All Questions
Tagged with locality non-locality
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Newton's second law - local laws and non-local laws
What are local laws? I was reading this line in a book...
Newtons second law is a local law. This means that it applies to a particle at a particular instant without taking into consideration any ...
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Are field theories where free energy density depends on 2nd-order derivative non-local?
It is accepted that infinite order of derivatives in field theory lead to non-local effects while finite number of them local.
reference within physics stack exchange
Let’s take a lattice with next-...
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Is there any limit to the utility of quantum measurements in the sense of a Lieb-Robinson bound?
So the Lieb-Robinson bound of 1972 derives an emergent maximum speed $v \ll c$ of the propagation of quantum information under time evolution generated by some local Hamiltonian $H(t)$. Basically, ...
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Why does it make sense to add/subtract the results of measuring in 2 different bases in Bell's inequality when each observer only measures 1 property?
In the CHSH inequality, we construct an experiment whereby two observers each receive a particle and measure two given properties of their particles, for which the outcomes are ±1. We then consider ...
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How is the non-locality of a theory apparent from its mathematical form?
I am reading Relativistic Quantum Mechanics by Bjorken and Drell and on page 5 they present the following attempt at a relativistic Hamiltonian for a free particle
\begin{equation}
i\hbar\frac{\...
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How localized are photons in a quantum field?
Are photons or other quanta at least somewhat localized in a quantum field?
My limited understanding of quantum field theory is that photons or other fundamental particles (quanta) are excitations of ...
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Is there something that violates "time locality"?
The way I understand locality is that for an object to influence another object away from it, it has to do so through the space that separates them. It can shoot out an EM wave to the other object, ...
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Local nature of physical laws
All the laws in physics are local in nature and that's why their formulation follows differential equations. My doubt is whether the locality is a proven theorem or it is a postulate?
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Locality of interactions and their high energy behavior
In a classic Georgi review of EFT, I have read the following quote
The result of eliminating heavy particles is inevitably a
nonrenormalizable theory, in which the nontrivial effects of the heavy
...
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Interpretations for Interaction-free measurements
So I read several papers on IFM by Vaidman, Dicke, and many others, In all of them I think the Pilot wave theory is able to adequately justify the observations, but then I came across several papers ...
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Is QFT "more" non-local than QM, at least mathematically?
Could physics still be local? Here's what I mean:
The Schrodinger/Dirac equations allow for quantum entanglement, right? So in that sense they are non-local physically. But they are mathematically ...
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Many worlds is nonlocal too after all according to some physicists?
Not a physicist but I have understood that MWI is unique in that it preserves local dynamics. There is a wavefunction - not in spacetime but in some more abstract space. But the worlds with spacetime ...
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Non-analytic functions and non-local Lagrangians
Infinite sums of increasingly higher-order derivatives, when present in Lagrangians, are typically taken as a sign of nonlocality. This is supposed to rule out fractional, negative and exotic (for ...
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Why quantum mechanics doesn’t break locality in entanglement but hidden variables theories will?
What makes it so that quantum mechanics doesn’t break locality in entanglement yet hidden variable theories will?
In Bell‘s inequality said that hidden variables theories need to break locality in ...
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What is locality?
In QFT and statistical mechanics, one is usually interested in studying integrals of the form:
$$Z(\phi) =\int d\mu_{C}(\phi')e^{-V(\phi+\phi')}$$
where $\mu_{C}$ is Gaussian measure with mean zero ...
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