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Gravitational wave

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Gravitational wave

LIGO/Virgo/NASA/Leo Singer/Axel Mellinger · CC BY 4.0

Gravitational waves are ripples in spacetime curvature that travel at the speed of light, produced by accelerating masses.[1][2] Since Einstein's initial prediction, scientists have observed hundreds of gravitational waves; the first indirect evidence came from binary-pulsar data, and direct observations began in 2015.[1]

Quick Facts

First predicted by
Albert Einstein
Speed
equal to speed of light in vacuum
Key observatories
  • LIGO
  • Virgo
  • KAGRA

Facts from the source article.

Key facts and history

In 1893 Oliver Heaviside discussed the possibility of gravitational waves traveling at light speed, using an analogy with electromagnetism.[3] Henri Poincaré in 1905 proposed that accelerated masses should produce gravitational waves, analogous to accelerating charges producing electromagnetic waves.[3] Einstein published his general theory of relativity in 1915 and by June 1916 concluded gravitational waves must propagate at light speed.[4][5] In 1922 Arthur Eddington showed two of Einstein's three wave types were coordinate artifacts, casting doubt on the physicality of the third type.[6]

In 1936 Einstein and Nathan Rosen submitted a paper claiming gravitational waves could not exist, but after peer review they rewrote it with the opposite conclusion.[7] Felix Pirani in 1956 rephrased gravitational waves in terms of the observable Riemann curvature tensor, resolving confusion from coordinate choices.[7] Richard Feynman's 1957 "sticky bead argument" demonstrated that gravitational waves could transmit energy.[8] The initial binary pulsar was identified in 1974 by Russell Alan Hulse and Joseph Hooton Taylor, Jr., and subsequent pulsar timing over roughly a decade revealed an orbital period decay that aligned with the energy and angular momentum loss predicted by general relativity for gravitational radiation.[9]

What the cited sources add

The same report quotes Prof David Reitze saying "It's the first time the Universe has spoken to us through gravitational waves"[10] A Scientific American article from March 2014 describes the BICEP2 experiment's claim of finding primordial B-mode polarization in the cosmic microwave background, which would be created only by gravitational waves from inflation.[11] A BBC News report from February 2016 states that the merger of the two black holes radiated an amount of pure gravitational energy equivalent to three times the mass of the sun.[10]

References

  1. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Einstein, "Näherungsweise Integration der Feldgleichungen der Gravitation", Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften Berlin, June 1916, p. 688–96; Einstein, "Über Gravitationswellen", Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften Berlin, 1918, p. 154–67; Thorne, "Black holes and time warps: Einstein's outrageous legacy", W.W. Norton, 1994; Susskind, "The black hole war: my battle with Stephen Hawking to make the world safe for quantum mechanics", Little, Brown, 2008; Hawking, " en.wikipedia.org
  2. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: James B. Hartle, Gravity: An Introduction to Einstein's General Relativity, Addison Wesley, 2003.; Robert M. Wald, General Relativity, University of Chicago Press, 1984.; Eric Poisson and Clifford M. Will, Gravity: Newtonian, Post-Newtonian, Relativistic, Cambridge University Press, 2014.; Eric Poisson and Clifford M. Will, Gravity: Newtonian, Post-Newtonian, Relativistic, Cambridge University Press, 2014.; Sean M. Carroll, Spacetime and Geometry: An Introduction to General Relativity, Addison Wesley, 2004.; Michele Maggiore, Gravita en.wikipedia.org
  3. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Heaviside, "Electromagnetic theory Vol 1", The Electrician printing and publishing company, limited, 1894, p. 455–66 Appendix B; (PDF) Membres de l'Académie des sciences depuis sa création : Henri Poincaré. Sur la dynamique de l' electron. Note de H. Poincaré. C.R. T.140 (1905) 1504–1508.; "page 1507"; Cervantes-Cota, "A Brief History of Gravitational Waves", Universe, 2016, p. 22 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Cervantes-Cota, "A Brief History of Gravitational Waves", Universe, 2016, p. 22 (original not read by us) en.wikipedia.org
  5. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Einstein, "Über Gravitationswellen", Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften Berlin, 1918, p. 154–67; Cervantes-Cota, "A Brief History of Gravitational Waves", Universe, 2016, p. 22 (we also read that source) en.wikipedia.org
  6. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Kennefick, "Traveling at the Speed of Thought: Einstein and the Quest for Gravitational Waves", Princeton University Press, 2016 (we also read that source) en.wikipedia.org
  7. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Cervantes-Cota, "A Brief History of Gravitational Waves", Universe, 2016, p. 22; Kennefick, "Traveling at the Speed of Thought: Einstein and the Quest for Gravitational Waves", Princeton University Press, 2016; F.A.E., "On the physical significance of the Riemann tensor", Acta Physica Polonica, 1956, p. 389–405 (we also read that source) en.wikipedia.org
  8. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Cervantes-Cota, "A Brief History of Gravitational Waves", Universe, 2016, p. 22; Robinson, "Gravitation and general relativity at King's College London", The European Physical Journal H, 2019, p. 181–270 (original not read by us) en.wikipedia.org
  9. Wikipedia, "Gravitational wave" (CC BY-SA 4.0), which cites: Nobel Prize Award (1993) Press Release The Royal Swedish Academy of Sciences.; Taylor, "A new test of general relativity – Gravitational radiation and the binary pulsar PSR 1913+16", The Astrophysical Journal, 1982, p. 908; Taylor, "Measurements of general relativistic effects in the binary pulsar PSR1913 + 16", Nature, 1979, p. 437–440; Cervantes-Cota, "A Brief History of Gravitational Waves", Universe, 2016, p. 22 (original not read by us) en.wikipedia.org
  10. "Gravitational waves from black holes detected", BBC News, 11 February 2016. facts only, no text reused. bbc.co.uk
  11. Moskowitz, "Gravity Waves from Big Bang Detected", Scientific American, 17 March 2014. facts only, no text reused. scientificamerican.com

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Gravitational wave (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Einstein field equationsEnergy–momentum relationFour-momentumFour-vectorGeneral covarianceGeodesics in general relativityGravitational constantGravitational fieldGravitational potentialGravitational singularityGravitational time dilationHawking radiation

Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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