I am be any size or shape and I can have the same volume, perimeter and area of anything. I can bend and flex and fit through anything. I can fly. And I can fall. I can be hot and cold. You can't hurt me. But I can kill you in a matter of minutes. I can weigh a gram and I can weigh 500 tons. If I am big enough, I can smush anything. I can be 2 inches tall or 500 feet tall.What am I?