Jedidah Isler: What Did It Take To Capture An Image Of A Black Hole? In April 2019, we saw the first image of a black hole ... ever. Astrophysicist Jedidah Isler explains how the team behind the Event Horizon Telescope achieved such a feat.

Jedidah Isler: What Did It Take To Capture An Image Of A Black Hole?

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On the show today - peering deeper into space. And we wanted to find out more about black holes like the ones Natasha was just describing in her TED Talk.

JEDIDAH ISLER: Yes. And I just have to be honest, I'm not sure that there are that many things that are as cool as a black hole. I'm just saying.

RAZ: This is Jedidah Isler. She's an astrophysicist who studies black holes.

ISLER: Yeah. It's amazing.

RAZ: ...Which Jedidah says are one of the most mysterious forces in the entire universe.

ISLER: For certain.

RAZ: So we all have some idea of what a black hole is - right? - these massive things that are formed by the death of a star, and then they suck everything in, even light. But it turns out it's a little more complicated than that.

ISLER: Yeah, it's one of those things that is both ubiquitous and also still widely misunderstood. So they are something that's so massive that there's - just nothing has enough energy to get out, not even light itself. That's what makes them unique, is that there they are a thing in the universe that doesn't shine, that doesn't give off any light at all, period. And that's why we call them black.

RAZ: And is it, like, a giant drainpipe?

ISLER: No. They're not just, like, sucking up everything all the way around indiscriminately. They're not vacuums in space.

RAZ: Oh, I mean, I still am imagining this incredibly powerful magnet-type vacuum that's just drawing everything around it for, you know, vast distances - just drawing it in.

ISLER: The easiest way that I can think of is to think about the fact that these black holes - they are spinning. And basically, everything in space is spinning. And so there is energy that's associated with that spin that keeps things from falling in. It's like you're sitting on a record spinning around, and as long as that record is going, then you're going to stay where you are.

RAZ: So there's a galaxy 55 million light-years away. It's called M87. And at its heart, there's a black hole the mass of six and a half billion suns.

ISLER: I'm just - I'm, like, legit over here cheesing (ph).

RAZ: This black hole is so far away, you would think it's impossible to see what it looks like.

ISLER: It's like seeing an orange on the surface of the moon.

RAZ: But this past year, we actually did. In April 2019, we saw the very first image ever of a black hole.

ISLER: Er (ph) my God. Like, I was so excited. It felt like I had been given a gift, like the universe had given me a gift. It was really, really amazing to see something so remarkable happen.

RAZ: More than 200 scientists and researchers, 60 institutes and 20 countries came together to capture the image, which you might remember was on the front page of almost every newspaper. Sheperd Doeleman, the project director of this massive team, was speaking on the TED stage just days after the image was released.


SHEPERD DOELEMAN: Until last week, we had no idea what a black hole really looked like. 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. We had to get lucky in a lot of different ways. Light had to come from the black hole. It had to come through the 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.


RAZ: Wow. So, Jedidah, you were there. You were at the TED conference, listening to this in the audience. Can you just explain a bit more about what made it possible to capture this image? Like, what were the breakthroughs that allowed us to actually see this thing?

ISLER: So there are a lot of breakthroughs that made it possible to get this image, and I don't want to give that short shrift at all, right? - because there were technological breakthroughs; that is to say in terms of just the image processing and the algorithms used to create simulations for which the actual image was compared. There were equipment breakthroughs in the sense that the sheer number of telescopes that were used - I think it was something like eight telescopes.

RAZ: Right.

ISLER: Those telescopes had never been stitched together in the way that they were in order to get this result. Being able to have these telescopes communicate with one another, there were many, many, many, many, many, many layers of innovation that were brought to bear for this to happen, which is part of the reason why it's so exciting - right? - is that...

RAZ: Yeah.

ISLER: The science result is amazing. But to think of all of the infrastructure and collaboration across the world - literally across the world that had to happen to make this work is really remarkable.

RAZ: Just I guess - because, obviously, we're on the radio, and it would just sound so much better coming from your voice than mine - can you kind of describe what this image looks like?

ISLER: Yes. Let's see. OK, so it looks like joy, but I'm not sure if that's going to translate well.

RAZ: (Laughter).

ISLER: So I will try to give you something else. So it's a black image with, in the center, sort of an orangey (ph), hazy - it kind of looks a little bit like the colors of a sunset. So you've got a circle with an absence of light in the middle, so it looks more dark or black again. But the ring of light that you see doesn't look completely symmetric; that is to say the same all the way around. We have measured more light on the lower half than on the top half but yet ultimately looks like a ring of light that is uneven around the circle with a absence of light in the center.


