The reason this is important to understand antimatter is because scientists found that when matter and antimatter touch each other , the amount of energy that is released comes very close to the amount of energy says should be all together in those two pieces . Known methods of producing antimatter from energy also produce an equal amount of normal matter , so the theoretical limit is that half of the input energy is converted to antimatter . Counterbalancing this , when antimatter annihilates with ordinary matter , energy equal to twice the mass of the antimatter is liberated â '' so energy storage in the form of antimatter could ( in theory ) be 100 % efficient .