During the break between schools, he worked as a research assistant for a company that was designing a fusion reactor. Such machines attempt to produce power by the fusion of hydrogen atoms, the same processes that fuel the hydrogen bomb and the burning of the sun. After earning a degree in physics from Cornell in 1977, Hernquist chose the California Institute of Technology for graduate school. There, he began leaning more toward basic physics than astronomy until he met astrophysicist Roger Blandford. With Blandford, Hernquist started working on neutron stars, sunlike stars that have burned up their hydrogen fuel and collapsed.
Some neutron stars rotate rapidly and give off regular, intense bursts of radio waves.
When first discovered in the 1960s, astronomers thought these were messages being sent by alien civilizations. By the 1980s, neutron stars had become unoccupied objects of scientific interest only. Hernquist studied them for his Ph.D. thesis, which he received in 1984. While at Caltech, Hernquist also began working on computer simulations of galaxies. He did research and taught at Santa Cruz from 1990 to last year.