A thought experiment on Quantum entanglement

[Mild mannered]

Hi

Not that I know a whole lot about Quantum Entanglement, but I was wondering about what would happen to Q E particles when subjected to a relativistic speeds thought experiment.

IE: Particles A and B are thoroughly connected, entangled. Particle A is in a lab on Earth and particle B is in a space ship accelerating away from the Earth at near light speed.

Obviously particle A "ages" at earth rate whilst Particle B moves in a much slower time frame as it's time is dilated. So when a few years Earth time has passed for B perhaps many thousands have passed for A.

My question is does the Q E survive this strange turn of events.

Are the particles Entangled though the time dimension as well as space?
(yes I'm aware the nature of this question betrays my ignorance of the specifics of the whole issue)

If they are still connected would this supply us with a nifty link from past to future - what problems would we run into testing this scenario?

Thanks, Mild

[Nereid]

The 'trick' is that entanglement occurs at a single point in space-time, when the pair is 'created', not 'observed'.

The counter-intuitive aspect is the apparent 'instantaneous' decoherence that occurs when either one of the entangled pairs is 'observed'.

From the quantum POV, it matters not one jot what the physical environments of either pair is, or their histories, at the time of decoherence. For example, you could have one be swallowed by a BH (whether the act of 'swallowing' would trigger the decoherence is, in principle, irrelevant)

And no, there is no way you can create

a nifty link from past to future

; no information whatsoever can be transmitted via the decoherence (that can't also be transmitted via 'ordinary' means). To see why, a good way is to attempt to describe, in sufficient detail, how the entanglement (and subsequent decoherence) can be used to send even one bit of information.

[Mild mannered]

Originally posted by Nereid@Aug 9 2005, 11:34 PM
no information whatsoever can be transmitted via the decoherence

Thanks Nereid

I kind of knew you couldn't pass information - there was a thread on this a while back I think. It was just a thought. I was really intrested in the time factor - whether they could remain entangled though in different time frames.

As I said I know little about all this - just thought it might be an interesting question - thanks again for the reply, always very illuminating