Inside the black hole image that made history | Sheperd Doeleman

Summary

In this fascinating discussion, Sheperd Doeleman explains the journey from Einstein's theory of gravity to capturing the first-ever image of a black hole. Using a global network of telescopes synchronized with atomic clocks, the team at the Event Horizon Telescope observed the supermassive black hole in galaxy M87, revealing the event horizon and the bending of space-time around it.

Takeaways

• 🌌 Einstein's theory of gravity, which describes how matter deforms space-time, is foundational to understanding black holes.
• 🌀 A black hole is a region in space where gravity is so strong that not even light can escape, essentially a 'puncture' in space-time.
• 🌞 The Earth's orbit around the Sun is due to the Sun's mass deforming space-time, not a direct pull.
• 🔍 Black holes can be detected by their gravitational effects and the light they bend around them, as seen in simulations.
• 🌌 The galaxy M87, located 55 million light-years away, contains a supermassive black hole with a mass equivalent to 6.5 billion suns.
• 📸 To image a black hole, scientists used a network of telescopes around the world, effectively creating an Earth-sized telescope.
• 🌐 The image of the black hole in M87 was made possible by synchronizing telescopes with atomic clocks and stitching data together.
• 🌟 The ring of light seen in the black hole image is the orbit of photons, where they move around the black hole due to its gravitational pull.
• 🚀 The first-ever image of a black hole was a significant scientific achievement, revealing the structure of space-time as predicted by Einstein.
• 🌐 The black hole in our own galaxy, the Milky Way, is also being studied, with data already collected and analysis underway.

Q & A

What did Einstein's geometric theory of gravity propose about the relationship between matter and space-time?

Einstein's geometric theory of gravity proposed that matter deforms space-time, and in turn, space-time tells matter how to move. When enough matter is concentrated into a small region, it can puncture space-time, creating a black hole from which even light cannot escape.

How does Einstein's theory explain the Earth's movement around the Sun?

According to Einstein's theory, the Sun changes the shape of space-time around it, causing the Earth to follow a curved path. This is why the Earth moves around the Sun; it is not directly pulled by the Sun, but rather follows the curved geometry of space-time.

What are black holes, and how are they formed according to the script?

Black holes are regions in space where the concentration of mass is so intense that it punctures space-time, preventing even light from escaping. They are formed when a large amount of matter is packed into a small enough space, causing the gravitational pull to become infinitely strong.

What is significant about the galaxy M87 mentioned in the script?

The galaxy M87 is significant because it contains a supermassive black hole at its center, with a mass of six-and-a-half billion solar masses. This black hole was the target for capturing the first-ever image of a black hole, and it is located 55 million light-years away from Earth.

Why is it challenging to capture an image of a black hole, and how was it achieved?

Capturing an image of a black hole is challenging due to their small size and the immense distance from Earth. To achieve this, a global network of synchronized telescopes was used, creating a virtual Earth-sized telescope. This method, known as Very Long Baseline Interferometry (VLBI), allows astronomers to gather data and synthesize an image with incredible resolution.

How was data collected for the black hole image, and why couldn't it be sent over the internet?

The data was collected using telescopes around the world, synchronized with atomic clocks. Each telescope recorded massive amounts of data, equivalent to half a petabyte, which was physically transported via hard drives. This was necessary because the bandwidth required to send such a large amount of data over the internet was impractical.

What does the first image of a black hole show, and why is it significant?

The first image of a black hole shows the shadow of the black hole surrounded by a bright ring of light, representing the event horizon where photons orbit. This image is significant because it visually confirms Einstein's predictions about the geometry of space-time around a black hole and provides the first direct visual evidence of black holes.

Why is part of the black hole image brighter, and what causes this effect?

The brighter part of the black hole image is due to the Doppler effect. As the black hole spins, some gas moves towards Earth, while some recedes. The gas moving towards us appears brighter because the light is Doppler-boosted, similar to how a train whistle has a higher pitch when approaching.

How does the size of the black hole's event horizon compare to our solar system?

The size of the black hole's event horizon is large enough to fit our entire solar system within it. This dark region signifies the event horizon, where light cannot escape, indicating the immense gravitational pull of the black hole.

