Abstract:
The standard model of cosmology has been remarkably successful in its predictions for current data given earlier data. One can react with sadness for the lack of evidence for new physics, chase marginal anomalies, or marvel at the success and soldier on toward better measurements knowing new physics may be just around the corner. In this talk I will reveal some of the inner workings of this success in order to communicate why I find it marvelous. For example, for the predictions to agree with cosmic microwave background (CMB) data we need, at very high statistical significance, a cosmic neutrino background, electron-positron annihilation occurring after neutrino decoupling, primordial helium and gravitational lensing. Perhaps most marvelous of all, from CMB data we can now rule out a sum of neutrino masses greater than about 1 eV because of their gravitational influence on freely streaming CMB photons.