Local or Nonlocal Physics: The Concept of "Fields" vs. "Entanglement

  • Thread starter guyingfei
  • Start date
  • Tags
    Local
In summary, the conversation discusses the concept of "fields" and "entanglement" in relation to the locality of physics. The meaning of "local" in quantum field theory and in discussions of Bell inequalities is different, but Einstein locality and locality in QFT are essentially the same thing. It is argued that correlations are not transported, and non-local correlations have nothing to do with Einstein locality. The conversation also touches on the idea that our universe is both local and nonlocal, and that non-locality is strictly a quantum phenomenon.
  • #1
guyingfei
8
0
The concept of “fields” told us that our physics is local, while the concept of "entanglement" seems to say that there is something nonlocal

So I wonder whether our physics laws are local?
 
Physics news on Phys.org
  • #2
guyingfei said:
The concept of “fields” told us that our physics is local, while the concept of "entanglement" seems to say that there is something nonlocal

So I wonder whether our physics laws are local?

The meaning of ''local'' in quantum field theory and in discussions of Bell inequalities is totally different. As always in language, you must respect the context to make sense out of statements involving words with multiple meanings.
 
  • #3
The field operator is a local object, but a product of two or more field operators at different points is a nonlocal object. When such nonlocal objects act on the vacuum, one gets a many-particle state, which may contain nonlocal features. (More precisely, one must take a superposition of such states to get entanglement, i.e., really nonlocal features.)
 
  • #4
A. Neumaier said:
The meaning of ''local'' in quantum field theory and in discussions of Bell inequalities is totally different. As always in language, you must respect the context to make sense out of statements involving words with multiple meanings.

I don't think that "local" in terms of quantum field theory was in mind in the OP, but the notion that gravitational force, for instance, is not a result of action at a distance but the result of local fields. This notion is applied in the EPR argument against quantum mechanical completeness.
 
Last edited:
  • #5
Phrak said:
I don't think that "local" in terms of quantum field theory was in mind in the OP, but the notion that gravitational force, for instance, is not a result of action at a distance but the result of local fields. This notion is applied in the EPR argument against quantum mechanical completeness.

Possibly; then we'd have three totally different meanings of locality. But in fact Einstein locality and locality in QFT are essentially the same thing, guaranteeing that the dynamics is hyperbolic, with a maximal speed of transport.

In any case, correlations are not transported, hence nonlocal correlations have nothing to do with Einstein locality.
 
  • #6
guyingfei said:
The concept of “fields” told us that our physics is local, while the concept of "entanglement" seems to say that there is something nonlocal

So I wonder whether our physics laws are local?

Evey quantum state which isn't a position eigenstate is non local i'd say.
 
  • #7
Demystifier said:
The field operator is a local object, but a product of two or more field operators at different points is a nonlocal object. When such nonlocal objects act on the vacuum, one gets a many-particle state, which may contain nonlocal features. (More precisely, one must take a superposition of such states to get entanglement, i.e., really nonlocal features.)

Do you mean by that that linear super-position for numerical quantities (in Hilbert space) is no longer valid for non-local features? In other words the math goes "non-linear"? Or do you mean that expected symmetries get broken?
 
  • #8
PhilDSP said:
Do you mean by that that linear super-position for numerical quantities (in Hilbert space) is no longer valid for non-local features? In other words the math goes "non-linear"? Or do you mean that expected symmetries get broken?
No, no, no.

A product and a sum of linear operators is still a linear operator.
 
  • #9
A. Neumaier said:
Possibly; then we'd have three totally different meanings of locality. But in fact Einstein locality and locality in QFT are essentially the same thing, guaranteeing that the dynamics is hyperbolic, with a maximal speed of transport.

In any case, correlations are not transported, hence nonlocal correlations have nothing to do with Einstein locality.

I don't see this as easily deducible from experimental results. How do you arrive at the conclusion that correlations are not transported?
 
  • #11
guyingfei said:
The concept of “fields” told us that our physics is local, while the concept of "entanglement" seems to say that there is something nonlocal

So I wonder whether our physics laws are local?

I recently said in a thread, that one axiom of quantum mechanics might be that:

''Non-locality is strictly a quantum phenomena. Whilst local conditions can be met quite well for arbitrarily large bodies.''

Our universe is not simply local. It is nonlocal as well, but never one always over the other. It's like accepting how tunnelling, and quantum interference patterns are accepted quantum phenomena, you never observe them therefore for bodies which are considered free of quantum effects. Non-locality seems to be similar in this regards and completely absent for macroscopic bodies.
 
  • #12
Phrak said:
I don't see this as easily deducible from experimental results. How do you arrive at the conclusion that correlations are not transported?

Correlations are things one computes from statistics on observations.

Transported are mass, energy, charge, momentum, etc..
 
  • #13
Phrak said:
I don't think that "local" in terms of quantum field theory was in mind in the OP, but the notion that gravitational force, for instance, is not a result of action at a distance but the result of local fields.

i agree
cos he ask:

guyingfei said:
So I wonder whether our physics laws are local?

the gravity on the Earth have nothing to do with some dust at UDFy-38135539.
 
Last edited:

1. What is the difference between local and nonlocal physics?

Local physics refers to the study of physical phenomena that can be explained by interactions between particles that are in close proximity to each other. Nonlocal physics, on the other hand, deals with phenomena that cannot be explained by local interactions and may involve the concept of entanglement.

2. What do "fields" and "entanglement" mean in the context of physics?

In physics, "fields" refer to regions in space where a force or energy is present, and particles can interact with each other. "Entanglement" refers to a phenomenon where two or more particles become connected in such a way that their states are inseparably linked, even when they are separated by large distances.

3. How does the concept of fields relate to local physics?

In local physics, fields are used to explain the interactions between particles in close proximity to each other. These fields are represented by mathematical equations that describe the strength and direction of the force between particles.

4. Can entanglement occur in local physics?

No, entanglement is a nonlocal phenomenon that cannot be explained by local interactions. It only occurs when particles are connected in such a way that their states are linked, regardless of the distance between them.

5. How does understanding local and nonlocal physics impact our understanding of the universe?

Studying both local and nonlocal physics is crucial for a complete understanding of the universe. Local physics helps us explain the interactions between particles on a small scale, while nonlocal physics allows us to understand phenomena that occur on a larger scale and may involve entanglement. Together, they provide a more comprehensive view of the physical world.

Similar threads

  • Quantum Physics
Replies
7
Views
1K
Replies
2
Views
947
Replies
6
Views
871
  • Quantum Physics
3
Replies
87
Views
5K
Replies
44
Views
3K
  • Quantum Interpretations and Foundations
2
Replies
37
Views
1K
Replies
9
Views
1K
Replies
18
Views
2K
Replies
7
Views
1K
  • Quantum Physics
Replies
8
Views
1K
Back
Top