Join Davos 2026 experts as they unpack insights from astrophysics on reality, perception and the unseen forces shaping the universe.
Astrophysicist Priyamvada Natarajan argues that black holes are not just cosmic curiosities but foundational to how galaxies—and potentially life—form. She explains how Einstein’s relativity reframed gravity as “the interplay between matter and the shape of space,” with black holes creating extreme distortions and a region from which “not even light can escape.” The central scientific puzzle is timing: Webb is finding enormous black holes when the universe was very young, akin to “a six month old child that weighs 75 kilos,” as Max Tegmark puts it. Natarajan’s work proposes a faster origin story: early “direct collapse of gas” that produces black holes born thousands to 100,000 solar masses, giving them a head start versus growth from dead stars. Observations of a candidate object, already ~10 million solar masses just 470 million years after the Big Bang, match predicted infrared and X-ray signatures and rely on gravitational lensing “magnifying glasses” to be seen. Beyond discovery, the speakers make a policy case: abstract physics underpins GPS and medical imaging, and basic research drives unexpected technology spillovers. As Tegmark notes, “no normal venture capitalist” would fund the satellite laser precision developed for gravitational-wave astronomy, yet it later enabled commercial systems.
My name is Priya Natarajan and I am for curiosity driven science. As an astrophysicist and a cosmologist, I co-lead the Yale Center for the Invisible Universe, where we conduct pioneering research on dark matter, dark energy, black holes, and neutrinos. From a very young age, I've been captivated by the elusive and the invisible constituents of the universe, particularly black holes. And I bet many of you are probably just as obsessed as I am about black holes. Black holes, as most of you are probably aware, were first proposed by Einstein in his general Theory of relativity. Newton explained to us how gravity actually works, but Einstein explained to us what it is. He showed us that gravity is the interplay between matter and the shape of space. So matter in the universe causes distortions in space time, which is sort of the four dimensional fabric that we all inhabit. That is the universe. And compact objects like the sun, neutron stars, and black holes cause extreme distortions in the shape of space. Black holes, in particular, are special. Not only do they extremely distort space time, they in fact create a puncture in spacetime. This idea of black holes, though it was proposed in 1915 as part of his theory of general relativity, it took a long time to become real, so to speak. The scientific community rejected it for about four decades, and the reason for that is black holes have really bizarre properties. Two of them, for instance, have to do with the fact that black holes encase a singularity. They are a place in the universe where it turns out that all laws of physics break down. There's a singularity in the middle in that puncture, where our understanding of the universe completely breaks down. Second, they actually have this region where not even light can escape. So understanding the role that they play in the universe has been tricky. However, over the past few decades, we have figured out a lot about what black holes are and what they really do, how they manifest in the universe. And this is where my own work comes in on the origin of the very first black holes in the universe. But before I go there, let me give you a little bit of an idea of what we knew about black holes and what we've known about them for a couple of decades. Black holes originate from the end states of stars. Massive stars live fast, die young, and leave behind a very glamorous corpse. Sometimes the most massive stars in the universe. And they leave behind black holes, which are tiny and compact. But these black holes that are small, black holes are the seeds from which the supermassive black holes that inhabit the centers of almost all galaxies, including our our own, are known. And it turns out that the origin of these black holes is a big question and open question, because we are finding them ubiquitously everywhere in the universe, with masses of 1 million to 1 billion times the mass of our sun, including in our own galaxy. So these are little red dots that the James Webb Space Telescope is rapidly revealing that contain a very actively growing black hole. So how did we figure out what black holes are doing in galaxies is by studying the black hole at the center of our own galaxy. And the mass of this black hole is determined by the motions of the stars that circulate around the inner parts of the galaxy. So the question is, how and when do these black holes form? And so my own work has resulted in trying to provide a new pathway for the formation of the first black holes, a pathway that kicks into gear very, very early in the universe. And it occurs from the direct collapse of gas in the very, very early universe. And this happens in a setting where you have a parent galaxy that has formed stars and has a satellite in which you form this direct collapse black hole. This object merges and it forms a very unique kind of galaxy. And over massive black hole galaxy whose light is dominated not by the stars, but by the black hole that is growing in its center. So this is an idea where the formation of the first black hole actually bypasses the standard star that I just finished telling you about as the origin of the tiniest black holes. So these black holes from the get go are a few thousand to maybe even 100,000 times the mass of the sun at birth. And this therefore gives them a head start and can explain the million and billion solar mass black holes that we are finding very, very early on in the universe in place. And this particular mechanism for forming the first black holes has very, very unique signatures, as I mentioned. And these signatures we predicted in work done with my postdoc about 15 years or so ago, that they should be detectable both by the James Webb Space Telescope as well as the Chandra X-ray telescope. And, of course, I've been very fortunate that the James Webb Space Telescope has indeed detected these objects. And it's a thrill to be around and within one career lifetime, to have had the fortune of making predictions that were testable, have been tested and have been validated. So one of the unique features of direct collapse black holes is the signature of their formation is carried in this very specific relationship between the mass of the black hole and the host galaxy, the properties of the host galaxy that contains it. And so these predictions are made not just in the infrared that the James Webb Space Telescope sees, but also in the X-rays detected by the Chandra space telescope. So it turns out now that we are able to peer really far back into the universe, and we are able to map all these invisible entities that shape our universe. And at this point, you might ask, why should you care? How does this impact your life, these abstract ideas? So it turns out that these monster objects in the universe, like this galaxy cluster bend light, as predicted by Einstein's theory of general relativity and the bending of light allows us to map the invisible. So there are these techniques, new algorithms that we developed, as you'll see, have come in handy for many other things. And black holes, for example, have a very intimate relationship with each and every one of you. You are carrying in your hands a smartphone. And you got here to Davos because the same equations that govern and explain black holes actually guide GPS. So we have this GPS technology today as a direct result of these fundamental abstract, mathematically obtuse results that appeared to be not useful decades ago. So basic fundamental science always translates. And as I mentioned, some of the algorithms that we have used to render the invisible visible, connect the visible universe to the dark matter that is shaping it. Those very image mapping algorithms are something you have encountered in your life very, very recently, and that has to do with MRIs and other medical imaging applications that have also come out of the work that's done in basic sciences. So science and technology come full circle and translation happens, although it might take a little longer. And the path, the arc to the translation may not be really obvious from the get go. So what I want to do here is to make a case for fundamental science, and for funding of fundamental science, and by governments, by philanthropies, and by the private sector, because the arc of science, the results and the scientific breakthroughs and how they are going to transform our life is not something we can predict today. But history shows us that science and technology have fundamentally changed our life. And given the pressing global problems that we are facing right now with climate change pandemics, there is no way out of funding basic science. Just stop here.
