GTR & Nonlocality: Exploring the Paradox

[Spathi]

TL;DR Summary

I have heard a phrase, that the general theory of relativity supports nonlocality. This phrase is strange for me, because I always thought, that Einstein was an opponent of the quantum mechanics because of its nonlocality ("spooky action at distance"). Can you help me understand this phrase?

I have heard a phrase, that the general theory of relativity supports nonlocality. This phrase is strange for me, because I always thought, that Einstein was an opponent of the quantum mechanics because of its nonlocality ("spooky action at distance"). Can you help me understand this phrase?

 

[Dale]

Where have you heard this specifically? It isn’t a common phrase. A specific reference that uses this phrase would help for context.

 

[PeroK]

I have heard a phrase, that the general theory of relativity supports nonlocality. This phrase is strange for me, because I always thought, that Einstein was an opponent of the quantum mechanics because of its nonlocality ("spooky action at distance"). Can you help me understand this phrase?

I'm not sure any of us is qualified to explain the strange voices in your head!

 

[Spathi]

Where have you heard this specifically? It isn’t a common phrase. A specific reference that uses this phrase would help for context.

I saw this phrase on some science forums.
Wikipedia says that the Alcubierre drive, which implies faster-than-light travel, is based on the Einstein field equations.

 

[Ibix]

Without an actual reference it's difficult to know, but I suspect your source of not really knowing what they're talking about. (And yes, I am aware of the irony in that statement.)

The Alcubierre metric is a spacetime with a kind of shortcut in it. All physical influences still propagate within lightcones, so there is no action at a distance in the sense that bothered Einstein.

 

[vanhees71]

TL;DR Summary: I have heard a phrase, that the general theory of relativity supports nonlocality. This phrase is strange for me, because I always thought, that Einstein was an opponent of the quantum mechanics because of its nonlocality ("spooky action at distance"). Can you help me understand this phrase?

I have heard a phrase, that the general theory of relativity supports nonlocality. This phrase is strange for me, because I always thought, that Einstein was an opponent of the quantum mechanics because of its nonlocality ("spooky action at distance"). Can you help me understand this phrase?

This is somehow ironic. Who the heck claims this? If there is one theory, which exhausts the locality principle to the extreme, it's GR. Even the fundamental space-time Poincare symmetry is "gauged", i.e., made local. The gauge group is general diffeomorphism invariance ("general covariance").

Let's not discuss the "non-locality" of QT in this part of the forum. For that have a look at the confusing status of these ideas even 80 years after the Bohr-Einstein debate in the quantum-interpretation subforum ;-)).

 

[LittleSchwinger]

Yeah, all influences in General Relativity travel within/along light-cones and cannot affect matter outside their light cone. The theory is constructed to be explicitly local, the equations are local, etc. There are no non-local effects.

The Alcubierre solution is an odd spacetime and you have to know GR for us to really get into it, but it's not "non-local".

 

[martinbn]

This is probably not what you have seen (somewhere), it is just a guess, but sometimes people say that there are non-local quantities in GR. For example mass. In general you cannot define what the mass of a part of a system is. You can for the whole space-time (under some restrictions).

 

[vanhees71]

I'd be very surprised, if you can define a quantity like mass which has a physical interpretation and cannot be measured by local observables.

 

[martinbn]

I'd be very surprised, if you can define a quantity like mass which has a physical interpretation and cannot be measured by local observables.

How do you measure the ADM mass locally?

 

[Spathi]

I will try to formulate my request later, if I get help at other forums. Now let me ask some more questions:

1) Do you observe that pseudoscientists usually attack the GTR, but not quntum mechanics?
2) Is there a phychological effect, that people who understand GTR don't like QM (like Einstein), while people who know QM do not like GTR?

 

[martinbn]

I will try to formulate my request later, if I get help at other forums. Now let me ask some more questions:

1) Do you observe that pseudoscientists usually attack the GTR, but not quntum mechanics?

No, I would say that usually the crackpots attack quantum mechanics and/or special relativity.

2) Is there a phychological effect, that people who understand GTR don't like QM (like Einstein), while people who know QM do not like GTR?

I'd say most people, who understand enough of GR and QM, like both. Actually I've never heard of anyone who doesn like GR. Usually it is called the "most beautifull theory".

 

[vanhees71]

How do you measure the ADM mass locally?

https://en.wikipedia.org/wiki/Mass_...ndi_masses_in_asymptotically_flat_space-times

The energy-momentum tensor is a local object, from which you can form scalars at a given space-time point, which represent observables.

I'm not sure whether ADM mass as a quantity derived by integrating over a "surface at infinity" is an observable though. I guess the experts on GR in this forum know this much better than I do ;-).

 

[PeroK]

It's sad when trolling proves successful on PF

 

[vanhees71]

Where is the trolling? I think that the notion of mass/energy is a pretty subtle subject in GR, isn't it?

 

[PeroK]

Where is the trolling?

Posts #1, #4 and #11.

 

[martinbn]

https://en.wikipedia.org/wiki/Mass_...ndi_masses_in_asymptotically_flat_space-times

The energy-momentum tensor is a local object, from which you can form scalars at a given space-time point, which represent observables.

I didn't talk about energy-momentum.

I'm not sure whether ADM mass as a quantity derived by integrating over a "surface at infinity" is an observable though. I guess the experts on GR in this forum know this much better than I do ;-).

I didn't say anything about abservables.

All i said was that mass is not licalisable and may be that is the nonlical aspect he saw in some foum being discussed.

 

[Dale]

I saw this phrase on some science forums.

This is not a reference. A reference would be, for example, a specific link to a science forum where an actual poster made this statement.

Please read the forum rules on acceptable references here. This thread is closed.

 

[PeterDonis]

I will try to formulate my request later, if I get help at other forums. Now let me ask some more questions:

1) Do you observe that pseudoscientists usually attack the GTR, but not quntum mechanics?
2) Is there a phychological effect, that people who understand GTR don't like QM (like Einstein), while people who know QM do not like GTR?

To add one comment for future reference, these questions are not on topic in this forum, since they are not about relativity.