Gravitational waves are transient displacements in a gravitational field – generated by the relative motion of gravitating masses – that radiate outward from their source at the speed of light . They were first proposed by Oliver Heaviside in 1893 and then later by Henri Poincaré in 1905 as the gravitational equivalent of electromagnetic waves . In 1916, Albert Einstein demonstrated that gravitational waves result from his general theory of relativity as ripples in spacetime .
90-497: GW170814 was a gravitational wave signal from two merging black holes , detected by the LIGO and Virgo observatories on 14 August 2017. On 27 September 2017, the LIGO and Virgo collaborations announced the observation of the signal, the fourth confirmed event after GW150914 , GW151226 and GW170104 . It was the first binary black hole merger detected by LIGO and Virgo together. The signal
180-438: A 5 σ {\displaystyle 5\sigma } -significance will be achieved by 2025 by combining the measurements of several collaborations. Gravitational waves are constantly passing Earth ; however, even the strongest have a minuscule effect and their sources are generally at a great distance. For example, the waves given off by the cataclysmic final merger of GW150914 reached Earth after travelling over
270-524: 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 and an honorary doctorate from the Physics Department of the Aristotle University of Thessaloniki . In 2024 he was awarded an honorary doctorate from University of Cambridge . He was elected to hold
360-776: A decay in the orbit by about 1 × 10 meters per day or roughly the diameter of a proton . At this rate, it would take the Earth approximately 3 × 10 times more than the current age of the universe to spiral onto the Sun. This estimate overlooks the decrease in r over time, but the radius varies only slowly for most of the time and plunges at later stages, as r ( t ) = r 0 ( 1 − t t coalesce ) 1 / 4 , {\displaystyle r(t)=r_{0}\left(1-{\frac {t}{t_{\text{coalesce}}}}\right)^{1/4},} with r 0 {\displaystyle r_{0}}
450-484: A hyper-compact stellar system . Or it may carry gas, allowing the recoiling black hole to appear temporarily as a " naked quasar ". The quasar SDSS J092712.65+294344.0 is thought to contain a recoiling supermassive black hole. Kip Thorne 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
540-516: A "cross"-polarized gravitational wave, h × , the effect on the test particles would be basically the same, but rotated by 45 degrees, as shown in the second animation. Just as with light polarization, the polarizations of gravitational waves may also be expressed in terms of circularly polarized waves. Gravitational waves are polarized because of the nature of their source. In general terms, gravitational waves are radiated by large, coherent motions of immense mass, especially in regions where gravity
630-408: A "kick" with amplitude as large as 4000 km/s. This is fast enough to eject the coalesced black hole completely from its host galaxy. Even if the kick is too small to eject the black hole completely, it can remove it temporarily from the nucleus of the galaxy, after which it will oscillate about the center, eventually coming to rest. A kicked black hole can also carry a star cluster with it, forming
720-465: A billion light-years , as a ripple in spacetime that changed the length of a 4 km LIGO arm by a thousandth of the width of a proton , proportionally equivalent to changing the distance to the nearest star outside the Solar System by one hair's width. This tiny effect from even extreme gravitational waves makes them observable on Earth only with the most sophisticated detectors. The effects of
810-534: 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 4 π G M c 2 {\displaystyle {\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 and his students have developed an unusual approach, called
900-480: A changing quadrupole moment . That is, the system will give off gravitational waves. In theory, the loss of energy through gravitational radiation could eventually drop the Earth into the Sun . However, the total energy of the Earth orbiting the Sun ( kinetic energy + gravitational potential energy ) is about 1.14 × 10 joules of which only 200 watts (joules per second) is lost through gravitational radiation, leading to
990-492: A complete relativistic theory of gravitation. He conjectured, like Poincare, that the equation would produce gravitational waves, but, as he mentions in a letter to Schwarzschild in February 1916, these could not be similar to electromagnetic waves. Electromagnetic waves can be produced by dipole motion, requiring both a positive and a negative charge. Gravitation has no equivalent to negative charge. Einstein continued to work through
SECTION 10
