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Things we didn’t know

When I was in grad school:

  • Then, not within a factor of two. Now H0 = 67.80 ± 0.77
  • Then ηearth > 10-9. Now ηearth = 0.22 ± 0.08
  • Suspicions about cold dark matter, vague notions about the cosmological constant being so out of sorts between the Stand Model and GR. Now, 96% of the universe is some sort of unknown matter/energy. Even though we can get the primordial baryon distribution right on the nose from first principles, that's only 4% of the universe.