Gas in a vacuum?

Good post. Thats the best explanation so far. Do you know how these stellar nebula's get started? Is there like some central point that sucks everything in, or do the gases just coincidentally run into each other and interact respectively.

Afraid not I'm just a chemist. I work in UHV so I know about molecular and continuum states of gases at low pressures. I work with some guys who study the gas-grain interactions in the ISM. I'll have a go though:

As far as I am aware nebula are formed from the ejecta of dying stars (bit of a chicken and egg scenario though). Lots of different stuff such as ice grains, but mostly molecular hydrogen. I think there is probably a critical mass / concentration that is reached and the cloud collapses in on itself under it's own gravity - this collapse causes heating and further collapse and then fusion starts, eh viola a star is formed. Not really answered your question, but I think the currently theory of stellar nebula /star formation is a cyclical one (gets them out of explaining what went on at the start). I think we're probably talking about early cosmo (which is theoretical I believe) and way, way out of my area.