Is Quantum Linear Superposition an Exact Principle of Nature? by Angelo Bassi, Tejinder Singh, and Hendrik Ulbricht

Dear Robert,

Thank you very much for your enlighening reply! You gave me more than a hint of the role of information theory in physics, which I would like to follow up further. I entered this essay contest in order to have the opportunity to ask some silly questions to people that are more knowing than me - and kind enough to answer. See, if you like, my essay "Every Why Hath a Wherefore".

You saved my day!

Inger

Dr. Singh and Colleagues:

You ask an important fundamental question about quantum linear superposition. But implicit in that question is the assumption that linear superposition should be universal. Instead, I would suggest that linear superposition applies ONLY to primary quantum fields such as electrons and photons. Please see my essay "The Rise and Fall of Wave-Particle Duality", http://fqxi.org/community/forum/topic/1296. In this picture, Quantum Mechanics is not a universal theory of all matter, but rather a mechanism for generating localized particle properties from primary continuous fields, where these localized (but not point) particles then follow classical trajectories (as derived from the quantum equations). Composites of fundamental fields such as nucleons and atoms are localized composite objects WITHOUT wave properties of their own, and hence completely without linear superposition. Beams of neutrons or atoms do not require de Broglie waves for quantum diffraction from a crystal lattice, which instead reflects quantized momentum transfer between the beam particle and the crystal. Remarkably, this reinvisioned quantum picture is logically consistent and avoids quantum paradoxes. Even more remarkably, this interpretation seems to be virtually new in the history of quantum theory, although it could have been proposed right at the beginning. The FQXi contest would seem to be an ideal venue to explore such concepts, but this has drawn relatively little attention.

Thank you.

Alan M. Kadin, Ph.D.

I don't think decoherence solves the measurement problem per se. It does indicate how superpositions of a quantum system are teken up by a reservoir of states in entanglements. This then reduces the density matrix of the system to a diagonal matrix which correspond to probabilities. Decoherence does not tell us which outcome actually happens.

I framed this within the decoherence perspective. It seemed as if the criterion for the sort of nonlinear quantum physics would happen when the time of the state reduction occurs at a time comparable to the Planck time. This can happen for a system with approximately 10^{18} amu or proton masses. This might be the maximal size at which a system can have quantum properties.

Cheers LC

Dear Dr. Bassi and Dr. Singh,

It was a pleasure to meet you at the Quantum Malta conference and I am delighted to see that you have made what is in my view one of the two most important features of quantum theory the subject of your paper.

I agree with the belief that quantum superposition does not hold for macroscopic objects (but for different reasons which are outlined in my paper) and am glad that the predictions of CSL are being put to the experimental test. I just hope that it won't take 20 years, as you suggest in your paper, to test the theory in an adequate regime.

All the best,

Armin

Hi Tejinder,

Can you point me to information on testing particles for interference (that I would understand)?

In the essay (http://www.fqxi.org/community/forum/topic/1403) I logically derive the Planck mass (via two methods) as the ultimate mass for a particle. This does not mean there are any particles in nature that can make it to this mass. I define particle as an object with mass that shows the property of interference. It does not surprise me that real particles never get close to the Planck mass.

This is why I was interested in diamonds. They are peculiar because they are hard crystals that are thought to be quantum mechanical at all sizes. I think they have a chance of getting close to the Planck mass.

Let me know what you think,

Thanks,

Don L.

Dear Authors,

Thank you for an interesting essay.

Maybe I am missing something, but, on the face of it, there may be some contradiction between the following statements in your essay:

1). "When one considers doing such an interference experiment for bigger objects such as a beam of large molecules the technological challenges become enormous."

2)."However when we look at the day to day world around us linear superposition does not seem to hold! A table for instance is never found to be `here' and `there' at the same time. In other words, superposition of position states does not seem to hold for macroscopic objects. In fact already at the level of a dust grain, which we can easily see with the bare eye, and which has some 1018 nucleons, the principle breaks down."

