E=mc2 what does it really mean
Energy=mass x the speed of light squared
One of Einstein's great insights was to realise that matter and energy are really different forms of the same thing. Matter can be turned into energy and energy into matter.
For example, consider a simple hydrogen atom, basically composed of a single proton. This subatomic particle has a mass of.
0.000 000 000 000 000 000 000 000 001 672kg
This is a tiny mass. But in everyday quantities of matter there a lot of atoms ! For instance, in one kilogram of pure water, the mass of hydrogen atoms amounts to just slightly more than 111grams or 0.111kg.
Einstein's formula tell's us the amount of energy this mass would be equivalent to, if it were suddenly turned into energy. It says that to find the energy, you multiply the mass by the square of the speed of light, this number being 300,000,000 meters per second:
E=mc2
=0.111 x 300,000,000 x 300,000,000
=10,000,000,000,000,000 Joules.