# Greatest Ideas

## RELATIVITY

While quantum theory deals with the smallest things, relativity deals with the largest: space, time and the universe itself. Its inventor, Albert Einstein, is often seen as the paradigm of a scientific genius. His special theory of relativity established that, for observers in relative motion, time intervals and distances are not the same, but the speed of light is constant; his general theory is still the best confirmed theory of gravity there is. The general theory is also well known for its prediction of black holes: regions of space whose gravitational fields are so intense not even light can escape them. This is physics at its most theoretical; but like all knowledge, it has some practical effects. Sadly, the most famous practical application of Einstein's special theory is the atom bomb, whose invention was aided by the equation E=mc2, linking matter and energy.