After almost two centuries of theorising, physicists have announced the observance of gravitational waves – ripples in the fabric of spacetime produced by violent events on a colossal scale.
Gravitational waves were first predicted in 1916 by Albert Einstein, along with his theory of general relativity.
Professor Neil Turok, director of the Perimeter Institute for Theoretical Physics, believes the groundbreaking discovery “signals a new era in astronomy”.
The research, conducted by LIGO, detected gravitational waves when ripples were produced by the formation of a binary black hole from two supermassive black holes approximately 1.3 billion light years from Earth.
The discovery is the culmination of work produced by LIGO since it was founded in 1992, and may offer the opportunity to further explore the Big Bang in ways not thought previously possible.
“(This) marks three milestones for physics: the direct detection of gravitational waves, the first detection of a binary black hole, and the most convincing evidence to date that nature’s black holes are the objects predicted by Einstein’s theory”.
What are ‘Gravitational waves’?
Gravitational waves are ripples in the fabric of spacetime, that occur as a result of violent events anywhere in the Universe. The easiest way to understand this is to imagine spacetime as a thin sheet of rubber the size of a football pitch – Many celestial bodies, such as planets, can be considered to be objects such as a marble resting on the sheet. This creates a ‘warp’ in the rubber – a dent in which it will sit. This is known as a ‘gravitational well’.
If you were to then place a less massive ball onto the slope of the dent, it would roll towards the first – in other words, the less massive object would be pulled towards the more massive object. This is the principle behind gravity itself.
However, if two massive objects were to collide on this sheet of rubber with enough force, it would make the sheet of rubber ripple.
Now, obviously the Universe isn’t a giant sheet of rubber, but the principle still applies – When events such as this occur, the metaphorical ‘rubber’ ripples, and the detection of these ripples proves Einstein’s theory.
How are gravitational waves detected?
The Ligo system splits a single laser beam into two, which will then travel in different directions down identical 4km tubes. The beam is reflected back once it reaches the end of tube, and is picked up by a detector.
If there is no distortion, the beams will arrive back at the detector at the exact same time, cancelling each other out.
However if the beams are distorted, as they would be by passing gravitational waves, they will arrive at the detector a different times. Although the arrival times may be an inconceivably small difference, it is still conclusive evidence of a gravitational wave passing through.
Previous efforts to explore the early Universe had been conducted with experiments using electromagnetic waves. This has yielded fountains of information about the formation of stars and planets, and changed science as we know it. However, it can only help to a certain point – electromagnetic waves are useless when attempting to understand the Universe before it hit 400,000 years old, as it was opaque to light.
Unlike electromagnetic waves, gravitational waves were present at the initial singularity – more commonly known as the Big Bang. Astrophysicists believe by taking advantage of gravitational waves, they can observe fluctuations in spacetime caused by the Big Bang itself.
It is very quickly becoming more and more likely that soon, scientists will be able to see what happened at the very birth of the Universe. Summed up rather succinctly by David Reitze (executive director of LIGO)…
“We did it”.