Re: [Phys-l] Relativisitic mass vs Invariant mass

[Laurent Hodges <lhodges@iastate.edu>]

> Laurent Hodges wrote:
> > I remember reading something by Einstein once (a paper? a chapter in a 
> book?)
> > and noting he didn't write E = m c^2  but  E-sub-0 = m c^2, where m was 
> clearly
> > what we call the rest mass.
>
> Well, that paper/book must have been a fairy tale.

I've located it.  It is on the bottom of page 46 of "The Meaning of 
Relativity" (Princeton University Press, 1922), apparently "consist[ing] of 
the text of Mr. Einstein's Stafford Little Lectures, delivered in May 1921 
at Princeton University."

Also on page 46, in natural units, he gives E (not E-sub-0) as E = m / 
sqrt( 1 - q^2) with q the speed.  It seems pretty clear that his "m" is the 
same as our "rest mass."  I'm looking at Einstein's equations, not the 
words in translation, which seem a little muddled in places.