of
quantum ontology, Bohr's only choice was to land in positivism.
Two different voices, then, meet (or clash) in Bohr's response to
EPR. The old voice, holding on to the notion of physical
disturbance, brings this notion to a dead end. The new, emerging
operational voice will culminate in unreserved verificationism and
a future repudiation of the notion of disturbance. Such complex,
polyphonic exploration is fitting for the interface between the old
and the new--the transition to a substantially different position
is not a Gestalt switch.
Other tensions, consequently, inhabit Bohr's paper, such as the
tension between "consistency" and "inevitability" arguments: the
first, operational answer introduces the inevitability motive, while
the second answer is more compatible with Bohr's assertions
of "soundness," "lack of contradictions," "rationality,"
and "consistency" of the quantum mechanical scheme (see chapter
9). Similarly, Bohr strikes two different chords on the theme
of "the radical revision of our attitude towards the concept of
physical reality" (1935a, 697). The first, operational answer
forbids any talk about objective, observer-independent reality.
This answer will culminate in Bohr's redefinition of physical
phenomena--no elementary phenomenon is a phenomenon until it is an
observed phenomenon. In relation to the revision of the concept of
reality, the second answer does not contain anything new--Bohr
merely repeats his pre-1935 arguments of "inseparability" of
measuring and measured, of object and subject (such inseparability
necessitates a change in the concept of reality, as I discuss
below). This reply accords well with Bohr's assertion that his
discussion of the EPR case does not contain any greater intricacies
than those in his previous analyses of simple mechanical
arrangements discussed in his publications before EPR.
Our description of the conflicting voices in Bohr's reply discloses
why Bohr's readers have such difficulty following his arguments.
9 Unless we acknowledge the different voices in Bohr's paper, its
tensions and contradictions, parts of the paper are
incomprehensible. Nor does the great labor spent on it, and "the
state of exaltation in which Bohr accomplished this work"
(Rosenfeld 1967, 131) make sense.
Bohr's Victory?
There is a widespread myth that Bohr enjoyed a triumph over Einstein
in their dialogue on EPR (see Rosenfeld 1967; Wheeler and Zurek
1983, 142-43). Yet none of Bohr's answers are satisfactory. I have
already pointed out that the answer built on the concept of
disturbance is fundamentally flawed. The other, operational answer
can be more properly seen as an enforced, ad hoc legitimation move,
rather than as an adequate confrontation with the deep challenge of
the EPR correlations. In particular, Bohr's operational answer
conceals rather than reveals entanglement and nonlocality, which is
the most powerful message of EPR. 10 Even if we accept Bohr's
changing the rules of the game, and his refusal to enter into
ontological inquiry, his operational reply falls apart under close
scrutiny. Quite aside from the general weaknesses of the
operational positivist stand, 11 operationalism is especially
unsuited---in fact it undermines--Bohr's philosophy of
complementarity.
In his discussion of a position measurement when the diaphragm is
rigidly bolted, Bohr argues that an "uncontrollable" amount of
momentum "passes into. . . support" (1935a, 697). The momentum
transferred from the particle to the measuring device cannot be
measured in principle. If it cannot be measured from an
operational point of view, it has no meaning. Yet in this case,
quantum uncertainty, contra Bohr, cannot arise (still
less "inevitably" follow) from the physical interaction between an
object and a measuring device (Beller and Fine 1994, 21) 12 The
conclusion of Fine and myself was that
"from the positivist perspective that Bohr eventually adopted, the
idea of an uncontrollable exchange of momentum, which is supposed
to ground his physical picture of quantum uncertainty, is
problematic. The only way around the problem seems to be to turn
the ground upside down, and to make the measurable uncertainty the
operational basis for the language of uncontrollable exchange. Thus
despite the lively imagery, when Bohr talks of an exchange or
transfer of momentum, there is literally nothing (and in particular,
no momentum) that is transferred or exchanged. Bohr conjures up a
robust physical picture: the feature of wholeness
or "individuality" of the quantum phenomena connected to an
uncontrollable interaction between object and apparatus-all giving
rise to the quantum uncertainty. Upon scrutiny, however, this
impression turns out to be the effect of a conjuring trick. Only
the quantum uncertainty itself is independently meaningful. From
the positivist point of view, the rest is a word-picture
constructed around the experimentally verifiable uncertainty
formulas, like a collage of printed words glued on to a radiant
object." (1994, 22-23)
We started with two superimposed answers to EPR by Bohr. We end up
with no answer at all! It is bewildering that Bohr's response was
ever considered, and is often still considered, an adequate (not to
mention triumphant"!) reply to EPR. I can suggest a few
explanations for this strange state of affairs. The myth is in part
connected with the general mythology of the Copenhagen
interpretation, the hero worship of Bohr, the fabrication of
the "winner's narrative"-issues I discuss in the chapters that
follow. Yet we also have to take into account the specifics of the
Bohr-Einstein confrontation over EPR. A few ingenious rhetorical
moves characterize Bohr's response and create the illusion of
victory. By giving a short, nonmathematical summary of the dense
and complex EPR paper, Bohr ensured that few would bother to read
the EPR paper itself. (Those who did, and immersed themselves in
the details of the EPR argumentation without bias, obtained a rich
harvest: Bell 1964, 1966; Bohm 1952.)
The overwhelming majority of presentations of the Bohr-Einstein
debate use Bohr's nonmathematical summary of EPR. Yet this summary
is misleading and introduces weaknesses not present in the original
EPR paper. Those who lightly dismiss the EPR challenge (Pais
1991,429-31) dismiss in fact Bohr's version of it (see Beller and
Fine 1994, 2-6, for a full discussion of the difference between EPR
and Bohr's EPR). A particularly obvious weakness is Bohr's
assignment of simultaneous position and momentum values to the
unmeasured particle. According to Bohr's summary, if we measure the
Qsub(l), then, according to the criterion of reality, we can assign
a definite value to Qsub(2) similarly, if we measure Psub(1), then,
according to this criterion, we can assign a definite value to Psub
(2). Yet, according to the criterion of reality, it is not clear
why we can assign Qsub(2) and Psub(2) at the same time, unless we
had measured Qsub(l) and Psub(1) simultaneously. The weakness is so
obvious that it seems we can dismiss the EPR argument at once.
Consequently, we might conclude, there is no reason to enter into
the mathematical intricacies of EPR argumentation.
As Fine and I have argued, EPR's demonstration of simultaneous P and
Q values depends not on the criterion of reality but on the state
descriptions in accord with the eigenstate-eigenvalue rule (the
criterion of reality is only introduced to show that it is
consistent with this rule; Beller and Fine 1994). The main point,
and the strength of the EPR argument, was to challenge the adequacy
of the quantum mechanical characterization of a system's state by
means of a wave function. A mathematical elucidation in the EPR
paper demonstrated that such a description introduces nonclassical
features of entanglement, or correlation, that are at odds with the
deeply entrenched intuitions about the individuation of physical
systems. Bohr's presentation of EPR conceals this crucial insight.
Thus the notion of "physical reality" is the focal point of Bohr's
summary of EPR, but not of the EPR paper itself. Bohr, as we have
noted, was not satisfied with stating his metaphysical disagreements
with Einstein--he wanted to "win" the discussion.13 He therefore
defined the ground of the discussion as if Einstein and he shared
some basic presuppositions about how physicists conceive of
reality: "The extent to which an unambiguous meaning can be
attributed to such an expression as 'physical reality' cannot of
course be deduced from a priori philosophical conceptions, but--*as
the authors of the article cited themselves emphasize*--must be
founded on a direct appeal to experiments and measurements" (Bohr
1935a, 696, my italics).
