Black Holes and Time Warps is a popular science book by physicist Kip Thorne, published in 1994. It provides an illustrated overview of the history and development of black hole theory, from its roots in Newtonian mechanics up to the early 1990s. Over fourteen chapters, Thorne proceeds roughly chronologically, tracing first the crisis in Newtonian physics precipitated by the Michelson–Morley experiment, and the subsequent development of Einstein’s theory of special relativity (given mathematical rigor in the form of Minkowski space), and later Einstein’s incorporation of gravity into the framework of general relativity.
Black holes were quickly recognized as a feasible solution of Einstein’s field equations, but were rejected as physically implausible by most physicists. Work by Subrahmanyan Chandrasekhar suggested that collapsing stars beyond a certain mass cannot be supported by degeneracy pressure, but this result was challenged by the more prestigious Arthur Stanley Eddington, and was not fully accepted for several decades. When the reality of objects which possess an event horizon finally achieved broad acceptance, the stage was set for a thorough investigation into the properties of such objects, yielding the surprising result that black holes have no hair—that is, that their properties are entirely determined by their mass, spin rate, and electrical charge.
Proceeding separately from theoretical research into relativity, and with the refinement of radio astronomy, astrophysics began to produce unusual observations of extremely intense radio sources, which were apparently located outside of the Milky Way. In consultation with theoretical physicists, it became apparent that the only sensible explanation for these sources were extremely large black holes residing in the cores of galaxies, producing intense radiation as they fed and, in the case of quasars, blasting out incredibly powerful jets of material in opposite directions, heating the surrounding galactic gas until it glowed in radio frequencies.
Thorne describes the much less mature search for gravitational waves, phenomena predicted to result from supernovae and black hole collisions, but as yet unobserved in 1993 (and, indeed, not directly observed until 2015, a discovery that led to Thorne being awarded a share of the 2017 Nobel Prize in Physics). In the 1970s came Stephen Hawking’s startling prediction of black hole evaporation, powered by quantum fluctuations near the event horizon. Toward the end of the text, Thorne deals with the much more speculative question of the nature of the core of a black hole; the so-called gravitational singularity predicted by Einstein’s field equations. By introducing quantum behavior to curved spacetime, several physicists have suggested that black holes do not possess a true mathematical singularity, but rather a region of chaotic space, in which time does not exist. The behavior of this space and the material which approaches it are not well understood, with a complete marriage of relativity and quantum physics yet to be achieved. In the final chapter, Thorne delves into even more speculative matters relating to black hole physics, including the existence and nature of wormholes and time machines.
The book features a foreword by Stephen Hawking and an introduction by Frederick Seitz. In addition to the main text, the book provides biographical summaries of the major scientists in the text, a chronology of key events in the history of black hole physics, a glossary of technical terms, twenty-three pages of notes, a bibliography, and alphabetical indices of subjects and people referred to in the text.
Of the book, The New York Times wrote, “the close and sometimes difficult reasoning it embodies is lightened by a deft, anecdotal approach, and by the author’s whimsical drawings and diagrams.” Kirkus Reviews opined that “the reader has to wade through many, many pages of theory and diagrams—obvious to the expert but too difficult for the lay reader. Thorne is in fact strongest for the novice reader when dealing with the history of the physics community.”
Kip Stephen Thorne is an American astrophysicist and author. He shared the 2017 Nobel Prize in Physics with Rainer Weiss and Barry C. Barish “for decisive contributions to the detector and the observation of gravitational waves.” With John A. Wheeler and Charles Misner, he coauthored the general relativity textbook Gravitation in 1973. He has also written popular science, notably Black Holes and Time Warps in 1994 which was awarded the Phi Beta Kappa Award in Science for that year. Thorne was the Richard P. Feynman Professor of Theoretical Physics at Caltech from 1991 until 2009. A longtime friend and colleague of Stephen Hawking and Carl Sagan, he advised Sagan on the physics of wormholes for his novel Contact. He was a scientific consultant for Christopher Nolan’s films Interstellar and Tenet. He received the 2018 Lewis Thomas Prize for science writing.
Thorne was born on June 1, 1940, in Logan, Utah. His father, D. Wynne Thorne, was a professor of soil chemistry at Utah State University, and his mother, Alison, was an economist and the first woman to receive a PhD in economics from Iowa State College. Raised in an academic environment, two of his four siblings also became professors. Thorne’s parents were members of the Church of Jesus Christ of Latter-day Saints and raised Thorne in the faith, though he now identifies as an atheist. Shortly before his mother’s death, she urged Kip and his siblings to leave the church because of its discrimination against women, which they all did. Regarding his views on science and religion, Thorne has stated: “There are large numbers of my finest colleagues who are quite devout and believe in God …. There is no fundamental incompatibility between science and religion. I happen to not believe in God.”
Thorne excelled at academics early in life, winning recognition in the Westinghouse Science Talent Search as a senior at Logan High School. He received his BS in physics degree from Caltech in 1962, and his master and PhD in physics from Princeton University in 1964 and 1965 under the supervision of John Archibald Wheeler with a doctoral dissertation on Geometrodynamics of Cylindrical Systems. He returned to Caltech as an associate professor in 1967 and became a professor of theoretical physics in 1970, becoming one of the youngest full professors in the history of Caltech at age 30. He became the William R. Kenan Jr. Professor in 1981, and the Feynman Professor of Theoretical Physics in 1991. He was an adjunct professor at the University of Utah from 1971 to 1998 and Andrew D. White Professor at Large at Cornell University from 1986 to 1992. Since 2009, Thorne has been the Feynman Professor of Theoretical Physics, emeritus.
