# Entanglement and general relativity

1. Apr 26, 2014

### ryan albery

The concepts of general relativity seem to fit (sorta) well with quantum physics, but how does the quantum world fit with general relativity? Specifically, I'm wondering if entanglement has any grounds that you can derive from GR?

2. Apr 26, 2014

### WannabeNewton

Entanglement is a purely quantum mechanical phenomenon that arises due to the linearity of the Schrodinger equation when applied to states of composite systems in superpositions of states of the subsystems. GR on the other hand is a purely classical field theory so you certainly cannot "derive" entanglement from it.

EDIT: Furthermore standard QM (and even standard QFT) are done on flat backgrounds so GR doesn't even come into play.

Last edited: Apr 26, 2014
3. Apr 26, 2014

### WannabeNewton

If the space-time geometry is flat there is no gravity so GR is of no relevance.

4. Apr 26, 2014

### ryan albery

I wish I could wrap my brain around that. A flat spacetime means no GR... is that true?

5. Apr 26, 2014

### Staff: Mentor

A flat spacetime means you don't need GR and can get by with just SR - although you can use the methods of GR if you wish. Special relativity is "special" because it applies only to the special case of flat zero-curvature spacetime, whereas general relativity works for the general case of any curvature, whether zero or not.

Many GR textbooks start with a general relativistic treatment of flat spacetime, so that the student can get comfortable with the new mathematical machinery in a familiar context.

6. Apr 26, 2014

### Mordred

there is both flat and curved treatments of relativity in QFT, referred to as gauge invariants.
types of gauge invarients are curved (space-time) and flat (tangent space) indices; coordinate (space-time) and local Lorentz (tangent space) symmetries. The flat and curved indices of Yang Mills can be found on page 591 on this QFT article. There are numerous other relativity treatments in this article. Been studying it for some time now, however my progress has been slow. Had to improve several fields of study to get even started on this article. So I am by no where near the level of discussion of it with any accuracy.

"Fields"

http://arxiv.org/pdf/hep-th/9912205v3.pdf

edit: I couldn't find any entanglement treatments in this paper. Was checking for it took some time. 885 pages lol

Last edited: Apr 26, 2014
7. Apr 26, 2014

### Mordred

there is some GR correlations to entanglement to GR in these article, however one is dealing with wormholes lol.

Wormholes and Entanglement
http://arxiv.org/pdf/1401.3416.pdf

Action and entanglement in gravity and field theory
http://arxiv.org/pdf/1310.1839v1.pdf

the fields article might have some detail, could be hidden under a metric I didn't recognize, those are the only articles I could find. Hope they help

edit found some more
http://arxiv.org/pdf/1212.5183v1.pdf
Gravitation and vacuum entanglement entropy
http://arxiv.org/abs/1204.6349

if you run through the supportive references, should lead to numerous articles

Last edited: Apr 27, 2014