Sorry if this doesn’t make much sense but my grasp of the relevant physics is very shakey. As I understand it certain types of particle can become entangled with a “twin” any where in the universe and changes in the state of one particle are reflected in the other. If one particle is moved relative to the other time will presumably pass at a different rate for the two particle. How does this effect the relationship (or do the particles have to move together) ?
I guess you’re thinking of the consequences of special relativity (SR), that a moving reference frame experiences time differently. This doesn’t cause any problems with entanglement, thanks to “relativistic quantum field theory”, which is fully consistent with SR. So there is no problem with entangled particles that are moving with respect to each other.
Measuring or messing with one particle of an entangled pair doesn’t so much “affect” the distant particle: it’s a matter of gaining information about the distant particle.
Nope, this is not the case. After their instantiation, changes to one particle don’t affect the other particle. Rather, measuring properties of one particle give you information about the other particle. If you were able to alter the second particle by manipulating the first, you would have effectively established a time machine.
Also, a particle can’t just become entangled with one anywhere in the Universe (at least, if they can, there’s no possible way to detect it). They have to be in contact in some way to become entangled, typically by being created at the same time. For example, when a neutral pion decays, it turns into two photons, and those two photons will initially (until someone measures one) be entangled.
Also, any given entangled pair can only be used once: Anything you do to one of them will break the entanglement (or at least, transfer the entanglement to another particle).
Thanks, I think I’ve got it