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 was set up on a blind date with Lynda Obst, later a film producer, by physicist Carl Sagan. They dated in 1979–1980, and parted but remained friends, to the extent that they later collaborated on the movie Interstellar. Thorne and his second wife, Carolee Joyce Winstein, a professor of biokinesiology and physical therapy at USC, married in 1984. In 2015, he collaborated with Obst and Stephen Hawking on a movie script, for which they wrote several drafts.
Throughout the years, Thorne has served as a mentor and thesis advisor to many students who became leaders in observational, experimental, or astrophysical aspects of general relativity. Approximately 50 physicists have received PhDs 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. 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. In 2017, Thorne gave the George Gamow Memorial Lecture at the University of Colorado Boulder, on “Probing the Warped Side of the Universe with Gravitational Waves: From the Big Bang to Black Holes.”
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 for his 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.
Thorne’s work has dealt with the prediction of gravitational 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 gravitational wave experiment for which Thorne has been a leading proponent – in 1984, he cofounded the LIGO Project. A significant aspect of his research is developing the mathematics necessary to analyze these objects. Thorne also carries out engineering design analyses for features of 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 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 harmonic oscillators – a technique applicable both in gravitational wave detection and quantum optics. On February 11, 2016, a team of physicists representing the LIGO Scientific Collaboration, announced that in September 2015, LIGO recorded the signature of two black holes colliding 1.3 billion light-years away. 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.
In 1963–1964, Thorne’s PhD mentor at Princeton, 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. After several months wrestling with the problem, he proved that it was impossible for cylindrical magnetic field lines to implode. Thorne determined that the gravitational force can overcome all interior pressure only when an object has been compressed in all directions, as in the case of a spherical star imploding under gravitational force. To express this realization, he proposed his hoop conjecture, which 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. That is, any object of mass M around which a hoop of circumference can be spun must be a black hole.
Thorne and his students have developed an approach to the theory of black holes called the “membrane paradigm”, 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. With his postdoc Wojciech Zurek, he showed that the entropy of a black hole 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 not any farther. This is probably the maximum black-hole spin allowed in nature.
Thorne and his co-workers at Caltech conducted 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 physical mechanism that may always prevent the creation of closed timelike curves. With Mike Morris and Ulvi Yurtsever, he showed that traversable wormholes can exist only if they are threaded by quantum fields in quantum states that violate the averaged null energy condition. With Anna Żytkow, Thorne predicted the existence of red supergiant stars with neutron-star cores. 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 their multipole moments 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. Thorne has also theoretically predicted the existence of universally antigravitating “exotic matter.” With Clifford Will and others of his students, he laid the foundations for the theoretical interpretation of experimental tests of relativistic theories of gravity.
In 1973, Thorne co-authored Gravitation with Charles Misner and John A. Wheeler. In 1994, he published Black Holes and Time Warps, which was awarded the Phi Beta Kappa Award in Science for that year. In 2014, he published The Science of Interstellar, in which he explains the science behind the film. In September 2017, Thorne and Roger D. Blandford published Modern Classical Physics. With artist Lia Halloran, Thorne used poetry and illustrations to explore astrophysics in The Warped Side of Our Universe.
Thorne has been elected to the American Academy of Arts and Sciences, National Academy of Sciences, Russian Academy of Sciences, and American Philosophical Society. He has received numerous awards including the American Institute of Physics Science Writing Award in Physics and Astronomy, Phi Beta Kappa Science Writing Award, American Physical Society’s Lilienfeld Prize, German Astronomical Society’s Karl Schwarzschild Medal, Robinson Prize in Cosmology, Sigma Xi Common Wealth Awards for Science and Invention, California Science Center’s California Scientist of the Year Award, Albert Einstein Medal, UNESCO Niels Bohr Medal, Special Breakthrough Prize in Fundamental Physics, Gruber Prize in Cosmology, Shaw Prize, Kavli Prize in Astrophysics, Tomalla Prize, Georges Lemaître Prize, Harvey Prize, Smithsonian Magazine American Ingenuity Award, Princess of Asturias Award, Nobel Prize in Physics, Lewis Thomas Prize, and Golden Plate Award of the American Academy of Achievement. He has been a Woodrow Wilson Fellow, Danforth Fellow, Guggenheim Fellow, and Fulbright Fellow. He has also received honorary doctorates from Claremont Graduate University and the Physics Department of the Aristotle University of Thessaloniki. He was awarded an honorary doctorate from University of Cambridge in 2024 and from Rochester Institute of Technology in 2026. He was elected to hold the Lorentz chair for the Leiden University in 2009.
Thorne contributed ideas on wormhole travel to Carl Sagan for use in his novel Contact. Thorne and Lynda Obst developed the concept for the Christopher Nolan film Interstellar. He also wrote a tie-in book, The Science of Interstellar, and advised Nolan on the physics of Tenet and Oppenheimer. In Larry Niven’s novel Rainbow Mars, the time travel technology used in the novel is based on Thorne’s wormhole theories. Thorne was portrayed by actor Enzo Cilenti in the film The Theory of Everything. He played himself in an episode of The Big Bang Theory and is featured in an episode of the documentary series The Craftsman.