Subject: Sciences and their founders Date: Wed, 22 Mar 95 09:51:23 +0000 From: wpc-AT-cs.strath.ac.uk Philip ---------- I don't think that Einstein's relativity theory extended Newton's laws to new conditions. The quote from Hawkins does not say that a science simply extends its founders to new conditions. Einstein's theory provided new terms and formulations for science Paul replies ------------ This argument is not significant on its own account but is from the standpoint of the conclusions that are being drawn from it. It seems to be part of a rather cavalier attitude towards the sciences that allows one to say things like : post Einstein Newton and Galileo are out the window, post Althusser Marx goes out the window etc. Since the specific example given to justify this is the apparent 'refutation' of Galileo and Newton by Einstein, I will try again to show that this is wrong. Galilean relativity states that the laws of motion of bodies are unaffected by an arbitrary choice of uniformly moving reference frame. This is accepted by modern physics which, however, is able using general relativity to extend this invariance to accelerating frames of reference. The result of Galileo that the acceleration of falling bodies is independent of the compostion is also unaffected. The Newtonian laws of motion, and in particular the inverse square law of gravitation are also retained. In particular the equivalence of gravitational and inertial mass has exhaustively tested and confirmed. ' In fact, it is fair to say that, not only does Einstein's theory not supplant Newtons theory, it explains Newton's theory. ( I think this is a point that is not often appreciated.) In Newton's work, the inverse square law appears as a means of accounting for the observations of the solar system, in particular Keplers interpretation of Brahes observations in terms of a relationship between periods and radii. ... There is no explanation in Newton's theory of why it had to be an inverse square law. This explanation was finally provided in 1915 and 1916 by Einsteins theory. If you adopt Einsteins theory that the force of gravity is due to a curvature in space time, and follow that where it leads you, you find out that you can not, without standing on your head make a theory of gravity in which the force at large distances is anything other than an inverse square law.' Stephen Weinberg in 300 Years of Gravitation CUP Beyond this it must be said that Newtonian formulations are much more usefull. It is only under the most extreme conditions that one has to introduce relativistic corrections. In practice, calculations of satellite orbits etc continue to use Newtonian methods. If Marx's theories had been so formulated that they could be subject to equivalent testing and with the same result, then this is the sort of 'refutation' that any theory could rest content with. --- from list marxism-AT-lists.village.virginia.edu --- ------------------
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