Compare this with the EPR wording: "The elements of the physical
reality cannot be determined by *a priori* philosophical
considerations, but must be found by an appeal to results of
experiment and measurements" (EPR, 777). Note the subtle change in
wording and fundamental change in meaning: EPR talked
about "elements of the physical reality," while Bohr talked about
the "meaning" of the notion of reality. In the EPR discussion, the
elements of physical reality are the physical variables that can be
predicted with certainty-one can reformulate the EPR wording in
terms of the adequacy of theoretical notions, without invoking the
concept of reality. Bohr reformulated the passage from EPR into a
metaphysical discussion of what physicists mean when they
say "reality." This reformulation, together with Bohr's repetition
of a few measurement procedures, has a strong rhetorical effect.
Following Bohr's analysis of measurement procedures time and time
again, the reader enters into Bohr's frame of mind and, without
noticing, loses any critical perspective on the verificationist
ground that Bohr gradually and carefully builds. By tinkering with
the wording of EPR, Bohr creates an illusion that Einstein, Bohr,
and the reader all share the same epistemological stand concerning
the connection between theory and experiment. It is on
this "common" ground that Bohr "defeats" Einstein.
The sloppy wording in the beginning of the EPR paper, where the
authors write about "objective reality, which is independent of any
theory," seems to support Bohr's ingenious rhetorical ploy. The
opening lines of the EPR paper express a naive, simplistic notion
of the "correspondence theory of truth," where theoretical "concepts
are intended to correspond with the objective reality" (EPR, 777).
Not much philosophical sophistication is needed in order to ask:
What kind of access do the EPR authors have to this reality, which
is "independent of any theory"? Is not their stand simply a
metaphysical prejudice? Is Bohr not right to combat their
unfounded position? In particular, is Bohr not right that a more
adequate definition of reality is badly needed?
As I have mentioned, EPR did not use this unfortunate conception of
physical reality in their paper. Yet their poor wording seems to
call for a response to their formulation of the concept of physical
reality. From the two notions of reality--the naive realist
version of EPR and the verificationist version of Bohr--the latter
is the more defensible and sophisticated. By fiat, the reader
seems to have no choice but to follow the lesser of the two evils.
Einstein appears to be a naive, outmoded scientific realist who "in
regard to quantum physics is out to lunch" (Pais 1991,434).
Quite apart from the fact that this poor definition of reality is
never used in the paper, such a simplistic notion of reality is not
Einstein's. Einstein himself ridiculed such a naive approach.
Einstein wrote: "'The world of bodies is real.' . . . The above
statement appears to me to be, in itself, meaningless, as if one
said: 'The world of bodies is cock-a-doodle-doo.' It seems to me
that 'real' is in itself an empty, meaningless category" (quoted in
Howard 1990, 368, Einstein's italics)14 Einstein's realism has
been described in Fine's (1986) pioneering analysis, and the
discussion further extended and analyzed in Howard (1990, 1993) and
Beller (forthcoming). For Einstein, the notion of scientific truth
is Kantian and holistic: the truth of a scientific statement does
not reside in its correspondence with reality but derives from the
adequacy of the unified conceptual model to which it belongs (the
empirical adequacy of such a model is one of the conditions for its
truth; the logical simplicity of its foundation is another).
Einstein's realism avoids the choice between naive realism and
simple-minded positivism.
As Fine (1986) has pointed out, the final draft of the EPR paper was
written by Boris Podolsky, so it seems that it is Podolsky's rather
than Einstein's conception of reality that is reflected in the
opening pages. Yet, due to the tendentious recollections of the
Gottingen-Copenhagen physicists and to some careless wording in the
EPR paper, Einstein's conception of reality is widely
misrepresented and misunderstood. The myth of Einstein the naive
realist and the myth of Bohr's triumphant defeat of Einstein in
their debate over EPR go hand in hand.
Disturbance, Reality, and Acausality
The EPR challenge forced Bohr to make basic changes in his philosophy
of complementarity, undermining the notion of disturbance on which
his pre-1935 philosophy was built (Fine 1986; Beller and Fine 1994).
Bohr's reaction to EPR was an opportunistic one, in the sense
of "opportunism" that I discussed in chapter 3. As I will shortly
argue, not only Bohr's concept of disturbance, but all the basic
tenets of Bohr's philosophy--the problem of reality, acausality,
and the nature of measurement--underwent a complete transformation,
even a reversal, from his early (pre-1935) work to his later (post-
1935) writings. Bohr's early and later philosophical writings
cannot be unified into a coherent interpretive structure. No wonder
scholars who assume that Bohr's philosophical framework underwent
no substantial change over the years (at most, some refinement of
terminology) experience formidable difficulties in understanding
Bohr's thought.
After 1935, operationalism became a focal point of Bohr's philosophy}
5 Bohr (1935b) presented the operational definition of concepts not
merely as plausible but as the only possible one, claiming that the
account of measuring instruments constitutes the only basis for the
definition of physical concepts. Despite the fact that Bohr
criticized Heisenberg's fallacious reasoning in his description of
the y-ray experiment in the uncertainty paper, Heisenberg's idea
of "uncontrollable disturbance" was the core of Bohr's pre-1935
writings. It inspired Bohr's understanding of the nature of
measurement, his stand on the interrelation between observation and
definition, and his elaboration of the philosophical problems of
causality and reality in the quantum domain.
The concept of disturbance, inaugurated in Heisenberg's uncertainty
paper, is an ill-fated and inconsistent one: it presupposes the
existence of objective exact values that are changed by measurement,
contrary to the desired conclusion of indeterminacy. Eventually,
Bohr (1939) would repudiate the disturbance concept. Bohr's
followers consequently minimized its significance in Bohr's
writings (Pais 1991). Yet disturbance imagery is entrenched in
Bohr's thought at the time. Disturbance is the reason for the
inseparability of phenomena and the means of observing them, for
complementarity (rather than a later identity between definition and
observation), and for Bohr's initial conflation of the problems of
objectivity and causality. According to Bohr, both objectivity and
causality presuppose the notion of the exact definition of the state
of a physical system, excluding in principle all disturbances.
Bohr argued that if in the quantum domain every measurement implied
intervention, or finite, nonnegligible interaction, then the
conclusion of inevitability and the final overthrow of both reality
and causality immediately follow. Later, when Bohr abandoned the
imagery of disturbance, the reality and acausality problems became
dissociated, and each underwent an independent transformation.
Bohr's early description of the nature of measurement invoked the
realistic imagery of existing phenomena (no operational definition
of concepts yet!) and of disturbance, or finite changes in the
phenomena, during measurement. This idea of disturbance is
elaborated in an early manuscript by Bohr: "Our usual description
of physical phenomena is based entirely on the idea that the
phenomena concerned may be observed without disturbing them
appreciably. . . . the quantum postulate implies that no observation
of atomic phenomena is possible without their *essential
disturbance*" (1927d; BCW, 6:91, my italics).
This is not an accidental, unhappy choice of terminology--the idea
persists in all of Bohr's writings in the late 1920s to early
1930s:
Unavoidable influence on atomic phenomena [is] caused by observing
them. (1929b, 100; BCW, 6:216)
Phenomena are influenced by observation. (1930, 134)
The measurement of the positional coordinate of a particle is
accompanied not only by finite change in the dynamical variables.
