The Cosmos in the Large Remains Astonishingly Simple

Measurements of the anisotropy patterns of the cosmic microwave background over the past 25 years has revealed an astonishing scientific result: the universe on observable scales is extremely well described by a physical model with only 8 parameters: 1 specifies the current time, 1 specifies the overall geometry, 3 quantify the content, and 2 quantify the amplitude and shape of a spectra of primordial sound waves.  The 8th parameter which specifies the time of reionization of the primordial gas could in principle be determined by the previous seven.  Future microwave data may reveal additional but more subtle “features” of the universe which might include primordial gravitational radiation and additional exotic types of matter.