Generation and Observability of Primordial Black Holes and Secondary Gravitational Waves in an Inflationary Universe

The 2017 Nobel Prize in Physics was awarded to three members of the U.S. LIGO team for the first detection of gravitational waves — signals produced about 1.3 billion light-years away by the merger of a binary black hole, each roughly 30 times the mass of the Sun. Theoretically, cosmological inflation in the very early universe is expected to have produced density fluctuations. Research on primordial black holes (PBHs) and gravitational waves on small scales is emerging as a key to unlocking the mysteries of the birth of the universe.