Bill Nye actually did die, but using the power of science, he resurrected himself, but as a side-effect he has become a lich. You might be saying, "But, liches are magic, you're wrong!", but his science is so powerful, it has become what everyone perceives magic to be. You might think, "But, I don't believe in magic, so is science fiction, too?", I will tell you no, science is real, as is magic, because magic is a higher level of science that a mere man can not comprehend, at least in this day and age, but Bill Nye is no mere man. He is a lich.