Asri-unix.914 net.space utcsrgv!utzoo!decvax!ucbvax!ARPAVAX:C70:sri-unix!ES@MIT-MC Sat Mar 6 20:23:54 1982 Constancy of c and G. The speed of light, c, and gravitational constant, G, are constant in the general theory of relativity. A variable c would imply either a preferred coordinate system with respect to which an absolute velocity could be measured, or a medium (the ether) whose elastic vibrations constitute electromagnetic radiation. The conjecture (not established fact) of a variable G arises as follows. An electron and proton are electrically attracted about 10^40 times stronger than they are gravitationally attracted. Also, the radius of the known universe is about 10^40 times the radius of a proton. Dirac suggested that so large a number as 10^40 could not occur by coincidence, and that perhaps G scales inversely with the radius of the universe. This has some consequences for celestial mechanics and geophysics, and I vaguely seem to remember that the observations are not consistent with the dG/dt required by the Hubble constant. More elaborate conjectures attempt to incorporate the estimate that the number of protons in the known universe is about (10^40)^2. Unlike the case of a variable c, I believe it is possible to concoct a theory with variable G without violating either experimental observation or strongly believed basic principles. ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.