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Comment by nabla9 | Hacker News Reader

This is my understanding of how the problem is framed:

Causality is local even in quantum physics. The "Spooky action at a distance" is just correlation

This leaves the "acausal action at a distance" aka nonlocal correlation. There is no controversy here. There is no superluminal messaging and there are no need for hidden variables and things like that. Entangled quantum _state_ of two distant entangled electrons has no coordinates in space. Quantum states are treated as ghosts.

For the authors there exist discord between instant correlation and special relativity. I have no idea what comes next. Somebody else should explain how Trace Dynamics works.

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How can things be correlated? what is correlation if there is no causation, I feel confused about that ... as your The "Spooky action at a distance" is just correlation.

Non-newtonian physics is by far the weakest of the hard sciences but as I understand it "[spooky] action at a distance" has a formal meaning[1] in particle physics that has to do with quantum entanglement. Here's the NIST article on the substantial findings that lends credence spooky action specifically[2]. (I'd imagine the physics stackexchange will have a great discussion on this, and the AskScience on Reddit will have a thread approachable for people who aren't Leonard Susskind or his coterie of brilliant post-docs.)

[1] https://en.wikipedia.org/wiki/Action_at_a_distance

[2] http://www.nist.gov/pml/div686/20151105loophole.cfm

> Non-newtonian physics is by far the weakest of the hard sciences

This assertion is ridiculous. The only fields "harder" (in the scientific sense) than modern physics are pure math fields. High-level physics is almost pure math anyway; much of it is abstract algebra and topology. That's not to say it's divorced from reality; reality seems to like using these principles under the hood.

The "soft" stuff you are talking about isn't modern physics; it's people taking (mostly uninformed) potshot guesses at how to interpret the hard results that modern physics offers. Within the physics community, these discussions are much more muted, because it's clear that the answers to physics questions won't come out of philosophical pontificating.

Physicists figure out which interpretations are compatible with experimentally verified theory, and then look for additional consequences of these interpretations that can be tested. Right now there are a number of plausible explanations of the observations of quantum mechanics, each with their own (often psychologically uncomfortable) way of dealing with its conclusions. It's rare to come across a physicist that is strongly convinced of one interpretation.

Here's an example. Imagine you have two cards, an ace and a king. You shuffle them, and without looking, you deal one card to yourself and one card to me. Then, you hop aboard a spaceship and fly many lightyears away, leaving me behind on Earth. You wonder to yourself which card was left behind on Earth. Even though we're lightyears apart, there is a way to measure my card instantly: you can simply look at your card and infer that I have the other. Upon seeing that it is a king, you can instantly conclude that my card is an ace. That 'conclusion' was able to travel faster than the speed of the light because it was based on correlation, but not causation. Your card was correlated with mine (knowledge of yours gave you knowledge about mine) but your card did not affect mine (e.g., erasing it and drawing an A on the corners would not turn mine into a king).

(This example, I hope, illustrates the difference between spooky correlation and causation. However, it is misleading about what really goes on in quantum mechanics. In quantum mechanics, the identity of our cards is not fixed after the deal, but remains in limbo until it is actually measured. And this limbo-like superposition state can be measured in different non-independent ways and these probabilities interact with each other and other probabilities. Nonetheless, even with all that added machinery, the general principle of correlation vs causation is the same as the two card example.)

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