[Confusion]

I think this is merely a terminological difference.

What happens is:

- before observing one particle, observations on the other particle are described and predicted by an entangled, superposition, state.

- after observing one particle, observations on the other particle are described and predicted by a non-entangled, non-superposition state. The possible outcomes of the observations on the other particle, both predicted and measured, are different after the observation on the first particle.

Of course the observation causes a change in the state of both particles simultaneously. And I understand that strictly speaking, in the physical sense of the word, there is no 'action'. But does it really matter if people say they are 'acting on' the remote particle by observing the local particle, as long as they mean the exact same thing?

[lisper]

In some sense, yes, this is just quibbling over terminology (as all pedagogical issues ultimately boil down to terminology). But the terminological quibble is very subtle and profound.

> after observing one particle, observations on the other particle are described and predicted by a non-entangled, non-superposition state.

This is the misleading part. It is not true in an absolute sense. It is only true for the observer that makes the "first" measurement (with "first" in scare quote because relativity). It is not true for the observer of the "other" particle. There is no measurement that can be made on the "other" particle that will tell you if the first particle has been measured.

> The possible outcomes of the observations on the other particle, both predicted and measured, are different after the observation on the first particle.

This too is misleading because it assumes that "possibility" is a universal property and it isn't. The "possible" outcomes for the "other" particle change for the observer of the "first" particle, but not for the observer of the "other" particle. And even this is not quite right because it depends on whether the observations are time-like or space-like separated, and whether or not there is a classical communications channel open between the two observers. It gets complicated. Read the paper.