Talk:Inverse-square law
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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 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