This thread is for any questions you may have regarding science! Everything you ever wanted to know from Quantum Theory to Evolution is welcome! Post your questions and those of us knowledgeable in those subjects will try to answer. To begin, here's a question that's I've been wondering about: Why don't the planets just spiral into the sun? If there's a gravitational force acting on them, shouldn't all of them just fall into the Sun instead of perpetually going around it?