#17328515615731080-490: A detailed version of the "sticky bead argument". This later led to a series of articles (1959 to 1989) by Bondi and Pirani that established the existence of plane wave solutions for gravitational waves. Paul Dirac further postulated the existence of gravitational waves, declaring them to have "physical significance" in his 1959 lecture at the Lindau Meetings . Further, it was Dirac who predicted gravitational waves with
1170-446: A frequency of 0.5 Hz, and a wavelength of about 600 000 km, or 47 times the diameter of the Earth. In the above example, it is assumed that the wave is linearly polarized with a "plus" polarization, written h + . Polarization of a gravitational wave is just like polarization of a light wave except that the polarizations of a gravitational wave are 45 degrees apart, as opposed to 90 degrees. In particular, in
1260-547: 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. Thorne also carries out engineering design analyses for features of
1350-612: A notable example of which was for the Christopher Nolan film Interstellar . Thorne was born on June 1, 1940, in Logan, Utah . His father, D. Wynne Thorne (1908–1979), was a professor of soil chemistry at Utah State University , and his mother, Alison (née Comish; 1914–2004), 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
1440-412: A pair of solar mass neutron stars in a circular orbit at a separation of 1.89 × 10 m (189,000 km) has an orbital period of 1,000 seconds, and an expected lifetime of 1.30 × 10 seconds or about 414,000 years. Such a system could be observed by LISA if it were not too far away. A far greater number of white dwarf binaries exist with orbital periods in this range. White dwarf binaries have masses in
1530-407: A passing gravitational wave, in an extremely exaggerated form, can be visualized by imagining a perfectly flat region of spacetime with a group of motionless test particles lying in a plane, e.g., the surface of a computer screen. As a gravitational wave passes through the particles along a line perpendicular to the plane of the particles, i.e., following the observer's line of vision into the screen,
1620-459: A professor of biokinesiology and physical therapy at USC , married in 1984. 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
1710-619: 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. In June 2009, he resigned his Feynman Professorship (he
1800-554: A signal generated by the merger of two black holes was received by the LIGO gravitational wave detectors in Livingston, Louisiana, and in Hanford, Washington. The 2017 Nobel Prize in Physics was subsequently awarded to Rainer Weiss , Kip Thorne and Barry Barish for their role in the direct detection of gravitational waves. In Albert Einstein 's general theory of relativity , gravity
1890-774: A total orbital lifetime that may have been billions of years. In August 2017, LIGO and Virgo observed the first binary neutron star inspiral in GW170817 , and 70 observatories collaborated to detect the electromagnetic counterpart, a kilonova in the galaxy NGC 4993 , 40 megaparsecs away, emitting a short gamma ray burst ( GRB 170817A ) seconds after the merger, followed by a longer optical transient ( AT 2017gfo ) powered by r-process nuclei. Advanced LIGO detectors should be able to detect such events up to 200 megaparsecs away; at this range, around 40 detections per year would be expected. Black hole binaries emit gravitational waves during their in-spiral, merger , and ring-down phases. Hence, in
SECTION 20
#17328515615731980-476: A universal gravitational wave background . North American Nanohertz Observatory for Gravitational Waves states, that they were created over cosmological time scales by supermassive black holes, identifying the distinctive Hellings-Downs curve in 15 years of radio observations of 25 pulsars. Similar results are published by European Pulsar Timing Array, who claimed a 3 σ {\displaystyle 3\sigma } -significance . They expect that
2070-540: A well defined energy density in 1964. After the Chapel Hill conference, Joseph Weber started designing and building the first gravitational wave detectors now known as Weber bars . In 1969, Weber claimed to have detected the first gravitational waves, and by 1970 he was "detecting" signals regularly from the Galactic Center ; however, the frequency of detection soon raised doubts on the validity of his observations as
2160-424: Is about 130,000 seconds or 36 hours. The orbital frequency will vary from 1 orbit per second at the start, to 918 orbits per second when the orbit has shrunk to 20 km at merger. The majority of gravitational radiation emitted will be at twice the orbital frequency. Just before merger, the inspiral could be observed by LIGO if such a binary were close enough. LIGO has only a few minutes to observe this merger out of
2250-491: Is absent from Newtonian physics. In gravitational-wave astronomy , observations of gravitational waves are used to infer data about the sources of gravitational waves. Sources that can be studied this way include binary star systems composed of white dwarfs , neutron stars , and black holes ; events such as supernovae ; and the formation of the early universe shortly after the Big Bang . The first indirect evidence for
