Quantum Entanglement and the Big Bang

[atlucas]

I don't know how to shorten this question. Deep breath:

If particles that interact physically and become separated are entangled, then once this was proven through experimentation wouldn't local realism theory have to be false since the universe as we know it arose from a singularity?

I know we are unfamiliar with the physical laws at a singularity, but in that case maybe I could say just large chunks of the universe are entangled as things "cooled down" and matter formed. And I suppose the heart of my question is: wouldn't that imply that most "natural" particles - particles that exist outside of a lab - are already entangled with other, perhaps distant, particles?

 

[DrChinese]

I don't know how to shorten this question. Deep breath:

If particles that interact physically and become separated are entangled, then once this was proven through experimentation wouldn't local realism theory have to be false since the universe as we know it arose from a singularity?

Welcome to PhysicsForums, atlucas!

As you describe it, the answer is no. Those conditions alone would not be enough to disprove local realism, as this could result from local conditions even after the universe separated. You still need something like Bell's Theorem.

 

[atlucas]

Okay, the follow up question: Can multiple particles become entangled? Say if two electrons share a bonding orbital in... carbon dioxide, then they are split up in some chemical process, are those electrons still entangled? Or would they become disentangled with one another and instead entangled with their new orbital "partners?"

It is my understanding that the wave function collapses only from/after observation, so by that postulate you could entangle a series of particles with one another, observe one, and make conclusions about the states of all the others in the series, yes?

 

[ibysaiyan]

Okay, the follow up question: Can multiple particles become entangled? Say if two electrons share a bonding orbital in... carbon dioxide, then they are split up in some chemical process, are those electrons still entangled? Or would they become disentangled with one another and instead entangled with their new orbital "partners?"

It is my understanding that the wave function collapses only from/after observation, so by that postulate you could entangle a series of particles with one another, observe one, and make conclusions about the states of all the others in the series, yes?

I am not much knowledgeable in QM ,yet I am sure DrChinese or any other respectable users will give you an in depth answer.
However , From what I have gathered so far entanglement of photons is preferred /convenient than say an electron,due to variables involved.Often particles in decay tend be entangled due to conservation laws of physics so I don't see why it'd be wrong to make assumptions of the other 'unobserved entangled counterpart/s' since we know that conservation comes into play.

-ibysaiyan

 

[DrChinese]

Okay, the follow up question: Can multiple particles become entangled? Say if two electrons share a bonding orbital in... carbon dioxide, then they are split up in some chemical process, are those electrons still entangled? Or would they become disentangled with one another and instead entangled with their new orbital "partners?"

It is my understanding that the wave function collapses only from/after observation, so by that postulate you could entangle a series of particles with one another, observe one, and make conclusions about the states of all the others in the series, yes?

Yes, you can entangle multiple particles and this has been demonstrated. However, the result is not quite as you might expect. Assume you have 3 particles: A, B and C and these are entangled with some observable such that:

A+B+C=0

If you later find A=+1, then you now know that B+C=-1. So you do not get certain knowledge of B alone from measuring A.