Scientists have proven the existence of gravitational waves in the universe, confirming Albert Einstein’s last unproven theory.
In one of the biggest scientific breakthroughs in decades, researchers at the Laser Interferometer Gravitational-Wave Observatory, or LIGO experiment have finally detected the cosmic ripples, after 10 years of trying.
The idea of gravitational waves was first put forward by Einstein in his ‘Theory of General Relativity’ 100 years ago and has been generally accepted by the scientific world but never before been proven.
What are gravitational waves?
Gravitational waves are concentric ripples in the fabric of spacetime, created by the collisions of black holes.
According to Einstein, space and time are in fact interwoven in a single continuum called spacetime. Rather than being a void, spacetime is a four-dimensional ‘fabric’ that can be pushed and pulled as objects move through it.
Dr. Albert Einstein pictured in 1940 (Nara Archives/REX Shutterstock)
This means that an object moving through spacetime creates ripples, similar to an object moving through water and making waves.
Small ripples, or gravitational waves, made by small objects in space fade out relatively quickly. However, those created by massive objects such as black holes, continue to spread all the way to Earth.
How are they detected?
As a gravitational wave passes, it stretches space in one direction and shrinks it in a perpendicular direction (at a right angle).
LIGO is made up of two huge instruments and can detect these changes using a laser beam which is split into two and sent off at perpendicular angles.
A passing gravitational wave can change the distance that each beam travels compared to its twin.
A technician inspects one of LIGO’s laser instruments (LIGO)
By measuring the beams that bounce back from space, scientists can detect these tiny changes caused by spacetime ripples.
LIGO’s two identical laser devices are located in the U.S states of Washington and Louisiana, enabling them to compare readings between the two stations.
What can gravitational waves tell us?
The breakthrough helps scientists’ understanding of the fundamental laws of the universe in a number of ways.
By proving that the gravitational waves have been produced by a black hole collision, the findings also help to prove the existence of black holes and the fact that they can merge when they collide with each other.
While there’s plenty of circumstantial evidence for the existence of black holes, scientists still know relatively little about them.
Proving the existence of gravitational waves could give more insight into the science of black holes (NASA/JPL-Caltech)
Whether gravitational waves travel at the speed of light is also an important question that could be answered by LIGO.
If the waves take longer to reach Earth than photon particles travelling at the speed of light, it could prove that the ‘graviton’ particles that make up the ripples, unlike photons, have mass. This would contradict current scientific theory.
Being able to detect gravitational waves could also prove the existence of ‘cosmic strings’ - theoretical fault lines in the universe.
The breakthrough could also provide new insight into other cosmic phenomena, such as neutron stars, which are formed from the remnants of bigger stars that have collapsed under their own weight.
What’s more, it could even help scientists to get a more accurate idea of how fast the universe is expanding.
Image credit: NASA/M. Helfenbein, Yale University / OPAC