What Happens if You Fall Into a Black Hole? (With Dr. Janna Levin)

Published October 10, 2025 at 11:42 AM EDT

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What happens if you fall into a black hole? What would it sound like? What would you see? Dean Regas chats with Dr. Janna Levin, Professor of Physics and Astronomy at Barnard College of Columbia University, to find out the answers to these questions and more.

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Episode Transcript:

Looking Up is transcribed using a combination of AI speech recognition and human editors. It may contain errors. Please check the corresponding audio before quoting in print. This transcript may include additional material from the conversation, not featured in the audio.

[Sound of TV Channels Changing]: A black hole? … A black hole! … Yes it is. A black hole…

Dean Regas: Black Holes. You know, why are they so fascinating to the average person? I mean, they are dark. Massive. Mysterious.

These are objects in space where gravity is so intense not even light can escape. Anything that falls in disappears. But w here does it go? No one knows.

Well, what if I fell into a black hole? Would I be stretched and crushed?
Today we’re going deep inside black holes and even deeper into the cosmic questions of the universe.

From the studios of Cincinnati Public Radio, I’m your host Dean Regas and this is Looking Up!

The show that takes you deep into the cosmos or just to the telescope in your backyard to learn more about what makes this amazing universe of ours so great.

My guest today is astrophysicist, cosmologist, and author of Black Hole Survivor Guide, Janna Levin.

Man, people are definitely fascinated by black holes. I mean like, when I give public talks, the questions about them are so frequent. And when I hear them part of me is like, “Really, black holes? That’s what you want to talk about? I mean I just talked about the rings of Saturn or swirling galaxies, but you want to know about black holes. I don’t know, I guess they’re cool.”

And my reaction is because there is only so much we can say about black holes. Scientifically, that is.

Let’s take the supermassive black hole at the center of our Milky Way galaxy. It’s called Sagittarius A* and is an object with the mass of 4 million suns. So, take our Sun that you see everyday, cram 4 million of them together – wham-o.

Yeah I mean, we can see how big it is, how far it is, its gravitational reach. But what’s going on inside a black hole?

Dr. Janna Levin: Hi, I am Janna Levin. I'm a professor of physics and astronomy at Barnard College of Columbia University, and my research is mostly around the early universe, black holes, the big bang, large scale structure of space time.

Dean Regas: Well, Janna, thanks so much for joining me today.

Dr. Janna Levin: Yeah, thanks for having me. I'm glad to be here.

Dean Regas: So you write, think, and study a lot about black holes. And I know the public has this unusual attraction for these mysterious objects. What makes them so fascinating to you?

Dr. Janna Levin: It's interesting, I take it for granted that black holes are fascinating. And so when somebody asked me that question again recently and I thought, oh gosh, isn't it fascinating to everyone?
But I have to say there is this extraordinary aspect to black holes that is sometimes overlooked. Of course, all of the fascinating aspects of what they do to space and time. Just the mystery of, of how dense or small, compact, powerful they are.

But there's really something else that stands out to me, and that is that black holes have this kind of fundamental character which is unlike anything else in the universe. It's as though they're almost like fundamental particles in the same way that say, an electron might be a fundamental particle. And I think that they literally are probably made in the big bang because they're so fundamental to our understanding of the universe.

And there's really nothing else macroscopic that you can think of that's like that at all.
Dean Regas: Well, they're still wrapped in mystery to me a little bit. So, what is a black hole?
Dr. Janna Levin: Yeah, where to begin?

Dean Regas: Are black holes, objects, you know, that take up physical space? Are they rips in space and time? Are they holes? Or are they all the above?

Dr. Janna Levin: Yeah. We, we use a lot of terminology to describe black holes, singularities, rips in space-time. But what I want to really press right from the beginning, is in a sense, black holes aren't objects at all. They're really places. They are locations in space time where this occurs, but there's no matter there, there's no material, there's no “thing”.

And anything else about the black hole, whether it has a singularity, whether it's a rip in space-time, all of these other aspects aren't relevant. All that really matters is this space time feature that we call the event horizon. Now you're gonna ask me what's an event horizon?

Dean Regas: Oh, I, no, I was gonna start down a line of questioning whose answers will always probably end up being no one really knows. But, the event horizon is kind of the edge of the black hole in a sense but, what happens when you fall into one?

Dr. Janna Levin: Yeah. So, as a star collapses, it is not a black hole. It is shining bright. And when it runs out of fuel and it begins to collapse under its own weight, eventually it does become a really dense object. Spectacularly, dense. Dense to states of matter that are incomprehensible to us, even in laboratory physics.

And eventually gets so dense that the event horizon forms, a region famously beyond which not even light can escape, and that includes the light from the star. The whole system goes dark. The star itself continues to collapse, and the event horizon is left empty.

That's really wild. So the event horizon is like a fossil record in space time marking the region beyond which light will never escape, but there's no material there anymore, and then the star continues to fall.
Now, if I were to jump in after the star, what would I find as the end state of catastrophic gravitational collapse? Would I find a singularity, a rip in space-time?

And yeah, you're right. You were right from the beginning. You answered your own question. Nobody knows. If you're a purist, you might say, look, that information is sealed behind the event horizon. It has no effect on the universe out here, and I think we're going to find a really complicated story that connects ultimately with the evaporation of the black hole.

Dean Regas: Well, in your book, Black Hole Survivor Guide, you walk us through a lot of this stuff. Can you give us the tips and tricks to getting close but not falling into a black hole? Or do you just recommend just going for it? Diving in like Matthew Mcconaughey in Interstellar?

[From Interstellar Film]: It’s all black…TARS do you read me? …All Blackness…

Dr. Janna Levin: So, you know, the real adventurists gotta dive right in. But whether you're choosing to skirt the outside and escape back out and live the rest of your days with the rest of us, or plunging in, you want a big black hole.

