Why you should be excited about Gravitational Waves

If you had asked me before Wednesday last week, the implications of the Laser Interferometer Gravitational-Wave Observatory’s (LIGO) impending announcement, I would have spent about thirty seconds floundering wildly before sighing and admitting that no, I hadn’t a clue.

And so I did some reading.

Turns out, the discovery of Gravitation Waves, announced on Thursday, is one of the greatest scientific breakthroughs of the 21st Century so far. Here’s why.

First things first, we need to understand a little bit of history, specifically the work of the one and only Albert Einstein. In 1916, on the back of his Theory of General Relativity, Einstein predicted the existence of minuscule ripples in the fabric of space and time. Remember the Gedanken experiments I mentioned in my last post? Well General Relativity began as a giant thought exercise.

The effects of objects with mass on the curvature of spacetime (www.livesciences.com)
Imagine you’re sitting on a trampoline underneath an oak tree. An acorn falls onto the stretched material; where does it go? It rolls towards you. The trampoline is spacetime, and you are the Earth. Gravity, Einstein realised, is caused by objects of mass warping the curvature of space and time. (Wibbly wobbly, timey wimey).

So how do we know this is actually a thing?

Well my favourite example of this warping can be found in the practicalities of timekeeping in GPS satellites. Because of the effects of the Earth’s mass on time itself, the closer you get to the centre of the Earth, the slower time moves. So satellite clocks need to be set slightly faster (about 45 millionths of a second faster) than those on the surface of our planet or else they would give us a location up to 10 km out of sync! Isn’t that insane?

Everything in the universe that has mass causes waves. There are waves moving through you right now. The thing is, these waves are smaller than miniscule. Which is why we needed to wait for something immense. Billions of years ago and light years away, two black holes began to circle one another. Black holes, in terms of general relativity, form gigantic warps in spacetime due to their mass. When these two began to merge, it resulted in giant ripples, like when you throw a rock into a pond. On September 14th, 2015, LIGO was able to measure one of these ripples.

LIGO is a facility in the USA specifically designed to look for gravitational waves. Its strange cross shape is deliberate. A laser runs down each arm of the in order to measure the distance between the detector and the end of the arm with an intense level of precision. Any changes in the distance the laser travels indicates a distortion in spacetime.

Einstein himself never thought a day would come when technology would reach a level of sensitivity able to detect gravitational waves. And it wasn’t as though he didn’t have faith in the scientific and engineering communities. According to Jorge Cham of PhD comics, finding these waves is like detecting a change of 5 mm in 1,000,000,000,000,000,000,000 metres.

So now that scientists have proven without a shadow of a doubt that they exist (you can read the paper here), what next?

This discovery means about as much to the field of astronomy as the invention of the telescope. It opens up an entirely new way of observing our universe. We’ll be able to see closer to the moment of the Big Bang than ever before. Theoretically, galaxies and stars that are beyond the current range of our telescopes, will be reachable.

I don’t know about you, but I think Einstein would be more than proud.



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