GEOFF BENNETT: Let's expand our horizons a bit wider and look at important findings that are literally about space-time and the cosmos as we know it.

You might remember that Albert Einstein theorized that as heavy objects move through time and space, they create ripple effects in the fabric of our universe.

Now an international team of scientists have detected new evidence of that.

Researchers found new signs of gravitational waves, waves that are affected by huge movements, such as the collision of black holes.

These are no small matters.

Our science correspondent, Miles O'Brien, is here to break it down.

So, Miles, Albert Einstein was apparently, what, 100 years ahead of his time in predicting these gravitational waves.

What are they exactly?

MILES O'BRIEN: Well, they are in fact ripples in the fabric of time, and Einstein predicted them in 1915.

They were verified by a ground-based observatory based on lasers called LIGO in 2015, so 100 years later.

What this latest discovery does is prove they're more ubiquitous and found at much longer wavelengths.

We're talking about a project called the North American Nanohertz Observatory for Gravitational Waves.

We're going to call it NANOGrav from now on funded by the National Science Foundation.

They have been working on this for 15 years.

I do think it's worth spending a couple of more moments trying to understand gravitational waves before we go much further.

Jeffrey Hazboun helped me out with this.

He's at Oregon State University.

He gave me a little 101 which we can sink our teeth into.

JEFF HAZBOUN, Oregon State University: One way to think about is if you think about space-time as being Jell-O, right?

You have this.

It's a little bit more firm than regular Jell-O.

But you have Jell-O.

And the space in between the sides of the Jell-O gets jiggled by these really massive objects.

And so you can imagine smack it on one side of a big giant cube of Jell-O and a wave would pass through that cube of Jell-O.

And so things would compress and expand as that perturbation moves through the chunk of Jell-O.

GEOFF BENNETT: So he paints quite a mental picture there.

Help us understand the scientific significance of this.

MILES O'BRIEN: Well, so the Earth-based LIGO, that laser beam observatory that I was telling you about from 2015, that was akin to Galileo pointing his telescope at Jupiter.

Now we're talking about much more complicated and larger telescopes, if you will, looking at other wavelengths, in this case, a wavelength that can be a light-year-long or longer.

And scientists have long hypothesized that if there were gravitational waves, there'd be kind of this background hum of gravitational waves out there.

But it was impossible for them to detect them with any sort of ground-based observatory to see these sort of ripples in space-time at that magnitude.

GEOFF BENNETT: I'm really struck by the quixotic nature of their endeavor, trying to find out if there's a background hum rippling throughout the universe.

How did these scientists do their work?

MILES O'BRIEN: Geoff, if you can imagine an observatory about the size of half of our galaxy, if that even computes with you, they took advantage of pulsars.

Pulsars are dead stars.

They are very dense, about the density of our sun, the size of our city -- a city.

So, NANOGrav used a technique called pulsar timing array, which means they use pulsars, which are dead stars, which have predictable kind of rotating beacons, and you can really set your clock to it.

And if there's any change in those, you can infer there's something happening, in this case, a gravitational wave, which is changing it ever so slightly.

So, they trained several radio observatories on our planet at 68 of these pulsars and were able to pick up these subtle changes and thus identify what they infer to be these big gravitational waves.

GEOFF BENNETT: These ripples in the fabric of time, do scientists know what causes them?

MILES O'BRIEN: Well, they don't know for sure, but they think that big, supermassive black holes have something to do with it.

The universe is rough place, Geoff.

Things are bouncing around a lot, banging into each other, including black holes.

And the idea is that, as this happens, this is kicking out this -- these perturbations which create these gravitational waves.

But I am now officially getting in deep for a history major.

So let's go back to Jeff Hazboun, Oregon State University, for his best current hypothesis.

JEFF HAZBOUN: It's most likely from an ensemble of millions of black hole binaries, supermassive gargantuan-sized black holes that live at the centers of galaxies.

When two of them settle in after a galaxy merger, that's when they give off the gravitational waves that we're looking for.

But it -- we aren't there yet.

GEOFF BENNETT: So he says we aren't there yet.

So, what's next, Miles?

What questions do these scientists hope to answer?

MILES O'BRIEN: They have identified the chorus.

Now they want to home in on some individual singers.

And, in so doing, they hope to connect the dots a little better between these bouncing around massive black holes and these long gravitational waves and, in so doing, create sort of a cosmic archaeology, understand more about how the universe formed and where it's going, and doing that by listening to the hum of the universe.

GEOFF BENNETT: Miles O'Brien, always enjoy speaking with you.

Thanks for being with us.

MILES O'BRIEN: You're welcome, Geoff.