Talk:Inverse-square law

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This article contains material from the Federal Standard 1037C, which, as a work of the United States Government, is in the public domain.

Inverse-square laws are about point sources, and yet it sounds like point sources can't actually exist. (Doesn't the Planck length, among other things, imply that things must have a certain minimum size?) In light of this apparent paradox, can someone explain why inverse-square laws are to any extent successful? Perhaps there are empirically-derived bounds along the lines of "if two masses both have volumes less than Vsmall, then Newton's gravitation law will give results that shall not deviate by more than 1x10^(-8) newtons from the true value"? --Ryguasu 17:31 Feb 6, 2003 (UTC)

Partly it's something along those lines. Notice that one of Newton's laws says that if no force acts on an object it continues at the same velocity, but one may object that there has never been an object on which no force acted, and the objection is somewhat parallel to what you're saying. Newton demonstrated mathematically that if the earth has uniform density then its gravitational field outside of the sphere in which its mass exists, is the same as if all the mass were concentrated at the center. So that's another reason. Michael Hardy 00:23 Feb 7, 2003 (UTC)

For example, Sol "provides" 9140W at the distance of Mercury (0.387AU); but only 1370W at the distance of Earth (1AU)

It would be useful if the formula to get the above values (9140 and 1370) were given too.

It does not make sense to use watts as the unit here. Perhaps watts-per-square-meter or something like that was intended instead? If so, it needs to say so. Michael Hardy 22:58, 12 Jan 2004 (UTC)

Looking at the Principia Mathematica first edition -- it may BE Robert Hooke who advance the Inverse-Square in relation to gravity first... - Sparky

Contents

[edit] The diagram

I just looked at the diagram I drew again and I realised it doesn't look terribly good. I am going to redraw it. Does anybody have some suggestions as to how I can make it better? -- Borb 00:39, 31 December 2005 (UTC)

Looks good to me. If you were specific about what you think needs improvement in it, maybe I could say more. Michael Hardy 02:44, 31 December 2005 (UTC)
It doesn't look very high quality, I was going to draw it again anyway, I just wondered if there was a different way I should draw it. A diagram could be either showing a quarter of the lines going through the same sized square, as in my diagram, or it could be showing the same number of lines going through a square 4 times the size of the original. Does anybody have a preference on which type I should draw? Also, technically the "squares" should be part of a sphere so I might try making them look like that. -- Borb 20:14, 2 January 2006 (UTC)
If you can access a copy of Edgar Allan Poe's Eureka, you will find a perfectly clear visual illustration of this law.Lestrade 15:21, 12 February 2006 (UTC)Lestrade

[edit] Diagram

The first diagram I ever saw of the inverse square law was better, in my opinion. It showed ...

Nevermind, I found some similar ones: [1] [2] — Omegatron 18:16, 19 February 2006 (UTC)

What about lasers?

- I agree on the diagram comment. Looking at the two linked images here the first did not work. The second is a great diagram. Displaying the four and then nine squares at each of the given distance values displays how the light is being spread out over greater distance.

p. 47 of Bill Bryson's A Short History of Nearly Everything explains that Halley (of Halley's Comet fame) was the one who went to Newton to ask him about a math problem concerning the inverse square law. Halley and Hooke were acquaintances and were involved in a bet to see who could solve the problem first. After Newton started publishing books with his findings, Hooke said he had already discovered the answer and accused Newton of plagiarism.

[edit] Light and other electromagnetic radiation

It would be appropriate to add the word "Interestingly" to the start of this section, I am perplexed attempting to explain connection Omeganumber (talk) 02:26, 1 March 2008 (UTC)

[edit] citation

how do you cite it? —Preceding unsigned comment added by 24.236.97.242 (talk) 18:34, 7 March 2008 (UTC)

[edit] New Diagram!

Well I finally got around to drawing a new diagram of the inverse square law. Comments/Suggestions etc? It's not the easiest law to illustrate... -- Borb (talk) 14:05, 2 April 2008 (UTC)