What role did collaboration play in capturing the first image of a black hole?

Collaboration was crucial in capturing the first image of a black hole. The project involved a global team of over 200 scientists from 60 institutes and 20 countries, working together to synchronize telescopes worldwide. This collaborative effort demonstrates the power of international cooperation in advancing scientific discovery.

Outlines

00:00

🌌 Understanding Black Holes from Einstein's Theory

In this paragraph, Chris Anderson interviews Sheperd Doeleman about the journey from Einstein's theory of gravity to the concept of a black hole. Doeleman explains that Einstein's theory describes how matter deforms space-time, and when enough matter is concentrated in a small area, it creates a gravitational force so strong that not even light can escape. This deformation of space-time is what causes the Earth to orbit the Sun, not a direct pull. The discussion moves to the visualization of a black hole, where Doeleman describes the ring of light observed in simulations as the orbit of photons around the black hole, and the hot gas surrounding it due to friction as it is drawn into the black hole. Anderson and Doeleman also discuss the ambitious project of imaging a real black hole, focusing on galaxy M87, which contains a supermassive black hole 55 million light-years away.

05:03

📡 Capturing the First Image of a Black Hole

Sheperd Doeleman shares the process and challenges of capturing the first-ever image of a black hole. The team used a global network of telescopes, synchronized with atomic clocks, to collect data from the black hole in galaxy M87. The data, equivalent to about half a petabyte, was physically transported to a central location due to the limitations of internet bandwidth. The process involved aligning the data with atomic clock precision to create an Earth-sized lens, which allowed them to resolve the black hole at a distance of 55 million light-years. Doeleman describes the image as the last orbit of photons, a direct observation of Einstein's geometric theory of gravity. The image reveals the black hole's spin, which affects the brightness of different parts of the ring, and the size of the dark region, which could contain our entire solar system. The conversation also touches on the nature of black holes, including the concept of the event horizon and the potential for imaging the black hole at the center of our Milky Way galaxy.

10:05

🌐 The Global Collaboration Behind the Black Hole Image

In the final paragraph, Doeleman emphasizes the collaborative nature of the project that led to the historic black hole image. The team consisted of 200 people from 60 institutes across 20 countries and regions, highlighting the importance of a global effort in such a monumental scientific achievement. The technique used, which involved linking telescopes around the world, bypassed some of the geopolitical issues that typically divide nations, bringing scientists together for a common goal. The image of the black hole resonated globally, appearing in newspapers worldwide, and Doeleman hopes it serves as an inspiration to everyone. The interview concludes with a nod to the team's work on imaging the black hole at the center of the Milky Way, with data already collected and analysis underway.

Keywords

💡Einstein's Equation

Einstein's Equation, also known as the field equations of general relativity, describes how mass and energy influence the geometry of space-time, causing it to curve. In the context of the video, it is foundational to understanding how gravity works and how it can lead to the formation of black holes. The script mentions how Einstein's theory of gravity deforms space-time, which is crucial for the discussion of black holes.

💡Black Hole

A black hole is a region in space where the gravitational pull is so strong that nothing, not even light, can escape it. The video script discusses how black holes are formed when enough matter collapses into a small region, puncturing space-time. The script also describes the imaging of a black hole for the first time, emphasizing its significance in astrophysics.

💡Event Horizon

The event horizon is the boundary around a black hole beyond which no information or matter can escape. The script mentions the event horizon in relation to the black hole image, describing it as the dark region from which no light emerges due to the black hole's gravitational pull.

💡Space-Time

Space-time is a four-dimensional continuum that combines the three dimensions of space with the one dimension of time. It is a central concept in the theory of relativity. The script uses the term to explain how matter deforms space-time and how this deformation dictates the motion of celestial bodies, including the behavior around black holes.

💡Galaxy M87

Galaxy M87, mentioned in the script, is a supergiant elliptical galaxy located 55 million light-years from Earth. It is significant in the video because it is the location of the supermassive black hole that was imaged for the first time by the Event Horizon Telescope project, as described in the script.

💡Supermassive Black Hole

A supermassive black hole is a black hole with a mass of millions to billions of times that of the Sun. The script refers to the black hole at the center of galaxy M87 as a six-and-a-half-billion-solar-mass black hole, illustrating the immense scale of such cosmic phenomena.

