Comment First 5 billion (Score 1) 307
Things are even bleaker in other galaxies, the researchers report. Compared with the Milky Way, most galaxies are small and low in metallicity. As a result, 90% of them should have too many long gamma ray bursts to sustain life, they argue. What’s more, for about 5 billion years after the big bang, all galaxies were like that, so long gamma ray bursts would have made life impossible anywhere.
Wouldn't that also imply that for the first 5 billion years planets in general would be low in metal? So you would have very few planets without iron cores and similer density as Earth. There would be a different chemical mix in most of the universe.