# Kip Thorne

Kip Thorne
Born June 1, 1940 (age 73)
Logan, Utah
Residence United States
Nationality American
Fields Physics
Institutions Caltech
Alma mater Caltech, Princeton University
Doctoral students Saul Teukolsky
Alan Lightman
William H. Press
Carlton M. Caves
Clifford M. Will
Richard H. Price
Lee Samuel Finn
William L. Burke
Bernard F. Schutz
Teviet Creighton
Sándor J. Kovács
David L. Lee
Known for Relativity and Cosmology

Kip Stephen Thorne (born June 1, 1940) is an American theoretical physicist, known for his prolific contributions in gravitational physics and astrophysics and for having trained a generation of scientists. A longtime friend and colleague of Stephen Hawking and Carl Sagan, he was the Feynman Professor of Theoretical Physics at the California Institute of Technology (Caltech) until 2009[1] and one of the world’s leading experts on the astrophysical implications of Einstein’s general theory of relativity. He continues to do scientific research and is also writing a film.

## Biography

Discussion in the main lecture hall at the École de Physique des Houches (Les Houches Physics School), 1972. From left, Yuval Ne'eman, Bryce DeWitt, Kip Thorne.

Thorne was born in Logan, Utah, the son of Utah State University professors D. Wynne Thorne and Alison C. Thorne, a soil chemist and an economist, respectively. Raised in an academic environment, two of his four siblings are also professors. He became interested in science at the age of eight, after attending a lecture about the solar system. Thorne and his mother then worked out calculations for their own model of the solar system.

Thorne rapidly excelled at academics early in life, becoming one of the youngest full professors in the history of the California Institute of Technology. He received his B.S. from Caltech in 1962, and Ph.D. from Princeton University in 1965. He wrote his Ph.D. thesis, Geometrodynamics of Cylindrical Systems, under the supervision of relativist John Wheeler. Thorne returned to Caltech as an associate professor in 1967 and became a professor of theoretical physics in 1970, the William R. Kenan, Jr. Professor in 1981, and the Feynman Professor of Theoretical Physics in 1991. In June 2009 he resigned his Feynman Professorship (he is now the Feynman Professor of Theoretical Physics, Emeritus) to pursue a career of writing and movie making. His first film project will team him with Christopher Nolan.

Throughout the years, Thorne has served as a mentor and thesis advisor for many leading theorists who now work on observational, experimental, or astrophysical aspects of general relativity. Approximately 50 physicists have received Ph.D.s at Caltech under Thorne's personal mentorship.

Thorne is known for his ability to convey the excitement and significance of discoveries in gravitation and astrophysics to both professional and lay audiences. In 1999, Thorne made some speculations on what the 21st century will find as the answers to the following questions:

• Is there a "dark side of the universe" populated by objects such as black holes?
• Can we observe the birth of the universe and its dark side using radiation made from space-time warpage, or so-called "gravitational waves"?
• Will 21st century technology reveal quantum behavior in the realm of human-size objects?

His presentations on subjects such as black holes, gravitational radiation, relativity, time travel, and wormholes have been included in PBS shows in the U.S. and in the United Kingdom on the BBC.

Thorne and Linda Jean Peterson married in 1960. Their children are Kares Anne and Bret Carter, an architect. Thorne and Peterson divorced in 1977. Thorne and his second wife, Carolee Joyce Winstein, a professor of biokinesiology and physical therapy at USC, married in 1984.

## Research

Thorne in 1972.

Thorne's research has principally focused on relativistic astrophysics and gravitation physics, with emphasis on relativistic stars, black holes and especially gravitational waves. He is perhaps best known to the public for his controversial theory that wormholes can conceivably be used for time travel. However, Thorne's scientific contributions, which center on the general nature of space, time, and gravity, span the full range of topics in general relativity.

### Gravitational waves and LIGO

Among a handful of physicists, Thorne is considered one of the world’s authorities on gravitational waves. In part, his work has dealt with the prediction of gravity-wave strengths and their temporal signatures as observed on Earth. These “signatures” are of great relevance to LIGO (Laser Interferometer Gravitational Wave Observatory), a multi-institution gravity-wave experiment for which Thorne has been a leading proponent — in 1984, he cofounded the LIGO Project (the largest project ever funded by the NSF) to discern and measure any fluctuations between two or more 'static' points; such fluctuations would be evidence of gravitational waves, as calculations describe. A significant aspect of his research is developing the mathematics necessary to analyze these objects.[2] Thorne also carries out engineering design analyses for features of the LIGO that cannot be developed on the basis of experiment and he gives advice on data analysis algorithms by which the waves will be sought. He has provided theoretical support for LIGO, including identifying gravitational wave sources that LIGO should target, designing the baffles to control scattered light in the LIGO beam tubes, and — in collaboration with Vladimir Braginsky's (Moscow, Russia) research group — inventing quantum nondemolition designs for advanced gravity-wave detectors and ways to reduce the most serious kind of noise in advanced detectors: thermoelastic noise. With Carlton M. Caves, Thorne invented the back-action-evasion approach to quantum nondemolition measurements of the quadrature amplitudes of harmonic oscillators — a technique applicable both in gravitational wave detection and quantum optics.

