Can Quantum Mechanics Be Derived?
Martin
In _A Brief History of Time_, Stephen Hawking argued that the human
brain is a biological machine and, thus, sees reality time developing
in the direction of increasing entropy. His argument was as follows:
we consider the "past" to be the things that have happened because we
remember them but memories are stored in the human brain through the
process of realining neurons. This is a physical process which uses
up chemical energy which eventually becomes heat, increasing the
entropy of the universe. The direction of increasing entropy
specifies the arrow of time, but things which we do not directly
observe do not have to obey the arrow of time.
"Things we do not directly observe" of course refers to quantum
processes. A good example would be vaccuum flucuations: an electron
and a positron are created and are annihilated, forming the photon
which creates them in the first place. Obviously the arrow of time is
ignored by these virtual particles. Photons really don't seem to care
at all about the arrow of time. Another example is x-ray decay: it
requires that one of the two daughter particles pick up momentum from
a photon emitted by a nucleus, but this happens _after_ the decay
itself. A quick look at the Feymann diagram, forgetting the direction
of time for a moment, and we see that it is the same as the diagram of
a photon scattering off a single electron. That Feymann diagrams can
be rotated to represent several different processes is a general rule.
But if the world isn't exactly how we see it, if we are only seeing
what our biological brains are capable of seeing, then what does the
world really look like and could we derive things like wave-particle
duality, self-interaction, quantum probability and the Heisenberg
Uncertainty Principle from first principles if we understood what was
really going on? I suspect we could.
First of all, wave-particle duality is implied by the two slit
experiment with electrons in place of photins except that now
electrons can pass through the slits one at a time and we see
"interference". How does an electron interfere with itself?
We can't see the electron directly so we only assume that electrons
only travel forwards in time. What if they don't? What if electrons
travel back in time continuously and therefore interact with
themselves? Perhaps the mass we detect is not the mass of a single
electron but the integrated total energy of an infinite number of
massless electrons that are actually a single electron constantly
doubling back on itself? Then when we make a measurement of the state
the electron is in we could be measuring the state of any one of those
electrons. Note that by making the measurement we have prevented the
electron from going back and assuming a new state as this would
violate causality for _us_. The Heisenberg Uncertainty Principle is a
result of the resulting wave nature of matter.
Please feel free to tell me this is all bullshit but let me know why
you would think it is.
Martin
Sam Wormley
Are you familiar with Feynman saying, "shut up an calculate"?
Books: Quantum Mechanics
http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html#quantum-mechanics
Martin
It would appear to be a myth that Feymann said that. See
http://www.physicstoday.org/vol-57/iss-5/p10.html
> Books: Quantum Mechanics
> http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html#qua
> Bjorken and Drell: Relativistic Quantum Mechanics/ Relativistic Quantum > Fields
> Ryder: Quantum Field Theory, 1984
> Itzykson and Zuber: Quantum Field Theory, 1980
I had that as a textbooks when I got my Ph.D. at McGill. They don't
address my question though. Neither have you.
Martin
Sam Wormley
Do you understand why Feynman might or might not have said, "shut up an
calculate"?
dedanoe
Martin :
try deriving it from the lever law.
good luck and have a lot of fun!
The_Man
>
> > Books: Quantum Mechanics
> > http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html#qua
> > Bjorken and Drell: Relativistic Quantum Mechanics/ Relativistic Quantum > Fields
> > Ryder: Quantum Field Theory, 1984
> > Itzykson and Zuber: Quantum Field Theory, 1980
>
> I had that as a textbooks when I got my Ph.D. at McGill. They don't
> address my question though. Neither have you.
Is your Ph.D. in physics?
QM is certainly derivable, but only within the formalism of QM itself.
There are many nice proofs of the HUP that you can find even online,
but, again, they are proofs that start within the formalism of QM.
You mention "first principles" of the electron coming from the double
slit experiment. We usually don't use "first principles" to refer to
the results of experiments."First principles" would be a calculation
using constants, and no adjustable parameters.
If you wish to derive QM, go ahead. It should keep you busy for a
while. As for everyone else, nobody cares. The REASON they don't care
is that the theory, wether derivable, derived, or given on gold
tablets on Mount Sinai. workd beautifully. It has never been shown to
be wrong. It predicts the results of experiments to an extraordinary
degree of accuracy. What more could we want?
If you want to image electrons moving backward in time, feel free. If
you can convert that into a self-consistent mathematical theory that
accuractely predicts the results of EVERY experiment, great. But all
you would have achieved is what is ALREADY possible with QM (and its
superset QED).
The feeling expressed in "Shut up and calculate" (Often ascribed to
Dirac, not Feynmann) is that metaphysical speculation is pointless for
physics. Scientists are concerned with the results of experiments, NOT
metphysics.
