ONE OF THE INTERESTING THINGS ABOUT INVISIBILITY IS THAT THINGS THAT WE CAN'T SEE WE ALSO CAN'T UNDERSTAND GRAVITY IS ONE THING THAT WE CAN'T SEE AND WHICH WE DON'T UNDERSTAND IT'S THE LEAST UNDERSTOOD OF ALL THE FOUR FUNDAMENTAL FORCES AND THE WEAKEST AND NOBODY REALLY KNOWS WHAT IT IS WHY IT'S THERE