Re: KuJomu - the writing

Christophe Grandsire wrote:
>En réponse à Nik Taylor <yonjuuni@...>:
>
> >
> > How is E=mc^2 misquoted?
> >
>
>It doesn't mean anything when quoted this way. The correct formula is
>E=gamma*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=mc^2
>is
>valid only when v=0 (for that reason, E0=mc^2 is called the resting energy
>or
>mass energy of the object. If it was quoted as E0=mc^2, I wouldn't have
>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=mc^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=mc^2, where "m"
denotes the relativistic mass m=ym0 (where y should be gamma and m0 is the
rest mass). He later did away with the concept of relativistic mass, landing
us with today's E=ymc^2.

Also, E0=mc^2 is not entirely stupid; there instances when you might want to
know the energy equivalent of a mass whose velocity relative to you is
practically zero.

                                                         Andreas

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