Here is the experiment that can be used to test this theory. It is based on a well-known experiment published in Physical review, March 2002, by S. P. Walborn, M. O. Terra Cunha, S. Padua and C. H. Monken.
An argon ion pump laser is set up to emit single photons. Each photon passes through a special nonlinear crystal called beta-barium borate (BBO), where it is converted to two entangled, longer wavelength photons. The two entangled photons go off in two different directions, p and s.
The s photons (those which go down path s) travel through a double-slit to detector Ds. The p photons travel directly to detector Dp. Detector Dp is configured to measure the polarization of each registered photon. Detector Ds is configured to measure both the polarization and the location of each photon.
With this set up we should observe an interference pattern on detector Ds. In other words, each s photon somehow “goes through both slits at once”.
(Source: Wikipedia)
Because p and s photons form entangled pairs, by measuring the linear polarization of each p photon, we can know the polarization of the corresponding s photon before it reaches the quarter wave plates. With this configuration, it is possible to figure out which slit the s photon went through, without disturbing the s photon in any way.
(Source: Wikipedia)
According to the observational interpretation, it is not necessary to actually measure the polarization of p and figure out what slit s passed through. Once the quarter wave plates are introduced, the mere possibility of making that measurement is enough to make the interference pattern disappear.
The explanation for this “weird” effect is that, by introducing the quarter wave plates, we are creating an entanglement between the probabilities of an s photon passing through slit 1 or slit 2 and the probabilities of observing our own physical bodies (our sense organs) in certain corresponding states. In a way, by setting up the experiment we are “forcing” consciousness to observe the path each photon is taking through the double-slit.
Each experiment is a question that we ask nature. Nature is forced to provide the answer. If we pay attention to the answer or not is irrelevant.
These experimental results
predicted by the observational interpretation are inconsistent with other formulations of quantum mechanics.
According to most mainstream interpretations, a quantum superposition of states disappears (the wave function collapses) the moment the quantum system interacts with a macroscopic object (the measurement apparatus).
In our double-slit experiment, it is obvious that the interaction between the entangled photons and the macroscopic detectors plays no role in the transition from a superposition to a definite state. In the first configuration of the system, with the two detectors in place, an interference pattern is observed.
Could it be that the “collapse of the wave function” is caused by the interaction of the s photons with the quarter wave plates, introduced in the second configuration?
This possibility can be discarded by placing a polarizer on the p path. This polarizer acts as a “quantum eraser”, making it no longer possible to know the linear polarization of s photons before they reach the quarter wave plates, and therefore making it no longer possible to figure out which slit each s photon goes through. Once the polarizer is in place, the interference pattern reappears.
Traditional interpretations of quantum mechanics cannot account for this.
There you have it! If I'm correct, this experiment directly shows the fundamental nature of consciousness.
If you want to check out the original experiment, you can find it here.
You can read an article explaining the experiment for non-professionals here.
And if you would like to read the essay where I explain my theory more fully, I posted it here.
Any comments and criticisms would be much appreciated!
According to most mainstream interpretations, a quantum superposition of states disappears (the wave function collapses) the moment the quantum system interacts with a macroscopic object (the measurement apparatus).
Precisely. As an idealist I say to my idealist friends: stop trying to see in the delayed choice and quantum eraser experiments evidence supporting idealism more than any other quantum phenomena does already (why is that not ample evidence for it already?). These experiments do not violate orthodox quantum mechanics or do not imply any temporal retro-causality. And stop also in seeing in quantum mechanics any “role of the observer” in the measurement process that necessitates a "mind or consciousness that collapses the wave function" (at least not in the form of an alter, it would be more interesting to analyze this from the perspective of M@L). There is no such thing in quantum mechanics (with or without Wheeler and his friend) and one doesn't need such misconceptions to support an idealist view. BK reformulated this a bit more elegantly invoking contextuality, but trying hard to reintroduce a wrong idea through the back door won’t make it become true. Contextuality doesn't need or imply any mind or conscious observer either. And to insist in pointing out that there is a measurement problem won't make it automatically a magic wand that confirms any idealist claim. The fact that the measurement problem isn't completely explained by decoherence alone is true, but it is a formal mathematical problem that needs mentation for its solution no more no less than any law of classical physics would need. The real problem is that we, as idealists, have one thing in common with physicalists: the confirmation bias. We love to jump to conclusions when something seems to confirm our ideological background, but does not. Quantum mechanics as it is, without any extra ingredients, points directly to an idealist view of reality and is a slap in the face to physicalism. We have it in front of our nose and there is no reason to search for it elsewhere in contrived and complicated experiments.
The fact that the measurement problem isn't completely explained by decoherence alone is true, but it is a formal mathematical problem that needs mentation for its solution no more no less than any law of classical physics would need.
According to the observational interpretation, it is not necessary to actually measure the polarization of p and figure out what slit s passed through. Once the quarter wave plates are introduced, the mere possibility of making that measurement is enough to make the interference pattern disappear.
Precisely. As an idealist I say to my idealist friends: stop trying to see in the delayed choice and quantum eraser experiments evidence supporting idealism more than any other quantum phenomena does already (why is that not ample evidence for it already?). These experiments do not violate orthodox quantum mechanics or do not imply any temporal retro-causality.
And stop also in seeing in quantum mechanics any “role of the observer” in the measurement process that necessitates a "mind or consciousness that collapses the wave function" (at least not in the form of an alter, it would be more interesting to analyze this from the perspective of M@L).
There is no such thing in quantum mechanics (with or without Wheeler and his friend) and one doesn't need such misconceptions to support an idealist view. BK reformulated this a bit more elegantly invoking contextuality, but trying hard to reintroduce a wrong idea through the back door won’t make it become true. Contextuality doesn't need or imply any mind or conscious observer either. And to insist in pointing out that there is a measurement problem won't make it automatically a magic wand that confirms any idealist claim.
The fact that the measurement problem isn't completely explained by decoherence alone is true, but it is a formal mathematical problem that needs mentation for its solution no more no less than any law of classical physics would need. The real problem is that we, as idealists, have one thing in common with physicalists: the confirmation bias. We love to jump to conclusions when something seems to confirm our ideological background, but does not. Quantum mechanics as it is, without any extra ingredients, points directly to an idealist view of reality and is a slap in the face to physicalism. We have it in front of our nose and there is no reason to search for it elsewhere in contrived and complicated experiments.
But the experiment I'm presenting does violate orthodox quantum mechanics. Here is the key: there is no measurement going on. We don't need to actually measure tthrough which slit each photon is passing. The mere possibility of making the measurement makes the interference pattern disappear. If you can explain this phenomenon using "orthodox quantum mechanics", I would be very interested to hear that explanation!
Aditya,I've read the tutorial you sent me and I've found that the experimental setup is very different to the setup of the experiment I'm talking about. Even so, reading it through made me rethink some of my ideas, which was helpful. Thanks!(However, I must say the tutorial is not aimed at first-semester students, but at upper-level students (including Ph.D. students). The results of the paper show that many upper-level students in quantum mechanics struggle with these concepts. In other words, this is not QM 101 day 1, like you said.)