Andreas Johansson scripsit: > > Christophe Grandsire wrote: > >En r=E9ponse =E0 Nik Taylor <[log in to unmask]>: > > > > > > > > How is E=3Dmc^2 misquoted? > > > > > > >It doesn't mean anything when quoted this way. The correct formula is > >E=3Dgamma*mc^2, and it's this gamma which is the most important for > >Einstein's > >Relativity Theory. It's equal to 1 over square root of 1 minus v^2/c^2, = > v > >being > >the speed of the object, c of course the speed of light. The formula E=3D= > mc^2 > >is > >valid only when v=3D0 (for that reason, E0=3Dmc^2 is called the resting = > energy > >or > >mass energy of the object. If it was quoted as E0=3Dmc^2, I wouldn't hav= > e > >anything against it, because E0 and E are different things), which is a > >very > >specialised case of the correct formula, and a stupid one at that, since= > if > >the > >object is at rest you don't need Relativity to explain its behaviour > >(actually, > >it would be stupid to do so! Restricted Relativity is only interested in > >the > >behaviour of objects whose speed is near the speed of light). > > > >In that sense E=3Dmc^2 is a misquote: it refers to a special case of the > >correct > >formula where it is nonsensical to use this formula at all! > > Unless several physics books and at least one University Professor are > telling me lies, Einstein originally DID have it as E=3Dmc^2, where "m" > denotes the relativistic mass m=3Dym0 (where y should be gamma and m0 is = > the > He later did away with the concept of relativistic mass, landing > us with today's E=3Dymc^2. And a good thing too. It prevents people from making blunders like calculating relativistic momentum using the relativistic mass and the Newtonian formula, a point my freshman physics teacher warned us against. > Also, E0=3Dmc^2 is not entirely stupid; there instances when you might wa= > nt to > know the energy equivalent of a mass whose velocity relative to you is > practically zero. As in calculating the yield of antimatter bombs. -- He made the Legislature meet at one-horse John Cowan tank-towns out in the alfalfa belt, so that [log in to unmask] hardly nobody could get there and most of http://www.reutershealth.com the leaders would stay home and let him go http://www.ccil.org/~cowan to work and do things as he pleased. --Mencken, _Declaration of Independence_