(1928,103)
The action of the measuring instruments on the object under
investigation cannot be disregarded. (1933, 7)
Interaction between these instruments and the atom itself [is] an
exchange of such magnitude that it erases all trace of the
phenomena we try to observe. (1935b, 219)
The idea of disturbance is intimately connected with the immediately
appealing-but in fact wrong-idea that the mere fact that measuring
devices are themselves composed of atoms necessitates the
inseparability of atomic phenomena and the means of observing
them. Bohr often emphasized the atomic structure of measuring
devices as the reason for the finitude, or wholeness, of the
quantum interaction, which, in turn, implies the inseparability of
phenomena and observation. The underlying--incorrect--intuition is
that because in the quantum domain the interaction of measuring is
of the same order of magnitude as the phenomena being measured, such
finite interaction (in contrast to the classical case) cannot be
neglected, or "accounted for." 16
The connection between finite disturbance and the atomic
constitution of measuring devices is prominent in Bohr's pre-1935
writings: "We cannot close our eyes to the fact that not only the
bodies under investigation, but also the measurement instruments
are built up of atoms" (1931b, 152) 17 The atomic constitution of
measuring devices implies not only difficulty in separating atomic
phenomena and observation but a "difficulty of distinguishing
between object and measuring instruments. With the latter problem
we are at once presented when it is necessary to take the atomic
constitution of the measuring instruments into account" (1931b,
155). The idea of disturbance implies a symmetry between measuring
devices and atomic objects: "The idea of the means of observation
independent of the phenomena or of phenomena independent of means of
observation cannot be maintained" (1927d, 91)--a claim that stands
in striking contrast to Bohr's later position that the nature of
atomic objects and the nature measuring devices are fundamentally
different.
The idea of disturbance, of "interference" with the course of
phenomena, underlay Bohr's pre-1935 writings on both objectivity
and causality. The discovery of the quantum of action throws "a new
light upon the old philosophical problem of the objective existence
of phenomena independently of our observations. Any observation
necessitates an *interference with the course of the
phenomena*. . . . the limit of speaking about phenomena as existing
objectively finds its expression. . . just in the formulas of
quantum mechanics" (1929a, 115; BCW, 6:249; my italics). Bohr's
understanding of the breakdown of objectivity initially implied the
introduction of a perceiving subject into physics18 --an idea that
Bohr would later deny vigorously (when he identified the act of
measurement with the permanence of the recordings of measuring
devices). The "close analogy" Bohr drew between the impossibility
of strictly separating phenomena and observation and the "general
limits of man's capacity to create concepts which have their roots
in our differentiation between subject and object," as well as
Bohr's idea of introspection when no separation between object and
subject exists, is inspired by his notion of disturbance. Bohr
illustrated the "unavoidable" introduction of "subjectivity" by
describing misleading analogies with relativity theory: "[The]
theory of relativity. . . was destined to reveal the subjective
character of all the concepts of classical physics" (1929b, 97;
BCW, 6:213).
After 1935, as a response to the EPR challenge, Bohr abandoned the
terminology and underlying imagery of disturbance. The problems of
reality and causality became dissociated, and Bohr made an about-
face in his opinions on the nature of measurement. In contrast to
the earlier symmetry between the measuring and the measured, Bohr
introduced the idea of a fundamental distinction between the nature
of atomic objects and that of measuring devices. In Bohr's later
writings an experimental device must be classical, "heavy," and its
atomic constitution must be, "in principle," disregarded. The
measurement interaction cannot be separated from phenomena, not
because one cannot neglect the quantum, but precisely because one
must neglect it: "The essentially new feature in the analysis of
quantum phenomena is, however, the introduction of the measuring
*apparatus and the objects under investigation*. This is a direct
consequence of the necessity of accounting for the functions of the
measuring instruments in purely classical terms, excluding, in
principle, any regard to the quantum of action" (1958c, 3, Bohr's
italics). The crux of Bohr's later arguments is precisely that the
measurement interaction is nonformalizable in principle. 19
As Bohr's ideas on the nature of measurement took an about-face, his
accounts of objectivity and causality changed fundamentally. In
Bohr's early writings the main psychological analogue of the
inseparability of phenomena and observation was introspection, in
which no sharp distinction can be made between object and subject.
As in psychology, so in physics, the idea of objectivity, which
avoids any reference to a perceiving subject, can no longer be
maintained. Bohr's implicit definition of objectivity was initially
metaphysical-the existence of objects and events having an
independent reality regardless of being observed or not. In
contrast, Bohr's later definition of objectivity was
intersubjective: Bohr identified an objective description with a
consistent method of recounting facts that can be understood
clearly by others. After 1935, Bohr was eager to retain objectivity,
not to dispense with it. It is not clear how the use of imprecise
common language ensures unambiguity of communication-one can easily
argue that esoteric technical language is more suitable, as
Heisenberg, in fact, did (see chapter 8).
This change in the conception of objectivity, from observer
independence to unambiguous communicability (a change forced by
EPR), corresponded directly to Bohr's about-face on the nature of
measurement: communication is only unambiguous if we put a
separation line between subject and object. Consequently, Bohr's
analogies between quantum physics and psychology change in
character, from the example of introspection, in which no
separation between subject and object exists, to the famous case of
Mo1ler's student, who becomes confused trying to untangle his
different selves. Some students of Bohr's thought read this example
incorrectly; Bohr advances it to argue that the line between object
and subject must be drawn sharply, not that the two are
inseparable. If we blur the line, as the poor philosophy student
does, we become incapacitated, unable to function in daily life and
to look for employment. Eventually, we may even fall into
madness: "This situation can give rise to what we call splitting of
personality." The chilling moral of Moller's humorous story is "how
essential it is to pay attention to the separation lines as for
example, in physics, separation between system and the observer"
(1958b, 715).
For the later Bohr, separating the "content of our consciousness"
and "the background loosely referred to as ourselves" is not only
not impossible-it is mandatory for "unambiguous communication," even
though the separation lines may be placed differently in various
contexts due to the "richness of the reality of conscious life"
(1960c, 13).
Bohr's Doctrine of the Indispensability of Classical Concepts and the Correspondence Principle
Bohr's doctrine of the indispensability of classical concepts
underlies his philosophy of complementarity. Give up this
doctrine, and the inevitability of complementarity in physics
dissolves. Even today, the most sympathetic interpreters of Bohr's
thought do not feel at ease with Bohr's categorical assertions of
the impossibility of concepts other than the classical (Hooker
1994; Howard 1994). In the past, some of Bohr's closest
collaborators, Heisenberg and Born, rejected this peculiar doctrine
(see chapter 8).
Bohr presented his doctrine of the indispensability of classical
concepts in a deceptively convincing way. Classical concepts, Bohr
argued, being direct extensions of our intuition, are necessary to
describe experiments and to communicate to others what we have done
and learned. Bohr's claim that classical concepts constitute a
necessary extension of our intuition is, however, both historically
and philosophically inaccurate. This claim disregards the
tremendous gap between our essentially Aristotelian intuition and
the sophisticated, abstract framework of NewtoRian physics (and
thus ignores the huge intellectual efforts of the founders of modem
science, who replaced the intuitive Aristotelian world with the
counterintuitive Galilean-Newtonian one). Nor is it obvious that
the most essential feature of a measuring device is the classically
described space-time configuration of its components. Dirac, for
example, at least initially, was at odds with Bohr on this point.
As Oskar Klein recalled: "Who did not quite agree with Bohr at
first was Dirac. . . . he made some kind of observation philosophy
which had to do with permanent marks. Bohr objected a lot to that
because it . . . is not the essential thing in the observation. But
Dirac made that, so to say, as the essential thing. . . because one
part of Bohr's view was that you had to . . . use the whole
classical theory in describing observation. And I think that was
not near to Dirac's mind at the time" (interview with Klein, AHQP).
