- These black stones are volcanic rock, and this is one of the youngest patches of land on planet Earth, but that same geological event that built this land has provided another window that allows us to observe a time when the universe was still cooling from the fire of its own formation.

And to see this, all we have to do is travel to a telescope on top of the tallest volcano in the world.

(ambient electronic music) So we're driving up to the summit of Mauna Kea on the Big Island of Hawaii.

This is the tallest volcano on the planet at 4,200 meters.

The oxygen up here is 60% sea level.

But astronomers deal with it because it is the premier astronomical observing site in the Northern Hemisphere.

To Hawaiians it is a sacred site.

And to astronomers, it's where the Earth meets the universe.

(ambient instrumental music) Wow!

It's amazing up here.

It's like being on another planet.

I can already feel the effect of the thinner atmosphere.

My natural impulse, bizarrely, is to hold my breath.

Must remember to keep breathing.

Here we have 13 of the greatest telescopes in the world, operated by 11 different countries.

We have the Japanese Subaru Telescope, the twin Keck domes.

Over here we have the Canada-France-Hawaii Telescope.

And this is Gemini.

That's where we're going.

We're here to talk about a very special observation.

In the spring of 2017, astronomers turned Gemini's great mirror towards the constellation of Bootes, the plowman.

They were looking for a faint speck of light that had been noticed in one of our great surveys of the sky.

Astronomers guessed the speck was a quasar, a vortex of radiant matter falling into a giant black hole.

(dramatic ambient music) Now, quasars are the most luminous objects in the universe.

What was strange about this one was its distance.

Its light was so red that astronomers realized that that light must have been stretched out, redshifted, by traveling many billions of years through our expanding universe.

The quasar appeared to be more distant than any we had ever seen, but that doesn't mean we can't unravel their mysteries.

And Gemini did exactly that.

To find out how, we're gonna need to go inside.

You've got to see this.

It's incredible.

Meet the Gemini telescope.

This is what a world-class telescope looks like these days.

It is enormous.

I still remember the first time I came to a telescope like this.

It blew me away.

Look at the size of this thing.

This is our window to the universe.

It's cold in here.

They keep the dome at the temperature of the upcoming night so that the giant structure doesn't warp and twist with the change in temperature.

That's a little below freezing right now.

And you hear that sound?

That's the cryogenics.

They keep the sensitive infrared cameras at 15 above absolute zero.

Let's actually talk about light for a second.

Light is a wave, and the wavelength of that wave determines the properties of light.

For example, visible light, the wavelength range that our eyes are sensitive to, spans only a tiny fraction of the spectrum.

That's why we create telescopes.

The universe looks very, very different at different wavelengths.

For example, viewed in visible light, the Andromeda Galaxy shows us newborn stars.

Our atmosphere is transparent to visible light, so a ground-based telescope can see a visible universe, as can we.

Gemini is built to be sensitive to the infrared.

The infrared Andromeda is a swirl of star-forming clouds and gas.

Some infrared light also makes it through the atmosphere, though it helps to be up here on a mountaintop.

Although the air above the observatory is crystal clear, it still blurs distant light somewhat.

Turbulence in the atmosphere causes incoming wavefronts of light to be warped, and it blurs our view.

To correct this, Gemini uses adaptive optics.

It has a deformable mirror that flexes and bends to match and correct the warping of incoming light.

To do this in real-time, Gemini creates its own artificial guide star by shooting lasers to twinkle off sodium atoms at 90 kilometers height, right off the edge of space.

(ambient electronic music) This is the instrument used to analyze the most distant quasar.

It's the Gemini North Infrared Spectrograph, GNIRS.

A spectrograph takes incoming light and breaks it into its component wavelengths similar to a prism, and it records how much energy is received at each wavelength.

We call that a spectrum.

When the light analyzed by this machine left its quasar it was ultraviolet.

But traveling through the expanding universe sapped energy and stretched the wavelength of that light so that it was infrared by the time it reached the Earth and this spectrograph.

Their redshift tells us how long that light has been traveling, 13.1 billion years, meaning the quasar lived when the universe was only five percent its current age.

There's a broad blank patch in the quasar spectrum.

It's a stretch of nothing that tells us a ton.

Shortly after the Big Bang, when things had cooled down a bit, the universe was filled with hydrogen gas.

It was murky, especially for ultraviolet lights.

Now, that gas collapsed into the very first stars, then the very first galaxies.

Those stars eventually melted away the remaining hydrogen in a process called reionization, leaving a crystal clear universe.

But this quasar shines out from the era of those first stars before they'd finished the job of reionization.

Much of the quasar's once ultraviolet light was sucked up before it escaped the older universe.

And what about the supermassive black hole at the center of the quasar?

The same signature wavelengths used to measure redshift are also broadened due to the extreme speeds of matter moving near the black hole.

That allows us to estimate the mass of the black hole, 800 million Suns.

If it replaced our Sun it would easily swallow Saturn's orbit.

Scientists struggled to figure out how it could grow to that insane size in a tiny fraction of the age of the universe.

We are expanding our understanding of physics to figure this one out.

That tiny speck is both a revelation and a mystery.

It literally shines a light on the earliest epochs of our universe, teaching us about our most fundamental origins.

But it also opens new questions, and our great telescopes, our portals to the universe past and present, will tackle those questions too, and ultimately bring us closer to understanding this mysterious, this magnificent space time.

Thanks to advances in our understanding of general relativity and some mind-blowing advances in technology, there are other ways humanity can see the universe beyond the electromagnetic spectrum that we observe with traditional telescopes.

We can now see ripples in the fabric of space time itself.

Look out for Physics Girl's exploration of gravitational waves at LIGO.