James Hartle

This memorial obituary was originally published by the Santa Fe Institute. Read the full article here.

James Hartle, External Professor at the Santa Fe Institute and Professor of Physics Emeritus at the University of California, Santa Barbara, passed away on May 17 in Switzerland at the age of 83. Even though he had Alzheimer’s, he continued to work on the problems that were his life’s work: the origin of the universe, how can quantum mechanics be applied to cosmology, and how to ensure that theories accurately model physical observations. Until the very end, he was passionate about physics.

Often referred to as the father of quantum cosmology, Hartle published landmark papers with game-changers in the field of theoretical physics — people like Murray Gell-Mann, Stephen Hawking, and Kip Thorne. His relationship with Gell-Mann, one of SFI’s co-founders, led to Hartle become a frequent visitor at the Institute and, in 2006, an SFI External Faculty member.

Hartle earned his Ph.D. in particle physics in 1964 from the California Institute of Technology, where Gell-Mann was his advisor. They remained friends long after both had moved away from particle physics — Hartle into cosmology and Gell-Mann into complexity. Hartle joined the UCSB faculty in 1966, mentoring students and postdocs of his own.

Throughout his life, Hartle pushed the boundaries of quantum mechanics, cosmology, astrophysics, and general relativity. In 1983, Hartle collaborated with Stephen Hawking to publish a paper on no-boundary wave function, postulating that the shape of the cosmos is similar to that of a shuttlecock. They derived a formula to describe this shape, or the “wave function of the universe,” as encompassing all of time —past, present, and future simultaneously. Their radical reconceptualization of time, which challenged existing hypotheses on the origin of the universe, has inspired physicists for many years.

He was a member of the US National Academy of Sciences, a fellow of the American Academy of Arts and Sciences, and is a founder and past director of the Institute for Theoretical Physics at Santa Barbara.

Hartle served on the Aspen Center for Physics board as a General Member from 1990-2006, and Honorary Member from 2006-2011.