[SEQ RERUN] Spooky Action at a Distance

MinibearRex

Today's post, Spooky Action at a Distance: The No-Communication Theorem was originally published on 05 May 2008. A summary (taken from the LW wiki):

As Einstein argued long ago, the quantum physics of his era - that is, the single-global-world interpretation of quantum physics, in which experiments have single unique random results - violates Special Relativity; it imposes a preferred space of simultaneity and requires a mysterious influence to be transmitted faster than light; which mysterious influence can never be used to transmit any useful information. Getting rid of the single global world dispels this mystery and puts everything back to normal again.

Discuss the post here (rather than in the comments to the original post).

This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was Bell's Theorem: No EPR "Reality", and you can use the sequence_reruns tag or rss feed to follow the rest of the series.

Sequence reruns are a community-driven effort. You can participate by re-reading the sequence post, discussing it here, posting the next day's sequence reruns post, or summarizing forthcoming articles on the wiki. Go here for more details, or to have meta discussions about the Rerunning the Sequences series.

Today's post, Spooky Action at a Distance: The No-Communication Theorem was originally published on 05 May 2008. A summary (taken from the LW wiki):

As Einstein argued long ago, the quantum physics of his era - that is, the single-global-world interpretation of quantum physics, in which experiments have single unique random results - violates Special Relativity; it imposes a preferred space of simultaneity and requires a mysterious influence to be transmitted faster than light; which mysterious influence can never be used to transmit any useful information. Getting rid of the single global world dispels this mystery and puts everything back to normal again.

There is no single universal rate at which decoherence propagates. The details will depend on the structure of the system and its environment. What we can say is that the speed of light sets an upper limit on the speed at which interactions can propagate, so decoherence will propagate at a finite rate.

As for measuring decoherence rates in specific cases, this has been done. Take this paper, for instance. The authors couple Be-9 ions prepared in superpositions of their energy eigenstates with various types of reservoirs, representing different environments. They then measured the coherence of the ion's state at different times, determining the rate at which the superpositions decohere given different environments and different interaction strengths. Is this the sort of experiment you were looking for?

As for measuring decoherence rates in specific cases, this has been done.

I thought we were discussing the (hypothetical) decoherence propagation rate, not the time it takes for a quantum system to decohere in the lab, which has nothing to do with relativity. It is even measured in different units (inverse seconds vs. meters/second). So no, this experiment is not what I was asking about.

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