Talk:Field (physics)

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Missing stuff

what is missing here: field properties, e.g: homogeneous vs. nonhomogeneous, conservative vs. dissipative, central field, curl-field...
—Preceding unsigned comment added by 15:45, 27 August 2005 (talk • contribs) Icare

Don't we want all sorts of things in here, such as 4-Lagrangians, Lorentz covariance, tensor notation, Euler-Lagrange equations for a field, examples of Classical Electrodynamics, the metric as a potentials for gravitation etc? -Masud 17:18, 3 November 2005 (UTC)

(Re-org)

Heavily re-organised the page, and linked to classical field theory. -Masud 03:06, 29 November 2005 (UTC)

(Continuous random fields)

Added continuous random fields, because the relationship between quantum fields and continuous random fields is my research interest. It's possible to formulate quantum fluctuations in a continuous random field formalism, as well as and distinct from thermal fluctuations. The significance of such is TBD. What I've added to the Field (physics) page is probably not contentious, whereas my research is. Linking to details in other pages seems appropriate for a Field (physics) page, rather than the details of 4-Lagrangians etc. being here -PeterQ 14:44, 30 May 2006 (UTC)

Dear Peter
I have read your section on Continuos Fields, but I do not understand what you are talking about. Would you be so kind to provide context:
what definition of random processes you are assuming
how would this be different from anything we use in QM - we have random processes over space time all times (collapsing wave functions)
how does temperature pops in???
why do you say we assume two times differentiability? we do use distributions all times - even before Scwartz formalised them Dirac did so and before him Heaviside too..
In summary: it is difficult to udnerstand what you haev got in mind!
Thanks Peter
Massimo Massimo.banfi (talk) 11:34, 10 May 2023 (UTC)

("Physical" link)

Quick note: the "physical" link in the first line goes to a disambiguation page in which there are no references to physics, the branch of science.
—Preceding unsigned comment added by 86.128.13.27 (talk) 16:35, 3 July 2007

Alert! Heavy Bias

This article is heavy biased towards the fields of high energy and elementary particle physics, and this problem must be corrected as soon as possible.

"In modern physics, the most often studied fields are those that model the four fundamental forces." -Actually, modern physics also includes quantum stat-mech, solid state physics, condensed matter physics, where fields that model things other than fundamental forces are common.

The only example of fields under classical fields are the elementary fields such as electromagnetic and gravitational. What about other classical fields that are ubiquitous in areas outside elementary physics, such as velocity, density, pressure fields in fluid dynamics?

The examples given under quantum fields are again, the elementary particle fields. What about the quantum fields used in condensed matter physics?

I am not an expert in any of these subjects, as I am myself a high energy particle physicist. If someone could rectify this problem, that would by much appreciated.

--TriTertButoxy (talk) 17:42, 12 January 2008 (UTC)

  • No problemo,I agree with you. I fix that( you should have,too!). — Preceding unsigned comment added by 5.151.82.5 (talk) 23:45, 6 November 2012 (UTC)


Metaphysical statements are presented as statements of natural fact. Specifically that a field is a physical object. This is consistent throughout the article in a variety of guises. The best justification that is offered is that it has high descriptive utility. I don't see a place for personal or institutional philosophical prejudices & metaphysics in an article intending to describe a mathematical representation of a physical theory. No? 50.247.101.139 (talk) 03:53, 3 June 2015 (UTC)

Particle/field principle

I see in many articles the statement that there is a particle associated with a field, but this statement is non-obvious. I believe this article should explain this idea better. Is there a name for this principle? Is this particle/field mapping unique? If so, how can unified field theory be justified? 70.247.169.197 (talk) 18:10, 21 August 2010 (UTC)

Agreed. This is an attribute of the field of high energy particle physics, not fields in general. Particle physics content should go in particle physics articles, not in general physics articles. Reading this article one would leave with the belief that the only physics is particle physics. Considering how conceptually flawed & incomplete that enterprise is, it is not the appropriate means for conveying the ideas of physics in general. — Preceding unsigned comment added by 50.247.101.139 (talk) 04:00, 3 June 2015 (UTC)

