The locality tag has no wiki summary.
18
votes
6answers
1k views
The speed of gravity?
Sorry for the layman question, but it's not my field.
Suppose this thought experiment is performed. Light takes 8 minutes to go from the surface of the Sun to Earth. Imagine the Sun is suddenly ...
26
votes
8answers
4k views
Why quantum entanglement is considered to be active link between particles?
From everything I've read about quantum mechanics and quantum entanglement phenomena it's unobvious for me, why quantum entanglement is considered to be active link. I.e. it's stated every time that ...
11
votes
3answers
1k views
14
votes
2answers
700 views
Definitions: 'locality' vs 'causality'
I'm having trouble unambiguously interpreting many answers here due to the fact that the terms locality and causality are sometimes used interchangeably, while other times seem to mean very different ...
13
votes
5answers
795 views
What combinations of realism, non-locality, and contextuality are ruled out in quantum theory?
Bell's inequality theorem, along with experimental evidence, shows that we cannot have both realism and locality. While I don't fully understand it, Leggett's inequality takes this a step further and ...
2
votes
1answer
242 views
Wavefunction in quantum mechanics and locality
Every wavefunction of a form $\Psi(x)$ can be described as a superposition of multiple free particle solutions.
We can see the following Fourier transform:
$$ \psi(x) = \int e^{ik\cdot x} \psi(k) dk ...
4
votes
1answer
86 views
How soon that a force affect another object?
Imagine this scenario: I have 2 objects in vacuum without any force exerted upon them not even a possible gravitational force between them.
Now if one of them gets a gravitational or magnetic force, ...
10
votes
3answers
475 views
Bell's theorem and why nonlocality is problematic
I generally hear it assumed that Bell's inequality implies violation of counterfactual definiteness, because locality is considered sacrosanct. I understand of course that measurable violations of ...
5
votes
4answers
435 views
Locality in Quantum Mechanics
We speak of locality or non-locality of an equation in QM, depending on whether
it has no differential operators of order higher than two.
My question is, how could one tell from looking at the ...
5
votes
1answer
168 views
How is the 'cluster decomposition principle' implemented in holographic theories?
Since holographic theories are non-local by definition, how is this principle implemented?
Naively, it seems to me it is not, at least, in some sense.
I would appreciate an explanation as simple ...
2
votes
1answer
195 views
How to tell local and unlocal in QFT?
I'm taking QFT course in this term. I'm quite curious that in QFT by which part of the mathematical expression can we tell a quantity or a theory is local or unlocal.
1
vote
2answers
158 views
$\nabla$ and non-locality in simple relativistic model of quantum mechanics
In Wavefunction in quantum mechanics and locality, wavefunction is constrained by $H = \sqrt{m^2 - \hbar^2 \nabla^2} $, and taylor-expanding $H$ results in:
$$ H = \dots = m\sqrt{1 - \hbar^2/m^2 ...
