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Freixas

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What I've learned from studying special relativity is to be suspect of any phrase using the words "simultaneous" or "instantly".

Cross-checking with Wikipedia, I see this: "According to

*some*interpretations of quantum mechanics, the effect of one measurement occurs instantly." There's that word again. And I think I've heard it used often when talking about entanglement.

I asked ChatGPT for a clarification and it responded: "In other words, if the particles are entangled and at rest relative to an observer, then a measurement made on one particle will instantaneously affect the state of the other particle, regardless of the distance between them, as seen by that observer. However, if the particles are in motion relative to the observer, or if the observer is in a different reference frame, then the effect of the measurement may appear to be delayed or even reversed, depending on the relative velocities of the particles and the observer."

I'm checking because this sounds like nonsense and the use of the word "instantaneously" seems like an unnecessary complication. It seems sufficient to say that, once measured, the measured state of two entangled particles will be perfectly correlated.

I suspect "instantaneously" is added because a particle is considered to exist as a quantum wave function until a measurement collapses the function. For an entangled pair, collapsing the wave function for one particle seems to collapse it for both, and classical thinking leads to talking about the collapses occurring "at the same time". However, I believe the collapse of the wave function is not detectable; therefore, worrying about the simultaneity of the wave collapse becomes a question for philosophy, not physics.

Am I thinking about this properly? If it were possible to know when a wave function collapses without making a measurement, I think I would have a lot of follow-up questions for the Special and General Relativity forum.