Gravitational waves are ripples in the curvature of space time
that are generated in certain gravitational interactions and propagate as waves
outward from their source at the speed of light. The possibility of
gravitational waves was discussed in 1893 by Oliver Heaviside using the analogy
between the inverse- square law in gravitation and electricity. In 1905 Henri Poincare
first proposed gravitational waves (ondes gravifiques) emanating from a body
and propagating at the speed of light as being required by the Lorentz
transformations. Predicted in 1916 by Albert Einstein on the basis of his
theory of general relativity, gravitational waves transport energy as gravitational
radiation, a form of radiant energy similar to electromagnetic radiation.
Gravitational waves cannot exist under Newton's law of universal gravitation
since that law is predicated on the assumption that physical interactions
propagate at infinite speed. Gravitational-wave astronomy is a branch of
observational astronomy which uses gravitational waves to collect observational
data about sources of detectable gravitational waves such as binary star
systems composed of white dwarfs, neutron stars, and black holes; and events such
as supernovae, and the formation of the early universe shortly after the Big
Bang.
On February 11, 2016, the LIGO and Virgo
Scientific Collaboration announced that they had made the first observation of
gravitational waves. The observation itself was made on 14 September 2015,
using the Advanced LIGO detectors. The gravity waves originated from a pair of
merging black holes After the initial announcement the LIGO instruments
detected two more confirmed, and one potential, gravitational wave events. In
August 2017, the two LIGO instruments, and the Virgo instrument, observed a
fourth gravitational wave from merging black holes. Several other
gravitational- wave detectors are planned or under construction.
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.
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