2340-438: Is introduced. If his results can be generalized, 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. With Anna Żytkow , Thorne predicted the existence of red supergiant stars with neutron-star cores ( Thorne–Żytkow objects ). He laid
2430-713: 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. 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,
2520-491: Is not fully understood, it is not easy to model the gravitational radiation emitted by them. As noted above, a mass distribution will emit gravitational radiation only when there is spherically asymmetric motion among the masses. A spinning neutron star will generally emit no gravitational radiation because neutron stars are highly dense objects with a strong gravitational field that keeps them almost perfectly spherical. In some cases, however, there might be slight deformities on
2610-409: Is not possible with conventional astronomy, since before recombination the universe was opaque to electromagnetic radiation. Precise measurements of gravitational waves will also allow scientists to test more thoroughly the general theory of relativity. In principle, gravitational waves can exist at any frequency. Very low frequency waves can be detected using pulsar timing arrays. In this technique,
2700-579: Is now the Feynman Professor of Theoretical Physics, Emeritus) to pursue a career of writing and movie making. His first film project was Interstellar , on which he worked with Christopher Nolan and Jonathan Nolan . 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. Approximately 50 physicists have received PhDs at Caltech under Thorne's personal mentorship. Thorne
2790-407: Is so strong that Newtonian gravity begins to fail. The effect does not occur in a purely spherically symmetric system. A simple example of this principle is a spinning dumbbell . If the dumbbell spins around its axis of symmetry, it will not radiate gravitational waves; if it tumbles end over end, as in the case of two planets orbiting each other, it will radiate gravitational waves. The heavier
GW170814 - Misplaced Pages Continue
2880-437: Is treated as a phenomenon resulting from the curvature of spacetime . This curvature is caused by the presence of mass. (See: Stress–energy tensor ) If the masses move, the curvature of spacetime changes. If the motion is not spherically symmetric, the motion can cause gravitational waves which propagate away at the speed of light . As a gravitational wave passes an observer, that observer will find spacetime distorted by
2970-412: The LIGO and Virgo detectors received gravitational wave signals at nearly the same time as gamma ray satellites and optical telescopes saw signals from a source located about 130 million light years away. The possibility of gravitational waves and that those might travel at the speed of light was discussed in 1893 by Oliver Heaviside , using the analogy between the inverse-square law of gravitation and
3060-608: The Westinghouse Science Talent Search as a senior at Logan High School . He received his BS in physics degree from the California Institute of Technology (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 entitled " Geometrodynamics of Cylindrical Systems". Thorne returned to Caltech as an associate professor in 1967 and became
3150-459: The complexity of the equations of general relativity to find an alternative wave model. The result was published in June 1916, and there he came to the conclusion that the gravitational wave must propagate with the speed of light, and there must, in fact, be three types of gravitational waves dubbed longitudinal–longitudinal, transverse–longitudinal, and transverse–transverse by Hermann Weyl . However,
3240-513: The electrostatic force . In 1905, Henri Poincaré proposed gravitational waves, emanating from a body and propagating at the speed of light, as being required by the Lorentz transformations and suggested that, in analogy to an accelerating electrical charge producing electromagnetic waves , accelerated masses in a relativistic field theory of gravity should produce gravitational waves. In 1915 Einstein published his general theory of relativity ,
3330-404: The quadrupole moment (or the l -th time derivative of the l -th multipole moment ) of an isolated system's stress–energy tensor must be non-zero in order for it to emit gravitational radiation. This is analogous to the changing dipole moment of charge or current that is necessary for the emission of electromagnetic radiation . Gravitational waves carry energy away from their sources and, in
3420-477: 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. With his postdoc Wojciech Zurek, he showed that the entropy of a black hole is the logarithm of the number of ways that