The historical context of Bohr's initial idea of the
indispensability of classical concepts was as follows: As I have
argued, the biggest philosophical quandary of the new matrix
mechanics involved its elimination of the space-time container from
the atomic world (chapter 2). Heisenberg, Born, and Jordan accepted
lack of visualization as the necessary price-and perhaps, in fact,
a bonus-of an outstanding technical advance. Even Bohr became "more
and more convinced of the need of a symbolization if one wants to
express the latest results of physics" (Bohr to Harald Heffding,
quoted in Jammer 1966, 347).
The great success of Schrodinger's competing version of quantum
mechanics changed Heisenberg's stand on this issue. As Klein
recalled, throughout fall 1926 and winter 1927, Bohr and Heisenberg
searched feverishly for a way "to introduce space and time into
these complex formulae" (interview with Klein, AHQP). Heisenberg
finally came out with the answer in his uncertainty paper-all
classical space-time concepts can be retained in the quantum domain
if one gives up their precise simultaneous use; yet, in contrast to
classical theory, variables in the quantum domain are subject to
the uncertainty relations.
What for Heisenberg was an exercise in possibility (though at times
he confused it with the rhetoric of inevitability; chapters 5 and
9) became, for Bohr, the argument for indispensability. The
indispensability of classical concepts was discussed thoroughly in
the correspondence between Bohr and Schrodinger at the time. Bohr's
dismissal of the possibility of developing "new" concepts was
expressed initially as an argument against Schrodinger's plan to
search for a new conceptual theoretical scheme that would avoid
quantum theory's peculiarities and "irrationalities." 20
When Bohr wrote that the "interpretation of the experimental
material rests extensively upon the classical ideas" (1927d, 91) or
that "it lies in the nature of physical observation that all
experience must ultimately be expressed in terms of classical
concepts, neglecting the quantum of action" (1929b, 94-95; BCW,
6:210-11), he was not referring to the idea of treating measuring
devices as classical in nature, as some commentators have understood
it, reading Bohr's later ideas backward. Instead, Bohr was making
a broad Kantian statement about the impossibility of describing
physical experience in general by any concepts other than classical
ones.
As in Heisenberg's uncertainty paper, so in Bohr's numerous
discussions of thought experiments in his pre-1935 writings,
classical concepts apply simultaneously to microscopic objects and
macroscopic measuring devices. In Bohr's early writings, he spoke
of the "preestablished harmony" between quantum theoretical concepts
and the possibilities of measurement: a measuring device seems to
be a perfect match to the wave theoretical definition of
particles: "Uncertainty cannot be avoided. . . . the experimental
devices. . . are seen to permit only conclusions regarding the
space-time extension of the . . . wave fields [associated with
particles]" (1928, 101) 21
The measurement interaction in Bohr's early writings was quantum
mechanical-quantum uncertainty applied even to the whole
macroscopic y-ray microscope as a measuring device: "A closer
investigation shows, however, that such a measurement [of the
momentum transmitted during measurement] is impossible, if at the
same time one wants to know the position of the microscope with
sufficient accuracy. In fact, *it follows from the experiences
which have found expression in the wave theory of matter that the
position of the center of gravity of a body and its total momentum
can only be defined within the limits of reciprocal accuracy given
by relation* (2) [the uncertainty relation]" (my italics). Bohr
summarized: "The uncertainty equally affects the description of the
agency of measurement and of the object" (1928, 101, 102).
In striking contrast to his later analyses, before 1935 Bohr claimed
that only by incorporating the atomic nature of measuring devices
more thoroughly into the analysis of the microdomain could the
interpretative program be advanced. After 1935 Bohr moved gradually
to an intermediate position, according to which one can "to a very
high degree of approximation disregard the molecular constitution of
the measuring instruments" (1948, 451, my italics).
This "approximation" later became a matter of principle-it was now
a "logical" necessity to ignore the atomic structure of measuring
devices and describe them in "purely classical terms, excluding in
principle any regard to the quantum of action" (1958c, 3-4).
This "essentially new feature" in the analysis of quantum phenomena
is tied directly to the "heaviness" of the measuring devices as
opposed to the microobjects: apparatus are "sufficiently large and
heavy to allow an account of their shape and relative positions and
displacements without any regard to any quantum features inherently
involved in their atomic constitutions" (1962, 24).
Similar passages are scattered throughout Bohr's later writings
(Bohr 1958b, 712; 1958c, 2-4). This "heaviness" is now crucial for
unambiguous communication, and, indeed, in order to talk about well-
defined experimental conditions at all. 22 After 1935 Bohr held
that the "heaviness" of the measuring apparatus, and the
fundamental distinction between measuring and measured that follows
from it, is the reason phenomena and observation are inseparable
(1958b, 712, my italics). 23
This fundamental distinction between the measuring and the measured
undermined Bohr's earlier arguments about the complementarity of
space-time and causality. These arguments relied on
the "uncontrollability" of the measuring interaction, which in turn
was demonstrated by applying the uncertainty relations to the
measuring devices regarded as objects of measurement. 14 But,
once Bohr introduced the idea that the fundamental distinction
between the measuring and the measured is tied directly to physical
constitution ("heaviness"), the same object simply cannot be used
as a measuring device and as a measured object even in different
contexts. 25 In this case, not only Bohr's arguments about the
complementarity of space-time and causality but the whole early
enterprise of demonstrating compatibility between the quantitative
conclusions of the quantum formalism (uncertainty relations) and
the experimental situation (analysis of measurements) is
undermined. It is only in some vague sense that one can claim, as
Bohr did after 1935, that the unsurveyability of the measurement
interaction and the consequent "wholeness" of quantum phenomena
dictate a departure from classical description (see chapter 9).
For example, it is not clear in Bohr's later writings why
this "wholeness" indicates the necessity of statistical description-
-in fact, it is not clear how one assesses the necessary features of
an appropriate description at all (see chapter 12). Bohr simply
retained an intuitive connection between the necessity of classical
concepts, the inseparability of phenomena and observation, and
acausality-ignoring their separate sources in now incompatible
arguments. This maneuver has resulted in the misconception that
Bohr's philosophical framework remained unchanged.
While the meaning of Bohr's doctrine of the indispensability of
classical concepts varied over the years, there is a sense in which
it remained unchanged. The claim that classical concepts are
necessary is connected with Bohr's principle of correspondence-a
principle that guided Bohr's early work in quantum theory, and to
which Bohr subscribed all his life. Bohr had introduced the
correspondence principle as a heuristic guide, as a methodological
principle of research-a "formal analogy between the quantum theory
and the classical theory." The correspondence principle stated,
not only that for large quantum numbers classical and quantum
calculations should coincide, but also that for small quantum
numbers there is a correspondence between various harmonic
components of motion computed classically and the characteristics of
various types of quantum transition from one stationary state to
another (Jammer 1966; Hendry 1984; Darrigol 1992a).
Bohr's correspondence principle, applied with ever increasing rigor
by Kramers, Born, and finally, in a fundamental way, by Heisenberg,
led to the formulation of the new quantum formalism. Even before
the discovery of the new quantum theory, mathematical physicists
(Sommerfeld, for example) perceived correspondence arguments as a
temporary heuristic tool, criticizing Bohr's elevation of the
principle into a "law of the quantum theory" (Mehra and Rechenberg
1982). After the discovery of matrix mechanics the natural
conclusion was that the consistent mathematical formalism should
supersede Bohr's correspondence principle. Yet Bohr never
abandoned it, both as a heuristic and as man interpretive
principle. Bohr had no doubt that correspondence considerations
must guide the development of quantum electrodynamics. 26
And it served as a touchstone in his later writings: "It is of
course important in each case to remember how far from the point of
view of correspondence we can acquaint ourselves with the new
situation" (1957c, 666).
