Gravitational waves: ripples in spacetime caused by the most violent and energetic phenomenon in the universe, such as colliding black holes and supernovas. To the untrained astrophysicist the very idea sounds futuristic, almost like science fiction; but in reality their existence was first predicted over 100 years ago as part of Albert Einstein’s General Theory of Relativity. (https://beautifulequations.co.uk/collections/theory-of-relativity)
His mathematics demonstrated that a system, today called a binary pulsar, where two massive accelerating objects such as a neutron and stars orbiting each other would send waves of undulating spacetime propagating in all directions.
Einstein’s theory was not confirmed until the 1970s when two astronomers at a Peruvian observatory discovered an example of this Binary Pulsar. After several years of observations, it was determined that the stars were getting closer together precisely at the rates predicted by Einstein’s general relativity, supporting the assumption that they were emitting gravitational waves. While this did confirm their existence, the evidence was always indirect or through mathematics rather than through direct contact.
This September celebrates six years since one of the greatest ever scientific achievements, when LIGO (Laser Interferometer Gravitational-Wave Observatory) directly detected gravitational waves. Colliding black holes 1.3 billion light years away produced gravitational waves that were sensed upon reaching earth by LIGO’s interferometer: when detected, they were billions of times smaller and so their effect on spacetime could only be observed in a scale almost 1,000 times smaller than a nucleus.
Since that discovery, LIGO continues to refine and improve its technology and has since detected several more distant objects emitting these waves. The observations allow scientists to study the events in the universe in a way never before possible, as these cosmic ripples carry information about their origins, and clues about the nature of gravity itself.
In 100 years, gravitational waves went from pure theory from one of the greatest physicists of all time to a proven and detected concept. If advancements continue at this rate, the wonders and understanding of the universe that this area of study may uncover in the next 100 years is impossible to predict, but will be truly exciting to follow!
For more information about gravitational waves and LIGO’s work see their website. Express your appreciation of Einstein’s work with the Beautiful Equations – Theory of Relativity (https://beautifulequations.co.uk/collections/theory-of-relativity) range.