We're an hour outside New Orleans
at the center of a revolution happening in astronomy.
This road leads to LIGO.
In 2017, scientists here
and at their sister observatory in Washington state
won the Nobel Prize in Physics for proving one
of Einstein's last unverified predictions about the universe.
But their work is just getting started.
For thousands of years, most astronomers have studied
the small fraction of the universe that
gives off light or other radiation.
These scientists are among thousands
finding ways to see things conventional telescopes can't.
The tools they're building can help us make observations without light.
And they could one day help us understand
the 95 percent of the universe that's completely invisible.
From a swamp near LIGO, I'm Michael Tabb.
This is Quartz.
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- When we actually saw light down at the ends,
we were dumbfounded it was there.
We were like, "Oh my god! It actually works."
Janeen Romie leads the detector engineering group at LIGO.
The work is so cutting edge, it's hard to explain.
- Every single time I tried to explain what I did,
most of the time I just gave up.
I just say it's an astronomical observatory
that's something like a telescope.
It's just easier that way.
But to understand why the work at LIGO is so revolutionary,
we've got to try to explain what she does.
- Can you see it?
It's crazy robust for being as small as it is.
It all starts with Einstein.
He devised his theory of general relativity in 1915
and basically no one understood what he was talking about.
He described the close relationship between space and time–
a relationship so close, we combine them into one word.
Spacetime is the so-called fabric of the universe,
and like a fabric, it bends under stress.
That bending creates what we call gravity.
Anything with mass– from a paperclip to a black hole–
bends spacetime.
The more mass, the more it bends.
Now what happens to the fabric of spacetime
when those objects speed up or change direction?
They create ripples disturbing spacetime.
- Like ripples our boat's creating on the surface of the swamp.
And if you're talking about really big things
like a star exploding or two galaxies colliding,
they create ripples big enough that we can actually detect them.
The ripples are called gravitational waves
and these waves offer incredibly valuable insights into
how our universe works.
Gravitational wave observatories can show us lots of things
that telescopes can't.
They offer a chance to study the biggest events
in our universe's history, and could explain everything
from how we got here to whether our best theories of physics
are actually correct.
Because as much as conventional telescopes can show us
from other galaxies to starlight bending around black holes,
which is really really cool,
they can't show us the dark parts of the universe.
Gravitational waves, on the other hand, can show us everything.
The only issue is that they're incredibly hard to detect.
They're hard to even understand.
- What really blows my mind about gravitational waves
is that it's the fabric of spacetime itself that's moving
and that's a really amazing,
but also a little bit of an uncomfortable thing to be thinking about.
These shifts are imperceptible to human beings
but they're happening all the time.
Until now, no instrument has ever been capable
of measuring gravitational waves.
In fact, Einstein thought it was impossible.
But that's exactly what LIGO does.
- Now let's just hope that the battery of this holds us
all the way till we get back.
Beautiful drive though, isn't it?
Here's how LIGO monitors for ripples in spacetime.
A gravitational wave squeezes and
stretches spacetime in a specific way.
So when one passes through this observatory,
one leg gets shorter while the other gets longer.
The change in length is really small.
Ten thousand times smaller than the
nucleus of a hydrogen atom.
But this is one of the most precise instruments on Earth.
- And you have to look in through that.
LIGO made history in 2015
when it detected two black holes merging
more than a billion light years away.
- The very first moment was seen
by someone in Europe, right?
Because it was like 4 a.m.
So that's who was awake.
And basically it was a computer scanning the data, essentially, right?
Because this was a possible gravitational wave.
But then you have a human set of eyes to look at it.
Since 2015, LIGO's detected several black hole collisions
as well as one collision between super dense objects
called neutron stars, but LIGO can only detect some gravitational waves
Its only able to hear very specific frequencies.
Other researchers are looking to study the gravitational waves
that LIGO can't hear -
whether it's because they never pass through the detector
or because the frequencies are too low.
- There wasn't always light in the universe.
If you want to study things that happened immediately
after the Big Bang, there was no light at that time.
But at the time we still did have gravity.
And it's possible to even detect gravitational waves
from the Big Bang with these gravitational wave experiments.
Chiara Mingarelli is an astrophysicist
and member of NANOGrav–
a consortium of scientists from around the US.
Along with their peers from Europe and Australia,
they're using a network of radio telescopes
to effectively create a gravitational wave detector
the size of our galaxy.
- It's so cool. Is it slippery?
This is Green Bank Telescope.
It captures radio waves from space
and it's a pretty important local landmark
because if you're anywhere near it,
you can't use your cell phone,
since it could screw up the observations.
For the past decade, researchers have been using
the telescope to observe spinning stars known as pulsars
that release bursts of radio waves.
These signals arrive with amazing consistency.
When a gravitational wave ripples through Earth,
it squeezes and stretches spacetime
making some signals ride faster than expected
and delaying others.
Gravitational wave researchers have been timing
dozens of pulsars across our galaxy since 2004
and looking for patterns that show gravitational waves
are passing through.
- A lot of light can obscure what's going on in the center of a galaxy.
But gravitational waves,
if you have a supermassive black hole merging with another one
at the center of a galaxy,
those gravitational waves don't care if there's stars
in the way or gas or dust because it's the
fabric of spacetime itself that's moving.
That means detecting gravitational waves
is sort of like seeing in the dark.
LIGO listens primarily for black holes around
ten times the mass of our sun crashing into each other,
which create waves that pass through us incredibly quickly.
Astronomers looking at pulsars are searching
for something very different.
- So when we first start to see it,
it probably won't even be very visible to the eye.
They're trying to hear the sum of all the gravitational waves
over the history of the universe.
They call it the Gravitational Wave Background.
They're also listening for supermassive black holes
at the center of galaxies crashing into each other.
These waves might take years to pass by,
meaning it could take decades of data
to be sure we've detected them.
- When we first started, about 10 years ago,
it seems like kind of a pipe dream, you know,
like it was a good idea. It was fun.
But it seemed like kind of way out there, you know.
And now it feels like we're on the brink of
just an entirely new field of astronomy
and physics and it's just so exciting to be part of that.
These experiments are just the beginning.
More countries are building detectors like LIGO
to join in an international effort to locate black hole
or neutron star collisions in the sky.
The European Space Agency is also planning
to launch an observatory into space in 2034.
It should work similarly to LIGO,
but with mirrors separated by millions of kilometers.
By eliminating background noise,
it should be more precise than any
gravitational wave observatory could be on Earth.
Now that we've detected gravitational waves,
the question isn't whether they exist,
but what they can teach us about outer space.
Observing them is like adding sound to a movie
that's always been silent.
They're a way to observe the invisible phenomena
that shape the cosmos,
complementing what we can see to help us finally
understand the universe.
- You think "Oh my god, what if it gets to a point
where it's not special effects and we actually
can see black holes actually colliding?"
What happens if we actually get to see two neutron stars
going in and spiral and actually exploding?
What if we get to see a supernova?
Because really that's like the gold standard for us.
These are like things we could actually be like in our future.