Quantum Entanglement vs. Now Slices (Relativity)

[DrSammyD]

So I watched this video talking about now slices, and how it seems that across vast distances of space, movement can affect what is actually the now of places far away.

https://www.youtube.com/watch?v=

This seems to be in direct conflict with what I've heard about quantum entanglement.

Let's say we move an entangled particle across such a distance. If we start moving away with our particle at very fast pace, the entangled particle on the other side will be affected in the past, where as if we start moving towards it, it will be affected in the future. But from what I've heard, entangled particles change "simultaneously" without regard to which "now slice" is happening.

Am I describing this correctly? Is anybody researching how these two phenomenon relate?

 

[Chalnoth]

There is no such thing as a global "now". Or, perhaps more accurately, there are many perfectly-valid slices of the universe that can be thought of as having equal time values. What's incorrect here is your understanding of quantum entanglement. But that's understandable, as quantum entanglement is a very strange effect that is frequently described incorrectly.

Here's a (hopefully) better way to think about it: quantum entanglement is, fundamentally, about consistency. If we have a quantum-mechanical system that splits into two particles, one whose spin is always opposite the other's, then any measurement of particle A's spin will be opposite of particle B's spin. That is, if I measure spin "up" on my particle A, and particle B travels towards you, then you will necessarily measure spin "down" on particle B. It does not matter if we measure the particles at the same time, or one before the other. The timing is irrelevant. The only thing that is relevant is that the two particles have spins that are consistent.

 

[DrSammyD]

Can the spin of the particle be measured without knowing what the other particle's spin is?

 

[justsomeguy]

Can the spin of the particle be measured without knowing what the other particle's spin is?

Measuring one tells you the state of both.

 

[sardar]

I find the concept of now slices and quantum entanglement fascinating. Both of these concepts are rooted in the theories of relativity and quantum mechanics, which are two of the most fundamental and well-supported theories in physics.

First, let's clarify what is meant by "now slices." In the theory of relativity, time is not absolute and can be experienced differently by observers in different reference frames. This means that events that are simultaneous for one observer may not be simultaneous for another. Now slices refer to the idea that at any given moment, there are multiple "nows" happening simultaneously for different observers.

On the other hand, quantum entanglement refers to the phenomenon where two particles can become correlated in such a way that the state of one particle affects the state of the other, regardless of the distance between them. This has been demonstrated through numerous experiments and is a well-established phenomenon in quantum mechanics.

So how do these two concepts relate? It is true that in the theory of relativity, the concept of simultaneity is relative and can vary depending on the observer's reference frame. However, in the case of quantum entanglement, the correlation between particles is instantaneous and not affected by the observer's reference frame. This is because the state of the particles is not determined by their position in space, but rather by their quantum properties.

In other words, while the concept of now slices may affect our perception of time and simultaneity, it does not change the fact that entangled particles are intrinsically linked and their states are correlated regardless of the distance between them.

There is ongoing research into how these two phenomena may be connected, and it is an exciting area of study in the field of quantum mechanics. But for now, we can say that while the concept of now slices may seem to contradict the principles of quantum entanglement, they can coexist within the framework of relativity and quantum mechanics.