THE PRINCIPLES AND DESIGNS OF COSMIC MICROWAVE BACKGROUND (CMB) EXPERIMENTS

Abstract

The cosmic microwave background (CMB) is one of our only sources of information about the earliest stages of the universe. According to the Big Bang theory, the universe was initially filled with a hot plasma of photons and subatomic particles. As the predicted modern-day remnant of this primordial plasma, the CMB offers some of the most compelling support for the Big Bang theory and is believed to carry information about the properties of the plasma and any earlier events that affected the plasma. In this paper, we explain how scientists extract cosmological information from data on specific characteristics of the CMB—including the energy scale of cosmic inflation, the density of matter and dark matter in the universe, and the Hubble constant—to verify their theories on the formation and evolution of the universe. We then describe the technological designs of important CMB experiments, focusing on how each experiment’s specific design allowed it to make more accurate and precise measurements than its predecessors. Finally, we review the experiments’ designs and achievements, looking for patterns to pinpoint what technological/design features future CMB experiments should have to further improve our measurements of the CMB and broaden our understanding of the early universe.