Kimberly- The only thing dumb about those questions is the hope that we will provide good answers. I'll do my best, but they're tough.
1. I often give a course in which we spend weeks working on this question. Long story very short: let's just say that we have a nice coherent mathematical description of how things move (Newton's laws) which works very well to describe the solar system and all sorts of particular things on earth (balls rolling down hills, etc.), but
only if we say that the planets go around the Sun. At our most precise current level (General Relativity) it turns out we are forced to use more complicated equations, and within those we can choose different descriptions, and we don't have to have the Sun be the nearly stationary thing. I'll answer this more if you want, but meanwhile on to the other Q's.
2. We don't know very much about what conditions are needed to allow life to evolve. My personal guess is that nothing life-like could evolve in a hot star, or on a completely frozen lump, because there aren't enough stable complicated structures. As for whether specific details like water are needed, we don't really have any compelling reason to think so.
3. I don't know who wrote that answer or what their justification was. We don't even know whether the phrase "in the very beginning" makes any sense, because we don't know what the form of spacetime would be at the start of the Big Bang, where quantum mechanics and gravity are both important.
I hope this serves as a small start.
Mike W.
(published on 10/22/2007)
