The Curious Case Of The Supermassive Black Hole

This episode delves into the mysterious origins and nature of black holes, especially focusing on the recent discoveries regarding supermassive black holes.

1. Black holes were initially predicted through mathematical equations before being observed.
2. Supermassive black holes differ significantly from smaller ones, challenging previous theories of their origin.
3. A new theory suggests supermassive black holes can start from a massive seed formed by a collapsing gas cloud in early galaxies.
4. Recent observations by the James Webb Space Telescope have confirmed this new theory.
5. The study of black holes is crucial for understanding the structure and evolution of the universe.

1: Introduction to Black Holes

Priya Natarajan outlines the various types of black holes and their defining characteristics, particularly focusing on the event horizon and singularity. Emily Kwong: "What exactly defines a black hole's boundary?" Priya Natarajan: "The event horizon is the critical boundary marking the black hole's point of no return."

2: Theoretical Background and Discoveries

The historical context of black hole theories is discussed, including Einstein's contributions and subsequent confirmations. Priya Natarajan: "Einstein's equations predicted black holes long before we observed them."

3: Supermassive Black Holes

The new theory of supermassive black hole formation is explained, contrasted with the traditional views tied to star deaths. Priya Natarajan: "Supermassive black holes may start from a massive, fast-collapsing gas cloud."

4: Implications of Recent Discoveries

Discussion on how recent findings from space telescopes have confirmed new theories and what this means for astronomy. Priya Natarajan: "The confirmation of these theories by James Webb has been exhilarating."

1. Stay Curious: Keep up with the latest astronomical discoveries to expand your understanding of the universe.
2. Educate Others: Share insights about black holes and their significance in cosmic structures with peers.
3. Support Science Education: Advocate for and support science programs that promote space exploration and astronomy.
4. Engage with Astronomy Clubs: Join local or online astronomy clubs to discuss and learn more about phenomena like black holes.
5. Follow Space Missions: Stay updated on missions and telescopes like James Webb for real-time discoveries.

Black holes are one of the most mysterious cosmological phenomena out there. Astrophysicist Priya Natarajan calls them "the point where all known laws of physics break down."

On the list of perplexing qualities: The origins of supermassive black holes. That story was only confirmed within the last year.

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Priya Natarajan, Emily Kwong

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Emily Kwong
You're listening to short wave from NPR.

Hey, short wavers, it's space camp. First Officer Emily Kwong here and today were investigating one of our most mysterious cosmological phenomena out black holes.

Priya Natarajan
Its like the point where all known laws of physics break down.

Emily Kwong
Priya Natarajan is an astrophysicist at Yale University, chair of the astronomy department, and she was named one of times 100 most influential people, all because of her boundary pushing work on black holes.

Priya Natarajan
So for me, the personal attraction, the gravitational pull, pun intended, toward black holes, I mean, really is that they kind of represent the limits of knowledge.

Emily Kwong
I first spoke with Priya in 2020, and she explained to me that the discovery of black holes first happened on paper through Einstein's math equations.

He described the universe as like a four dimensional fabric fusing space and time. And the fabric is bumpy, dotted with planets and other kinds of matter.

Priya Natarajan
And what matter does, it causes little potholes and issues. You drop mass somewhere, you create a pothole.

Emily Kwong
And Einstein's peers wondered, okay, well, what happens when you have an object whose mass is so compact that the pothole becomes a puncture in the fabric of spacetime itself?

Priya Natarajan
And so the black hole solution is one of the simplest solutions to these very complex equations.

Emily Kwong
This theory of black holes was eventually confirmed in 1964, but it set up another mystery, which is how do black holes even begin?

For a long time, scientists were only sure about one origin, that black holes were created through the collapse of a dying star.

But that didnt fully explain how supermassive black holes came to be. Their origin story was only confirmed in the last year.

Today on the show, black holes reimagined. First we venture on a mind bending journey into a black hole where the laws of physics break down. And then Priya shares this alternate origin story, which has transformed our understanding of the early universe.

I'm Emily Kwong, and this is short wave from NPR.

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Emily Kwong
We're talking with Priya Natarajan, an astrophysicist at Yale, and our black hole guide.

Priya Natarajan
First of all, right, let me just sort of clarify, right? There are different kinds of black holes. So there are black holes that are.

