Keith Thompson
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 Aug 25 comment How does gravity work underground? The ancient Greeks knew about Newtonian gravity? Jun 4 awarded Necromancer Jun 4 awarded Nice Question Apr 28 awarded Enlightened Apr 28 awarded Nice Answer Mar 12 comment Why would a pendulum experiment give $g > 9.8\ \mathrm{m/s^2}$? @Kvothe: Yes, but wouldn't applying the formula for larger angles (where the pendulum will take longer to swing back and forth than the simple formula implies) yields a smaller value for the gravitational acceleration -- assuming accurate measurements? Mar 8 comment How can I destroy earth with physics? Last December, I received a text message from the USGS which said there had been an earthquake near Polson, Montana with a magnitude of 22.0. My first thought was that the Solar System would have a new asteroid belt, but my calculations indicated that there probably wouldn't be enough left to form one; the energy released would be about 250,000 times Earth's gravitational binding energy, more than enough to vaporize the planet. Unfortunately for your evil schemes, a followup message revised the magnitude to 2.2. Feb 14 comment Why gravity decreases as we go down into the earth? The pull of gravity is zero at the center, since the entire planet pulls on you from all directions. It falls off from 1g to 0g (more or less smoothly, but not uniformly) as you go from the surface to the center. But due to the greater density of the core, it actually increases until you reach the bottom of the mantle. See also this question. Jan 24 comment How physical objects (e.g. Earth and Apple) are aware and do computation about each other? @MikeDunlavey: I'd say that both Newton's and Einstein's theories (as distinct from what they personally might have said about their theories) are observations about how things behave. Neither addresses the question of "why". Jan 24 comment How physical objects (e.g. Earth and Apple) are aware and do computation about each other? Nobody does. We observe how objects behave, and we refer to certain aspects of that behavior as "gravity". That doesn't mean we ultimately understand what, if anything, "causes" gravity. But I see no reason at all to assume that the underlying causes, if any, involve computation or awareness. Jan 24 comment How physical objects (e.g. Earth and Apple) are aware and do computation about each other? Why do you assume physical processes (which we may or may not entirely understand) require awareness and computation? Jan 19 awarded Nice Answer Dec 21 comment Didn't Newton's Corpuscular theory fail to explain reflection? @VINAY: As I said, the idea is that the corpuscles interact with ordinary matter but not (significantly) with each other. For example, there might be one chance in a thousand of a corpuscle colliding with an atom of ordinary matter, but only one chance in a million of two corpuscles colliding. But we know that the corpuscular theory is wrong, so you can only go go so far in making it consistent with reality. Dec 21 comment How to initiate fusion explosion without a fission trigger Please tell me your interest is just theoretical! 8-)} Dec 21 answered Gravitation law paradox for very close objects? Dec 21 answered Didn't Newton's Corpuscular theory fail to explain reflection? Dec 21 revised Didn't Newton's Corpuscular theory fail to explain reflection? edited body Oct 31 comment Is self gravitation theoretically impossible? Wouldn't that imply perpetual motion? I doubt that even GR permits that, but I don't know enough to comment further. Oct 12 awarded Yearling Oct 8 answered A question once confused Confucius