You want the biggest black hole you can possibly find trillions of times. The massive sun, the bigger black hole, surprisingly, is safer for us. That might be counterintuitive, that, oh, a big black hole is really going to be so powerful and it's gonna churn up space time, and destroy everything. Actually, if you think about it, the bigger a curved object, the less you notice curvature.

So, for instance, I walk around on the surface of the earth, and I don't obviously notice that it's round just by walking on it, but if I tried to walk on a basketball, I would absolutely know that it was round. And so the curvature of the smaller object is actually more important. And the black hole is all about the curvature of space time.

So the bigger black hole actually feels kind of straight and flat and smoother, and you won't be totally torn apart. If you go near a very, very, very big black hole, you will actually be able to cross the event horizon.

There will be no drama. You will drift across as gently and comfortably as if you had stepped into the shadow of a tree and you wouldn't even really know that you had made this irreversible decision.

And then you'd be inside the black hole and it would be too late. But once you're inside the black hole, the other thing you want to do to survive is you want to prolong the time that you spend falling in. You don't want to take the shortest shot in, and if you worked very hard at a very, very big black hole, you might be able to survive a year like that.

There will be no drama. You will drift across as gently and comfortably as if you had stepped into the shadow of a tree and you wouldn't even really know that you had made this irreversible decision.

Dean Regas: I always thought you just like, you have to just keep rotating, because you know the part that's closest to the black hole is going get spaghettified so-

Dr. Janna Levin: Right. Well, it's very strange on the inside of the black hole. The singularity, in your point of view, no longer looks like it's a point in the center. It actually looks like a point in the future.

And so you cannot avoid that singularity. The way you can avoid a point in space. It comes at you the way the future comes at you. And so that's where the singularity is absolutely unavoidable. A limitless amount of accelerant and fuel could not allow you to avoid the center forever. You eventually will encounter it.

Dean Regas: You know, one of the biggest stories of the decade to me is when astronomers are capturing black holes colliding, how did they do that? And why was this such a huge deal?

Dr. Janna Levin: Such a big deal! It surprises people to know that we don't take pictures of black holes, At least, only twice has it ever happened. And that has been very, very, very recently.

What we do is we indirectly detect the effect of the black hole, usually the mayhem it's causing in its environment. And we can deduce, oh, that's a lot of energy, that's a lot of mayhem in a very, very, very tiny space, very massive object. And what else could it be, but a black hole? That's usually what we mean. We can't take an image of it.

So the first time there was what we would say, a more direct detection, some would argue, of black holes also involved Kip Thorne and the Great Ray Weiss, who recently passed away.

[Nobel Prize Award Ceremony, 2017]: The Royal Swedish Academy of Sciences has decided to award the 2017 Nobel Prize in physics with one half to Rainer Weiss and the other half jointly to Barry C. Barish and Kip S Thorne. For decisive contributions to the LIGO detector and the observation of gravitational waves.
Dr. Janna Levin: The idea was, look, take two black holes that have no material around them, they're completely dark. You are never going to take a picture of that system. There is nothing coming out of them in light.

But if they're orbiting each other, just as we orbit the sun and the sun orbits the center of the galaxy, they will churn up space time like mallets banging on a drum. Their incredible concentrations and their motions will cause space time literally to ring.

And, 100 years later, after spending 50 years building one of the most sensitive instruments humanity has ever devised, they recorded the shape of space time ringing here on earth from the collision of two black holes, two black holes, orbiting, merging, banging on space time, well over a billion years ago.
And so you could say that this was real evidence of bare black holes with no light around it. It was the most a power powerful event human beings had detected since the detection of the Big Bang itself. And none of it came out as light. All of it came out in this banging of space-time.

Dean Regas: So you talked about with the merger of black holes, that it kind of had a sound like a ringing drum. What does a black hole sound like? Does the sound come out?

Dr. Janna Levin: Yeah, so it, it doesn't come from the interior of the black hole, but it's like the mallets on the drum. The drum makes the sound. The black holes are the mallets banging on the drum. And it sounds really funny.

The way we describe the collision of two black holes is as a chirp. It sounds like this little like [mimics the chirp]. And it sounds that way where it scoops up in frequency like that because the black holes are getting faster in their final orbits before they merge and make one bigger black hole.

It's so fast that your ear can't actually interpret, it also can't hear it. It's too low amplitude, but that is aided by slowing it down in our techniques and our technologies.

But theoretically it's conceivable that if you were floating in empty space, around two colliding black holes, that the squeezing and stretching of shape, which is what the gravitational waves are, they're a deformation in the shape of space. So the squeezing and stretching of the space, the ringing of the space from the merger of these two black holes could actually excite your ear mechanism and you would literally hear it even in the absence of air.

Dean Regas: This is why I always tell people at, at parties, find the cosmologists and hang out with them 'cause they will like expand your mind. And so, this has been so awesome, Janna, thanks so much for taking the time and expanding my mind and the universe.
Dr. Janna Levin: Thanks Dean. Really fun to talk.

Cosmologists like Janna Levin definitely think some deep thoughts. I picture them just sitting around sipping herbal tea, stroking their chins and pondering the vastness of the universe. “Yeah, what about if we are all just living inside a black hole, right now!” You know stuff like that.

One example, that Janna does actually think about is about the whole universe. Is the universe truly infinite - as in does it go one forever and encompass everything? Or is it finite - does it have a certain size and actual edges?

And we hear all the time that the universe is getting bigger. It’s expanding. One of my favorite conversations to illustrate the tone of cosmology was this:

I ask the cosmologist…

[Dean to Cosmologist]: Is the universe infinite?

Dean Regas: The cosmologist replies…