Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 GARFIELD 20/11/84; site garfield.UUCP Path: utzoo!utcsri!garfield!robertj From: robertj@garfield.UUCP (Robert Janes) Newsgroups: net.sf-lovers,net.physics Subject: RE:FLT ( fundamental laws of physics ) Message-ID: <3295@garfield.UUCP> Date: Wed, 17-Jul-85 15:37:44 EDT Article-I.D.: garfield.3295 Posted: Wed Jul 17 15:37:44 1985 Date-Received: Wed, 17-Jul-85 17:27:13 EDT Distribution: net Organization: Memorial U. of Nfld. C.S. Dept., St. John's Lines: 86 Just a few comments on an article posted to net.sf-lovers which may be of interest to physics people on the net. The comments reflect my own probably inadequate understanding of the subject but here goes anyways. >Subject: RE: FLT >From: jagardner@watmath.UUCP (Jim Gardner) >Reply-To: jagardner@watmath.UUCP (Jim Gardner) >Organization: U of Waterloo, Ontario . . >A little relativity theory: we begin with the basic law of >physics F=ma. This equation is a >special case< of the the basic law law of physics called Newton's Second Law. Newton original framed somewhat in this fashion: " force is porportional to the change in the quantity of movement". Quantity of movement is what we now call momentum and thus the basic law is reformulated as: F = (dp)/(dt) where p = momentum and t = time ( you run into certain problems when you try to establish what you mean by time in high velocity situations ) In classical mechanics and in relativistic mechanics if we are careful about what we mean by m we have: p = mv apply ing the product rule we get F = m*dv/dt + v*dm/dt where if m is constant and we denote dv/dt by a we have F = ma. Newton however made the assumption that m was independent of v which is not in fact the case as was shown by Einstein. In fact mass ( as measured by an observer not moving with the object ) does depend upon v as follows m = m0/sqrt( 1 - (v/c)**2) Using this we see that m increases assymptotically as v->c. Thus the basic law is still quite sound if properly applied! Einstein did though as a consequence of his work on time, velocity and electromagnetic bodies show that we had to refine our understanding of the relationship between mass and velocity. >Tachyons get around the problem by _starting_out_ going faster >than the speed of light. Since they're already past the boundary, >you don't run into the infinite force problem, so they can happily >do whatever they want. >Jim Gardner >University of Waterloo But then we have the following problem: if v>>c then 1-(v/c)**2 < 0 hence sqrt( 1 -(v/c)**2) is imaginary !! What is imaginary mass and why is it necessarily more tangible and acceptable then infinite mass ? There is no scientific evidence for the existence of tachyons nor do any of the current models of physics require their existence so while they may exist there is no reason to believe they do save for ( at present ) wishfull thinking. I don't read net.physics so please send any critiques or corrections by mail. I would be interested in followups relativity theory is a favorite area. cheers Robert Janes Memorial University of Newfoundland