Emily Kwong
Stellar mass black holes, intermediate mass black holes, supermassive black holes, and ultramassive black holes. And each black hole, at least mathematically, has a kind of boundary called the event horizon.

Priya Natarajan
That is the region that encloses that puncture in space time. And this puncture is technically called a singularity. That's the black hole. And what is special about this event horizon is that any object that crosses the event horizon, it's the point of no return, because that is the region within which the grip of gravity of the black hole is such that you have nowhere to go but in. You get sucked in.

Emily Kwong
And what if a person were to fall into a black hole? What would they see and experience?

Priya Natarajan
Right. So the. Okay, so first thing that.

Emily Kwong
Not that I want to do that, but it is not a thought experiment.

Priya Natarajan
It is not a fate that you want to actually experience.

So it's going to matter if you are going to fall into a stellar mass black hole or a supermassive black hole. A stellar mass black hole, the pothole is dramatically deeper because it's so much more compact. So if you are falling into a stellar mass black hole, then say you're diving in head first, right? So your hair is hanging down. So the difference in the strength of gravity between your hair and the tips of your toes would be so strong that the gravity would rip you apart. It would stretch you out into a spaghetti. It's called spaghettification. It's a technical term.

Emily Kwong
It's called spaghettification, yes.

Priya Natarajan
And so you would be, like, stretched out, painfully stretched out. Right. And of course, no one can hear you scream once you cross the event horizon. So that would be your fate. Whereas in a supermassive black hole, it's a slightly gentler, horrific end.

So once you fall into the event horizon, as you are approaching the event horizon, you would be able to see the entire universe around you. You'll be able to see all the stars, the light from the stars, except you would, you would start to see the sort of multiple copies of the universe outside and you would see them kind of inverted. You'd see all these effects. The extreme light bending effects are called gravitational lensing.

And then it would all become black and then you would experience something that is really weird.

So one of the things that happens once you cross the event horizon is the role of space and time kind of switch.

So you will be actually falling in time rather than space. And what that really means is that every direction, any direction, back, front, right, left, you would be hurtling towards the singularity. It's super disorienting.

Emily Kwong
So when you're being spaghettified, as you're.

Priya Natarajan
Following through a black hole, stellar mass black hole.

Emily Kwong
Yeah, the stellar mass black hole. You're moving through the spacetime, the fabric.

Priya Natarajan
Of the universe, the fabric has now switched.

Emily Kwong
Ah.

Priya Natarajan
So when you're falling past the event horizon and you have been spaghettified, then you are hurtling towards the singularity, which is this point where all laws of physics break down.

That is the puncture in space time.

So that's the other way of thinking about black holes. Space time would be extremely curved once you have passed the event horizon. And in fact, it won't really be space time as it is outside the event horizon, because here the nature of space and time swap. And so you're kind of falling in time, as it were, rather than space. We, of course, don't have data on this.

Emily Kwong
As you can imagine, no human has fallen through time.

But what would it mean to fall through time?

Priya Natarajan
Yeah, you know, I can think of like a different sense of what happens to time in the gravitational field of an object. So, you know, time actually slows down when you are in an intense gravitational field.

So an experience of a difference in the flow of time, what is kind.

Priya Natarajan
Of a moot point?

Priya Natarajan
Like, how are you experiencing it? Because, you know, I think by then all your cells would have stopped functioning and you would be clinically dead.

Emily Kwong
I didn't experience anything.

Priya Natarajan
That's right.

Emily Kwong
But this idea is that you just.

Priya Natarajan
Cannot escape the grip of gravity.

Emily Kwong
And it's an infinite fall as you're falling towards the singularity.

Priya Natarajan
Absolutely.

Emily Kwong
And this infinite fall would be experienced in the flow of time as really slowed down.

Priya Natarajan
Yes.

Emily Kwong
So it's like a stretching out, slowing down.

Priya Natarajan
That's right.

Emily Kwong
Experience.

Priya Natarajan
The other sort of peculiar way in which it would manifest is that the, you know, the friend who was waiting outside and let you, sadly fall into the black hole, their clock and your clock would no longer be synchronized, right. Because your clock would have slowed down enormously.

Emily Kwong
Wild.

So recently, scientists have been able to figure out even more about black holes. Priya, the first time we talked, you explained to me how stellar mass black holes are thought to have originated from dying stars. These are smaller black holes. But that origin story need not work for supermassive black holes. So why is that like, what was the traditional explanation, and why did it not work?

