Awesome web site, but its mostly over my head... with my physics expirence limited to high school. I have always wondered this.... if space is a vacuum... and gasses in a vacuum tend to .... uh... for a lack of a vocabulary... de-concentrate... disperse... what causes earth's gases to stay where they are? is it merely gravity overcoming the vacuum? if so... then how would it ever begin??? with everything naturally attempting to be as-spread-out-as-possible... then how would masses large enough to have enough gravity to influence other particals form??? inform my ignorance, plz.