What's the scoop on older generation stars? What I'm getting at is that AFAIK over the life of the universe, there have been different generations of stars. Like, say, the stars that popped up 10bn years ago were fundamentally different than the ones that pop up now.

If this is true, I'd like to know more, because of my interest in the Great Filter and Fermi's Paradox. If, for example, complex life could be supported in 10bn year old star systems, it means there is probably a Great Filter that is killing off virtually every advanced species. Otherwise, one or more would have expanded galactically by now.

However, if it is thought that complex life might only be able to exist in the kind of star generation we have -- and if that system didn't exist long enough in the past -- then it could make sense why the galaxy is not populated by a species that had billions of years of technological advancement before our star system even came about.