Quantum physics & synchroization of 2 particles.

[davisbunch]

Ok, based on quantum physics, it is possible to synchronize 2 particles. If, theoretically, you fly particle A out 1 light year away, while leaving particle B on earth, by the understood laws, if you flip the spin of B, A's spin should simultaneously flip. This would violate Einstein concept of c (speed of light) as an inviolable constant. Please Explain.

 

[Demystifier]

Moving faster than c is not in contradiction with the theory of relativity. See e.g.
http://en.wikipedia.org/wiki/Tachyon

 

[Bill_K]

Tachyons were an interesting idea many years ago, but they have dead-ended, except in the context of condensation as mentioned in the Wikipedia article.

davisbunch, it is possible to entangle the spins of two particles. If you fly one particle out one light year, they will still be entangled. If you measure the spin of B, the spin of A is determined. This does not imply an influence can be propagated faster than light. On the other hand, if you flip the spin of B, you do not affect A's spin, rather you have destroyed the entanglement.

 

[ZapperZ]

Ok, based on quantum physics, it is possible to synchronize 2 particles. If, theoretically, you fly particle A out 1 light year away, while leaving particle B on earth, by the understood laws, if you flip the spin of B, A's spin should simultaneously flip. This would violate Einstein concept of c (speed of light) as an inviolable constant. Please Explain.

First of all, you don't "flip" the spin. You measure one, and that automatically determines what the orientation of the other particle's spin is.

Secondly, nothing travels. There's no signal that goes from one particle to the other. So nothing is moving at faster than c that we know of.

Thirdly, it isn't "synchronize". It is called "entanglement". If you do a search on this forum, there's already tons of threads on such a discussion. You may, for example, want to start here:

https://www.physicsforums.com/showthread.php?t=492479

Zz.

 

[Demystifier]

Tachyons were an interesting idea many years ago, but they have dead-ended ...

Sure, but it is irritating how often one can see the claim that "faster than light is not compatible with relativity". It is compatible, period. Even if tachyons do not exist in nature, even if they lead to problems with stability and causality (which can be solved by reinterpreting the concept of "time"), even if ..., they are still compatible with relativity.