What the hell are gravitational waves? We asked that cool astronomer to explain.

It’s not often that physics makes front page news, but it did today because, for the first time ever, scientists have been able to confirm the existence of gravitational waves.

This discovery represents the final confirmation of Einstein’s theory of relativity, which is a big deal.

While we understand the gravity of all of this, the actual science behind it… not so much.

This morning we put a call for help out into the cosmos and, happily, the universe provided answers straight from the mouth of our favourite astronomer Dr. Alan Duffy.

Here’s what he had to say when he, very obligingly, answered my terrible questions.

So, what the hell is a gravitational wave?

A gravitational wave is the final prediction of Einstein’s theory of relativity.

Basically,  it is that the space and time that we move in, that we experience, actually ripples.

Think about this: If you throw a rock into a lake you get ripples coming up on the surface of the water.

If you get two really massive objects, like black holes, coming together you’ll get similar ripples across space and time.

Two black holes colliding, eh? That sounds… unlikely, is it?

We know that black holes collide all the time and these collisions are big enough to see these ripples for millions of light years.

What’s surprising is that that just a few days after our newly upgraded technology had actually turned on, these ripples hit us it was.

Sort of jumping ahead, two black holes that were 20 times more massive then our sun, plunged together and the waves capsized for hundreds of millions of years and then hit earth just days after we turned on the detectors.

So that was little bit of luck and we can all be grateful  because it really is one of the biggest discoveries ever made in science.

It is that fundamental, we are looking out into the the universe with fundamentally new eyes.

And it looks a little like this:

Could you give us a quick refresher on Einstein’s general theory of relativity, E=MC^2, that is?

Einstein told us that mass bends space and time and that bending in space and time actually tells mass where to go.

So if you’ve ever got a sheet and you put a ball in the middle of the sheet then you see the sheet pull down, what we are seeing something similar to that.

This theory is 100 years old and yet Einstein’s vital predication, that space time can ripple and we can have gravitational waves had yet to be confirmed.


In fact, Einstein never believed that it could be because they are so small, these ripples are so tiny.

How tiny is tiny? Teacup pig tiny, or can’t possibly comprehend tiny?

Imagine again, you have the surface of the lake and you throw a rock, if you throw a big enough rock, you can cause a wave that will pick you up and then set you back down.

When you get a massive objects, like a black hole, these space time ripples, they don’t pick you up as such, they actually run through you and it’s happening right now.

So, you get stretched in one way and then you get squashed back up.

So, I know this is silly, but why can’t I feel it?

You don’t notice that in your daily life because it’s a very very small effect, it’s actually less than the width of the nucleus of an atom.

It is a mind bogglingly small amount.

What do they sound like?

I think it’s really amazing, the universe colliding black holes ended up having the frequency, the sound of the collision, was “Middle C” on the piano.

It’s really tragically underwhelming.

You can listen to it here:

So what now for science, do you guys get to just shut up shop or what?

This detection means that a century long hunt for Einstein’s final prediction is over, but it also means the beginning of  new era where, as a species, we get up to look up at the universe around us with new eyes and we get to see the fundamentally invisible — black holes don’t emit any light — yet now we can see the ripples they are emitting thanks to gravitational waves.

Things are just going to get more exciting.

To summarise, this is a very cool big deal. You can find out more on the LIGO website.

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