Julius Edgar Lilienfeld Prize (2020): New Challenges in Cosmology, Galaxy Formation, and Planets

The Hubble tension between early universe and local measurements of H0 can be resolved by a brief episode of dark energy contributing about 10% of cosmic energy density at redshift z ∼ 3500. New N-body simulations have shown that this Early Dark Energy scenario predicts earlier structure formation, e.g. 50% more clusters than ΛCDM at redshift z ∼ 1. Galaxies were long thought to start as disks, but HST images show that most galaxies instead start prolate (pickle shaped). Galaxy simulations can explain this as a consequence of the filamentary nature of the ΛCDM dark matter distribution. But comparisons between simulations and observations using novel machine learning methods reveal other potential challenges. Earth may be a radioactively Goldilocks planet, with just the right amount of radiogenic heating by Th and U for plate tectonics and a magnetic field both of which may be necessary for the evolution of complex life. Production of these elements in rare neutron star mergers implies incomplete mixing. A factor of 2 increase would have stopped Earth’s magnetic dynamo for hundreds of millions of years and also caused widespread vulcanism. A factor of 2 decrease could have stopped plate tectonics