Colloquium, March 27th, 2014 -- Cosmology After Planck

David Spergel Princeton University Cosmology After Planck The Planck Telescope has made an accurate full-sky measurement of the cosmic microwave background (CMB) temperature, the leftover heat from the Big Bang. These measurements probe both the physics of the very early universe and the basic properties of the universe today. The Planck measurements confirm the earlier results from the WMAP telescope and rigorously test our standard cosmological model and provide an accurate determination of basic cosmological parameters (the shape of the universe, its age, and its composition). When combined with other astronomical measurements, the measurements constrain the properties of the dark energy and the nature of dark matter. The observations also directly probe the physics of first moments of the Big Bang: the current data are consistent with the idea that the early universe underwent a period of rapid expansion called inflation. I will present a recent reanalysis of the Planck data and will look forward to upcoming data from ground-based polarization data. Many key cosmological questions remain unanswered: What happened during the first moments of the big bang? What is the dark energy? What were the properties of the first stars? I will discuss the role of ongoing and future CMB observations and describe how the combination of large-scale structure, supernova and CMB data can be used to address these key cosmological questions.