Multiverse Understanding of Cosmological Coincidences
  There is a deep cosmological mystery: although dependent on very different
underlying physics, the timescales of structure formation, of galaxy cooling
(both radiatively and against the CMB), and of vacuum domination do not differ
by many orders of magnitude, but are all comparable to the present age of the
universe. By scanning four landscape parameters simultaneously, we show that
this quadruple coincidence is resolved. We assume only that the statistical
distribution of parameter values in the multiverse grows towards certain
catastrophic boundaries we identify, across which there are drastic regime
changes. We find order-of-magnitude predictions for the cosmological constant,
the primordial density contrast, the temperature at matter-radiation equality,
the typical galaxy mass, and the age of the universe, in terms of the fine
structure constant and the electron, proton and Planck masses. Our approach
permits a systematic evaluation of measure proposals; with the causal patch
measure, we find no runaway of the primordial density contrast and the
cosmological constant to large values.
