[drauh]

QM does not open up any avenues for violating causality. bmeacham.com is crackpot based on my reading the first 2 paragraphs.

Usually, misunderstandings about causality come from a naive reading of the terms "advanced" and "retarded" solutions to wave equations, which also show up in classical electromagnetic theory.

https://en.wikipedia.org/wiki/Green's_function_(many-body_th...

[Practicality]

Ok. Here is a better source for you: https://arxiv.org/abs/1401.0167

bmeacham was just the first search result that was trying to explain the general concept I was referring to, so I don't have to write an article in the comments :)

[jessriedel]

That paper is discussing nonlinear quantum mechanics, models of which are almost always internally inconsistent. More importantly, it's just speculation; the kind of quantum mechanics that has been confirmed in the lab is linear.

It's well known that quantum mechanics does not violate causality (when defined appropriately in terms of actual observations).

[Practicality]

But my whole point was speculating that it's possible, not that it's proven to be true. So of course I am citing speculative sources, this is speculation... :\

[jessriedel]

Although it may sound like it, I don't believe it's splitting hairs to draw an important distinction between (a) speculation that might be observable in our lifetime, or might have relevance to stock trading, and (b) speculation that has fundamental inconsistencies with deep principles on which the entire known body of physics knowledge is based, and which would revolutionize our understanding of the universe and the nature of reality if true. Here's another way to say it: time travel is strictly less crazy than acausality.

Sorry, not trying to be a buzzkill :)

[Practicality]

Not a problem. I prefer learning to being right :)

[Practicality]

Cornell seems to like putting out phd theses on this subject:

https://arxiv.org/abs/1607.07871 https://arxiv.org/abs/1608.01528 https://arxiv.org/abs/1607.00381 https://arxiv.org/abs/1605.06022

Seems like Cornell is wasting a lot of time researching something that you've already determined is impossible.

[jessriedel]

Everything you're linking too is either highly speculative (e.g, hypothetically taking place yoctoseconds after the big bang, and completely unconfirmed) or is addressing some subtle interpretative senses of causality which are very distinct from the normal sense (such as the paper by Leifer and Pusey, who worked/work down the hall from me).