The universe is the poor man's particle accelerator

One thing I wanted to add to Mark's post about the New Views conference. The conference as a whole was dedicated to the memory of David Schramm, whose 60th birthday would have been this year; he died while piloting his own airplane in 1997. Schramm was an enormously influential figure in contemporary cosmology, one of the prime movers in bringing together particle physics and astrophysics in the study of the early universe. In particular, he was a pioneer in the use of Big-Bang Nucleosynthesis as a way to understand both particle physics and cosmology. Between a few seconds and a few minutes after the Big Bang, the universe was a nuclear reactor, converting nucleons (neutrons and protons) into nuclei of helium, lithium, and deuterium. At very high temperatures the nucleons can't bind together without being knocked apart; at low temperatures they would like to be bound into their lowest-energy state, ...