Christopher John Pethick

Theoretical physicist, who contributions in areas as diverse as neutron stars, ultracold atomic gases, and low-temperature and condensed matter physics have set standards for the fields. Applying concepts across disciplines he has achieved penetrating physical insights. His theories of neutron stars are classic: he co-developed the first consistent descriptions of dense matter from low densities to the liquid interior in neutron stars and in stellar collapse; proposed that compact X-ray sources are accreting neutron stars, and has driven our understanding of neutron star cooling. In condensed matter physics, he provided the basis of understanding of liquid helium-3 at nonzero temperature, and showed how related ideas could be applied to the transport properties of heavy-fermion compounds, and in a very different context, quark matter at high densities. Pioneered applying condensed matter concepts to ultracold atomic gases, successfully bridging the gap between atomic and condensed-matter physics. Awarded the Onsager Prize and the Bethe Prize of the American Physical Society.