The wavefunction obtained by the Schrödinger equation is indeed time dependent, so it is possible for the probability of measuring a certain eigenvalue of a physical quantity described by an operator on the wavefunction to change over time. I don’t quite get what you are trying to say here. Are you talking about whether quantum entanglement breaks relativity? Measuring for example one electron spin up will get you the information that the other one (maybe a few light-years away) is of a certain other state (maybe spin down). This does not allow to transfer a message between the two locations, as measuring the state on the senders end is still completely random. They would have to send a lookup table which is still only possible with the speed of light
Comment on a real danger of quantum computing
yucandu@lemmy.world 1 week ago
Did anyone check and see if the state of those quantum-linked pairs are related to time? And it’s just like a function of milliseconds since linking determines whether positive or negative, and that’s how you can know the other one is the exact opposite, without any “information being transmitted”… did anyone check if it’s time?
Paulemeister@feddit.org 1 week ago
bunchberry@lemmy.world 1 week ago
Trying to think of classical models to explain the EPR paradox kinda misses the point of the EPR paradox, because the point of the EPR paradox is to assume that there is indeed nothing linking the two particles until you look to then show you that this leads to a contradiction with Einstein’s definition of locality.† You can indeed trivially think of classical explanations to explain the EPR paradox and how the +1 and -1 particles might be linked and predetermined, but that’s not the point of the EPR paper which is to explore what happens if we don’t make this assumption.
The paper that instead explores what happens if we do assume they are predetermined is Bell’s theorem, and Bell’s theorem is more complicated than just assuming that the particles are entangled and opposites such that one will be measured to be +1 and the other to be -1. Bell’s theorem shows that the behavior of the individual particle can be dependent upon the configuration of a collection of measurement devices, even if the particle only ever interacts with one measurement device in the collection. That not only violates Einstein’s definition of locality, but if you try to make it deterministic, it ends up violating special relativity as well.
The simplest demonstration of this is with three particles in the GHZ experiment. The point is, again, not merely that the particles have correlated values but that (1) those values are statistically dependent upon the configuration of the measurement device and (2) the values for an individual particle can be statistically dependent upon the configuration of a collection of measurement devices even if it never interacts with most of the devices in the collection.
† “Locality” is used in two different senses in the literature. One is relativistic locality which means nothing can travel faster than light. The other is what I like to call coordinate locality which is what Einstein had in mind with the EPR paper, which is the idea that things have to locally interact to become dependent upon one another. The EPR paper is a proof by contradiction that quantum mechanics without hidden variables violates coordinate locality specifically.