3510-400: The 'hum' of various SMBH mergers occurring in the universe. Stephen Hawking and Werner Israel list different frequency bands for gravitational waves that could plausibly be detected, ranging from 10 Hz up to 10 Hz. The speed of gravitational waves in the general theory of relativity is equal to the speed of light in vacuum, c . Within the theory of special relativity ,
3600-532: The BICEP2 collaboration claimed that they had detected the imprint of gravitational waves in the cosmic microwave background . However, they were later forced to retract this result. In 2017, the Nobel Prize in Physics was awarded to Rainer Weiss , Kip Thorne and Barry Barish for their role in the detection of gravitational waves. In 2023, NANOGrav, EPTA, PPTA, and IPTA announced that they found evidence of
3690-624: The Church of Jesus Christ of Latter-day Saints (LDS Church) and raised Thorne in the LDS faith, though he now describes himself as atheist . 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 rapidly excelled at academics early in life, winning recognition in
GW170814 - Misplaced Pages Continue
3780-526: 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
3870-628: The Universe when space expanded by a large factor in a very short amount of time. If this expansion was not symmetric in all directions, it may have emitted gravitational radiation detectable today as a gravitational wave background . This background signal is too weak for any currently operational gravitational wave detector to observe, and it is thought it may be decades before such an observation can be made. Water waves, sound waves, and electromagnetic waves are able to carry energy , momentum , and angular momentum and by doing so they carry those away from
3960-443: The astronomical distances to these sources, the effects when measured on Earth are predicted to be very small, having strains of less than 1 part in 10 . Scientists demonstrate the existence of these waves with highly-sensitive detectors at multiple observation sites. As of 2012 , the LIGO and VIRGO observatories were the most sensitive detectors, operating at resolutions of about one part in 5 × 10 . The Japanese detector KAGRA
4050-513: The case of orbiting bodies, this is associated with an in-spiral or decrease in orbit. Imagine for example a simple system of two masses – such as the Earth–Sun system – moving slowly compared to the speed of light in circular orbits. Assume that these two masses orbit each other in a circular orbit in the x – y plane. To a good approximation, the masses follow simple Keplerian orbits . However, such an orbit represents
4140-412: The constant c is not only about light; instead it is the highest possible speed for any interaction in nature. Formally, c is a conversion factor for changing the unit of time to the unit of space. This makes it the only speed which does not depend either on the motion of an observer or a source of light and/or gravity. Thus, the speed of "light" is also the speed of gravitational waves, and, further,
4230-501: The construction of GEO600 , LIGO , and Virgo . After years of producing null results, improved detectors became operational in 2015. On 11 February 2016, the LIGO-Virgo collaborations announced the first observation of gravitational waves , from a signal (dubbed GW150914 ) detected at 09:50:45 GMT on 14 September 2015 of two black holes with masses of 29 and 36 solar masses merging about 1.3 billion light-years away. During
4320-455: The detection of gravitational waves using laser interferometers. The idea of using a laser interferometer for this seems to have been floated independently by various people, including M.E. Gertsenshtein and V. I. Pustovoit in 1962, and Vladimir B. Braginskiĭ in 1966. The first prototypes were developed in the 1970s by Robert L. Forward and Rainer Weiss. In the decades that followed, ever more sensitive instruments were constructed, culminating in
4410-401: The dumbbell, and the faster it tumbles, the greater is the gravitational radiation it will give off. In an extreme case, such as when the two weights of the dumbbell are massive stars like neutron stars or black holes, orbiting each other quickly, then significant amounts of gravitational radiation would be given off. Some more detailed examples: More technically, the second time derivative of
4500-486: The early 1990s the physics community rallied around a concerted effort to predict the waveforms of gravitational waves from these systems with the Binary Black Hole Grand Challenge Alliance . The largest amplitude of emission occurs during the merger phase, which can be modeled with the techniques of numerical relativity. The first direct detection of gravitational waves, GW150914 , came from
4590-485: The effects of strain . Distances between objects increase and decrease rhythmically as the wave passes, at a frequency equal to that of the wave. The magnitude of this effect is inversely proportional to the distance (not distance squared) from the source. Inspiraling binary neutron stars are predicted to be a powerful source of gravitational waves as they coalesce , due to the very large acceleration of their masses as they orbit close to one another. However, due to
