YOU NEVER THINK about the weight of your organs inside you. Your heart is a half-pound clapper hanging off the end of your aorta. Your arms burden your shoulders like buckets on a yoke. The colon uses the uterus as a beanbag chair. Even the weight of your hair imparts a sensation on your scalp. In weightlessness, all this disappears. You organs float inside your torso.* The result is a subtle physical euphoria, an indescribable sense of being freed from something you did not realize was there.