So if technological challenges are enormous for large molecules, one would think they are downright prohibitive for dust grains or tables, so the principle does not break down, but we just cannot solve the technological challenges to demonstrate it for such objects? The following analogy may be appropriate: we cannot demonstrate reversibility for large objects (e.g., when we break a vase), furthermore, thermodynamics is based on irreversibility, but that does not mean that reversibility fails for large objects.

Another remark. For what it's worth, I expect interference to exist for arbitrarily large objects. My reasoning is based on the following almost forgotten ideas of Duane (W. Duane, Proc. Natl. Acad. Science 9, 158 (1923)) and Lande (A. Lande, British Journal for the Philosophy of Science 15, 307 (1965)): the direction of motion of electron in the interference experiment is determined by the momentum transferred to the screen, and this momentum corresponds to quanta (e.g. phonons) with spatial frequencies from the spatial Fourier transform of matter distribution of the screen. So I tend to make the following conclusion: when the mass of the incident particle increases, the momentum transferred to the screen remains the same, but the angle of deflection of the incident particle becomes smaller, as its momentum is greater. So the mass of the incident particle is in some sense an "external" parameter for the interference experiment.

Thank you

Best regards

Andrey Akhmeteli

Hi, Post above was by Don Limuti, and not anonymous. Time-out got me.

Hi Tejinder,

Thank you. http://in.arxiv.org/abs/1109.5937 was very good. There is a lot of "art" and science in these measurements.

Here is conclusion of my essay:

Particles can never be accelerated to "c" because they hit their respective Vmax values first and can not be accelerated further. This is because particles are characterized by their Compton wavelength and at Vmax the Compton wavelength has shrunk to the Planck length, as short as anything can get. The Lorentz contraction (1-v2/c2)0.5 seems to indicate that that the velocity of a particle v can be taken to c but as shown in this essay it can only be taken to Vmax just short of c. Say goodbye to the elephant.

At Vmax all particles:

a. Have the same Compton wavelength which is the Planck length.

b. Have the same mass which is the Planck mass.

c. Have a Lorentz contraction that is equal to m0/Pm

d. Have a Schwarzschild radius that is two Planck lengths.

My contention is that quantum mechanics ends at the Planck mass. This does not mean we can find particles that have this super mass. This is why I am interested in diamonds and your essay which explores this most interesting mass zone from the Buckyball to the Planck mass. I suspect that a diamond with a mass below the Planck mass will show interference and a diamond above the Planck mass will not show interference.

Check out the logic for yourself: http://www.fqxi.org/community/forum/topic/1403

Thanks again,

Don L.

Very interesting and clear. Your proposal seems to solve many very difficult problems at the foundation of quantum theory. I wish you luck in the contest, and above all, in the development of your research programme.

Best Regards

Daniel

Thank you for the explanation of your position.

Dear Authors:

Thank you for responding to my comment, but you have missed the key point which is at the heart of the quantum paradoxes. The quantum diffraction experiments (all referenced in my essay) are obviously correct, but their interpretation is based on an assumption that is incorrect. As described in my essay, and referenced to the work of Van Vliet, the scattering of a neutron requires a quantum transition of the crystal, which in turn requires a quantized momentum transfer to a degenerate phonon with momentum hG, where G is a reciprocal lattice vector. This gives rise to the classical wave diffraction result, but does NOT require an incident coherent wave. The same is true for an atom, molecule, or buckyball. They are all localized particles, not extended phase-coherent waves. (This is in contrast to electron and photon waves, which really are extended coherent waves with linear superposition.) I realize that this is heresy, but that is exactly the point of this FQXi essay contest - to question assumptions that no one ever questions. Please read my essay more carefully. I have taken great pains to explain everything clearly and consistently. I would be happy to discuss this offline, if that would be appropriate. My email is given in my bio.

Alan M. Kadin, Ph.D.

Dear Alan Kadin,

"The FQXi contest would seem to be an ideal venue to explore such concepts, but this has drawn relatively little attention."

Perhaps you meant the attention to your essay rather than to the contest. Be sure you explained your remarkable result clearly, consistently, and understandably enough as to persuade any unbiased reader. Your essay was the only one that I called more convincing than quantum logics while everybody so far called my essay overly critical.

