Capturing a Black Hole: Honma Mareki / Astronomer/Professor, National Astronomical Observatory of Japan

"Direct Talk"

Our guest today is Professor Honma Mareki,

an astronomer at Japan's national observatory.

In 2019,

an international team of 200-plus scholars

that includes Honma made a landmark scientific discovery.

They announced that they had captured

the first images of a black hole in human history.

In 2022,

they announced they had succeeded a second time.

This time, it was the black hole at the center of our galaxy,

the Milky Way.

It was once thought that seeing a black hole was impossible.

Now, our understanding is changing.

We asked Professor Honma,

a key member of this international project,

about his team's work,

and what their achievements mean for humanity today.

A black hole is really the strangest astronomical body there is.

What's so amazing is, once it absorbs something, it can't escape.

Not even light.

Supermassive black holes

are millions or billions of times the mass of our Sun.

Just immense.

Black holes are so mysterious.

That's what makes them so interesting!

The city of Oshu in Iwate Prefecture

is home to the Mizusawa VLBI Observatory,

a national astronomy facility.

Honma is the observatory's director.

He's been studying black holes for many years now.

The existence of black holes

was first postulated in 1915 by Albert Einstein,

as part of his general theory of relativity.

Einstein's theory states that any object with mass

distorts the spacetime around it

and that this distortion is what we call gravity.

We can therefore assume that if an object is dense enough,

it will possess enough gravity to distort spacetime infinitely.

Even light will be sucked in.

Such an object would be a "black hole."

But a century after Einstein's theory,

no one had succeeded in visually verifying the existence of a black hole.

Astronomers thought a black hole

might look something like the depiction in this video

and they were desperate to find one.

By definition a black hole is completely dark,

and therefore almost impossible to observe.

And they're extremely far away from us,

maybe thousands of light years away, maybe even billions.

So to our eyes, they're really small.

Smaller than the head of a pin.

Seeing one presented such a huge challenge.

But in April 2019,

Honma and his colleagues made astronomical history.

This is a black hole,

seen for the first time by humanity.

This black hole was approximately 55 million light years from Earth,

at the center of Galaxy M87.

Hundred years after Einstein's theory,

we have proof that black holes exist.

This is an extremely important finding.

Black holes are virtually invisible.

Just how did Honma and the rest of the project team

manage to capture their images?

Even as a child, Honma loved gazing at the stars in the night sky.

He earned admittance to the prestigious University of Tokyo.

At this time, his focus wasn't on astronomy

but in fact, the college orchestra.

I didn't really study too hard in college.

I put the orchestra first. My studies came second.

Even to this day, I still love music.

If I could have made a living doing music,

I'd rather be doing that than astronomy, to be honest.

But that wasn't my fate.

Honma eventually gave up on becoming a musician,

and by his third year of university, he was an astronomy major.

Rather than doing research that would make a difference today,

I longed to do some sort of grand project

that would solve the mysteries of the universe.

I drew on that same passion I had as a child looking up at the stars,

at the universe.

Honma continued on to graduate school,

where he became interested in "radio astronomy."

It involves observing the universe not with light,

but with radio waves.

The light emitted by celestial bodies is distorted

by dust and gas floating in space,

but the same is not true of radio waves.

This means radio telescopes can peer deeper into the cosmos.

Radio telescopes observe radio waves from celestial bodies

and record these waves as data.

Then, we analyze it.

The initial data is just massive sequences of numbers,

so it's not easy to process.

But it allows us to do highly detailed, complex analysis.

What makes radio astronomy special

is this ability to see things we can't with the naked eye.

You're seeing things you can't with an optical telescope.

In 1999,

Honma did his first project with the National Astronomical Observatory of Japan.

It involved the mapping of the Milky Way, the galaxy we call home.

The resolution of a radio telescope is proportional to the diameter of its antenna.

The resolution can be improved by combining multiple telescopes.

The farther apart the telescopes are, the better.

Honma synthesized data from the telescope

at his homebase in Mizusawa with three others.

In effect,

he created one giant telescope with a diameter of 2,300 kilometers,

spanning the length of Japan.

The massive scope and difficulty of the project posed a great challenge to Honma.

The project involved incredibly precise measurement of stars' positions.

Think about a protractor, it's divided by degrees.

We were measuring the position of stars on a "protractor"

with 400 million divisions.

We didn't have the answer in front of us.

Was the measurement correct? It was up to us to confirm.

