Such a simple equation ... 3 variables ... and you have recipe for how matter and energy are equivalent. But is it accurate? Does it hold up even decades later as our understanding of the quantum world deepens? A new round of experiments by a host of institutes finds Einstein's famous equation to be accurate out to .00004% ... I'd say that's pretty good eh?
I love that equation as I think it really shows the fingerprint of God...simple, elegant, and to the point.
BEST DIRECT TEST OF E=mc^2. Albert Einstein's formulation of how matter and energy are equivalent is an important enunciation of the principle of conserved energy. As far as we know, it is at work at the moment an atom bomb explodes, when the fissioning of uranium is exploited for making commercial electricity, or when an electron and positron annihilate inside a PET scanner. A new experiment---conducted by scientists from MIT, Universite Laval, Florida State, Oxford, NIST, and Institut Laue-Langevin---keeps careful account of both matter mass and electromagnetic energy for a process in which ions of sulphur and silicon absorb neutrons, transforming them into new isotopes as they emit gamma rays. In this transaction Einstein's equation is shown experimentally to be true at a level of 0.00004%, a factor of 55 better than the previous best test. (Rainville et al., Nature, 22/29 December 2005.)