### Black hole cosmology

Thorne has made prolific contributions to black hole cosmology. Thorne proposed his Hoop Conjecture that cast aside the thought of a naked singularity. The Hoop Conjecture describes an imploding star turning into a black hole when the critical circumference of the designed hoop can be placed around it and set into rotation.[3] That is, any object of mass M around which a hoop of circumference $\begin{matrix} \frac{4 \pi GM}{c^2} \end{matrix}$ can be spun must be a black hole. As a tool to be used in both enterprises, astrophysics and theoretical physics, Thorne has developed an unusual approach, called the "Membrane Paradigm", to the theory of black holes and used it to clarify the "Blandford-Znajek" mechanism by which black holes may power some quasars and active galactic nuclei. Thorne has investigated the quantum statistical mechanical origin of the entropy of a black hole and the entropy of a cosmological horizon in an inflationary model of the universe. With Wojciech Zurek he showed that the entropy of a black hole of known mass, angular momentum, and electric charge is the logarithm of the number of ways that the hole could have been made. With Igor Novikov and Don Page he developed the general relativistic theory of thin accretion disks around black holes, and using this theory he deduced that with a doubling of its mass by such accretion a black hole will be spun up to 0.998 of the maximum spin allowed by general relativity, but never any farther; this is probably the maximum black-hole spin allowed in Nature. He, along with his mentor John Wheeler, additionally proved that it was impossible for cylindrical magnetic field lines to implode. Both Hawking and Thorne have theorized that a singularity exists in the interior of a black hole.

### Wormholes and time travel

Thorne was one of the first people to conduct scientific research on whether the laws of physics permit space and time to be multiply connected (can there exist classical, traversable wormholes and "time machines"?). With Sung-Won Kim, Thorne identified a universal physical mechanism (the explosive growth of vacuum polarization of quantum fields), that may always prevent spacetime from developing closed timelike curves (i.e., prevent "backward time travel"). With Mike Morris and Ulvi Yurtsever he showed that traversable Lorentzian wormholes can exist in the structure of spacetime only if they are threaded by quantum fields in quantum states that violate the averaged null energy condition (i.e. have negative renormalized energy spread over a sufficiently large region). This has triggered research to explore the ability of quantum fields to possess such extended negative energy. Recent calculations by Thorne indicate that simple masses passing through traversable wormholes could never engender paradoxes — there are no initial conditions that lead to paradox once time travel is introduced. If his results can be generalised, they would suggest that none of the supposed paradoxes formulated in time travel stories can actually be formulated at a precise physical level: that is, that any situation in a time travel story turns out to permit many consistent solutions.

### Relativistic stars, multipole moments and other endeavors

With Anna Żytkow, Thorne predicted the existence of red supergiant stars with neutron-star cores (Thorne-Żytkow objects). Most importantly, he laid the foundations for the theory of pulsations of relativistic stars and the gravitational radiation they emit. With James Hartle, Thorne 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 to the spacetime curvature of nearby objects. Thorne has also theoretically predicted the existence of universally antigravitating "exotic matter" — the element needed to accelerate the expansion rate of the universe, keep traversable wormhole "Star Gates" open and keep timelike geodesic free float "warp drives" working. With Clifford Will and others of his students, he laid foundations for the theoretical interpretation of experimental tests of relativistic theories of gravity — foundations on which Will and others then built. Thorne is currently interested in the origin of classical space and time from the quantum foam of quantum gravity theory.

## Publications

Thorne has written and edited books on topics in gravitational theory and high-energy astrophysics. In 1973, he co-authored the classic textbook Gravitation with Charles Misner and John Wheeler;[4] from which most of the present generation of scientists have learned general relativity theory. In 1994, he published Black Holes and Time Warps: Einstein's Outrageous Legacy, a landmark book for non-scientists for which he received numerous awards. This book has been published in six languages, and editions in Chinese, Italian, Czech, and Polish are in press.

Thorne's work has appeared in magazines and encyclopedias such as:

Thorne has published more than 150 articles in scholarly journals.

## Honors and awards

Thorne has been elected to:

He has been recognized by numerous awards including:

He has been a Woodrow Wilson Fellow, Danforth Fellow, Guggenheim Fellow, and Fulbright Fellow. He has also received the honorary degree of doctor of humane letters from Claremont Graduate University.

He has been elected to hold Lorentz chair for the year 2009 Leiden University, the Netherlands.

Thorne has served on:

An upcoming film titled Interstellar is based on Thorne's theories of gravity fields, wormholes and several hypotheses that Albert Einstein was never able to prove.

## Partial bibliography

• Thorne, K. S., in 300 Years of Gravitation, (Eds.) S. W. Hawking and W. Israel, 1987, (Chicago: Univ. of Chicago Press), Gravitational Radiation.
• Thorne, K. S., Price, R. H. and Macdonald, D. M., Black Holes, The Membrane Paradigm, 1986, (New Haven: Yale Univ. Press).