Bohr's insistence on the continuing importance of the correspondence
principle seems puzzling. Dirac, who had himself initially used
correspondence arguments in a most ingenious way (Darrigol 1992a),
did not share Bohr's attitude: "He [Bohr] still referred to the
correspondence principle for some years, I think, after quantum
mechanics really made definite equations which would replace the
correspondence principle. . . . When one gets so absorbed with one
idea, one does stick to it always" (interview with Dirac, 14 May
1963, AHQP). Why did Bohr need correspondence arguments to acquaint
himself "with the new situation"? Why did he not refer in his
writings to features of the quantum formalism, and to such
associated interpretive schemes as the projection postulate? Why
did he never consider the quantum formalism with articulated bridge
principles a viable interpretive option?
I can suggest part of the answer: For Bohr, the necessity of the
correspondence principle and the indispensability of classical
concepts were not merely the subjects of an abstract philosophical
inquiry. The purely philosophical considerations were invoked
to "dress up" a methodological question--the question of the success
of a particular program of investigation. His heuristics, which he
internalized because of long and successful use by himself and
others, eventually became the most essential feature of all possible
research programs for Bohr. 27 It is precisely because Bohr did
not (and possibly could not-see chapter 12) participate in the
mathematical elaboration and consolidation of quantum theory that
classical theories with their underlying mathematical structures
appeared to him the only tools one could use to grapple with the
quantum world. In this way, personal idiosyncrasy was transformed
into an overarching principle of knowledge. Since the claim that
classical concepts are necessary is the least defensible of Bohr's
assertions, its rhetorical underpinnings are especially strong. It
is usually presented as "obvious," as a "simple logical demand"
(1948; 1950,512-13; 1958d, 727).
I have argued that it is impossible to combine Bohr's pre-1935 and
post-1935 writings into a unified, coherent structure, and that a
basic change occurred in Bohr's notions of disturbance, reality,
acausality, and the indispensability of classical concepts. It is
tempting to assume that perhaps Bohr's early and later writings,
taken separately, are systematic and free of contradictions. Yet
textual evidence does not support this assumption either. Bohr's
discussions of causality are a case in point.
Despite Bohr's lifelong preoccupation with the issue of causality,
his use of this concept was unsystematic and contradictory. His
notion of causality was very "thick": Sometimes it was a cause-
effect relationship. Sometimes it was "determinism." Sometimes it
was an epistemological, other times an ontological, definition.
Sometimes causality was equated with the applicability of the
conservation laws of energy and momentum, other times with the
simultaneous applicability of space-time and energy-momentum
concepts. Sometimes Bohr's understanding of causality was
probabilistic, applied to an individual system; and sometimes it was
a statistical interpretation, applied to an ensemble of similar
systems. Bohr often conflated determinism and predictability,
which are in fact different notions.
In Bohr's later writings, he often employed a definition of causal
description as predictability: "In physics, causal description. . .
rests on the assumption that the knowledge of the state of a
material system at a given time permits the prediction of its state
at any subsequent time" (1948,445). Note that such a definition
of "causality," and correspondingly of "acausality," is compatible
both with the idea that the laws of nature themselves are
statistical (Born's view) and with the position that the laws of
nature are deterministic and statistics is introduced only because
of an inability to determine simultaneously and exactly all the
physical variables of a state (Heisenberg's view). Bohr employed
both of these mutually contradictory concepts of acausality at
roughly the same time. He spoke in an ontological vein, about
a "free choice of nature": "The specification of the state of a
physical system evidently cannot determine the choice between
different individual processes" (1948, 446). In an earlier paper
Bohr argued that "quantum postulates . . . imply an explicit
renunciation of any causal description. . . . as regards its
possible transitions from a given stationary state to another
stationary state. . . the *atom may be said to be confronted with a
choice* for which, according to the whole character of the
description, *there is no determining circumstance*" (1939, 385, my
italics). Yet, in the same paper, a few pages later, Bohr used
Heisenberg's argument for acausality, incompatible with the
position just cited: "The essentially statistical nature of this
account [is] a direct consequence of the fact that the commutation
rules prevent us to identify at any instant more than a half of the
symbols representing the canonical variables with definite values of
the corresponding classical quantities" (1939, 387).
contradictions characterize the interpretive pronouncements of
other quantum physicists. The Copenhagen interpretation was
erected, not as a consistent philosophical framework, but as a
collection of local responses to changing challenges from the
opposition."
1. My presentation of Bohr's response to EPR (Bohr 1935a) follows
Beller and Fine (1994) closely. I am deeply grateful to Arthur Fine
for most rewarding work together.
2. In the EPR mathematical presentation, the variables are a
position coordinate and linear momentum.
3. The argument of EPR is a complex one-it was first analyzed in
Fine (1986, chap. 3) and extended in Beller and Fine (1994). In
particular, Beller and Fine discuss the issues of "incompleteness"
and "inconsistency" in the EPR argument, and the crucial
differences between the EPR argument and Bohr's summary of it.
4. The authors did not use this criterion in the paper. The only
time they referred to it was to demonstrate that such a criterion
is consistent with the eigenstate-eigenvalue rule, whose
applications constitute accepted" quantum mechanical ideas of
reality" (EPR, 778; see also Beller and Fine 1994).
5. It is this answer that Bohr himself later singled out (Bohr
1949); most commentators follow Bohr's later presentations, unaware
of the second voice, discussed in Beller and Fine (1994).
6. It was here that Bohr found" an ambiguity as regards the meaning
of the expression 'without in any way disturbing the system.'"
7. "This conclusion [EPR's] can be attacked by anyone who prefers to
say that P and Q could possess reality only if [they both] could be
simultaneously measured" (Ruark 1935,466).
8. The possibility of such a reading was first suggested to me by
Alon Drory.
9. Bohr himself wrote later that he was "deeply aware of the
inefficiency of expression which must have made it very difficult
to appreciate the trend of the argumentation aiming to bring out the
essential ambiguity" (1949, 234).
10. As argued in Beller and Fine (1994), Bohr's talk about
the "wholeness of the experimental situation" reflected his
positivist solution to EPR (where the operational presupposition
implies the inclusion of all the aspects of conditions of
measurement), and not his endorsement of a nonlocal or nonseparable
conception of reality. In fact, Bohr, as did Einstein, considered
the option of nonlocality unacceptable (Beller and Fine 1994).
Bohr's notorious ambiguity creates room for later, charitable
scholars to ascribe to him insights about the nonlocality of the
EPR situation that he in fact did not express (see chapter 12).
11. I discussed these weaknesses in chapter 3. I will further
analyze this issue in chapter 8 and argue that positivism is not a
natural stand for the working scientist.
12. Beller and Fine discuss some potential responses to this
difficulty and find them unsatisfactory (1994,21).
13. From the point of view of the second reading, Bohr probably
imagined initially that he had won the discussion.
14. On other occasions Einstein also rejected the notion that
the "truth" of a theory lay in its "correspondence with
reality." "He [the scientist] will never be able to compare his
picture with real mechanism, and he cannot even imagine the
possibility of the meaning of such a comparison" (quoted in Fine
1986, 93).
15. As I have argued, in 1927 (the Como lecture) Bohr objected to
the operational emphasis in Heisenberg's approach. The definition
of concepts, claimed Bohr at the time, is independent of, and prior
to, any procedure of measurement. As I argued in chapter 6, Bohr
held that the only way to connect the quantum formalism with
observable space-time concepts was through wave theoretical imagery.
