In article <firstname.lastname@example.org>, email@example.com (Sandra Russell) writes: >In <firstname.lastname@example.org> email@example.com >(Madhudvisa dasa ) writes: [Swami ...] >>You have explained all the observations with the model of fixed stars and >>a rotating earth. In your model the rotation of the earth causes the sun, >>the planets, the moon and the stars to rise and set every 24 hours. My >>point is it could well be [and we have no way of telling] that the earth >>is fixed and the whole universe is rotating around it every 24 hours... [Steve Harris using the "nom de plume" Sandra Russell ?? ...] >Yeah, but if the Earth doesn't rotate, how come the plane of swing of a >Foucault pendulum at the pole does? And how come this pendulum plane >"rotation" period at a pole matches the rotation of the stars, and not >that of the moon or sun? Coincidence? If I may interject momentarily from the talk.origins audience, the Swami is referring to "Mach's Principle". This is the solution proposed by Ernst Mach to Isaac Newton's "spinning bucket" problem, which eventually made its way into general relativity, expressed by way of the principle of equivalence. The point is that the Swami's effect is postulated. Newton's "spinning bucket" problem supposes an observer sitting on the edge of a spinning bucket of water. The surface of the water will be curved, even though the bucket and the water are spinning at the same rate, and therefore at rest with respect to eact other. The non-spinning bucket water has a flat surface, and the water and bucket are at rest with respect to each other in this case as well. Newton considered the problem: what if the bucket remains still and the universe rotates around it? Will the water surface be curved, as is the case if the bucket spins, or flat, since the bucket is not spinning, the universe is? Newton had no answer that I am aware of, but Ernst Mach *postulated* that the water surface would be curved, that the two situations *must* be entirely equivalent in every observable way. If one accepts Mach's postulate, than all of the pendulum questions are easily and obviously answered. Einstein borrowed this notion for his principle of equivalence, that being at rest in a constant gravitational field is observably equivalent to accelerating at a constant rate (observed locally). My point is that the matter is not so obvious, and really contains some very profound philosophy. However, it should also be pointed out that this has nothing I can think of to do with whether or not the Earth is flat (I have personally observed the fact that it is not flat anyway). -- ----------------------------------------------------------------- Timothy J. Thompson, Timothy.J.Thompson@jpl.nasa.gov California Institute of Technology, Jet Propulsion Laboratory ... Earth & Space Sciences Division, Terrestrial Science Element ... ASTER Project Atmospheric Corrections Science Team ... Vice President, Mount Wilson Observatory Association ... Board of Directors, Los Angeles Astronomical Society.