James Burkett Hartle (August 20, 1939) is an American

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

. He has been a professor of physics at the

University of California, Santa Barbara The University of California, Santa Barbara (UC Santa Barbara or UCSB) is a Public university, public Land-grant university, land-grant research university in Santa Barbara County, California, Santa Barbara, California with 23,196 undergraduate ...

since 1966, and he is currently a member of the external faculty of the

Santa Fe Institute The Santa Fe Institute (SFI) is an independent, nonprofit theoretical research institute located in Santa Fe, New Mexico, United States and dedicated to the multidisciplinary study of the fundamental principles of complex adaptive systems, includ ...

. Hartle is known for his work in

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...

, and

interpretation of quantum mechanics An interpretation of quantum mechanics is an attempt to explain how the mathematical theory of quantum mechanics might correspond to experienced reality. Although quantum mechanics has held up to rigorous and extremely precise tests in an extraord ...

Work

In collaboration with

Murray Gell-Mann Murray Gell-Mann (; September 15, 1929 – May 24, 2019) was an American physicist who received the 1969 Nobel Prize in Physics for his work on the theory of elementary particles. He was the Robert Andrews Millikan Professor of Theoretical ...

and others, Hartle developed an alternative to the standard

Copenhagen interpretation The Copenhagen interpretation is a collection of views about the meaning of quantum mechanics, principally attributed to Niels Bohr and Werner Heisenberg. It is one of the oldest of numerous proposed interpretations of quantum mechanics, as featu ...

, more general and appropriate to

quantum cosmology Quantum cosmology is the attempt in theoretical physics to develop a quantum theory of the universe. This approach attempts to answer open questions of classical physical cosmology, particularly those related to the first phases of the universe. ...

, based on

consistent histories In quantum mechanics, the consistent histories (also referred to as decoherent histories) approach is intended to give a modern interpretation of quantum mechanics, generalising the conventional Copenhagen interpretation and providing a natural i ...

. With Dieter Brill in 1964, he discovered the Brill–Hartle geon, an approximate solution realizing

Wheeler Wheeler may refer to: Places United States * Wheeler, Alabama, an unincorporated community * Wheeler, Arkansas, an unincorporated community * Wheeler, California, an unincorporated community * Wheeler, Illinois, a village * Wheeler, Indiana, a ...

's suggestion of a hypothetical phenomenon in which a gravitational wave packet is confined to a compact region of spacetime by the gravitational attraction of its own field energy. With

Kip Thorne Kip Stephen Thorne (born June 1, 1940) is an American theoretical physicist known for his contributions in gravitational physics and astrophysics. A longtime friend and colleague of Stephen Hawking and Carl Sagan, he was the Richard P. Fey ...

, Hartle derived from general relativity the laws of motion and precession of black holes and other relativistic bodies, including the influence of the coupling of their

multipole moments A multipole expansion is a mathematical series representing a function that depends on angles—usually the two angles used in the spherical coordinate system (the polar and azimuthal angles) for three-dimensional Euclidean space, \R^3. Similarly ...

to the spacetime curvature of nearby objects, as well as writing down the Hartle-Thorne metric, an approximate solution which describes the exterior of a slowly and rigidly rotating, stationary and axially symmetric body. Working at the

Enrico Fermi Institute __NOTOC__ The Institute for Nuclear Studies was founded September 1945 as part of the University of Chicago with Samuel King Allison as director. On November 20, 1955, it was renamed The Enrico Fermi Institute for Nuclear Studies. The name was s ...

at the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...

in 1983, he developed the Hartle–Hawking wavefunction of the Universe in collaboration with Stephen Hawking. This specific solution to the

Wheeler–deWitt equation The Wheeler–DeWitt equation for theoretical physics and applied mathematics, is a field equation attributed to John Archibald Wheeler and Bryce DeWitt. The equation attempts to mathematically combine the ideas of quantum mechanics and general ...

is meant to explain the initial conditions of the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...

cosmology. Hartle is the author of the textbook on general relativity entitled ''Gravity: an Introduction to Einstein's General Relativity''. Hartle was elected to the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

in 2016.

References

External links

James Hartle homepageFaculty profile"The Future of Gravity"
– April, 2000 online lecture (

RealAudio RealAudio, or also spelled as Real Audio is a proprietary audio format developed by RealNetworks and first released in April 1995. It uses a variety of audio codecs, ranging from low-bitrate formats that can be used over dialup modems, to high-fid ...

plus slides)
"Spacetime Quantum Mechanics"
online RealAudio lecture

online RealAudio lecture *
"The Quantum Universe: Essays on Quantum Mechanics, Quantum Cosmology, and Physics in General"
book (World Scientific, 2021) Living people 21st-century American physicists American relativity theorists American textbook writers American male non-fiction writers University of California, Santa Barbara faculty Members of the United States National Academy of Sciences 1939 births Santa Fe Institute people Members of the American Philosophical Society Fellows of the American Academy of Arts and Sciences Fellows of the American Physical Society {{US-physicist-stub