16. The idea of disturbance has, of course, a counterpart in the
quantum formalism: the change of a quantum state, or "reduction of
a wave packet." If an atomic system is not in the eigenstate of an
observable, the measurement of this observable alters its state
from a superposition to the eigenfunction corresponding to the
measured value. It is not clear at all how the rules of the quantum
calculus are implied by, or even connected to, the "finitude" of
the quantum of action.
17. The atomic structure of measuring instruments, according to
Bohr, does not merely have far-reaching epistemological
consequences; a more thorough and explicit incorporation of this
fact will eventually lead to further development of the physical
theory itself: "The present formulation of quantum mechanics in
spite of its great fruitfulness would yet seem to be no more than a
first step in the necessary generalization of the classical mode of
description, justified only by the possibility of disregarding in
its domain of application the atomic structure of the measuring
instruments themselves in the interpretation of the results of
experiment" (1937c, 247). A similar idea was developed in Bohr's
(1937d) Hitchcock lectures at Berkeley.
18. "The feature which characterizes the so-called exact sciences
is, in general, the attempt to attain to uniqueness by avoiding all
reference to [a] perceiving subject. This endeavor is found most
consciously, perhaps, in mathematical symbolism which sets up for
our contemplation an ideal of objectivity to the attainment of
which scarcely any limits are set, so long as we remain within a
self-contained field of applied logic. In the natural sciences
there can be no question of a strictly self-contained field of
application of the logical principles, since we must continually
count on the appearance of new facts" (Bohr 1929b, 96-97, BCW, 6:212-
13).
19. "It is decisive to realize. . . that the description of the
experimental arrangements . . . must be based on common
language. . . . This circumstance. . . excludes any separate account
of the interaction between the measuring device and the atomic
objects under investigation" (Bohr 1960c, 773).
20. "1 am scarcely in complete agreement with your stress on the
necessity of developing 'new' concepts. Not only, as far as 1 can
see, we have up to now no cues for such a re-arrangement, but
the 'old' experiential concepts seem to me to be inseparably
connected with the foundation of man's power of visualizing" (Bohr
to Schrodinger, 23 May 1927, AHQP; quoted from Murdoch 1987,101).
21. A similar idea is expressed in the following
passage: "Limitation on the possibilities of measurement is
directly related to apparent contradictions in the discussion of
the nature of light and of material particles" (contradictions that
are removed, according to Bohr, by using the wave theoretical
definition of particles; Bohr 1929b, 95; BCW, 6:211).
22. "In the description of the experimental arrangements we must
certainly use our ordinary language. . . . We can by experiments
only understand something about which we are able to tell others
what we've done and what we've learnt. . . . The rea.son that one
can describe experimental conditions in this matter is that one uses
as apparatus heavy bodies, bodies which are so heavy, immensely
heavy, compared with the single atomic particles that we can, in
the description entirely neglect all implications of the quantum"
(Bohr 1958d, 727).
23. It is this unbridgeable gap between the classical and the
quantum that implies the unsurveyability, or unformalizability, of
the interaction, implying in turn a "wholeness," or the necessity of
specifying the experimental conditions for any definition of
quantum phenomena (Bohr 1961, 77-78). This gap is made even larger
as Bohr talks of the necessity of using not even "classical" but
only "plain" or "ordinary" language (1958c, 2-3; 1958e, 695).
24. Thus, in EPR, one cannot use the exchange of momentum between a
suspended diaphragm and a particle to predict the exact value of
the particle's momentum, because, in order to measure a diaphragm's
momentum, "this body can no longer be used as a measuring
instrument. . . but must. . . be treated, like the particle
traversing the slit, as an object of investigation, in the sense
that the quantum-mechanical uncertainty relations regarding its
position and momentum must be explicitly taken into account" (Bohr
1935a, 698).
25. This fundamental distinction is not merely a semantic one
(the "cut" as discussed in chapter 9) of the context in which, for
example, the diaphragm is used.
26. "That for the moment the paradoxes connected with the use of the
idealization of point charge for the electron are preventing the
development on correspondence lines of a comprehensive relativistic
quantum electrodynamics, must indeed rather be imputed to our
failure. . . to grasp some deeper feature of the stability of the
individual particles themselves than to any lack of soundness of
the general lines on which the incorporation of the quantum of
action in atomic theory has been achieved" (Bohr 1939, 389).
27. In this sense, Bohr is similar to Einstein. An enlightening
analysis of Einstein's philosophical makeup was given by Arthur
Fine (1986), who argued that for Einstein philosophical questions
about "realism" and "determinism" were not abstract philosophical
questions but questions of the success of research programs assuming
these notions.
JohnEB
JohnEB
Is it possible that the current dominant paradigm in physics is wrong on everything? Here is the result on supersymmetry (SUSY):
String Theorists Throw SUSY Under the Bus
http://www.math.columbia.edu/~woit/wordpress/?p=3864
JohnEB
So, the bottom line is that they see nothing, but a press release has been issued about how wonderful it is that they have looked for evidence of a Multiverse, without mentioning that they found nothing. As one would expect, this kind of behavior leads to BBC stories about how the Multiverse has “received a boost”, exactly the opposite of what the scientific evidence shows.
http://www.math.columbia.edu/~woit/wordpress/?p=3879
JohnEB
More fairytale physics:
The Fabric of the Cosmos on PBS
A four-part NOVA series based upon Brian Greene’s The Fabric of the Cosmos is coming to PBS this fall, starting November 2. In some sense this is a follow-on to his wildly successful The Elegant Universe NOVA series from 2003, which was largely devoted to promoting string theory. From the program description and preview it appears that the new shows don’t emphasize string theory, although the fourth of the series promotes the Multiverse (Clifford Johnson joins the effort here), along the lines of Brian’s latest book The Hidden Reality.
JohnEB
world’s leading experts on Einstein’s general theory of relativity and co-author, with Stephen Hawking, of the seminal book The Large
Scale Structure of Space-Time (Cambridge University Press, 1975).
The notion of parallel universes leapt out of the pages of fiction into scientific journals in the 1990s.
Many scientists claim that megamillions of other universes, each with its own laws of physics, lie out
there, beyond our visual horizon. They are collectively known as the multiverse. The trouble is that
no possible astronomical observations can ever see those other universes. The arguments are indirect at best.
And even if the multiverse exists, it leaves the deep mysteries of nature unexplained.
_________________________________________________
What Lies Beyond?
When astronomers peer into the universe, they see out to a distance of about 42 billion lightyears‚
our cosmic horizon, which represents how far light has been able to travel since the big bang (as well as how
much the universe has expanded in size since then). Assuming that space does not just stop there and may well
be infinitely big, cosmologists make educated guesses as to what the
rest of it looks like.
Level 1 Multiverse: Plausible
The most straightforward assumption is that our volume of space is a representative
sample of the whole. Distant alien beings see different volumes‚ but all of these look
basically alike, apart from random variations in the distribution of matter. Together these
regions, seen and unseen, form a basic type of multiverse.
Level 2 Multiverse: Questionable
Many cosmologists go further and speculate that, sufficiently far away, things look quite
different from what we see. Our environs may be one of many bubbles floating in an otherwise
empty background. The laws of physics would differ from bubble to bubble, leading to an almost
inconceivable variety of outcomes. Those other bubbles may be impossible to observe even in
principle. The author and other skeptics feel dubious about this type of multiverse.
