Six reasons you should be excited about gravitational waves
Has the discovery of gravitational waves left you baffled? Here are six reasons why everyone is so excited
It’s very easy to glaze over when confronted when phrases like "black holes", "relativity" and "curvature of spacetime" are used with reckless abandon, but the discovery of gravitational waves is a huge deal in the world of physics.
In short, gravitational waves – theoretical until yesterday – are shockwaves that occur when two objects bump together. These send out waves that subtly alter the space and time around them. Now, technically this can be done by any two objects colliding, but given that a supernova explosion within our own galaxy would only alter the distance between us and the sun by a the length of an atom for a few hundredths of a second, you never notice them.
And that’s why they’ve been so damned fiendish to pinpoint.
It’s not just a huge technical achievement, though, there are other reasons to celebrate the discovery’s confirmation. Here are six of them.
1. The technology involved is mind-bending
So, gravitational waves are really, really small, which makes them extremely hard to detect. As I said, we’re talking about the difference between the fraction of an atom for a huge event within our galaxy. What’s more, because it distorts everything, typical measurement technology also distorts with it: imagine you’re trying to measure the diameter of a swelling football with a ruler, but the ruler is also swelling alongside it – you'd see no change.
So how have scientists managed it? By using the speed of light, which remains constant, as the measuring stick. In other words, if spacetime is compressed, light should travel fractionally faster, but if spacetime is stretched, then it should be marginally slower. Enter LIGO – or the Laser Interferometer Gravitational Wave Observatory: it’s a pair of 4km-long tunnels that use lasers to measure changes in the distances between the ends of the tunnels. Scientists "simply" need to measure the interference of the lasers to prove their existence.
I put simply in speech marks because, again, these are ridiculously small changes. The technology involved needs to measure changes in the laser that are about one ten-thousandth of the diameter of a proton.
2. It proves Einstein was right
At this point, it’s become pretty unfashionable to argue that Einstein was wrong about the whole relativity thing, but there was one big sticking point in the theory: his predicted gravitational waves had never been seen. Exactly 100 years after the theory of relativity was first put forward, the discovery means that we can pretty much confirm that he was right about relativity.
Which is just as well really, because if it was wrong, then a lot of our assumptions about the world around us and how we go about doing things would also be wrong.
3. It could also prove the Big Bang Theory
Gravitational waves can offer an insight into the very early history of the universe, by tracing them back to their source. As Bruce Allen from the Max Planck Institute for Gravitational Physics told Reuters: “Gravitational waves can travel freely, back to very early times. So one cool thing is one day we'll be able to see what the universe looked like in very early times using gravitational waves. That's what actually got me interested in the field 25 years ago.”
4. It’ll let us "see" a lot more of the universe
Our current telescopes can’t see that far into the universe. Even the discovery of Kepler-452b was inferred by the passing of its shadow past its star rather than seeing it. Gravitational waves could help us build telescopes to compile images of parts of the universe previously beyond our reach.
5. We’ll also learn more about black holes
The trouble with black holes is that by their very nature they don’t emit any light. Gravitational waves could be the answer. As Allen says: “If two black holes orbit each other, we can't see it any way other than gravitational waves, because black holes don't emit any light, radio waves, X-rays or anything.”
Which is handy, because it’s the collision of black holes and neutron stars – really heavy objects – that makes waves that can be measured here on Earth.
6. And finally… the news was broken by cake
If you don’t think any of this is hugely noteworthy (seriously, what is wrong with you?), then I’ll make one final appeal to your sweet tooth: the most significant discovery in physics this century was broken in edible format. — Erin Ryan (@erinleeryan) February 11, 2016
— Erin Ryan (@erinleeryan) February 11, 2016
Dr Erin Ryan, a scientist associated with NASA, accidently broke news of the announcement before it was officially made, in a delicious way. Rumours were already pretty strong, but confirmation from a source like this seemed to confirm it ahead of the embargo. Still, as Ryan pointed out: @JosephGruber I know, right? Embargo was already broken to tell the baker! — Erin Ryan (@erinleeryan) February 11, 2016
@JosephGruber I know, right? Embargo was already broken to tell the baker!
— Erin Ryan (@erinleeryan) February 11, 2016