Why the discovery of gravitational waves is so important

Today, in my day job I wrote about the momentous discovery of gravitational waves by LIGO.

There are four major discoveries associated with the detection:

First of all, today it was announced that on 14th September 2015 gravitational waves were observed by both LIGO detectors. This is the first time an experiment has been able to detect them, and it’s thanks to the upgrade that it received that it was able to reach the much higher sensitivity.

The second important discovery is that gravity moves at the speed of light. This has long been suspected but it is good to have it as a confirmation. This has one important implication: the graviton, the particle that carries the force of gravity, must be massless.

The third is that we finally have a detection of intermediate mass black holes. The merger between the two black holes that LIGO was able to detect was between a black hole weighing 36 solar masses, and one that weighed 29 solar masses. Stellar black holes reach at most 15 solar masses, so these are different. They were probably formed by the first generations of stars. Intermediate black holes like these will experience many mergers in their lifetimes and eventually evolve into the supermassive black holes that reside at the centre of galaxies.

Last but not least, the detection shows that the technology works. There are already several more gravitational wave observatories planned. Some are already in construction, and many more will be added to the list. Being able to see gravity will allow us to see better and further than ever before.

Gravitational waves can be thought of as analogous to electromagnetic waves, but while light is absorbed, gravitational waves cross the universe unchallenged. There are no shadows that shield us from gravity.

Today we are limited when we look towards the beginning of the universe, and the furthest we can see is at the first light, 300,000 years after the Big Bang. But gravity allows us to look beyond the veil, to “see” what happened right after the Big Bang.

Obviously, this is the first step for a brand new technology. Maxwell and Faraday had no idea how their laws of electromagnetism would go on to revolutionise society, but with a critical eye on the past and a good dose of hope, we can dare to dream of the wonderful things awaiting us in our future.

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