Thursday - February 16, 2012
One of the most powerful ideas in modern physics is that the universe is governed by symmetry. This is the idea that certain properties of a system do not change when it undergoes a transformation of some kind. For example, if a system behaves the same way regardless of its orientation or movement in space, it must obey the law of conservation of momentum. If a system produces the same result regardless of when it takes place, it must obey the law of conservation of energy.