DOELEMAN: 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 is a higher pitch when it's coming towards you, there's more energy from the gas coming towards us than going away from us. But when you get enough light from all this hot gas swirling around the black hole, then you wind up seeing the definition of this ring begin to come into shape. And that's what Einstein predicted over a hundred years ago. Einstein came up with this geometric theory of gravity, which deformed spacetime. So matter deformed spacetime, and then spacetime tells matter, in turn, how to move around it. You're seeing Einstein's geometry laid bare. The puncture in spacetime is so deep that there's a point at which light orbits the black hole.


ISLER: I know that we say it a lot - but to keep in mind that this theory that Einstein came up with over a hundred years ago now still holds with our most precise measurements of a black hole ever using literally the whole world as a telescope. And we find that he's still right, right? So we shouldn't overlook how incredibly powerful that result is.

RAZ: I'm curious. Like, how does this imagery of black holes - how does it affect and change the research, you know, that's happening around black holes and around other incredible phenomenon in space?

ISLER: So now you can start looking at things like, well, what is the spin of black holes? - which is almost impossible to measure any other way. You can start to say something about spacetime curvature, and we can start to really dig into the details of general relativity now that you have this kind of detailed data. So, hopefully, these images will allow us to put some constraints. They won't give us the final answer. There's still a lot of work to do, but it'll start to give us a sense of if these observations are consistent.


RAZ: So if you could have a suit, like a space suit that would protect you - because I know you would die. But let's say you...

ISLER: (Laughter).

RAZ: ...Could use this really awesome space suit that was air conditioned, and you had, like, a - you know, movies in there and a popcorn machine - it was like one of those first-class seats, you know...

ISLER: Right.

RAZ: ...In, like, a transatlantic flight, you know, what would happen? Like, is it like Matthew McConaughey in the movie where, like, you can just pick which direction your path is?

ISLER: Oh, my goodness. And it's just so funny because, like, "Interstellar" is legit, like, my favorite science movie.

RAZ: Oh, really? (Laughter).

ISLER: Like, I am a nerd. And, like, I, like, legit shed a tear. I was like, oh, it's so beautiful.

RAZ: Even though you knew it was all B.S.

ISLER: It didn't matter.

RAZ: It didn't matter, right?

ISLER: It's beautiful.

RAZ: It's so cool. All right, so let's say you can just go into it like "Interstellar"-style. What would happen? What would you see around you?

ISLER: So, you know, what happens to you as you're approaching a black hole is among some of the most exotic physics out there because now you've got very strong gravity pulling on you. And, you know, when you're standing on the planet - right? - and you're - wherever you're standing right now, there's slightly more pulling on you from the top of your head to your feet just because of the way that gravity works, right?

RAZ: Yeah.

ISLER: That same effect is magnified in a galaxy-sized way.

RAZ: You would just be squashed.

ISLER: You would - it's sort of the other direction that, like - your head's not going towards a black hole as fast as your feet, and so you're sort of stretched out.

RAZ: My God.

ISLER: But, yeah, it would not be pleasant.

RAZ: But what if it could be pleasant and you had, like, snacks and you were safe from that? What - you're traveling in that black hole and - like, does it stop?

ISLER: You know, this is the place where physics and philosophy have to break.

RAZ: Yeah.

ISLER: Right? Once you get inside, we're in the philosophy. And I'm just not credentialed to do that, Guy.

RAZ: But if you could travel to a black hole, like, you would - you'd go for it, right?

ISLER: Oh, I'd - in a minute.

RAZ: Yeah.

ISLER: And then I'd, like, take out my iPhone. And I'd record the whole thing, and I'd be like, see.

RAZ: Yup.

ISLER: I told y'all.


RAZ: That's Jedidah Isler. She's a professor of physics and astronomy at Dartmouth College. She has two TED talks. You can see them both, along with Sheperd Doeleman's talk, at


ERIC IDLE: (Singing) Our galaxy itself contains 100 billion stars. It's 100,000 light-years side to side. It bulges in the middle, 16,000 light-years thick. But out by us, it's just 3,000 light-years wide. We're 30,000 light-years from galactic central point. We go round every 200 million years. And our galaxy is only one of millions of billions in this amazing and expanding universe.

RAZ: Hey. Thanks for listening to our show, peering deeper into space this week. If you want to find out more about who was on it, go to To see hundreds more TED Talks, check out or the TED app. Our production staff here at NPR includes Jeff Rogers, Sanaz Meshkinpour, Janae West, Neva Grant, Rund Abdelfatah, Casey Herman and Rachel Faulkner with help from Daniel Shukin and Benjamin Clempe (ph). Our intern is Diba Mohtasham. Our partners at TED are Chris Anderson, Colin Helms, Anna Phelan and Janet Lee. If you want to let us know what you think about the show, please go to Apple podcasts and write a review. You can also write us directly at And you can tweet us. It's @TEDradiohour. I'm Guy Raz, and you've been listening to ideas worth spreading right here on the TED Radio Hour from NPR.

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