I hope, those who read uncommon or even heretical ideas will memorize them and eventually be in position to judge independent of the crowd.

Concerning the discrete vs. analog or linear vs. non-linear issue I would like to iterate what I tied to make aware of in the previous contest where it got unnoticed among more than 400 posts:

Cosine or Fourier transformations are non-linear integral transformations that render a continuous function of (elapsed or anticipated as elapsed) time into a discrete function of (likewise positive) frequency and vice versa.

Regards,

Eckard

Please:

I show by experiment in this essay contest how quantum theory is an approximation. My experiments refute the Born rule. A singly emitted gamma-ray should go one way or another at a beam splitter, but I show coincident detection exceeding chance. Similarly for an alpha-ray. This supports the Loading Theory, which was misrepresented and misunderstood for ~70 years, which is why no one considers it. There are two problems:

(1) There are accepted experiments that may be adjusting things to favor QM, and also that researchers have not looked for certain artifacts. A good example is macromolecule diffraction. I do not expect a macromolecule could load up. My experiments and analysis indicate the universe is not crazy and that macromolecules are real particles. But atoms can take on either a wave state or a particle state. My enhanced version of the Loading Theory can explain wave-particle duality up to at least atoms. Physicists may think a macromolecule is neutral, but it is easily charged. It is very likely that many experiments are looking at field deflection effects. To further back my claims, I analyzed one of the Vienna experiments in my essay, and cite several anomalies that do not fit diffraction theory.

(2) The other problem is that my work is so sensational that you are not likely to take it seriously unless other physicists examine it. I have been offering to demonstrate to physicists for 10 years and have performed public demonstration of the gamma-split experiment with little recognition. What I have is for-real and I go with full confidence to face any scrutiny. I made an offer to demonstrate to FQXI people in Brendan Foster's blog on the essay contest.

Please be careful: I do not need to be the one to say bad things about physicists who embrace quantum weirdness because they are invested in it. Now we have a good experimental reason to resolve the paradox instead of embracing it. The history that has misled generations of physicists is in my essay. We no longer need acts of desperation, like superluminal magical collapse of the wave function, etc.

Please see A Challenge to Quantized Absorption by Experiment and Theory. Also please see Ragazas' paper that supports the Loading Theory.

Thank you, Eric Reiter, September 12, 2012.

Dear Angelo, Tejinder, and Hendrik,

You present a very good idea, all the more so because of the very realistic possibility of experimental verification in the near future. I don't know if it's right, but the case you present for pursuing this direction is quite convincing. Indeed, I hope it's wrong, because it would wreck some of my own ideas about quantum gravity! The universe is oblivious to such considerations, however. A few questions and comments:

1. Presumably this provides an arrow of time, since collapse is irreversible, but perhaps time in this sense fades out of the picture on the fundamental scale where the superposition lifetime becomes infinite?

2. I'm sure this has been addressed, but it seems that there might be some issues involving things like locality and "microscopic constituents" of "macroscopic systems." Roughly speaking, how does a microscopic system "know" if it is supposed to preserve its own superposition or recognize that it is part of a larger system, which must collapse? One of the main points of the decoherence explanation of the measurement problem is that one must consider microstate, apparatus, and environment simultaneously. I am wondering how this all fits together.

3. You mention Adler's view that it's the wrong approach to quantize classical dynamics. This may be correct, but it seems to me that it is simply a choice of assumptions: does one start with the correspondence principle, in which case classical physics is viewed as a limit of quantum theory, or does one start with the superposition principle, in which case quantum theory is built up from classical alternatives? Perhaps the experiments you mention will settle this one way or the other.

4. I will have to look at your reference by Oreshkov et al., to see exactly what they mean by "order." Again, this might wreck my own ideas if it is right.

5. I don't expect that you will agree much with my own approach, but if you're interested to see the motivation for my questions, my submission is here: On the Foundational Assumptions of Modern Physics.

Thanks for the interesting read. Take care,

Ben Dribus