_________________________________________________
In the past decade an extraordinary claim has captivated cosmologists: that the expanding
universe we see around us is not the only one; that billions of other universes are out there,
too. There is not one universe—there is a multiverse. In Scientific American articles and
books such as Brian Greene’s latest, The Hidden Reality, leading scientists have spoken of a
super-Copernican revolution. In this view, not only is our planet one among many, but even
our entire universe is insignificant on the cosmic scale of things. It is just one of countless
universes, each doing its own thing.
of about 42 billion light-years, our cosmic visual horizon. We have no reason to suspect the universe
stops there. Beyond it could be many—even infinitely many—domains much like the one
we see. Each has a different initial distribution of matter, but the same laws of physics operate
in all. Nearly all cosmologists today (including me) accept this type of multiverse, which Max
Tegmark calls “level 1.” Yet some go further. They suggest completely different kinds of universes,
with different physics, different histories, maybe different numbers of spatial dimensions.
Most will be sterile, although some will be teeming with life. A chief proponent of this “level 2”
multiverse is Alexander Vilenkin, who paints a dramatic picture of an infinite set of universes with
an infinite number of galaxies, an infinite number of planets and an infinite number of people
with your name who are reading this article. Similar claims have been made since antiquity by many
cultures. What is new is the assertion that the multiverse is a scientific theory, with all that
implies about being mathematically rigorous and experimentally testable. I am skeptical about this
claim. I do not believe the existence of those other universes has been proved—or ever could be.
Proponents of the multiverse, as well as greatly enlarging our conception of physical reality, are
implicitly redefining what is meant by “science.”
.
.
.
The proponents are telling us we can state in broad terms what happens 1,000 times as far as our cosmic
horizon, 10100 times, 101,000,000 times, an infinity—all from data we obtain within the horizon. It
is an extrapolation of an extraordinary kind. Maybe the universe closes up on a very large scale, and
there is no infinity out there. Maybe all the matter in the universe ends somewhere, and there is empty
space forever after. Maybe space and time come to an end at a singularity that bounds the universe. We
just do not know what actually happens, for we have no information about these regions and never will.
_________________________________________________
SEVEN QUESTIONABLE ARGUMENTS
Most multiverse proponents are careful scientists who are quite aware of this problem but think we can
still make educated guesses about what is going on out there. Their arguments fall into seven broad
types, each of which runs into trouble.
Space has no end.
Few dispute that space extends beyond our cosmic horizon and that many other domains lie beyond what
we see. If this limited type of multiverse exists, we can extrapolate what we see to domains beyond
the horizon, with more and more uncertainty as regards the farther-out regions. It is then easy to imagine
more elaborate types of variation, including alternative physics occurring out where we cannot see.
But the trouble with this type of extrapolation, from the known to the ununknown, is that no one can prove
you wrong. How can scientists decide whether their picture of an unobservable region of spacetime is a
reasonable or an unreasonable extrapolation of what we see? Might other universes have different initial
distributions of matter, or might they also have different values of fundamental physical constants, such as
those that set the strength of nuclear forces? You could get either, depending on what you assume.
Known physics predicts other domains.
Proposed unified theories predict entities such as scalar fields, a
hypothesized relative of other space-filling fields such as the magnetic field. Such fields should drive cosmic
inflation and create universes ad infinitum. These theories are well grounded theoretically, but the
nature of the hypothesized fields is unknown, and experimentalists have yet to demonstrate their existence,
let alone measure their supposed properties. Crucially, physicists have not substantiated that the dynamics
of these fields would cause different laws of physics to operate in different bubble universes.
The theory that predicts an infinity of universes passes a key observational test.
The cosmic microwave background radiation reveals what the universe looked like at the end of its hot
early expansion era. Patterns in it suggest that our universe really did undergo a period of inflation.
But not all types of inflation go on forever and create an infinite number of bubble universes. Observations
do not single out the required type of inflation from other types. Some cosmologists such as Steinhardt even
argue that eternal inflation would have led to different patterns in the background radiation than we see
[see “The Inflation Debate,” by Paul J. Steinhardt; Scientific American, April]. Linde and others
disagree. Who is right? It all depends on what you assume about the physics of the inflationary field.
Fundamental constants are finely tuned for life.
A remarkable fact about our universe is that physical constants have just the right values needed to allow
for complex structures, including living things. Steven Weinberg, Martin Rees, Leonard Susskind and others
contend that an exotic multiverse provides a tidy explanation for this apparent coincidence: if all possible
values occur in a large enough collection of universes, then viable ones for life will surely be found somewhere.
This reasoning has been applied, in particular, to explaining the density of the dark energy that is speeding up
the expansion of the universe today. I agree that the multiverse is a possible valid explanation for the
value of this density; arguably, it is the only scientifically based option we have right now. But we have no
hope of testing it observationally. Additionally, most analyses of the issue assume the basic equations of physics
are the same everywhere, with only the constants differing—but if one takes the multiverse seriously, this
need not be so [see “Looking for Life in the Multiverse,” by Alejandro Jenkins and Gilad Perez; Scientific American,
January 2010].
Fundamental constants match multiverse predictions.
This argument refines the previous one by suggesting that the universe is no more finely tuned for life than it
strictly needs to be. Proponents have assessed the probabilities of various values of the dark energy density.
The higher the value is, the more probable it is, but the more hostile the universe would be to life.
The value we observe should be just on the borderline of uninhabitability, and it does appear to be so.
Where the argument stumbles is that we cannot apply a probability argument if there is no multiverse to apply the
concept of probability to. This argument thus assumes the desired outcome before it starts; it simply is not
applicable if there is only one physically existing universe. Probability is a probe of the consistency
of the multiverse proposal, not a proof of its existence.
String theory predicts a diversity of universes.
String theory has moved from being a theory that explains everything to a theory where almost anything is possible.
In its current form, it predicts that many essential properties of our universe are pure happenstance. If the
universe is one of a kind, those properties seem inexplicable. How can we understand, for example, the fact
that physics has precisely those highly constrained properties that allow life to exist? If the universe is one
of many, those properties make perfect sense. Nothing singled them out; they are simply the ones that arose in
our region of space. Had we lived elsewhere, we would have observed different properties, if we could indeed
exist there (life would be impossible in most places). But string theory is not a tried-and-tested theory; it is not
even a complete theory. If we had proof that string theory is correct, its theoretical predictions could be a
legitimate, experimentally based argument for a multiverse. We do not have such proof.
In seeking to explain why nature obeys certain laws and not others, some physicists and philosophers have speculated
that nature never made any such choice: all conceivable laws apply somewhere. The idea is inspired in part by quantum
mechanics, which, as Murray Gell-Mann memorably put it, holds that everything not forbidden is compulsory. A particle
takes all the paths it can, and what we see is the weighted average of all those possibilities. Perhaps the
same is true of the entire universe, implying a multiverse. But astronomers have not the slightest chance of
observing this multiplicity of possibilities. Indeed, we cannot even know what the possibilities are. We can only
make sense of this proposal in the face of some unverifiable organizing principle or framework that decides what is
allowed and what is not—for example, that all possible mathematical structures must be realized in some physical
domain (as proposed by Tegmark). But we have no idea what kinds of existence this principle entails, apart from the
fact that it must, of necessity, include the world we see around us. And we have no way whatsoever to verify the
existence or nature of any such organizing principle. It is in some ways an attractive proposition, but its proposed
application to reality is pure speculation.
ABSENCE OF EVIDENCE
Although the theoretical arguments fall short, cosmologists have also suggested various empirical tests for parallel
universes. The cosmic microwave background radiation might bear some traces of other bubble universes if, for example,
our universe has ever collided with another bubble of the kind implied by the chaotic inflation scenario. The
background radiation might also contain remnants of universes that existed before the big bang in an endless cycle of
universes. These are indeed ways one might get real evidence of other universes. Some cosmologists have even
claimed to see such remnants. The observational claims are strongly disputed, however, and many of the hypothetically
possible multiverses would not lead to such evidence. So observers can test only some specific classes of multiverse
models in this way. A second observational test is to look for variations in one or more fundamental constants, which
would corroborate the premise that the laws of physics are not so immutable after all. Some astronomers claim to have
found such variations [see “Inconstant Constants,” by John D. Barrow and John K. Webb; Scientific American, June 2005].
