Kip Stephen Thorne (born June 1, 1940) is an American theoretical physicist and writer known for his contributions in gravitational physics and astrophysics.

Along with Rainer Weiss and Barry C. Barish, he was awarded the 2017 Nobel Prize in Physics for his contributions to the LIGO detector and the observation of gravitational waves.

[4][5][6][7] A longtime friend and colleague of Stephen Hawking and Carl Sagan, he was the Richard P. Feynman Professor of Theoretical Physics at the California Institute of Technology (Caltech) until 2009[8] and speaks of the astrophysical implications of the general theory of relativity.

"[15] Thorne rapidly excelled at academics early in life, winning recognition in the Westinghouse Science Talent Search as a senior at Logan High School.

[8] Throughout the years, Thorne has served as a mentor and thesis advisor to many leading theorists who now work on observational, experimental, or astrophysical aspects of general relativity.

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 on the BBC in the United Kingdom.

Thorne's work has dealt with the prediction of gravitational wave strengths and their temporal signatures as observed on Earth.

[23] 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.

This recorded detection was the first direct observation of the fleeting chirp of a gravitational wave and confirmed a prediction of the general theory of relativity.

[24][25][26][27][28] While studying for his PhD at Princeton University, his mentor John Wheeler assigned him a problem to think about: find out whether or not a cylindrical bundle of repulsive magnetic field lines will implode under its own attractive gravitational force.

[29]: 445–446 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 not any farther.

[32] With Mike Morris and Ulvi Yurtsever, he showed that traversable 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).

[citation needed] With Anna Żytkow, Thorne predicted the existence of red supergiant stars with neutron-star cores (Thorne–Żytkow objects).

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,[35] 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.

[citation needed] Thorne has written and edited books on topics in gravitational theory and high-energy astrophysics.

[38] In 1994, he published Black Holes and Time Warps: Einstein's Outrageous Legacy, a book for non-scientists for which he received numerous awards.