PBS Space Time Season 2015 Episode 7 Cosmic Microwave Background Explained

PBS Space Time season 2015 episode 7, titled "Cosmic Microwave Background Explained," explores the history and significance of the cosmic microwave background radiation (CMB) that permeates the universe.

The episode begins by explaining the origins of the CMB, which dates back to the very early universe shortly after the Big Bang. At this point, the universe was incredibly hot and dense, and photons (light particles) were constantly colliding with matter. As the universe expanded and cooled down, the photons were able to travel more freely without colliding, and the CMB radiation was created.

The CMB is an extremely important tool for astronomers studying the universe. It provides a snapshot of the early universe and contains information about the size, age, and composition of the universe. The episode discusses how scientists use the CMB to support the theory of cosmic inflation, which posits that the universe underwent a brief period of exponential expansion shortly after the Big Bang.

The episode goes on to explain the various instruments and experiments used to study the CMB. One such instrument is the Cosmic Background Explorer (COBE), launched in 1989 by NASA. COBE was the first satellite to measure the CMB radiation, and its measurements confirmed several predictions made by the theory of cosmic inflation.

The episode also discusses the Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency's Planck satellite, both of which were able to make extremely precise measurements of the CMB radiation. These measurements have helped astronomers create a detailed map of the CMB, which shows small fluctuations in temperature and density.

One of the most fascinating aspects of the CMB radiation is its uniformity. The temperature of the CMB radiation is almost exactly the same in all directions, with only small fluctuations. This suggests that the early universe was extremely homogeneous, with matter distributed evenly throughout. The episode explores the implications of this uniformity for our understanding of the universe.

Finally, the episode discusses the future of CMB research. One exciting area of study is the possibility of finding evidence of gravitational waves in the CMB. Gravitational waves are ripples in spacetime that were first predicted by Einstein's theory of general relativity, and their discovery would provide further evidence for the theory of cosmic inflation. Several experiments are currently underway to search for these gravitational waves, including the BICEP (Background Imaging of Cosmic Extragalactic Polarization) and the Keck Array.

Overall, PBS Space Time season 2015 episode 7 provides a fascinating and accessible introduction to the cosmic microwave background radiation, its history, and its significance for our understanding of the universe. It is a must-watch for anyone interested in astronomy or cosmology.