💡Radio Waves

Radio waves are a type of electromagnetic radiation with longer wavelengths than those of visible light. The script mentions that black holes emit copious radio waves, which is why the Event Horizon Telescope used radio observations to capture the image of the black hole in M87.

💡Intergalactic Space

Intergalactic space refers to the vast regions of space between galaxies. The script discusses how light from the black hole in M87 had to travel through intergalactic space to reach Earth, highlighting the immense distances involved in astronomical observations.

💡Atmospheric Absorption

Atmospheric absorption is the process by which gases in a planet's atmosphere absorb certain wavelengths of electromagnetic radiation. The script notes that water vapor in Earth's atmosphere can absorb radio waves, which is a factor that must be considered in astronomical observations.

💡Global Telescope

A global telescope refers to a network of telescopes distributed around the world that work together to observe astronomical phenomena. The script describes how the Event Horizon Telescope project synchronized telescopes globally to create a virtual Earth-sized telescope to capture the image of the black hole.

💡Singularity

In the context of black holes, a singularity is the point at the center where matter is thought to be infinitely dense. The script mentions that what's inside a black hole is a singularity, where all the forces of nature become unified, but it is hidden from us.

Highlights

Einstein's theory of gravity deforms space-time, leading to the concept of black holes where gravity is so strong that not even light can escape.

The geometry of space-time dictates the movement of celestial bodies, such as Earth orbiting the Sun due to the space's deformation around the Sun.

Black holes can be visualized as punctures in space-time with a ring of light representing the orbit of photons around them.

The first image of a black hole was revealed, marking a significant achievement in astrophysics and technology.

The galaxy M87, located 55 million light-years away, was the focus of the black hole imaging mission.

The black hole at the center of M87 has a mass of 6.5 billion times that of our Sun, influencing the galaxy's energetics.

To capture an image of a black hole, a resolution equivalent to observing a grapefruit on the Moon from Earth was required.

The Event Horizon Telescope project synchronized telescopes worldwide to create an Earth-sized virtual telescope to capture the black hole's image.

Data from the black hole observations required careful alignment with atomic clock precision to recreate the image.

The imaging process involved a massive amount of data, equivalent to the lifetime selfie capacity of 5,000 people.

The black hole's image revealed the last orbit of photons and demonstrated Einstein's theory of relativity.

The black hole's spin causes the gas around it to move towards and away from us, affecting the brightness of the observed ring.

The size of the black hole's shadow could contain our entire solar system, with the dark region indicating the event horizon.

The black hole in our Milky Way galaxy is smaller but closer, presenting a similar angular size to the one in M87.

The Event Horizon Telescope team consists of 200 people from 60 institutes across 20 countries and regions, showcasing global scientific collaboration.

The successful imaging of a black hole has inspired people worldwide and demonstrates the power of international scientific cooperation.

The black hole's singularity, where all forces unify, remains a central mystery of our age, hidden by the universe's ultimate invisibility cloak.

Transcripts

Chris Anderson: Shep, thank you so much for coming.

I think your plane landed literally two hours ago in Vancouver.

Such a treat to have you.

So, talk us through how do you get from Einstein's equation to a black hole?

Sheperd Doeleman: Over 100 years ago,

Einstein came up with this geometric theory of gravity

which deforms space-time.

So, matter deforms space-time,

and then space-time tells matter in turn how to move around it.

And you can get enough matter into a small enough region

that it punctures space-time,

and that even light can't escape,

the force of gravity keeps even light inside.

CA: And so, before that, the reason the Earth moves around the Sun

is not because the Sun is pulling the Earth as we think,

but it's literally changed the shape of space

so that we just sort of fall around the Sun.

SD: Exactly, the geometry of space-time

tells the Earth how to move around the Sun.

You're almost seeing a black hole puncture through space-time,

and when it goes so deeply in,

then there's a point at which light orbits the black hole.

CA: And so that's, I guess, is what's happening here.

This is not an image,

this is a computer simulation of what we always thought,

like, the event horizon around the black hole.

SD: Until last week, we had no idea what a black hole really looked like.

The best we could do were simulations like this in supercomputers,

but even here you see this ring of light,

which is the orbit of photons.

