Gravitational waves are fluctuations in the fabric of space-time caused by the motion of matter.
Violent events in the universe, such as two black holes colliding, produce these ripples that propagate through space at, or near, the speed of light. They travel much like a wave, stretching and shrinking distances but becoming weaker as they move further from their source. While the movement of any matter produces gravitational waves, it is only large-scale events that will produce any detectable readings.
Gravitational waves, predicted by Einstein’s theory of general relativity, have so far been almost impossible to detect, and the main proof to date of their existence was the discovery of a binary system containing two neutron stars in 1974. Measuring the oscillation of space-time due to gravitational waves is equivalent to measuring the change in the size of an atom within the distance from the Sun to the Earth.
The search for a detectable gravitational has been carried out at observatories in the USA, by firing light down two long tubes measuring 2.5 miles (4km) at right angles to each other and detecting differences in the reflected light.
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