Talk:Einstein–Podolsky–Rosen paradox

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Section under "the crux of the matter" is wrong

The section under "the crux of the matter" is wrong. By only measuring the x or z axis you cannot distinguish between a classical system with hidden variables and a quantum system. One has to measure at 45 degrees also. The description is wrong.

Sorry, I meant to put this somewhere else, but I do not know how to delete this.

Observer as Variable

The impact of consciousness is unquestioned, how much more abstract is consciousness greater will its power both in size and complexity?

The "Paradox" paper

" According to Heisenberg's uncertainty principle, it is impossible to measure both the momentum and the position of particle B exactly; however, it is possible to measure the exact position of particle A. By calculation, therefore, with the exact position of particle A known, the exact position of particle B can be known. Alternatively, the exact momentum of particle A can be measured, so the exact momentum of particle B can be worked out. "

Well, no. As per Heisenberg's uncertainty, no measurement is absolute, neither combined nor separate. There are always digits missing, and thus exactness is never reached. However, both can be approximated at nearly the same approximated time, which all measurements are. Hence, no true predictions are possible, and yet approximations are, which will invariably vary over the entire extrapolation, increasing in variablility over the main components, time and distance, if and when these apply.

What they mean is that the measurements are done in complementary basis, and measurement collapses the state which causes the values of the state viewed in this complementary basis to become inaccessible after the measurement. The fourier transform of the quantum state gives the relation momentum and the position. In the simplest case when the quantum system is a two-state device, the fourier transform is equivalent to the hadamard transform, which makes it easier to think about, if you want to do the math.

The Einstein–Podolsky–Rosen (EPR) paradox is a thought experiment

Is it though? The source given for this statement is the original paper, and back then it was a thought experiment, but since then we have tested it in actual reality. Its can be made as a fairly simple program that can run on freely accessible cloud quantum computers today. I propose we remove the suggestion that this is a "thought experiment". Thanks 2001:9B1:26FE:C700:F2E2:8CFF:FE35:5907 (talk) 21:20, 7 January 2025 (UTC)[reply]

There have been various experiments closely related to the EPR paper proposal. These could be described and discussed, say under "Later developments". Then a corresponding sentence or two could be added to the intro. But the EPR paradox itself was published long ago and is a thought experiment. Johnjbarton (talk) 23:00, 7 January 2025 (UTC)[reply]

Reid inequality

The additional information about the Reid inequality and quantum optics topics was removed. This discussion article is intended to open a channel to resolve this dispute courteously. Simply removing all the added material and references seems rather unhelpful to the reader.

One statement that was disputed was that the Nobel prize-winning loop-hole free experiment used SPDC, but see https://www.nobelprize.org/prizes/physics/2022/advanced-information/. This is a completely truthful statement. The Nobel committee had reasons for awarding the prize to Zeilinger, and they no doubt investigated this carefully. As the Nobel website points out, this technology is used in applications like Bell-inequality based cryptography, and hence it is appropriate to mention it.

On the question of the CV Reid inequality, the first experiment by Ou et al on continuous variable EPR, which was the main topic of the EPR paper, used the precise approach and inequality that Reid published, and referenced her work. Reid's original EPR paper has been cited more than 1000 times, and she was the first physicist to prove there is a link between EPR's paper and downconversion. Her review, already mentioned in this article, cites many similar experiments, and they are very close to the original EPR proposal.

Whether one uses the term "Reid inequality" or not is a subjective question. This is the shortest heading that appears appropriate, since it is an inequality and was discovered by Reid, just as the Bell inequality was discovered by Bell. Other wikipedia contributors may propose a better heading, and of course such contributions are always welcome. If other contributors prefer, they may wish to change the heading to one that is more appropriate, but that is not a reason to delete the entire section. Patu-tessa (talk) 12:02, 8 February 2025 (UTC)[reply]