Apologies if this has been asked before. I did some searching but didn't see it anywhere asked quite like this. Thanks in advance for any insights.
Caveat: I am an organic chemist and thus appreciate qualitative descriptions of the behavior of matter more than quantitative ones and tend to struggle when I can't envision a physical correlate for mathematical descriptions. I have found simple and intuitive analogies that readily explain away many of the supposed "paradoxes" of quantum mechanics, but I am stuck on this one.
It's my understanding that locality can be a problem for various interpretations of QM since entangled particles at infinite separation appear to instantaneously determine each other's behavior. The argument goes something along the lines of:
"No information can be transferred from one particle to another faster than the speed of light, so the instantaneous exchange of information between entangled particles separated by some infinite distance must be a violation of the principle of realism or locality."
My question is this: A) why is it assumed that information must be exchanged between entangled particles when one is disturbed/measured and B) why must some intermediary of this information that is constrained by the speed of light be invoked in the sharing of this information?
If I tie a 1.5 mile long length of rope between two trees and then cut the rope at a point 1/3 of its distance between the trees, how long does it take for the far end of the rope to know that it is now only one mile long? It seems the answer is that there is no lag and no need for the invocation of the speed of light - the rope is instantaneously shorter along its entire length in the instant of its cutting. In other words, the system is instantaneously and universally redefined as soon as I interfere with it at any point and there is no need to complain about "locallity" (i.e. arguments that "the cut was made a mile away, therefore it can't instantaneously affect the far end of the rope" are absurd - one instant the rope was universally 1.5 miles long, the next instant it was 1.0 miles long).
If we are going to then consider two entangled particles, the various wavefunctions describing the various behaviors of the particles are not only descriptive of the individual particles but in fact define the entire system universally, do they not? This being the case, if we interfere with either of the particles, thereby introducing a change to a component wavefunction, aren't we necessarily and by definition redefining the entire system? And isn't the entire system redefined universally in the very instant of the interaction, thereby resulting in any dependent change occurring instantaneously (like a spin-flip in the other particle, for instance)? Why is there an expectation of some time lag that is limited by the speed of light any more than in the instance of cutting our rope above?