SECTION 50
#17328515615734680-532: The existence of gravitational waves came in 1974 from the observed orbital decay of the Hulse–Taylor binary pulsar , which matched the decay predicted by general relativity as energy is lost to gravitational radiation. In 1993, Russell A. Hulse and Joseph Hooton Taylor Jr. received the Nobel Prize in Physics for this discovery. The first direct observation of gravitational waves was made in September 2015, when
4770-428: 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 " – 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
4860-426: The final fraction of a second of the merger, it released more than 50 times the power of all the stars in the observable universe combined. The signal increased in frequency from 35 to 250 Hz over 10 cycles (5 orbits) as it rose in strength for a period of 0.2 second. The mass of the new merged black hole was 62 solar masses. Energy equivalent to three solar masses was emitted as gravitational waves. The signal
4950-420: The foundations for the theoretical interpretation of experimental tests of relativistic theories of gravity – foundations on which Will and others then built. As of 2005 , Thorne was interested in the origin of classical space and time from the quantum foam of quantum gravity theory. Thorne has written and edited books on topics in gravitational theory and high-energy astrophysics . In 1973, he co-authored
5040-514: 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, as well as writing down the Hartle-Thorne metric , an approximate solution which describes
5130-417: 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
5220-504: 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
5310-500: The implied rate of energy loss of the Milky Way would drain our galaxy of energy on a timescale much shorter than its inferred age. These doubts were strengthened when, by the mid-1970s, repeated experiments from other groups building their own Weber bars across the globe failed to find any signals, and by the late 1970s consensus was that Weber's results were spurious. In the same period, the first indirect evidence of gravitational waves
5400-537: The initial radius and t coalesce {\displaystyle t_{\text{coalesce}}} the total time needed to fully coalesce. More generally, the rate of orbital decay can be approximated by where r is the separation between the bodies, t time, G the gravitational constant , c the speed of light , and m 1 and m 2 the masses of the bodies. This leads to an expected time to merger of Compact stars like white dwarfs and neutron stars can be constituents of binaries. For example,
5490-401: The kind of oscillations associated with gravitational waves as produced by a pair of masses in a circular orbit . In this case the amplitude of the gravitational wave is constant, but its plane of polarization changes or rotates at twice the orbital rate, so the time-varying gravitational wave size, or 'periodic spacetime strain', exhibits a variation as shown in the animation. If the orbit of
SECTION 60
#17328515615735580-490: 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 wormholes can exist in
5670-489: The masses is elliptical then the gravitational wave's amplitude also varies with time according to Einstein's quadrupole formula . As with other waves , there are a number of characteristics used to describe a gravitational wave: The speed, wavelength, and frequency of a gravitational wave are related by the equation c = λf , just like the equation for a light wave . For example, the animations shown here oscillate roughly once every two seconds. This would correspond to
5760-449: The merger of two black holes. A supernova is a transient astronomical event that occurs during the last stellar evolutionary stages of a massive star's life, whose dramatic and catastrophic destruction is marked by one final titanic explosion. This explosion can happen in one of many ways, but in all of them a significant proportion of the matter in the star is blown away into the surrounding space at extremely high velocities (up to 10% of
5850-525: 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 four physicists representing the LIGO Scientific Collaboration , announced that in September 2015, LIGO recorded
5940-400: The nature of Einstein's approximations led many (including Einstein himself) to doubt the result. In 1922, Arthur Eddington showed that two of Einstein's types of waves were artifacts of the coordinate system he used, and could be made to propagate at any speed by choosing appropriate coordinates, leading Eddington to jest that they "propagate at the speed of thought". This also cast doubt on
6030-424: The observation of events involving exotic objects in the distant universe that cannot be observed with more traditional means such as optical telescopes or radio telescopes ; accordingly, gravitational wave astronomy gives new insights into the workings of the universe. In particular, gravitational waves could be of interest to cosmologists as they offer a possible way of observing the very early universe. This
