Riddle: I am be ANY size, 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. And 500 feet tall.
Who am I?