Energy is never lost completely, it only changes form. For example, If you drop a rubber ball onto a hard floor, the ball bounces a few times and then stops. Each bounce is lower than the one before it because the ball loses some energy as heat and sound. The energy lost from the ball is gained by the floor and the air. The same happens with mass, matter cannot be created or destroyed. Scientist then discovered that energy and matter can be changed into each other under extraordinary conditions. For example, nuclear energy results when matter changes to energy. Because of this new evidence, scientist developed a new law that states that the total amount of matter and energy does not change.