|MadSci Network: Physics|
I have been reading Stephen Hawking for Beginners by J.P. McEvoy & O. Zarate who state that Hawking proved that though general relativity theory reliably describes the expansion of the Universe since the Big Bang (don't forget that in the rapidly expanding universe energy would have been present in forms other than heat eg. kinetic, forces between particles) it can't be used at its starting point. According to Hawking general relativity theory predicts the existence a singularity of space-time at the starting point of the Big Bang. A singularity was explained by Roger Penrose as a point where time comes to an end and the laws of physics break down, singularities can occur under certain conditions when a dying star collapses in on itself. As Einstein's general relativity theory is a classical theory of the physics of space and time it too breaks down and cannot be used to explain the events at the beginning of the Universe. So you cannot use E=mc^2 in the way you have proposed in your question. Hawking goes on to describe the events of the Big Bang using quantum theory, I suggest you read his works " A Brief History of Time" and "Black Holes and Baby Universes". Dr J. M. Wishart Dept of Education Loughborough University LE11 3TU UK
Try the links in the MadSci Library for more information on Physics.