Comment Re:FTL communications? (Score 3, Informative) 109
So I think this means that either the no-communication theorem is wrong, or the change in mass of an entangled particle cannot be measured.
That's an interesting point, but on my reading of the paper (which was pretty cursory, admittedly) the extra mass term comes from the joint wavefunction, which means both particles would have to be measured. It looks like the pair has greater mass, not the individual particles.
This makes sense because insofar as they are entangled it doesn't even make sense to talk about the individual particles. Furthermore, if one were to measure either of the particles individually, that would break the entanglement and the extra mass term would fall to zero.
Thing of the highly idealized experiment of two sources on a balance beam, one that emits pairs of non-entangled particles, one that emits pairs of entangled particles. The theory says that the balance will tip toward the side of the entangled pairs, but it does not follow from this that measurements on any of the individual particles will reveal increased mass.