>
> Martin- Hide quoted text -
>
> - Show quoted text -
Androcles
"Martin" <phipps...@hotmail.com> wrote in message
news:1183893919....@i13g2000prf.googlegroups.com...
: I'm sorry if this question has been asked before.
:
: In _A Brief History of Time_, Stephen Hawking argued that the human
: brain is a biological machine and, thus, sees reality time developing
: in the direction of increasing entropy. His argument was as follows:
: we consider the "past" to be the things that have happened because we
: remember them but memories are stored in the human brain
Hawking is an idiot, memory is stored in RAM, ROM, CD-ROM,
on your hard drive, in books, cast in concrete, on tombstones,
lots of places.
: through the
: process of realining neurons. This is a physical process which uses
: up chemical energy which eventually becomes heat, increasing the
: entropy of the universe. The direction of increasing entropy
: specifies the arrow of time, but things which we do not directly
: observe do not have to obey the arrow of time.
:
: "Things we do not directly observe" of course refers to quantum
: processes.
Bullshit. You did not directly observe the building of the Golden
Gate Bridge, but it exists.
:A good example would be vaccuum flucuations
More bullshit, and learn to spell.
: an electron
: and a positron are created and are annihilated, forming the photon
: which creates them in the first place.
If you can prove a photon violated conservation of momentum to
make an electron and a positron I might listen to you.
: Obviously the arrow of time is
: ignored by these virtual particles.
Oh, so electrons are not real, they are virtual. Got it.
Obviously you have no idea what "obvious" means.
Obviously you are making it up.
: Photons really don't seem to care
: at all about the arrow of time.
"Seem" means "obvious", does it?
: Another example is x-ray decay: it
: requires that one of the two daughter particles pick up momentum from
: a photon emitted by a nucleus, but this happens _after_ the decay
: itself. A quick look at the Feymann diagram, forgetting the direction
: of time for a moment, and we see that it is the same as the diagram of
: a photon scattering off a single electron. That Feymann diagrams can
: be rotated to represent several different processes is a general rule.
:
: But if the world isn't exactly how we see it, if we are only seeing
: what our biological brains are capable of seeing, then what does the
: world really look like and could we derive things like wave-particle
: duality, self-interaction, quantum probability and the Heisenberg
: Uncertainty Principle from first principles if we understood what was
: really going on? I suspect we could.
Have a nice suspicion, it's no different to guessing anyway.
: First of all, wave-particle duality is implied
No it isn't implied at all. That's like saying air-currents from
ceiling fans imply clocks, both go round.
by the two slit
: experiment with electrons in place of photins except that now
: electrons can pass through the slits one at a time and we see
: "interference". How does an electron interfere with itself?
The same way water passes through coffee filter and emerges
has whole drips. How can it do that, eh?
Have you ever seen an electron? J J Thompson invented electrons
from cathode rays, then Millikan invented mass for them.
They are virtual particles, Phippsmartin said so.
: We can't see the electron directly so we only assume that electrons
: only travel forwards in time. What if they don't?
What if bright green flying elephants lay their eggs in black holes?
What if they don't?
: What if electrons
: travel back in time continuously and therefore interact with
: themselves?
What if, what if, what if...
What if you quit daydreaming?
: Perhaps the mass we detect
Who's this "we"?
What mass have *you* ever detected?
: Please feel free to tell me this is all bullshit but let me know why
: you would think it is.
:
: Martin
It is all bullshit because it is your wild speculation unsupported
by evidence of any kind whatsoever and shows your total lack
of understanding of the difference between theory and observation.
Ben Rudiak-Gould
> We can't see the electron directly so we only assume that electrons
> only travel forwards in time. What if they don't? What if electrons
> travel back in time continuously and therefore interact with
> themselves?
The problem I have with ideas like this is that you're using temporal
language in a context where is doesn't appear to make sense. If something is
travelling back in time, then its properties (specifically spacetime
coordinates) are changing with respect to something, but not with time;
that's already accounted for. Absent some well-defined second time
dimension, you can't talk about things changing in spacetime. Objects don't
move along their worldlines, not even in the forward direction. They just
are their worldlines.
I've seen ideas like this before, like the famous work by Feynman and
somebody (Wheeler or Tomonaga?) on explaining the electromagnetic
backreaction with retarded potentials, and John Cramer's transactional
interpretation of quantum mechanics. None of them have ever made sense to me
for the reason I gave above. But I'd like to understand them, and presumably
Feynman did, so if you can carefully define what you mean by "travelling
back in time" then I'll find it very helpful.