About that cheatsheet

   The "Reviewing Cheatsheet", now a box among the other headers in the lead section, started out as a full-width first section (before all the chronologically earlier discussion), apparently in conjunction with the accompanying article being designated as a WikiProject's article of the week (i.e., i presume, to encourage concerted effort upon it). That was via two edits on 8 July 2008; a single entry was actually ever made, a week shy of two months later (2008-09-01), to what apparently was an insertion of two versions of some boilerplate. Two more years (and one new comment) on it appears to me to have been mostly an intimidating obstruction.
    I don't recall ever seeing anything to compare to it on any talk page, so it may either be a persistent peculiarity of the Physics WkProj, or have been a passing one. (The most recent physics article i recall editing, that even remotely approached the accompanying article in theoretical emphasis, was Diode bridge -- 14th and 18th edits to the page, in the first quarter of 2004! -- so how would i know....) But IMO, my taming it into a box among the other header boxes -- with "Skip to ToC" links available before and after reading the talk-page header -- should preserve its apparently small usefulness, without significant loss of ease of use, while making it easier to bypass.
--Jerzy•t 08:30, 31 August 2010 (UTC)

Illustrations

I added new illustrations also showing the direction of the field(s). I suppose this looks better, but I am open to suggestions. Is the relationship between direction and colour clear? Should I remove the "colour legend" (lower right corners) or add some arrows to it? Please let me know. I was honestly surprised to see the original greyscale illustrations survive for so long on multiple wikipedias. Vegard (talk) 18:20, 5 July 2012 (UTC)

Thanks! The illustrations are colourful, but I'm sorry to say they didn't help me. I can see how intensity would map to magnitude, but my brain can't map hue to direction. Is blue up? Red down? Green left? What's right? Also there seems to be some artifact: the field should taper off smoothly, but it seems to have a hard edge to it. Sorry to be a wet blanket. I'm more of a "field of little arrows" person. Woz2 (talk) 11:43, 13 July 2012 (UTC)
I'll try to explain it here, maybe we can work it into the image page or something. Do you see that circle in the lower right corner? That's the "legend" showing how colours map to directions; red maps to left, cyan maps to right, yellow/green maps to up, and purple/blue maps to down. So if you dropped a particle at any point which is mostly red, the particle would accelerate leftwards. For the first illustration (the one with two equally charged particles), there is a black part in the middle; if you dropped a particle exactly in the center there, it would stay perfectly still. If you dropped it slightly to the left or to the right, it would swerve to the center; if you dropped it slightly above or below, it would drift away from the center. About the hard edge, you are right: This is an artifact. The magnitude is capped at a threshold, i.e. you can't distinguish between two magnitudes above this threshold. The reason is simply that force is proportional with the square of the distance, so as you get closer to the center of the particle, the force quickly goes beyond what you can actually display on a screen. What I could try to do is to make those parts above the threshold fade to white, but then you'd lose some information about the direction again... I'll give it a shot and see if it's better. Thanks for the feedback! Vegard (talk) 09:44, 14 July 2012 (UTC)
So I tried to use HSL instead, which first makes a transition from black -> fully saturated -> white: (different strengths). I think it looks worse, because it's not actually clear, intuitively, what white represents (it actually represents "incredibly strong force") and it hides the direction of the field. It also actually doesn't help the problem with the artifacts, I just created another problem. So here's another one that shows the logarithmic magnitude: . I think this is the only way to really get around the problem of displaying very strong forces, but the viewer has to keep in mind that intensity now corresponds to log-magnitude. Vegard (talk) 13:40, 14 July 2012 (UTC)
I added some topographic lines (at exponentially increasing intervals) and quantised the colours: Vegard (talk) 18:38, 14 July 2012 (UTC)
I like the log version best. I didn't get what the inset was for: I would remove it and instead add words in the caption "hue represent the field direction: red means left, cyan means right, yellow/green means up, and purple/blue means down." Cheers! Woz2 (talk) 19:48, 14 July 2012 (UTC)
Logarithmic magnitudes and contour lines. Better? Two positive charges. One positive and one negative charge. Vegard (talk) 19:29, 15 July 2012 (UTC)
I like the log but I prefer them without the contour lines. My $0.02. Cheers! Woz2 (talk) 20:45, 15 July 2012 (UTC)

More illustrations

Nice electric field images added by Vegard. Thanks!

If it's ok, I plan to add more field-line diagrams for other fields like classical and relativistic gravity, EM (including electric/magnetic monopoles), and quark-gluon fields for colour charge... Maschen (talk) 02:24, 27 August 2012 (UTC)

