January 15, 2016

Gravitational Waves – Why Do We Even Care If We Find Them?

It can only take one tweet to cause an uproar of bickering, debating and speculation on the internet. And this week, it was a tweet by well-known physicist Lawrence Krauss, a cosmologist at Arizona State University who hinted that scientists may have observed a brand new and long-anticipated signal that would revolutionise the face of science. The signal from a gravitational wave.

The informal king of physics, Albert Einstein, first predicted gravitational waves in 1916. He imagined that a sort of fabric stretched across the universe and that objects with mass would bend and warp it – the more mass an object had, the more it would warp. He called it spacetime, and it made sense that occasionally there would be ripples in spacetime, like ripples in a pond, only on a much smaller scale. In fact, the effect is so small that it requires the most sensitive instruments to have even the remotest chance of ever spotting them.
The Advanced Laser Interferometer Gravitational-Wave Observatory (or Ligo) was built for this very purpose. It has been operational since 2002, and in all this time it has never seen a gravitational wave. In 2015 it received some upgrades to increase its sensitivity, and as rumours would have it, these upgrade may have paid off with the first ever hint of a gravitational wave.
Krauss certainly thinks so.
So what would the existence of gravitational waves mean for the next generation of science? Firstly, it would be yet more evidence that Einstein’s theory of general relativity is correct, but there is also a glittering treasure trove of new discoveries that scientists would be itching to dive into if we finally had the eyes to see gravitational waves.
All the information we currently have about the universe outside of our solar system is gleaned from measurements of only one thing: light. Visible light, x-rays, infrared, radio, microwave – these wavelengths of light tell us everything we currently know about celestial objects. If scientists can now see gravitational waves, then it opens up a brand new way of looking into the cosmos.
Here are some of the many exciting things that scientists can begin to look at in a new light:
The Beginning of The Universe
The Big Bang, the explosion that began the universe, is predicted to be a gravitationally active event. This means that we could still spot the echoes of the gravitational waves produced here resonating around the universe. A chance to find out more about our true origins. Specifically, we could learn a lot about inflation, the period of the universe just after the big bang where the universe has a faster-than-light growth spurt.
Black Holes
The goliaths of the universe are often referenced in science fiction as the final, destructive stages of a supermassive star. Black holes are so dense and massive that not even light can escape their greedy clutches, which has left scientists a bit limited with the tools they can use to find out more about them. However, they would be the perfect candidates for creating gravitational waves. A delight for astronomers who would finally have a way of looking at them.
Dark Matter
Were knocking out all of the buzzwords in this article! Dark matter is as elusive as gravitational waves themselves. It is a substance with mass that doesnt emit any light (hence why it is called dark matter) and interacts only via gravity. Scientists have predicted that there is quite a lot of dark matter floating about the universe: about five times more than the matter we can see (stars, galaxies, etc.) This means that while dark matter may not emit light; it is probable that it will emit gravitational waves, and if it’s true that we finally have the means to detect these signals then it would be the first time that scientists could gather direct evidence of dark matter’s existence.
The implications of the discovery of gravitational waves are so exciting that scientists are leaping all over the rumour, and its easy to see why. The ability to see gravitational waves would open our eyes to another version of the universe. And this hidden world would be ripe for discovery. However, all it is at the moment is a rumour. And although it might be difficult, its important not to get our hopes up. The only signals to have ever come from gravitational wave experiments have been false signals, so theres no reason for this one to be any different. The team at Ligo, where the wave was reportedly seen, will now take their time writing up and evaluating their evidence.
Now, the discovery of gravitational waves, one of the most elusive and exciting predictions in the universe since the Higg’s boson, is just a waiting game.

Posted in Blogging, Science