That's where photons literally move around the black hole,

and around that is this hot gas that's drawn to the black hole,

and it's hot because of friction.

All this gas is trying to get into a very small volume, so it heats up.

CA: A few years ago, you embarked on this mission

to try and actually image one of these things.

And I guess you took --

you focused on this galaxy way out there.

Tell us about this galaxy.

SD: This is the galaxy --

we're going to zoom into the galaxy M87, it's 55 million light-years away.

CA: Fifty-five million.

SD: Which is a long way.

And at its heart,

there's a six-and-a-half-billion- solar-mass black hole.

That's hard for us to really fathom, right?

Six and a half billion suns compressed into a single point.

And it's governing some of the energetics of the center of this galaxy.

CA: But even though that thing is so huge, because it's so far away,

to actually dream of getting an image of it,

that's incredibly hard.

The resolution would be incredible that you need.

SD: Black holes are the smallest objects in the known universe.

But they have these outsize effects on whole galaxies.

But to see one,

you would need to build a telescope as large as the Earth,

because the black hole that we're looking at

gives off copious radio waves.

It's emitting all the time.

CA: And that's exactly what you did.

SD: Exactly. What you're seeing here

is we used telescopes all around the world,

we synchronized them perfectly with atomic clocks,

so they received the light waves from this black hole,

and then we stitched all of that data together to make an image.

CA: To do that

the weather had to be right

in all of those locations at the same time,

so you could actually get a clear view.

SD: We had to get lucky in a lot of different ways.

And sometimes, it's better to be lucky than good.

In this case, we were both, I like to think.

But light had to come from the black hole.

It had to come through intergalactic space,

through the Earth's atmosphere, where water vapor can absorb it,

and everything worked out perfectly,

the size of the Earth at that wavelength of light,

one millimeter wavelength,

was just right to resolve that black hole, 55 million light-years away.

The universe was telling us what to do.

CA: So you started capturing huge amounts of data.

I think this is like half the data from just one telescope.

SD: Yeah, this is one of the members of our team, Lindy Blackburn,

and he's sitting with half the data

recorded at the Large Millimeter Telescope,

which is atop a 15,000-foot mountain in Mexico.

And what he's holding there is about half a petabyte.

Which, to put it in terms that we might understand,

it's about 5,000 people's lifetime selfie budget.

(Laughter)

CA: It's a lot of data.

So this was all shipped, you couldn't send this over the internet.

All this data was shipped to one place

and the massive computer effort began to try and analyze it.

And you didn't really know

what you were going to see coming out of this.

SD: The way this technique works that we used --

imagine taking an optical mirror and smashing it

and putting all the shards in different places.

The way a normal mirror works

is the light rays bounce off the surface, which is perfect,

and they focus in a certain point at the same time.

We take all these recordings,

and with atomic clock precision

we align them perfectly, later in a supercomputer.

And we recreate kind of an Earth-sized lens.

And the only way to do that is to bring the data back by plane.

You can't beat the bandwidth of a 747 filled with hard discs.

(Laughter)

CA: And so, I guess a few weeks or a few months ago,

on a computer screen somewhere,

this started to come into view.

This moment.

SD: Well, it took a long time.

CA: I mean, look at this.

That was it.

That was the first image.

(Applause)

So tell us what we're really looking at there.

SD: I still love it.

(Laughter)

So what you're seeing is that last orbit of photons.

You're seeing Einstein's geometry laid bare.

The puncture in space-time is so deep

that light moves around in orbit,

so that light behind the black hole, as I think we'll see soon,

moves around and comes to us on these parallel lines

at exactly that orbit.

It turns out, that orbit is the square root of 27

times just a handful of fundamental constants.

It's extraordinary when you think about it.

CA: When ...

In my head, initially, when I thought of black holes,

I'm thinking that is the event horizon,

there's lots of matter and light whirling around in that shape.

But it's actually more complicated than that.

Well, talk us through this animation, because it's light being lensed around it.

SD: You'll see here that some light from behind it gets lensed,

and some light does a loop-the-loop around the entire orbit of the black hole.

