I Solving Quantum Mechanics in Space-Time: Effects of General Relativity

[davidge]

I have been wondering what effects a quantum mechanical system would cause in space time.
Pick a general state of the system. This would not generaly be in one of the energy eigenstates -rather, it would be on a superposition of energy states. Now, each one of them would cause a different space time curvature.

But we do not see such thing happening -the space time has one, and only one, curvature. So would that mean as we look out in the space time we are causing the system to collapse to become a classical system?

 

[PAllen]

This is a good question, and here are some speculations on this by a major GR theorist (see, e.g. p.3):

https://arxiv.org/abs/0812.0240/

 

[davidge]

This is a good question, and here are some speculations on this by a major GR theorist (see, e.g. p.3):

https://arxiv.org/abs/0812.0240/

Very interesting indeed. What are the chances for what he discusses to be correct?

 

[cosmik debris]

I have been wondering what effects a quantum mechanical system would cause in space time.
Pick a general state of the system. This would not generaly be in one of the energy eigenstates -rather, it would be on a superposition of energy states. Now, each one of them would cause a different space time curvature.

But we do not see such thing happening -the space time has one, and only one, curvature. So would that mean as we look out in the space time we are causing the system to collapse to become a classical system?

We don't see it happening at the large scales but it could at small scales. This is the basis of Penrose's arguments for Orchestrated Reduction Collapse (Orch-OR) where gravity is the cause of decoherence.

Cheers

 

[Paul Colby]

But we do not see such thing happening -the space time has one, and only one, curvature.

We should question this statement since there is no observational proof of this.

 

[Haelfix]

Before asking this question about GR, ask the question of a macroscopic open system in normal quantum mechanics. Namely, why don't we see sqrt(2)/2 table over here and sqrt(2)/2 of the table on the other side of the room?

I would say the modern answer to that still open puzzle is environmentally selected decoherence, namely that the table collapses to a definite position bc of its interaction with the environment. Likewise you could imagine that the stress energy tensor is some sort of expectation value of many quantum objects that have all collapsed to some classical pointer state(s). However, the exact details and consistency of that sort of process in the gravitational context are simply not known in detail.