this post was submitted on 10 Apr 2024
253 points (91.2% liked)

Showerthoughts

29202 readers
1728 users here now

A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. The best ones are thoughts that many people can relate to and they find something funny or interesting in regular stuff.

Rules

founded 1 year ago
MODERATORS
 

Sort of similar to the Great Filter theory, but applied to time travel technology.

you are viewing a single comment's thread
view the rest of the comments
[–] SmoothOperator@lemmy.world 1 points 5 months ago

The "message" does not have any local effect on reality - when you measure your particle, you have no way of figuring out if its partner was already measured elsewhere. The effect it does have is on the global state, maintaining the correlation that was encoded from the start.

If you write up the density matrix for the system before and after measurement of one of the particles, you can see that while the density matrix changes, it does not change in a way one can measure.

What I will concede is that before the first measurement the global state is |00>+|11>, afterwards it is |00> or |11>. This projection appears to happen instantaneously, no matter the distance, which is indeed faster than light.

But calling the wave function collapse a signal or a message or a transfer of information is misleading, I would say. In your example, we know that the initial state is |00>+|11>, and that the result of the first measurement is then, say, 1. Then no further information is required to know that the other measurement will result in 1. No messages required, no hidden variables, simply the process of elimination.

I would like to say that this is indeed a confusing subject, but that the math is clear, and that I am arguing what is my impression of the mainstream view in the field.