A college physics professor was explaining a particularly complicated concept to his class when a pre-med student interrupted him. "Why do we have to learn this stuff? " the frustrated student blurted out. "To save lives," the professor responded before continuing the lecture. A few minutes later the student spoke up again. "So how does physics save lives? "The professor stared at the student without saying a word. "Physics saves lives," he finally continued, "because it keeps the idiots out of medical school. "