Q&A: Cosmology

Q:
What are multiple universes? Picture a nuclear atom. You have a gravitational center with orbiting atoms. Funny it looks like a solar system. Our solar system is but a point of light in a galaxy. Do galaxies also rotate around a gravitational center? We have very powerful telescopes to view our universe. Could our universe also be but a point of light like a solar system rotating in a galaxy?

A:
On Multiple universes: Some cosmologists distinguish between the universe, which is everything there is, and the universe, which is the universe in which we live, and is but one of many universes in the universe. The idea is that the universe may give rise to many universes, each one of which has slightly different physics. This could be one explanation of why we live in a universe that seems to be finely tuned,in terms of the various forces of nature, for the existence of life.