Cornell has long been a leader in theoretical astrophysics-the modeling of phenomena in our solar system, galaxy, distant galaxies and the early universe. In 1967, the late Professor Hans Bethe was awarded the Nobel Prize for his explanation of how stars shine by converting hydrogen to helium. Today, Cornell astrophysicists explore a wide variety of phenomena through theory, analysis and the development of new experimental/observational techniques, including: neutron stars, black holes, gravitational waves, dark matter, dark energy, the cosmic microwave background and inflation in the early universe.<br>The study of astrophysical phenomena can involve several areas of theoretical physics, including atomic physics, nuclear physics, condensed-matter and plasma physics, superfluidity, general relativity, quantum-field theory and string theory. In addition to the physics faculty listed above, Liam McAllister, Maxim Perelstein and Henry Tye pursue research at the interface of cosmology and elementary particle physics. It is easy for theoretical astrophysics students to work in more than one research area, or with more than one professor in both the physics department and the astronomy department.