How can gravitational waves be measured?

Question

Matthew Arnold · Accepted Answer

Gravitational waves are measured, or detected rather, by the "swinging" of mirrors.

"All you need to build a gravitational-wave interferometer is two light beams, travelling between pairs of mirrors down pipes running in different directions, say north and west. The effect of a passing gravitational wave should stretch space in one direction and shrink it in the direction that is at right angles. On Earth, that would cause the mirrors to swing by tiny amounts, so that the distance between one pair of mirrors gets smaller, while the other gets larger. The swinging is actually the mirrors responding to the stretching and compression of space-time, which is just amazing." - Ed Daw, Reader in Physics, University of Sheffield

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The reason Earth is effected by gravitational waves is typically two supermassive objects interacting in a way in which the object is non-consistent, such as two black holes orbiting one another.

Evan Ashley · Answer

undefined Interferometers, like the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo interferometer, are used to measure gravitational waves by measuring minute variations in arm lengths brought about by gravitational waves passing through and producing distinctive patterns in the interference of laser beams.

Emilia Acosta · Answer

undefined Gravitational waves can be measured using interferometers, such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo. These instruments utilize lasers to monitor minute changes in the length of perpendicular arms caused by passing gravitational waves. When a gravitational wave passes through Earth, it distorts spacetime, causing one arm of the interferometer to lengthen while the other shortens, and vice versa. By comparing the light travel times between the arms, scientists can detect and measure gravitational waves.

Additionally, pulsar timing arrays can be used to detect gravitational waves indirectly. Pulsars are rapidly rotating neutron stars that emit regular pulses of electromagnetic radiation. Gravitational waves passing through the universe cause slight variations in the arrival times of these pulses on Earth. By precisely timing the arrival of pulses from multiple pulsars, scientists can detect the subtle signatures of gravitational waves.

Finally, space-based interferometers such as the Laser Interferometer Space Antenna (LISA) are being developed to observe gravitational waves from space. LISA consists of three spacecraft separated by millions of kilometers, forming an interferometer in space. This configuration allows LISA to detect lower frequency gravitational waves that cannot be observed by ground-based detectors due to terrestrial noise.

Overall, gravitational waves can be measured using interferometers on Earth, pulsar timing arrays, and space-based detectors, enabling scientists to explore the universe in a new way and uncover phenomena such as black hole mergers, neutron star collisions, and the dynamics of the early universe.