"E = mNow this is E = m. You already heard it with the c^2 on there, but that's just how many s equals a . When Einstein found out they were measuring the same thing in grams as in ergs, he has to know how many ergs makes a gram, and an erg is the kinetic energy of a 2 gram beetle walking 1 centimeter per second and running into your shoe. ...The gram is the energy of the Hiroshima bomb, and he had to know how many beetles... to get rid of Berkeley. ...[T]hat's what the c^2 is all about, 9 times 10^{20}. ...The kinetic energy of 9 times 10^{20} 2 gram beetles walking 1 centimeter per second would vaporize Berkeley."