If one metric ton of antimatter comes into contact with one metric ton of matter, how much energy would be released? — TC 

Since the discovery of relativity, people have recognized that there is energy associated with rest mass and that the amount of that energy is given by Einstein's famous equation: E=mc^{2}. However, the energy associated with rest mass is hard to release and only tiny fractions of it can be obtained through conventional means. Chemical reactions free only parts per billion of a material's rest mass as energy and even nuclear fission and fusion can release only about 1% of it. But when equal quantities of matter and antimatter collide, it's possible for 100% of their combined rest mass to become energy. Since two metric tons is 2000 kilograms and the speed of light is 300,000,000 meters/second, the energy in Einstein's formula is 1.8x10^{20} kilogrammeters^{2}/second^{2} or 1.8x10^{20} joules. To give you an idea of how much energy that is, it could keep a 100watt light bulb lit for 57 billion years.