Part 4 of the TED Radio Hour episode Peering Into Space.
About Jedidah Isler's TED Talk
Scientists believe at the center of every galaxy is a supermassive black hole. Jedidah Isler describes how gamma ray telescopes have expanded our knowledge of this mysterious aspect of space.
About Jedidah Isler
Jedidah Isler is an astrophysicist whose research focuses on hyperactive supermassive black holes, particularly the physics of blazar jets — one of the most powerful forms of particle acceleration in the universe.
She is currently a National Science Foundation Astronomy & Astrophysics Postdoctoral Fellow at Vanderbilt University. In 2014, she became the first African-American woman to receive a PhD in Astrophysics from Yale.
Isler is also the creator and host of "Vanguard: Conversations with Women of Color in STEM," and is a major advocate of inclusive STEM education.
GUY RAZ, HOST:
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: And as Natasha Hurley-Walker pointed out just a few minutes ago in her TED Talk, not all black holes are alike - for example, supermassive black holes.
ISLER: Yes, yes, exactly. So a supermassive black hole is a black hole that is a million to a billion times the mass of our own sun. So we're really talking about the largest black holes that can be measured.
RAZ: And Jedidah happens to study supermassive hyperactive black holes, which she explains from the TED stage.
(SOUNDBITE OF TED TALK)
ISLER: These galactic black holes are devouring material at a rate of upwards of a thousand times more than your average supermassive black hole.
ISLER: These two characteristics, with a few others, make them quasars. The objects I studied are producing some of the most powerful particle streams ever observed. These narrow streams, called jets, are moving at 99.99 percent of the speed of light and are pointed directly at the Earth. These jetted, Earth-pointed hyperactive and supermassive black holes are called blazars, or blazing quasars.
What makes blazars so special is that they're some of the universe's most efficient particle accelerators, transporting incredible amounts of energy throughout a galaxy. The dinner plate by which material falls onto the black hole is called the accretion disc. Some of that material is slingshotted around the black hole and accelerated to insanely high speeds in the jet. Although the blazar system is rare, the process by which nature pulls that material via a disc and then flings some of it out via a jet is more common.
(SOUNDBITE OF MUSIC)
RAZ: OK, so you have these massive black holes devouring all of this stuff, right?
ISLER: Mmm hmm.
RAZ: And they've got these really powerful jets moving out at, like, 99 percent of the speed of light, and they're just pushing energy back out into the universe.
RAZ: And you said these are pointed directly at Earth.
RAZ: OK, so let me just understand this. Does this mean that at some point, we here on Earth are going to be swallowed by these quasars?
ISLER: Well, no. We're at a safe distance, so we won't be swallowed by them. But we do receive light that comes from them.
ISLER: Yeah. So the thing that allows us to observe them the way that we do is that they are - they just happen to be aligned towards the Earth line of sight, but because they are very far away - we call that cosmological distance - they're not going to impact us.
RAZ: Phew. I was worried.
(SOUNDBITE OF TED TALK)
ISLER: One of the hot topics in blazar astrophysics right now is where the highest-energy jet emission comes from. Clear answers to this question were almost completely inaccessible until 2008 when NASA launched a new telescope that better detects gamma ray light. That is light with energies a million times higher than your standard X-ray scan. I simultaneously compare variations between the gamma ray light data and the visible light data from day to day and year to year to better localize these gamma ray blobs. As we more confidently localize where these gamma ray blobs are forming, we can better understand how jets are being accelerated and ultimately reveal the dynamic processes by which some of the most fascinating objects in our universe are formed.
RAZ: So you mentioned that everything changed in 2008 because NASA launched a new satellite that year, which was - I think that was Fermi, right?
RAZ: So that was a thing that really revolutionized your field.
ISLER: That's right.
RAZ: How? What happened?