But when you get enough light

from all this hot gas swirling around the black hole,

then you wind up seeing all of these light rays

come together on this screen,

which is a stand-in for where you and I are.

And you see the definition of this ring begin to come into shape.

And that's what Einstein predicted over 100 years ago.

CA: Yeah, that is amazing.

So tell us more about what we're actually looking at here.

First of all, why is part of it brighter than the rest?

SD: So what's happening is that the black hole is spinning.

And you wind up with some of the gas moving towards us below

and receding from us on the top.

And just as the train whistle has a higher pitch

when it's coming towards you,

there's more energy from the gas coming towards us than going away from us.

You see the bottom part brighter

because the light is actually being boosted in our direction.

CA: And how physically big is that?

SD: Our entire solar system would fit well within that dark region.

And if I may,

that dark region is the signature of the event horizon.

The reason we don't see light from there,

is that the light that would come to us from that place

was swallowed by the event horizon.

So that -- that's it.

CA: And so when we think of a black hole,

you think of these huge rays jetting out of it,

which are pointed directly in our direction.

Why don't we see them?

SD: This is a very powerful black hole.

Not by universal standards, it's still powerful,

and from the north and south poles of this black hole

we think that jets are coming.

Now, we're too close to really see all the jet structure,

but it's the base of those jets that are illuminating the space-time.

And that's what's being bent around the black hole.

CA: And if you were in a spaceship whirling around that thing somehow,

how long would it take to actually go around it?

SD: First, I would give anything to be in that spaceship.

(Laughter)

Sign me up.

There’s something called the -- if I can get wonky for one moment --

the innermost stable circular orbit,

that's the innermost orbit at which matter can move around a black hole

before it spirals in.

And for this black hole, it's going to be between three days and about a month.

CA: It's so powerful, it's weirdly slow at one level.

I mean, you wouldn't even notice

falling into that event horizon if you were there.

SD: So you may have heard of "spaghettification,"

where you fall into a black hole

and the gravitational field on your feet is much stronger than on your head,

so you're ripped apart.

This black hole is so big

that you're not going to become a spaghetti noodle.

You're just going to drift right through that event horizon.

CA: So, it's like a giant tornado.

When Dorothy was whipped by a tornado, she ended up in Oz.

Where do you end up if you fall into a black hole?

(Laughter)

SD: Vancouver.

(Laughter)

CA: Oh, my God.

(Applause)

It's the red circle, that's terrifying.

No, really.

SD: Black holes really are the central mystery of our age,

because that's where the quantum world and the gravitational world come together.

What's inside is a singularity.

And that's where all the forces become unified,

because gravity finally is strong enough to compete with all the other forces.

But it's hidden from us,

the universe has cloaked it in the ultimate invisibility cloak.

So we don't know what happens in there.

CA: So there's a smaller one of these in our own galaxy.

Can we go back to our own beautiful galaxy?

This is the Milky Way, this is home.

And somewhere in the middle of that there's another one,

which you're trying to find as well.

SD: We already know it's there, and we've already taken data on it.

And we're working on those data right now.

So we hope to have something in the near future, I can't say when.

CA: It's way closer but also a lot smaller,

maybe the similar kind of size to what we saw?

SD: Right. So it turns out that the black hole in M87,

that we saw before,

is six and a half billion solar masses.

But it's so far away that it appears a certain size.

The black hole in the center of our galaxy is a thousand times less massive,

but also a thousand times closer.

So it looks the same angular size on the sky.

CA: Finally, I guess, a nod to a remarkable group of people.

Who are these guys?

SD: So these are only some of the team.

We marveled at the resonance that this image has had.

If you told me that it would be above the fold in all of these newspapers,

I'm not sure I would have believed you, but it was.

Because this is a great mystery,

and it's inspiring for us, and I hope it's inspiring to everyone.

But the more important thing is that this is just a small number of the team.

We're 200 people strong with 60 institutes

and 20 countries and regions.

If you want to build a global telescope you need a global team.

And this technique that we use of linking telescopes around the world

kind of effortlessly sidesteps some of the issues that divide us.

And as scientists, we naturally come together to do something like this.

CA: Wow, boy, that's inspiring for our whole team this week.

Shep, thank you so much for what you did and for coming here.

SD: Thank you.

(Applause)