On a snowy St. Patrick’s Day, our offices officially shut down by a late-winter storm, the Science News staff was abuzz over the biggest thing since the Higgs boson. On March 17, scientists announced the first direct evidence of the theory of cosmic inflation: primordial gravitational waves. The news spread fast, even rippling out to the front page of the New York Times.
Cosmic expansion was one of the most important discoveries of the 20th century; before Einstein and Hubble, people assumed the universe was static. Explaining the universe’s expansion led to the idea of the Big Bang and later to inflation (SN: 7/28/12, p. 20): a moment of explosive, exponential growth in the moments after the Big Bang that accounts for the uniformity of