Static field

I removed the entire section; of the 4 references, none meets the reliability standard for a science article, and some of the (referenced) statements are outright false. — Arthur Rubin (talk) 05:41, 6 January 2013 (UTC)

plasma field interaction to create motion

with a simple glass plasma globe filled with various gasses,and the interaction with a non magnetic stainless steel mesh placed over said globe, the interaction with the vacuume of space can be observed.with the use of newer thyristor material ,general circuitry ,a second plasma field, a 1 to 1 induction transformation device and a coil of wire ,a varying field can be set up in said coil and the interaction with a magnetic field will result in the observable up and down motion of said coil. a source of negative ions needed to complete the one wire circuit from mesh on active plasma globe can easily be achieved by the interaction with you the observer , a wire to earth,ie. ground or another piece of non magnetic stainless steel. the plasma globe acting as a positive source of ions due to its attraction with the chromium/carbon content outside the vacume. you will find that all elements in the carbon group all hold interesting phenomenon, when interacting either with the initial plasma field or with other plasma fields and their various gasses initiated by their interaction with the primary plasma field.Ronald sykes (talk) 01:38, 22 July 2013 (UTC)

Can someone verify the basic supposition of this article, please?

I wonder at the presumption that (in physics) fields are "real", "occupy" space, and are measurable (ie physical quantities)? I thought there were a variety of fields which either are not (directly) measurable (ie QFT ψ) and/or do NOT "exist" in Newtonian 3-Space nor Minkowskian/Riemannian 4-space. Aren't there an enormous number of examples of fields in phase spaces which do not (directly) "exist" in "normal" space? Also (and excuse my ignorance) are spinors and tensors "measurable" physical quantities? (I thought they were more abstract objects than those we can physically "measure"). I'm not very knowledgeable here, but it seems to me that this article presupposes a certain set of classical and quantum fields as the ONLY ones to be included here, ignoring many others. Its also not clear to me why "real 'things'" are so emphasized here. I'd argue that most things of interest in science are abstractions rather than "real" objects (energy, entropy, time, space, conservation/symmetry as examples). I realize some of this has to do with ontology and what "real" or "physical" actually mean... But how can we claim "field X" is "real" when it be speculative (Supersymmetric extensions to the standard model, M-theory, ...)? Asserting the reality of an abstraction seems to me to be without much meaning. Surely no Classical 'field' is 'real' since its an approximation to the relativistic or quantum?Abitslow (talk) 21:06, 17 July 2014 (UTC)

The lede here needs a lot of work. For one there needs to be a distinction between dynamical fundamental fields (like the EM field, quark/letpon fields, gauge fields etc.) on the one hand. Which (in some sense) are real objects. More real anyway than e.g. particles. And non-dynamical fields that merely describe physical quantities, like e.g. temperature or wind speed.TR 10:55, 18 July 2014 (UTC)
Timothy: Good point. The weather forecast example in the first paragraph is mine, I was trying to give a more concrete example to follow on from the first sentence "A field is a physical quantity that has a value for each point in space and time." (Previously it just went straight into "A field can be classified as a scalar field..." which seemed completely offputting.) However, I think you're right - the rest of the article purely treats fields as carriers of interactions, but what the first sentence defines is really just a function of position and time. I agree with you that the lede needs work, and I think that (if nothing else) the example I wrote should be replaced with a better one - maybe the Earth's gravity? Having said all of that, I don't think this answers Abitslow's question! Djr32 (talk) 22:12, 19 July 2014 (UTC)
I actually like your weather map example. It is something everybody can visualize and has seen. Moreover, it is a field. Fields like that are very common in physics.TR 18:38, 20 July 2014 (UTC)
The basic presumptions are fine.
The Earth's gravitational field is a description of how an object would be affected by gravity if it were placed somewhere near the Earth. It's a measurable thing, i.e. you could put a rock on a table in your house, or in an orbit 1000 km above the equator, and you could see how it is affected by gravity. On the other hand, you can't put an object in all possible places, and even if you could, they would be affected by each other as well... Even if our model of gravity is wrong (whether in the mathematical details - if it were to actually drop off faster than 1/r2 at large distances - or the whole picture - things fall to the ground because invisible pixies move them) the interaction still exists, and the concept of a "field" is still a useful one, it just means that our model of the field is wrong.
I think you're wrong to get hung up on measurability here. (I was surprised to find that the article doesn't contain the word "measure", "measurement" or anything similar.) Tensors are certainly measurable things, e.g. the Cauchy stress tensor of a solid body is real and measurable in exactly the same sense that the pressure (a scalar quantity) is for a gas.
Real things are important because the goal of physics is to describe the real world. Energy, entropy, time, ... are all real things (though they aren't "objects"). Models contain simplifications and abstractions, but ultimately the point of physics isn't the models, it's the reality that they are trying to model. Djr32 (talk) 23:00, 19 July 2014 (UTC)


What should content of the lead be?

Some loose ends

External links modified

"Static field" listed at Redirects for discussion

"a field is a physical quantity"

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