I'm collaborating with some other writers on a sci-fi webseries. It's set on a heavy gravity prison planet. My question is, how heavy can the gravity get before a normal, Earth-bred human is rendered incapable of functioning normally? One draft mentions that the planet is 7 times the size of Earth. If we're talking 7 times Earth's mass, thus 7 times its gravity, that sounds rediculous to me. Am I wrong?