Talk:Action at a distance

Bad intro?

Quote: This term was used most often with early theories of gravity and electromagnetism to describe how an object could "know" the mass (in the case of gravity) or charge (in electromagnetism) of another distant object. This seems like an abstract way of describing the real problem, which is how particles, mass, can cause a force on another particle without ever coming into physical contact, and vice versa. The intro is pretty important to the reader... --Nabo0o (talk) 00:26, 23 February 2011 (UTC)

Electromagnetism.

The last paragraph of electromagnetism is ambiguous.

"Various proofs, beginning with that of Dirac have shown that direct interaction theories (under reasonable assumptions) do not admit Lagrangian or Hamiltonian formulations (these are the so-called No Interaction Theorems). Consequently, the Fokker-Tetrode action is mainly of historic interest. Still, attempts to recapture action at a distance without a field, which is often difficult to quantize, lead directly to the development of the quantum electrodynamics of Feynman and Schwinger."

I believe a reference or two are needed here on the various proofs, and the sentence has to be more precise. The field is still live and active, see for example a not that historic article: Hoyle, F., & Narkilar, J. V. (1995). Cosmolgy and action at a distance electrodynamics. Rev. Modern Phys., 67(1), 113. — Preceding unsigned comment added by BahramH (talk • contribs) 06:42, 29 August 2013 (UTC)

Quantum nonlocality hyperlink

I advocate the removal of the "nonlocality" hyperlink to the "Quantum nonlocality" article from the body of the "Quantum mechanics" section. I found that link confusing. plus the "Quantum nonlocality" main article is linked to at the beginning of the section already anyway, and too many hyperlinks can be dispersive. — Preceding unsigned comment added by 195.139.114.220 (talk) 08:31, 13 April 2020 (UTC)

TNT?

@Johnjbarton: this article might interest you. It is a hot mess, many facts are stated without a clear goal and unrelated things are compared. Maybe it deserves some WP:TNT. ReyHahn (talk) 22:51, 6 October 2023 (UTC)

TNT completed. Please review. Johnjbarton (talk) 16:44, 31 October 2023 (UTC)

Great article as always. I left a templates to indicate that it is not clear what is meant. For example when it is written Action at a distance and actions in a continuous medium may be easily distinguished when the medium has properties other than transmitting force, such as being visible, like water or an elastic solid what do you have in mind? Two other mentions that I think might be missing are Heinrich Hertz's experiments and Poincaré prediction of gravitational waves in analogy with electromagnetism. Additionally, what should we do with the discussion of action at a distance in principle of locality? (If I do not respond, it is because I have a blocked proxy problem, I might get it solved soon).--ReyHahn (talk) 18:07, 31 October 2023 (UTC)

I tried rewriting the sentence to be more straight forward. Is this version better? The point is: why aren't fields obvious? Oh, because they are invisible and thus have to be inferred.

I understand Hertz's critical role in showing the electron + field, but what is the action at a distance angle? Similarly Poincare. Over all I feel that the history section has to fight flowing off into a history. It feels choppy in places, because I was trying to avoid this pull. I tried always to focus on "what is the action at a distance aspect".

I realize a final bit on Yukawa QFT force mediation is missing. That is why the two/three issue in the categories. With a force mediation section, the categories can have an action-at-distance vs mediation, if I can find sources. Johnjbarton (talk) 18:23, 31 October 2023 (UTC)

In the end is that what seals the deal for electromagnetism and gravitation to be action-with-retardation theories is the existence of electromagnetic and gravitational waves. Hertz also wrote extensively against Newton's action at distance, if I find something I will share it.--ReyHahn (talk) 18:41, 31 October 2023 (UTC)