We constructed this big telescope,

but it was so painstaking to figure out

if our measurements were actually right.

In 2007,

Honma and his team measured the precise distance

of an object 17,250 light years away.

At the time, this was a world record.

No one had observed a more distant object within the Milky Way.

On the heels of this success,

Honma was drawn into the hunt for black holes

by an interesting paper he read.

Some scientists published a paper

saying they had used radio waves to observe fine details of the black hole

at the center of the Milky Way.

This was autumn 2008.

Using three telescopes in the US,

they measured the size of this black hole.

It seemed like in five or ten years,

we would actually be able to see this black hole.

We didn't want to let research teams outside Japan

do this fascinating work without us.

So we asked if we could collaborate with them on that work.

When we announced we were working together,

some European scientists said they were working on it too,

almost immediately afterwards.

I think America and Japan teaming up spurred scientists in other countries

to get involved.

The project became quite an international effort.

In 2009, with Honma's encouragement,

a new project was launched,

comprising more than 200 scientists from 13 research institutions around the globe.

This group was named the Event Horizon Telescope Collaboration.

The first object they would try to observe

was the black hole at the center of Galaxy M87,

55 million light years away.

Although distant,

it was believed to be one of the biggest black holes in the universe,

with a mass 3 billion times that of our Sun.

Theoretically, it would be relatively easy to see.

Eight radio telescopes in six locations, all connected,

forming one giant telescope with a diameter exceeding 10,000 kilometers.

A telescope as big as the Earth itself.

It could view space with 3 million times the power of the human eye.

From Earth, the resolution was sharp enough to see a golf ball on the Moon.

But even so, how would they manage to see a virtually invisible black hole?

It's completely impossible to see a black hole directly,

so we would have to capture its shadow.

The gas swirling around a black hole is very, very hot,

hundreds of millions of degrees Celsius.

This high-temperature gas emits radio waves, which fly around the black hole.

So, you look for a black hole,

with all this gas and light swirling around it,

and then capture the shadow that's there in the middle.

Even before the observation of the black hole could begin,

the project took about eight years of preparation.

It was difficult to coordinate between scientists from different countries,

and the project required the construction of entirely new telescopes.

It was a succession of failures.

In research, you always fail nine times out of ten.

But you try to learn something from those failures.

What gave us the motivation to keep moving forward is our love of the cosmos.

And black holes themselves are such fascinating phenomena

that we simply have to understand them.

In April 2017, observation of the black hole could finally begin.

This observation was done over four days

at the six different telescope locations around the world.

Then, a year was spent checking and synthesizing the data from each telescope,

and preparing for a visual analysis.

In June 2018, the researchers received the fully analyzed data,

and the team in Japan used software developed by Honma and his colleagues,

in order to turn this data into images.

There it is! You can really see it!

Well done, everyone! That's astonishing.

A black hole might be impossible to see, but its outline isn't.

The team had succeeded.

I mean, it was a wonderful moment.

Seeing that ring with my own eyes.

It was the moment I'd been waiting and preparing for, for ten years.

And there it was.

I think some people go their entire lives

without experiencing an incredible, moving moment like that.

Other research teams on the project

generated their own images of the black hole

and they looked almost identical.

Basically, we used three different types of software.

Different teams, different methods.

But all three came up with the same answer.

That same ring shape appeared for all of us.

That's science, I think.

No matter who or how you get there,

you end up with the same objective result.

Honma had observed a black hole.

A groundbreaking feat.

What significance does his research have for us today?

There's one view that at the beginning of the universe,

the seeds of black holes formed,

and then these black holes formed the basis of our galaxies.

Some scientists believe that.

If that hypothesis is correct, galaxies form within the universe,

and stars form within galaxies, and those stars give rise to life.

Black holes are key players to life itself.

Our research on black holes probably doesn't have much use for people today.

Because it's fundamental research about the far reaches of the universe.

But fundamental research is very important.

In fact, almost all the science and technology in our daily lives

is ultimately based on different applications of various kinds of fundamental research.

I think the potential for black hole research to benefit humanity in,

say, 100 years, is considerable.

(Do you have any words to live by?)

"In the heavens, you see Earth's value and humanity's way."

As astronomers, we look to the heavens and do all kinds of research on space.

The Earth's value is how precious our planet is.

If we look at the universe, we understand that.

And humanity's way is the future of the human race.

I hope that our observations of the universe

can help show us the right path forward.