Undergrad A 5th Dimension May Explain Quantum Theory

[Secan]

At least according to Tim Anderson Ph.D who wrote the paper in Physics Review.

https://news.knowledia.com/US/en/ar...dium-6f1d6fd371e068a07f357b9babe9ab2eec06d034

What do you make of this?

"The paper simply presents, mathematically, why a fifth dimension makes sense in a quantum theory.

The basic idea is that the universe has a fifth dimension, but we can’t ordinarily detect the dimension, not because everything is exactly the same, but because, when we make measurements of anything, we only perceive either an average or random value.

If this is true, it would mean that rather than being random, quantum mechanics is simply the result of classical motion in a largely invisible dimension.

Let’s look at an analogy: imagine a sealed box of gas. The box of gas is in equilibrium, so its state does not change with time. When we put a barometer or a thermometer into the box, it always reads the same value, e.g., 1 atmosphere and 20 degrees Celsius. Nevertheless, all the individual gas molecules in the box are in constant motion. So it is changing in time, but we cannot perceive that change because we are so large we can only measure the averages which never change.

It is the same in quantum mechanics. Our universe changes not only in time but in this fifth dimension."

 

[Nugatory]

What do you make of this?

The most solid conclusion is that non-technical summaries in the popular press are of limited value.

 

[mfb]

It's better to look at the actual study: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.99.016012
Or at least the laypeople-friendly explanation by the author in its original place, not some mirror of questionable copyright status: A 5th dimension may explain quantum theory

Here is a 2014 review (found by @bhobba): https://arxiv.org/abs/1402.6562

It's unclear if this is more than a mathematical trick, but it's still interesting to see what they figure out.

 

[Demystifier]

The paper argues that loop Feynman diagrams in 1+3 dimensions can be obtained from tree diagrams in 1+4 dimensions by averaging over the extra dimension. If it's right that's interesting, but it would be incorrect to conclude that this implies that quantum physics in 1+3 dimension can be obtained from classical physics in 1+4 dimensions. Such a conclusion would be correct if it was true that the only difference between classical and quantum field theory is the fact that the latter contains loop Feynman diagrams. But that's not true, the appearance of loop diagrams is not the only difference. In particular there are no loop diagrams for free quantum fields, yet even for free fields there is a difference between classical and quantum field theory. The difference is in some principles (e.g. the Born rule, which is valid only for quantum fields) that are not encoded in Feynman diagrams. Even at a perturbative level, quantum theory is much more than computation of Feynman diagrams. Hence quantum physics as a whole cannot be obtained from classical physics with one dimension more.