6120-437: The order of the Sun , and diameters in the order of the Earth. They cannot get much closer together than 10,000 km before they will merge and explode in a supernova which would also end the emission of gravitational waves. Until then, their gravitational radiation would be comparable to that of a neutron star binary. When the orbit of a neutron star binary has decayed to 1.89 × 10 m (1890 km), its remaining lifetime
6210-441: The paper was rewritten with the opposite conclusion and published elsewhere. In 1956, Felix Pirani remedied the confusion caused by the use of various coordinate systems by rephrasing the gravitational waves in terms of the manifestly observable Riemann curvature tensor . At the time, Pirani's work was overshadowed by the community's focus on a different question: whether gravitational waves could transmit energy . This matter
6300-478: The particles will follow the distortion in spacetime, oscillating in a " cruciform " manner, as shown in the animations. The area enclosed by the test particles does not change and there is no motion along the direction of propagation. The oscillations depicted in the animation are exaggerated for the purpose of discussion – in reality a gravitational wave has a very small amplitude (as formulated in linearized gravity ). However, they help illustrate
6390-510: The physicality of the third (transverse–transverse) type that Eddington showed always propagate at the speed of light regardless of coordinate system. In 1936, Einstein and Nathan Rosen submitted a paper to Physical Review in which they claimed gravitational waves could not exist in the full general theory of relativity because any such solution of the field equations would have a singularity. The journal sent their manuscript to be reviewed by Howard P. Robertson , who anonymously reported that
6480-578: The problem, he proved that it was impossible for cylindrical magnetic field lines to implode . Why won't a cylindrical bundle of magnetic field lines implode, while spherical stars will implode under their own gravitational force? Thorne tried to explore the theoretical ridge between these two phenomena. He eventually determined that the gravitational force can overcome all interior pressure only when an object has been compressed in all directions. To express this realization, Thorne proposed his hoop conjecture , which describes an imploding star turning into
6570-575: The science behind Christopher Nolan's film Interstellar ; Nolan wrote the foreword to the book. In September 2017, Thorne and Roger D. Blandford published Modern Classical Physics: Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics , a graduate-level textbook covering the six major areas of physics listed in the title. Thorne's articles have appeared in publications such as: Thorne has published more than 150 articles in scholarly journals. Thorne has been elected to: He has been recognized by numerous awards including: He has been
6660-471: The signal resulted from the inspiral and merger of a pair of black holes (BBH) with 30.5 +5.7 −3.0 and 25.3 +2.8 −4.2 times the mass of the Sun , at a distance of 540 +130 −210 megaparsecs ( 1.8 +0.4 −0.7 billion light years) from Earth. The resulting black hole had a mass of 53.2 +3.2 −2.5 solar masses, 2.7 +0.4 −0.3 solar masses having been radiated away as gravitational energy . The peak luminosity of GW170814
6750-540: 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. 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. After several months wrestling with
6840-457: The singularities in question were simply the harmless coordinate singularities of the employed cylindrical coordinates. Einstein, who was unfamiliar with the concept of peer review, angrily withdrew the manuscript, never to publish in Physical Review again. Nonetheless, his assistant Leopold Infeld , who had been in contact with Robertson, convinced Einstein that the criticism was correct, and
6930-457: The source. Gravitational waves perform the same function. Thus, for example, a binary system loses angular momentum as the two orbiting objects spiral towards each other – the angular momentum is radiated away by gravitational waves. The waves can also carry off linear momentum, a possibility that has some interesting implications for astrophysics . After two supermassive black holes coalesce, emission of linear momentum can produce
7020-411: The speed of any massless particle. Such particles include the gluon (carrier of the strong force), the photons that make up light (hence carrier of electromagnetic force), and the hypothetical gravitons (which are the presumptive field particles associated with gravity; however, an understanding of the graviton, if any exist, requires an as-yet unavailable theory of quantum gravity). In August 2017,
7110-414: The speed of light). Unless there is perfect spherical symmetry in these explosions (i.e., unless matter is spewed out evenly in all directions), there will be gravitational radiation from the explosion. This is because gravitational waves are generated by a changing quadrupole moment , which can happen only when there is asymmetrical movement of masses. Since the exact mechanism by which supernovae take place
7200-541: 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
7290-403: The surface called "mountains", which are bumps extending no more than 10 centimeters (4 inches) above the surface, that make the spinning spherically asymmetric. This gives the star a quadrupole moment that changes with time, and it will emit gravitational waves until the deformities are smoothed out. Many models of the Universe suggest that there was an inflationary epoch in the early history of
7380-611: The textbook Gravitation with Charles Misner and John Wheeler ; that according to John C. Baez and Chris Hillman, is one of the great scientific books of all time and has inspired two generations of students. In 1994, he published Black Holes and Time Warps: Einstein's Outrageous Legacy , a 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. In 2014, Thorne published The Science of Interstellar in which he explains
7470-421: The timing of approximately 100 pulsars spread widely across our galaxy is monitored over the course of years. Detectable changes in the arrival time of their signals can result from passing gravitational waves generated by merging supermassive black holes with wavelengths measured in lightyears. These timing changes can be used to locate the source of the waves. Using this technique, astronomers have discovered
7560-717: Was 3.7 +0.5 −0.5 × 10 W . General relativity predicts that gravitational waves have a tensor -like (spin-2) polarization . The detection in all three detectors led to strong experimental evidence for pure tensor polarization over pure scalar or pure vector polarizations. Gravitational wave Gravitational waves transport energy as gravitational radiation , a form of radiant energy similar to electromagnetic radiation . Newton's law of universal gravitation , part of classical mechanics , does not provide for their existence, instead asserting that gravity has instantaneous effect everywhere. Gravitational waves therefore stand as an important relativistic phenomenon that
7650-543: Was awarded the 2017 Nobel Prize in Physics for his contributions to the LIGO detector and the observation of gravitational waves . 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 and speaks of the astrophysical implications of the general theory of relativity . He continues to do scientific research and scientific consulting,
7740-635: Was completed in 2019; its first joint detection with LIGO and VIRGO was reported in 2021. Another European ground-based detector, the Einstein Telescope , is under development. A space-based observatory, the Laser Interferometer Space Antenna (LISA), is also being developed by the European Space Agency . Gravitational waves do not strongly interact with matter in the way that electromagnetic radiation does. This allows for
7830-422: Was detected at 10:30:43 UTC . The Livingston detector was the first to receive the signal, followed by the Hanford detector 8 milliseconds later and Virgo received the signal 14 milliseconds after Livingston. The detection in all three detectors lead to a very accurate estimate of the position of the source, with a 90% credible region of just 60 deg , a factor 20 times more accurate than before. Analysis indicated
7920-653: Was discovered. In 1974, Russell Alan Hulse and Joseph Hooton Taylor, Jr. discovered the first binary pulsar , which earned them the 1993 Nobel Prize in Physics . Pulsar timing observations over the next decade showed a gradual decay of the orbital period of the Hulse–Taylor pulsar that matched the loss of energy and angular momentum in gravitational radiation predicted by general relativity. This indirect detection of gravitational waves motivated further searches, despite Weber's discredited result. Some groups continued to improve Weber's original concept, while others pursued
8010-534: Was seen by both LIGO detectors in Livingston and Hanford, with a time difference of 7 milliseconds due to the angle between the two detectors and the source. The signal came from the Southern Celestial Hemisphere , in the rough direction of (but much farther away than) the Magellanic Clouds . The confidence level of this being an observation of gravitational waves was 99.99994%. A year earlier,
8100-439: Was settled by a thought experiment proposed by Richard Feynman during the first "GR" conference at Chapel Hill in 1957. In short, his argument known as the " sticky bead argument " notes that if one takes a rod with beads then the effect of a passing gravitational wave would be to move the beads along the rod; friction would then produce heat, implying that the passing wave had done work . Shortly after, Hermann Bondi published
#572427