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## Main Question or Discussion Point

I strongly disagree with the collapse hypothesis.

Why does microcausal QFT obeying the linked-cluster theorem imply there cannot be any instantaneous collapse? Is this the strongest argument against instantaneous collapse?Since relativistic local and microcausal QFT, the fundamental starting point for the Standard Model of elementary particle physics, obey the linked-cluster theorem, there cannot be any instantaneous collapse, and there is no "spooky action at a distance" as Einstein called it.

Is linked-cluster the same concept as cluster decomposition?

I found this discussion on cluster decomposition and EPR: https://www.physicsforums.com/threads/cluster-decomposition-and-epr-correlations.409861/

Humanino said

The cluster decomposition principle is an interpretation of the factorization of the S matric for separated reaction

From <https://www.physicsforums.com/threads/cluster-decomposition-and-epr-correlations.409861/#post-2773207>

Demystifier said:

Indeed, in Sec. 4.3 Weinberg explicitly says:

"It is one of the fundamental principles of physics ... that experiments that are sufficiently separated in space have unrelated results."

...

"... the cluster decomposition principle states that if multi-particle processes ... are studied in N very distant laboratories, then the S-matrix element for the overall process factorizes."

Clearly, these statements formulated as such are incompatible with EPR correlations, and are therefore wrong.

From <https://www.physicsforums.com/threads/cluster-decomposition-and-epr-correlations.409861/#post-2773207>

Demystifier also said:

I would summarize and formalize it this way:

CDP says that if

1. the initial state (of spatially separated subsystems) can be factorized

and

2. the subsystems remain spatially separated all the time

then

the final state can also be factorized.

This is a correct form of CDP in QFT. But this is not the form explicitly stated by Weinberg.

From <https://www.physicsforums.com/threads/cluster-decomposition-and-epr-correlations.409861/#post-2773207>

Humanino said:

In this situation, once the initial state (half final state of an EPR exp.) has been measured it becomes separated and the CDP applies.

From <https://www.physicsforums.com/threads/cluster-decomposition-and-epr-correlations.409861/#post-2773207>

My understanding of the comments by Humanino and Demystifier is that the CDP applies only after the collapse. So CDP in this case is not an argument against collapse. What am I missing?

Thanks.