EPR paradox, 5

One important question raised by this ambiguity is whether Einstein’s theory of relativity is compatible with the experimental results demonstrating nonlocality. Relativistic quantum field theory requires interactions to propagate at speeds less than or equal to the speed of light, so “quantum entanglement” cannot be used for faster-than-light-speed propagation of matter, energy, or information.

Measurements of one particle will be correlated with measurements on the other particle, but this is only known after the experiment is performed and notes are compared, therefore there is no way to actually send information faster than the speed of light.

On the other hand, relativity predicts causal ambiguities will result from the nonlocal interaction. In terms of the EPR experiment, in some reference frames measurement of photon A will cause the wave function to collapse, but in other reference frames the measurement of photon B will cause the collapse.

— 02:57, 16 June 2012

— Wikipedia on Action at a distance (physics)

Correlation does not imply causation.

If two events A and B have no causal relationship, they can have different time orders in different frames of reference. In some frames, A happened at a time earlier than B. In some other frames, B happened at a time earlier than A.

However, if they have causal relationship, their time order is the same with respect to any frame of reference.

— Me@2012-11-18 10:44:59 PM

2012.11.19 Monday (c) All rights reserved by ACHK