Priya Natarajan
The traditional explanation is that you have a first generation of stars that were supermassive, that were probably heavier than the stars that we see forming around us now. Today, they would still be only about 100, maybe 50 to 100 times the mass of the sun. So to form a supermassive black hole, which is a million times the mass of the sun, you would have to grow a lot. It turns out, however, that there was a bit of a timing crunch. There's just not enough time to grow that much. So we came up with an alternative. We proposed, theoretically an alternative almost 20 years ago now.

Emily Kwong
And the other way was gas. You proposed that a huge cloud of collapsing gas created the seed of a supermassive black hole.

Priya Natarajan
Yeah, it was pretty rad. So it took us, of course, a long time to figure this out. Right? It took us several years to really understand how this happens to. But essentially, the idea is that when you have a galaxy very early in the universe, before it forms stars, right? Stars form out of gas. So the gas settles down into a disk, and then this disk of gas can just become unstable, you know, much like the vortex that forms when you pull the plug in your bathtub. And the water really rushes in really fast.

Something similar happens in the early universe, and all of that gas can siphon in very quickly to the center, and it could form a very massive seed.

Emily Kwong
The start of a heavier seed that would then grow into a supermassive black hole.

Priya Natarajan
Right. They could start life right away from birth, be already thousand, 10,000, maybe even hundred thousand times the mass of the sun to start with, which then makes it easy peasy to just grow to a million times the mass of the.

Emily Kwong
Sun, which also solves the timing problem. I mean, it's brilliant. Okay, so you proposed this in 2006.

Decades pass.

It's all just theoretical, this idea. But then along comes the James Webb space telescope and that telescope and the Chandra x ray observatory found this very distant, very young galaxy called UHC, one with a supermassive black hole at the center that began just the way you theorized through this cloud of collapsing gas.

How did it feel to finally have the proof of it all these years later?

Priya Natarajan
I literally fell off my chair.

Emily Kwong
Yeah.

Priya Natarajan
As a theorist, right. You propose these ideas. You are excited about them, right? I mean, we published these papers, like, 20 years ago, and so it's 20 years. I mean, it felt like a long time, but, you know, in the grand scheme of things, it's not a long time. And, yeah, I mean, and I just.

Priya Natarajan
You know, we couldn't believe that almost every aspect.

Priya Natarajan
Right. It matched every one of them.

Emily Kwong
What did it reveal anew for you about black holes and how they work?

Priya Natarajan
I think what was, for me, kind of, uh, revealing about this discovery and the validation is that, you know, nature really does make black holes in a lot of different ways and that they're definitely, therefore not marginal like we always thought. You know, they were peculiar and they were kind of marginal bit players in the cosmic drama, but they're not. So, you know, we are increasingly seeing that they're starting to play a starring role. Right?

Emily Kwong
Yeah.

Priya Natarajan
I think now it is impossible to come up with a deep and clear understanding of how our universe was structured, how the galaxies formed and grew and evolved over cosmic time without taking black holes into account.

Emily Kwong
Yeah, they have that main character energy, and you've been one of their number one champions.

Priya Natarajan
That's right.

Emily Kwong
Priya Natarajan is an astrophysicist at Yale University, where she studies black holes and dark matter. Just a reminder, we will be back tomorrow with more regular shortwave and back Tuesday with our next installment of the Space Camp series, which features not just one, but two experts.

Chandra Prescott Weinstein
Hey, shortwave. It's Chandra Prescott Weinstein and Renee logic.

Renee Logic
We're your experts in space theory and in practice.

Chandra Prescott Weinstein
We're tuning in to remind you that regardless of where you are, you're swimming in the light juice left over from the big bang.

Renee Logic
And based on our measurements of that big bang juice, the scientific name for it is the cosmic microwave background. We're learning more and more about the early era of our universe.

Emily Kwong
Big bang juice. I'm intrigued. All right, well, tune in next week, everyone.

Our original black holes episode was produced by Rebecca Ramirez and edited by Viet Leh and fact checked by Emily Vaughn. This space camp version was produced by Hannah Chin and Rachel Carlson. Regina Barber, Hannah and I check the facts. Julia Carney is our space camp project manager. Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. Special thanks to our friends at the US Space and Rocket center, home of Space camp. I'm Emily Kwong. Thank you for listening to short wave from NPrdez.

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