ISLER: So blazars - I mean, we've known about them for decades. We've known that they have these jets. We've known that most of the light that comes from blazars comes at high energies, comes at gamma ray energies. So we launched Fermi, and the reason why that has been revolutionary for our field is because it means that you constantly have a measure of how many gamma rays, and that means the things that are spinning at the most energetic things we can see, you get a sense of what those are.
RAZ: Like, how much has that expanded our knowledge of how many quasars or blazars are out there?
ISLER: You know, we colloquially call Fermi a blazar finder. It literally has, like, found so many blazars that I think, at last count, we were upwards of 3,000.
RAZ: That's in 10 years, less than 10 years.
ISLER: I would say we went from hundreds to thousands.
RAZ: Wow. And there are, of course, black holes in our very own galaxy, right?
ISLER: Yes. So it depends on the mass of the black hole you're talking about. So we have our own supermassive black hole, which we call Sagittarius A*. It's at the center of our galaxy.
RAZ: Right - of course, right at the center of our galaxy is a supermassive black hole.
ISLER: That's right.
RAZ: And at the center of every other galaxy as well, right?
ISLER: We think as a community that the answer is that yes, absolutely there is a supermassive black hole at the center of every galaxy. And, in fact, what we thought at first was that only the most-massive galaxies would have these supermassive black holes. But what we found as we've been able to look at smaller and smaller and smaller galaxies is that they actually have supermassive black holes at the center of their galaxies too.
RAZ: I mean, we think about things in terms of the solar system, right? That's our neighborhood in our galaxy. And we spin around the Sun, and the Sun is the center of our solar system. But actually, black holes are really the center of everything.
ISLER: Yes. Yes. So if you looked at a picture let's say of Andromeda, which is our neighboring galaxy, it looks like a little spiral. And at the very center of that spiral is the supermassive black hole. And in principle, we call it the gravitational center. That's where the most mass of the system sits since everything is spinning. So the black hole is spinning on its axis, and the galaxy is spinning around the black hole. Everything has energy to keep it where it is. And it's only the things that get close enough that the black hole can basically erode (laughter) some of the energy that it has that it is able to fall in.
RAZ: So if you had kind of a suit, like a space suit that would protect you - because I know you would die - But let's say you could, you had this really awesome spacesuit. It's air-conditioned and you have like, you know, movies in there and a popcorn machine. It's like one of those first-class seats, you know, like a transatlantic flight. You know, what would happen, like you get sucked in? And is it like Matthew McConaughey in the movie where he like - you could just pick which direction?
ISLER: Oh, my goodness. It's so funny because like "Interstellar" is legit like my favorite science movie.
RAZ: Oh, really?
ISLER: Like, I am a nerd and, like, I legit shed a tear. I was like, oh, it's so beautiful (laughter).
RAZ: Even though you knew it was all BS?
ISLER: It didn't matter.
RAZ: It didn't matter, right? 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?
ISLER: That same effect is magnified in a galaxy-size way.
RAZ: You'd just be squashed.
ISLER: You - 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? You're travelling in that black hole and, like, does it stop?
ISLER: You know, this is the place where physics and philosophy have to break, 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 go for it, right?
ISLER: Oh, in a minute. And then I'd like take out my iPhone and I'd record the whole thing. And I'd be like, see, I told y'all.
(SOUNDBITE OF MUSIC)
RAZ: Astrophysicist Jedidah Isler. You can see her entire talk at ted.com.
(SOUNDBITE OF SONG, "GALAXY SONG")
MONTY PYTHON: (Singing) Our galaxy itself contains a hundred billion stars. It's a hundred thousand 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 around 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 ted.npr.org. To see hundreds more TED Talks, check out ted.com or the TED app. Our production staff here at NPR includes Jeff Rogers, Sanaz Meshkinpour, Jinae West, Neva Grant, Rund Abdelfatah, Casey Herman and Rachel Faulkner with help from Daniel Shukin and Benjamin Klempay. Our intern is Deba Motasham (ph).
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 firstname.lastname@example.org. 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. Transcript provided by NPR, Copyright NPR.