-- Ben
galathaea
there are logical interpretations of quantum mechanics
from the temporal logics
which accept the unidrectional foundational view of time
like the "internal logic" approaches of fotini markopoulou
and certain formulations of "consistent histories" approaches
they are formulated in computational toposes
time becomes the progressive applications
of an evolution morphism on a state space
even for field theories
these approaches do not need posit
" moving backward in time "
their ontology makes such questions meaningless
that's also true in operationalist interpretations
for different (verificationist) reasons
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
galathaea: prankster, fablist, magician, liar
gyans...@gmail.com
What rot! Remember Maxwell and his demons - many Physicists have
active imaginations and more than often this is how giant leaps are
made. Einstein did many thought experiments. Of course he went on to
describe mathematically what happens and that is stage 2. To say that
such a theory would be useless is not true. What we need is what
actually happens, not just a model so if his model is nearer reality
then we would use it instead - maybe the results would be the same for
most cases. Remember Newtons laws only hold under certain conditions
and we had to build on that too. Don't be so bloody negative.
Jeffâ Relf
going through the slits as a particle or a wave ?
What about electrons from the laser hitting metal ?
Does my choice of models tell you about me, the physics or both ?
Modeling something as a wave doesn't make it wave,
it just means I know, a priori, the wavelength.
The_Man
> Hmmm... Should I model my laser ( or cooper-pair condensate )
> going through the slits as a particle or a wave ?
> What about electrons from the laser hitting metal ?
It depends. It will exhibit wave characteristics or particle
characteristics, but not both in the same experiment.
Martin Phipps
> "Martin" <phippsmar...@hotmail.com> wrote in message
>
> news:1183893919....@i13g2000prf.googlegroups.com...
> : I'm sorry if this question has been asked before.
> :
> : In _A Brief History of Time_, Stephen Hawking argued that the human
> : brain is a biological machine and, thus, sees reality time developing
> : in the direction of increasing entropy. His argument was as follows:
> : we consider the "past" to be the things that have happened because we
> : remember them but memories are stored in the human brain
>
> Hawking is an idiot, memory is stored in RAM, ROM, CD-ROM,
> on your hard drive, in books, cast in concrete, on tombstones,
> lots of places.
Computer memory storage also obeys the second law of thermodynamics.
<the rest of the gibberish snipped>
Martin
Martin Phipps
> > only travel forwards in time. What if they don't? What if electrons
> > travel back in time continuously and therefore interact with
> > themselves?
>
> The problem I have with ideas like this is that you're using temporal
> language in a context where is doesn't appear to make sense. If something is
> travelling back in time, then its properties (specifically spacetime
> coordinates) are changing with respect to something, but not with time;
> that's already accounted for. Absent some well-defined second time
> dimension, you can't talk about things changing in spacetime. Objects don't
> move along their worldlines, not even in the forward direction. They just
> are their worldlines.
I see what you mean but why should the forward direction of time of an
electron be the same as our forward direction of time? We can only
observe a time developing electron when we make measurements and these
measurements themselves determine a direction of time.
> I've seen ideas like this before, like the famous work by Feynman and
> somebody (Wheeler or Tomonaga?) on explaining the electromagnetic
> backreaction with retarded potentials, and John Cramer's transactional
> interpretation of quantum mechanics. None of them have ever made sense to me
> for the reason I gave above. But I'd like to understand them, and presumably
> Feynman did, so if you can carefully define what you mean by "travelling
> back in time" then I'll find it very helpful.
To be honest, I've always been a bit suspicious of "time ordering" in
quantum mechanics because when I was studying quantum mechanics
precisely as a result of Hawking's Brief History of Time and because I
had already encountered the "arrow of time" problem in an issue of
Scientific American. Why should the universe be like a movie with X
number of frames already having happened and Y number of frames yet to
come? So it occurs to me now that these "snapshots" are just how we
see the universe and not how it really is.
I'm in no hurry. I'm not currently employed at an institution that
expects me to publish something every year. The drawback, of course,
is that it will be that much harder for me to get the information I
would need to satisfy my curiosity.
Martin
George Chen
> Please feel free to tell me this is all bullshit
Okay. It's bullshit.
> but let me know why you would think it is.
Because you can't explain quantum tunneling. Why would a single
electron suddenly appear on the other side of a potential barrier? An
electron has to be a probability distribution defined by the square of
it's wavefunction.
Another thing. Why do bosons obey Bose-Einstein statistics while
fermions obey Fermi-Dirac statistics?
Martin
Martin Phipps
> On Jul 8, 7:25 pm, Martin <phippsmar...@hotmail.com> wrote:
>
> > Please feel free to tell me this is all bullshit
>
> Okay. It's bullshit.
Oh dear. Really?
> > but let me know why you would think it is.
>
> Because you can't explain quantum tunneling.
Ah.
> Why would a single
> electron suddenly appear on the other side of a potential barrier? An
> electron has to be a probability distribution defined by the square of
> it's wavefunction.
Damn. For a moment there I thought I had actually found the answer to
life, the universe and everything.
> Another thing. Why do bosons obey Bose-Einstein statistics while
> fermions obey Fermi-Dirac statistics?
42.
Martin