Most, though, consider the evidence dubious. A third test is to measure the shape of the observable universe:
Is it spherical (positively curved), hyperbolic (negatively curved) or “flat” (uncurved)? Multiverse scenarios
generally predict that the universe is not spherical, because a sphere closes up on itself, allowing for only a finite
volume. Unfortunately, this test is not a clean one. The universe beyond our horizon could have a different shape from
that in the observed part; what is more, not all multiverse theories rule out a spherical geometry. A better test is
the topology of the universe: Does it wrap around like a doughnut or pretzel? If so, it would be finite in size,
which would definitely disprove most versions of inflation and, in particular, multiverse scenarios based on chaotic
inflation. Such a shape would produce recurring patterns in the sky, such as giant circles in the cosmic microwave
background radiation [see “Is Space Finite?” by Jean-Pierre Luminet, Glenn D. Starkman and Jeffrey R. Weeks; Scientific
American, April 1999]. Observers have looked for and failed to find any such patterns. But this null result cannot be
taken as a point in favor of the multiverse. Finally, physicists might hope to prove or disprove some of the theories
that predict a multiverse. They might find observational evidence against chaotic versions of inflation or discover a
mathematical or empirical inconsistency that forces them to abandon the landscape of string theory. That scenario would
undermine much of the motivation for supporting the multiverse idea, although it would not rule the concept out altogether.
TOO MUCH WIGGLE ROOM
All in all, the case for the multiverse is inconclusive. The basic reason is the extreme flexibility of the proposal:
it is more a concept than a well-defined theory. Most proposals involve a patchwork of different ideas rather than a
coherent whole. The basic mechanism for eternal inflation does not itself cause physics to be different in each domain
in a multiverse; for that, it needs to be coupled to another speculative theory. Although they can be fitted together,
there is nothing inevitable about it. The key step in justifying a multiverse is extrapolation from the known to the
unknown, from the testable to the untestable. You get different answers depending on what you choose to extrapolate.
Because theories involving a multiverse can explain almost anything whatsoever, any observation can be accommodated
by some multiverse variant. The various “proofs,” in effect, propose that we should accept a theoretical explanation
instead of insisting on observational testing. But such testing has, up until now, been the central requirement of the
scientific endeavor, and we abandon it at our peril. If we weaken the requirement of solid data, we weaken the core
reason for the success of science over the past centuries. Now, it is true that a satisfactory unifying explanation of
some range of phenomena carries greater weight than a hodgepodge of separate arguments for the same phenomena. If the
unifying explanation assumes the existence of unobservable entities such as parallel universes, we might well feel
compelled to accept those entities. But a key issue here is how many unverifiable entities are needed. Specifically,
are we hypothesizing more or fewer entities than the number of phenomena to be explained? In the case of the multiverse,
we are supposing the existence of a huge number—perhaps even an infinity—of unobservable entities to explain just one
existing universe. It hardly fits 14th-century English philosopher William of Ockham’s stricture that “entities must not
be multiplied beyond necessity.” Proponents of the multiverse make one final argument: that there are no good
alternatives. As distasteful as scientists might find the proliferation of parallel worlds, if it is the best
explanation, we would be driven to accept it; conversely, if we are to give up the multiverse, we need a viable
alternative. This exploration of alternatives depends on what kind of explanation we are prepared to accept. Physicists’
hope has always been that the laws of nature are inevitable—that things are the way they are because there is
no other way they might have been—but we have been unable to show this is true. Other options exist, too. The universe
might be pure happenstance—it just turned out that way. Or things might in some sense be meant to be the way they
are—purpose or intent somehow underlies existence. Science cannot determine which is the case, because these are
metaphysical issues. Scientists proposed the multiverse as a way of resolving deep issues about the nature of
existence, but the proposal leaves the ultimate issues unresolved. All the same issues that arise in relation
to the universe arise again in relation to the multiverse. If the multiverse exists, did it come into existence through
necessity, chance or purpose? That is a metaphysical question that no physical theory can answer for either the universe
or the multiverse. To make progress, we need to keep to the idea that empirical testing is the core of science. We need
some kind of causal contact with whatever entities we propose; otherwise, there are no limits. The link can be a bit
indirect. If an entity is unobservable but absolutely essential for properties of other entities that are indeed verified,
it can be taken as verified. But then the onus of proving it is absolutely essential to the web of explanation. The
challenge I pose to multiverse proponents is: Can you prove that unseeable parallel universes are vital to explain the
world we do see? And is the link essential and inescapable? As skeptical as I am, I think the contemplation of the
multiverse is an excellent opportunity to reflect on the nature of science and on the ultimate nature of existence:
why we are here. It leads to new and interesting insights and so is a productive research program. In looking at this
concept, we need an open mind, though not too open. It is a delicate path to tread. Parallel universes may or may not
exist; the case is unproved. We are going to have to live with that uncertainty. Nothing is wrong with scientifically
based philosophical speculation, which is what multiverse proposals are. But we should name it for what it is.
JohnEB
JohnEB
"If you don't want to deal with infinities in your physics, then don't put them in."
JohnEB
Higgs boson signals fade at Large Hadron Collider
Cern scientist says he sees 'no striking evidence of anything that could resemble a discovery' in hunt for Higgs boson
The Current Paradigm is really getting skunked!!!
JohnEB
JohnEB
Welcome to the Multiverse
The October issue of Discover magazine has a new feature, a column by Sean Carroll, whose inaugural effort is now on-line as Welcome to the Multiverse. Sean makes the argument that opposition to multiverse mania is due to people having too naive an idea about what science is. They don’t realize that testing those parts of a theory you can directly observe allows you to draw conclusions about those parts you can’t directly observe:
A lot of people, both inside and outside the scientific community, are viscerally opposed to the idea of other universes, for the simple reason that we can’t observe them—at least as far as we know. It’s possible that another universe bumped into ours early on and left a detectable signature in the cosmic background radiation; cosmologists are actively looking. But the multiverse might be impossible to test directly. Even if such a theory were true, the worry goes, how would we ever know? Is it scientific to even talk about it?
These concerns stem from an overly simple demarcation between science and nonscience. Science depends on being able to observe something, but not necessarily everything, predicted by a theory. It’s a mistake to think of the multiverse as a theory, invented by desperate physicists at the end of their imaginative ropes. The multiverse is a prediction of certain theories—most notably, of inflation plus string theory. The question is not whether we will ever be able to see other universes; it’s whether we will ever be able to test the theories that predict they exist.
JohnEB
JohnEB
Luke Setzer
> Using Quantum Logic, I propose that this new machine could be based in
> Greece. Energy would be supplied to the machine by burning Euros.
all governments act in a fiscally responsible manner using sound money.
JohnEB
Maybe you'll get your wish at 11:11 today! But I guess the machine will have to go back in time.
JohnEB
JohnEB
More useless nonsense >>
The Ultimate Guide to the Multiverse
Yet another cover story about the Multiverse can be found this week at New Scientist, which calls it The Ultimate Guide to the Multiverse. As just one more in a long line of such stories over the last decade, a trend that shows no signs of slowing down, one can be pretty sure that this is not the yet the “ultimate” one, nor even the penultimate one.
JohnEB
2011: A Banner Year for String Theory Hype
JohnEB
the current dominant paradigm gives us an infinite Multiverse: