# Timeline of gravitational physics and relativity

The following is a **timeline of gravitational physics and general relativity**.

## Before 1500

- 3rd century BC - Aristarchus of Samos proposes heliocentric model, measures the distance to the Moon and its size

## 1500s

- 1543 – Nicolaus Copernicus places the Sun at the gravitational center, starting a revolution in science
- 1583 – Galileo Galilei induces the period relationship of a pendulum from observations (according to later biographer).
- 1586 – Simon Stevin demonstrates that two objects of different mass accelerate at the same rate when dropped.
- 1589 – Galileo Galilei describes a hydrostatic balance for measuring specific gravity.
- 1590 – Galileo Galilei formulates modified Aristotelean theory of motion (later retracted) based on density rather than weight of objects.

## 1600s

- 1602 – Galileo Galilei conducts experiments on pendulum motion.
- 1604 – Galileo Galilei conducts experiments with inclined planes and induces the law of falling objects.
- 1607 – Galileo Galilei arrives a mathematical formulation of the law of falling objects based on his earlier experiments.
- 1608 – Galileo Galilei discovers the parabolic arc of projectiles through experiment.
- 1609 – Johannes Kepler describes the motion of planets around the Sun, now known as Kepler's laws of planetary motion.
- 1640 – Ismaël Bullialdus suggests an inverse-square gravitational force law.
- 1665 – Isaac Newton introduces an inverse-square universal law of gravitation uniting terrestrial and celestial theories of motion and uses it to predict the orbit of the Moon and the parabolic arc of projectiles.
- 1684 – Isaac Newton proves that planets moving under an inverse-square force law will obey Kepler's laws
- 1686 – Isaac Newton uses a fixed length pendulum with weights of varying composition to test the weak equivalence principle to 1 part in 1000

## 1700s

- 1798 – Henry Cavendish measures the force of gravity between two masses, leading to the first accurate value for the gravitational constant

## 1800s

- 1846 – Urbain Le Verrier and John Couch Adams, studying Uranus' orbit, independently prove that another, farther planet must exist. Neptune was found at the predicted moment and position.
- 1855 – Le Verrier observes a 35 arcsecond per century excess precession of Mercury's orbit and attributes it to another planet, inside Mercury's orbit. The planet was never found. See Vulcan.
- 1876 – William Kingdon Clifford suggests that the motion of matter may be due to changes in the geometry of space
- 1882 – Simon Newcomb observes a 43 arcsecond per century excess precession of Mercury's orbit
- 1887 – Albert A. Michelson and Edward W. Morley in their famous experiment do not detect the ether drift
- 1889 – Loránd Eötvös uses a torsion balance to test the weak equivalence principle to 1 part in one billion
- 1893 – Ernst Mach states Mach's principle; first constructive attack on the idea of Newtonian absolute space
- 1898 – Henri Poincaré states that simultaneity is relative
- 1899 – Hendrik Antoon Lorentz published Lorentz transformations

## 1900s

- 1904 – Henri Poincaré presents the principle of relativity for electromagnetism
- 1905 – Albert Einstein completes his theory of special relativity and states the law of mass-energy conservation: E=mc
^{2} - 1907 – Albert Einstein introduces the principle of equivalence of gravitation and inertia and uses it to predict the gravitational redshift
- 1915 – Albert Einstein completes his theory of general relativity. The new theory explains Mercury's strange motions that baffled Urbain Le Verrier.
- 1915 – Karl Schwarzschild publishes the Schwarzschild metric about a month after Einstein published his general theory of relativity. This was the first solution to the Einstein field equations other than the trivial flat space solution.
- 1916 – Albert Einstein shows that the field equations of general relativity admit wavelike solutions
- 1918 – J. Lense and Hans Thirring find the gravitomagnetic precession of gyroscopes in the equations of general relativity
- 1919 – Arthur Eddington leads a solar eclipse expedition which claims to detect gravitational deflection of light by the Sun
- 1921 – Theodor Kaluza demonstrates that a five-dimensional version of Einstein's equations unifies gravitation and electromagnetism
- 1937 – Fritz Zwicky states that galaxies could act as gravitational lenses
- 1937 – Albert Einstein, Leopold Infeld, and Banesh Hoffmann show that the geodesic equations of general relativity can be deduced from its field equations

#### 1950s

- 1953 – P. C. Vaidya Newtonian time in general relativity, Nature,
**171**, p260. - 1956 – John Lighton Synge publishes the first relativity text emphasizing spacetime diagrams and geometrical methods,
- 1957 – Felix A. E. Pirani uses Petrov classification to understand gravitational radiation,
- 1957 – Richard Feynman introduces sticky bead argument,
- 1957 – John Wheeler discusses the breakdown of classical general relativity near singularities and the need for quantum gravity
- 1959 – Pound–Rebka experiment, first precision test of gravitational redshift,
- 1959 – Lluís Bel introduces Bel–Robinson tensor and the Bel decomposition of the Riemann tensor,
- 1959 – Arthur Komar introduces the Komar mass,
- 1959 – Richard Arnowitt, Stanley Deser and Charles W. Misner developed ADM formalism.

#### 1960s

- 1960 – Martin Kruskal and George Szekeres independently introduce the Kruskal–Szekeres coordinates for the Schwarzschild vacuum,
- 1960 – Shapiro effect confirmed,
- 1960 – Thomas Matthews and Allan R. Sandage associate 3C 48 with a point-like optical image, show radio source can be at most 15 light minutes in diameter,
- 1960 – Carl H. Brans and Robert H. Dicke introduce Brans–Dicke theory, the first viable alternative theory with a clear physical motivation,
- 1960 – Ivor M. Robinson and Andrzej Trautman discover the Robinson-Trautman null dust solution[1]
- 1961 – Pascual Jordan and Jürgen Ehlers develop the
*kinematic decomposition*of a timelike congruence, - 1960 – Robert Pound and Glen Rebka test the gravitational redshift predicted by the equivalence principle to approximately 1%
- 1962 – Roger Penrose and Ezra T. Newman introduce the Newman–Penrose formalism,
- 1962 – Ehlers and Wolfgang Kundt classify the symmetries of Pp-wave spacetimes,
- 1962: –Joshua Goldberg and Rainer K. Sachs prove the Goldberg–Sachs theorem,
- 1962 – Ehlers introduces Ehlers transformations, a new solution generating method,
- 1962 – Cornelius Lanczos introduces the Lanczos potential for the Weyl tensor,
- 1962 – Richard Arnowitt, Stanley Deser, and Charles W. Misner introduce the ADM reformulation and global hyperbolicity,
- 1962 – Yvonne Choquet-Bruhat on Cauchy problem and global hyperbolicity,
- 1962 – Istvan Ozsvath and Englbert Schücking rediscover the circularly polarized monochromomatic gravitational wave,
- 1962 – Hans Adolph Buchdahl discovers Buchdahl's theorem,
- 1962 – Hermann Bondi introduces Bondi mass,
- 1962 – Robert Dicke, Peter Roll, and R. Krotkov use a torsion fiber balance to test the weak equivalence principle to 2 parts in 100 billion,
- 1962 - Hermann Bondi, M. G. van der Burg, A. W. Metzner, and Rainer K. Sachs introduce the asymptotic symmetry group of asymptotically flat, Lorentzian spacetimes at null (
*i.e.*, light-like) infinity. - 1963 – Roy Kerr discovers the Kerr vacuum solution of Einstein's field equations,
- 1963 – Redshifts of 3C 273 and other quasars show they are very distant; hence very luminous,
- 1963 – Newman, T. Unti and L.A. Tamburino introduce the NUT vacuum solution,
- 1963 – Roger Penrose introduces Penrose diagrams and Penrose limits,
- 1963 – First Texas Symposium on Relativistic Astrophysics held in Dallas, 16–18 December,
- 1964 – R. W. Sharp and Misner introduce the Misner–Sharp mass,
- 1964 – M. A. Melvin discovers the Melvin electrovacuum solution (aka the
*Melvin magnetic universe*), - 1964 – Irwin Shapiro predicts a gravitational time delay of radiation travel as a test of general relativity
- 1965 – Roger Penrose proves first of the singularity theorems,
- 1965 – Newman and others discover the Kerr–Newman electrovacuum solution,
- 1965 – Penrose discovers the structure of the light cones in gravitational plane wave spacetimes,
- 1965 – Kerr and Alfred Schild introduce Kerr-Schild spacetime,
- 1965 – Subrahmanyan Chandrasekhar determines a stability criterion,
- 1965 – Arno Penzias and Robert Wilson discover the cosmic microwave background radiation,
- 1965 – Joseph Weber puts the first Weber bar gravitational wave detector into operation
- 1966 – Sachs and Ronald Kantowski discover the Kantowski-Sachs dust solution,
- 1967 – Jocelyn Bell and Antony Hewish discover pulsars,
- 1967 – Robert H. Boyer and R. W. Lindquist introduce Boyer–Lindquist coordinates for the Kerr vacuum,
- 1967 – Bryce DeWitt publishes on canonical quantum gravity,
- 1967 – Werner Israel proves the no-hair theorem,
- 1967 – Kenneth Nordtvedt develops PPN formalism,
- 1967 – Mendel Sachs publishes factorization of Einstein's field equations,
- 1967 – Hans Stephani discovers the Stephani dust solution,
- 1968 – F. J. Ernst discovers the Ernst equation,
- 1968 – B. Kent Harrison discovers the Harrison transformation, a solution-generating method,
- 1968 – Brandon Carter solves the geodesic equations for Kerr–Newmann electrovacuum,
- 1968 – Hugo D. Wahlquist discovers the Wahlquist fluid,
- 1968 – Irwin Shapiro presents the first detection of the Shapiro delay
- 1968 – Kenneth Nordtvedt studies a possible violation of the weak equivalence principle for self-gravitating bodies and proposes a new test of the weak equivalence principle based on observing the relative motion of the Earth and Moon in the Sun's gravitational field
- 1969 – William B. Bonnor introduces the Bonnor beam,
- 1969 – Joseph Weber reports observation of gravitational waves[2] (a claim now generally discounted),
- 1969 – Penrose proposes the (weak) cosmic censorship hypothesis and the Penrose process,
- 1969 – Stephen W. Hawking proves area theorem for black holes,
- 1969 – Misner introduces the mixmaster universe,

#### 1970s

- 1970 – Frank J. Zerilli derives the Zerilli equation,
- 1970 – Vladimir A. Belinskiǐ, Isaak Markovich Khalatnikov, and Evgeny Lifshitz introduce the BKL conjecture,
- 1970 – Chandrasekhar pushes on to 5/2 post-Newtonian order,
- 1970 – Hawking and Penrose prove trapped surfaces must arise in black holes,
- 1970 – the Kinnersley-Walker photon rocket,
- 1970 – Peter Szekeres introduces colliding plane waves,
- 1971 – Peter C. Aichelburg and Roman U. Sexl introduce the Aichelburg–Sexl ultraboost,
- 1971 – Introduction of the Khan–Penrose vacuum, a simple explicit colliding plane wave spacetime,
- 1971 – Robert H. Gowdy introduces the Gowdy vacuum solutions (cosmological models containing circulating gravitational waves),
- 1971 – Cygnus X-1, the first solid black hole candidate, discovered by Uhuru satellite,
- 1971 – William H. Press discovers black hole ringing by numerical simulation,
- 1971 – Harrison and Estabrook algorithm for solving systems of PDEs,
- 1971 – James W. York introduces conformal method generating initial data for ADM initial value formulation,
- 1971 – Robert Geroch introduces Geroch group and a solution generating method,
- 1972 – Jacob Bekenstein proposes that black holes have a non-decreasing entropy which can be identified with the area,
- 1972 – Carter, Hawking and James M. Bardeen propose the four laws of black hole mechanics,
- 1972 – Sachs introduces optical scalars and proves peeling theorem,
- 1972 – Rainer Weiss proposes concept of interferometric gravitational wave detector,
- 1972 – J. C. Hafele and R. E. Keating perform Hafele–Keating experiment,
- 1972 – Richard H. Price studies gravitational collapse with numerical simulations,
- 1972 – Saul Teukolsky derives the Teukolsky equation,
- 1972 – Yakov B. Zel'dovich predicts the transmutation of electromagnetic and gravitational radiation,
- 1973 – P. C. Vaidya and L. K. Patel introduce the Kerr–Vaidya null dust solution,
- 1973 – Publication by Charles W. Misner, Kip S. Thorne and John A. Wheeler of the treatise
*Gravitation*, the first modern textbook on general relativity, - 1973 – Publication by Stephen W. Hawking and George Ellis of the monograph
*The Large Scale Structure of Space-Time*, - 1973 – Geroch introduces the GHP formalism,
- 1974 – Russell Hulse and Joseph Hooton Taylor, Jr. discover the Hulse–Taylor binary pulsar,
- 1974 – James W. York and Niall Ó Murchadha present the analysis of the initial value formulation and examine the stability of its solutions,
- 1974 – R. O. Hansen introduces Hansen–Geroch multipole moments,
- 1974: –Tullio Regge introduces the Regge calculus,
- 1974 – Hawking discovers Hawking radiation,
- 1975 – Chandrasekhar and Steven Detweiler compute quasinormal modes,
- 1975 – Szekeres and D. A. Szafron discover the Szekeres–Szafron dust solutions,
- 1976 – Penrose introduces Penrose limits (every null geodesic in a Lorentzian spacetime behaves like a plane wave),
- 1976 – Gravity Probe A experiment confirmed slowing the flow of time caused by gravity matching the predicted effects to an accuracy of about 70 parts per million.
- 1976 – Robert Vessot and Martin Levine use a hydrogen maser clock on a Scout D rocket to test the gravitational redshift predicted by the equivalence principle to approximately 0.007%
- 1978 – Penrose introduces the notion of a
*thunderbolt*, - 1978 – Belinskiǐ and Zakharov show how to solve Einstein's field equations using the inverse scattering transform; the first gravitational solitons,
- 1979 – Richard Schoen and Shing-Tung Yau prove the positive mass theorem.
- 1979 – Dennis Walsh, Robert Carswell, and Ray Weymann discover the gravitationally lensed quasar Q0957+561

#### After 1980

- 1982 – Joseph Taylor and Joel Weisberg show that the rate of energy loss from the binary pulsar PSR B1913+16 agrees with that predicted by the general relativistic quadrupole formula to within 5%
- 2002 – First data collection of the Laser Interferometer Gravitational-Wave Observatory (LIGO).
- 2005 – The first stable numerical solutions of a binary black hole orbit are calculated independently by three different research groups.
- 2007 – End of Gravity Probe B experiment.
- 2015 – Advanced LIGO reports the first direct detections of gravitational waves (GW150914 and GW151226).
- 2017 – Advanced LIGO and Fermi Gamma-ray Space Telescope constrain the speed of gravity to 1 part in of the speed of light with GW170817.
- 2019 – The Event Horizon Telescope images the shadow of supermassive black hole M87*

## See also

## References

- Robinson, Ivor; Trautman, A. (1960). "Spherical Gravitational Waves".
*Physical Review Letters*. Cdsads.u-strasbg.fr.**4**(8): 431. Bibcode:1960PhRvL...4..431R. doi:10.1103/PhysRevLett.4.431. Retrieved 2012-07-20. - "Making Waves".
*TERP*. 2016-08-18. Retrieved 2016-11-07.