Hi everybody,

I have a question which bothers me since long time and maybe with your help
I can find the answer at last. Since I heard the formule E=mc^2 for the
first time it struck me that there seems to be no logical relation between
the energy contained in a mass and the speed of light. I have no
difficulties to understand that the energy contained in a mass is equivalent
to that mass.

My problem is: what the hell has this to do with the speed of something else
(an electromagnetic wave). I cannot see the connection between them. These
two things: mass and energy on one side and the speed of light on the other
side seem too disparate to me to allow a logical link between them.

I wonder, if someone can explain this connection. I wouldn't have been
surprised if the Joule (the unit for energy) had been established in
consequence of this formula, but I think both Joule, kg, m/s were already
existent before E=mc^2.

I learned from Wikipedia that James Joule died in 1889, thus before Einstein
discovered his famous formula, which I think happened in 1905.

Greetings
Jacques