Wonderful. Thank you so much, Priya. Now you get to relax and sit down. Thank you. Oh.
Thank you. Please.
I'm Max Tegmark, physics professor from MIT. So it's such an honor for me to be here with one of the great rock stars of of astrophysics and talk about one of my favorite topics, black holes. So to start off, just to make sure we're all on the same page and got this right here. Is it fair to say that, there's this basic mystery? You began with? It's kind of like if you walk into a. Daycare center and you see this six month old child that weighs 75 kilos and you're like, oh my gosh, how did this child get so big so fast? And then we have this, View that's been held by some astrophysicists for a while, that there was a black hole that maybe came from a dead star, and it was kind of gobbling up other stars like popcorn, one star at a time. And when it eats these stars, it gets more massive and it grows. And then you have this very interesting alternative. Theory that actually, no, it wasn't mostly popcorn or eating stars. It actually started out eating gas from the very beginning. So so some very curious this, these, this very dense disk of gas which forms the black hole. Where are we now, if you can unpack this a little more observationally, and actually seeing these or seeing indirect evidence of them.
Yeah. So I think you have an absolute apt analogy for, understanding that the growth history, both the birth and the growth history of these objects is very special and peculiar and non-standard. You know, you've done yourself some pioneering work on the very first stars, right? So here the you need a set of cosmic conditions and a couple of different settings, and there are many settings available in our universe where this can happen and where basically you can form from direct gravitational collapse. So aggregating a lot of matter into a really tiny space in this very interesting, fairly commonplace setting. And the prediction is that the satellite where you form the direct collapse black hole will merge with the parent, and the parent is already formed stars. However, this object, which is an over massive black hole galaxy. Sorry for the slightly unimaginative title, would actually glow and the emission that you would get from it would be dominated by accretion onto the black hole and not from the stars. So we predicted this in 2017 with detailed spectral predictions and, you know, ratio.
Of do I understand you're talking about the creation that happens after it falls into the bigger galaxy, or are you talking about when it formed.
, when it forms both. So accretion is what governs everything. It's when it forms as well as once it merges with the parent galaxy. So the first object that James Webb detected that really matched all our prediction. And there were seven predictions, you know, detailed both the spectral shape, the amount of energy that comes out in the infrared that James Webb should detect, the amount of energy that comes out in the x ray that Chandra should detect. So there was an object, Z one, which was in place about 10 million times the mass of the sun already when the universe was barely 470 million years after the Big Bang. So it's extremely early, and there is no way without huge amount of fine tuning, that you could start with a stellar remnant black hole and grow it up that rapidly.
Yeah. Just to clarify, you know, our sun is going to go for a total of 10 billion years or so until it dies. And even the stars that, as you said, live hard, die young, you know, the most massive ones, you know, they might need quite a number of millions of years to before they can, before they start their death process. So this is crazy fast.
And and so there's been this one object. These are very faint. I mean, this is so far away, it's really faint. And that's where I sort of, you know, my interest in mapping dark matter and black holes kind of collided in a virtuous way because we were able to see this, because these conglomerations of dark matter in the universe behaved like magnifying glasses. They actually deflect and focus light, much like the magnifying glasses that we use. And this faint object happened to. And this was therefore a gift from the universe, right behind a very strong magnifying glass that brought it into view. Otherwise we may have never seen it. And there are many other candidates now which have the similar properties to us. One and are seem to be kind of, you know, very aligned with the idea of having a direct collapse as the origin for the central black hole.
Right now. So for reference, raise your hand if you have kids. So you know that kids tend to be pretty messy eaters from their little. Right. You try to feed them and but a lot of the stuff might come flying back out again. It's sort of fortunate that black holes are messy eaters too. So you might you might think seeing a black object on a black background is just completely impossible. And that is indeed one of the reasons Priya has to work so hard to find the black holes. But, when they eat stuff gas, for example, a lot of stuff comes flying out. The a lot of x rays and other kinds of photons and, and, and various other things. So. This, can you say a little bit more the is most of the data that you have which has been conveniently magnified and you can see is it mostly data on, what what the black hole is doing after it's fallen into this bigger galaxy? Or is it, mostly from this very gas dominated little birthplace that it had?
So the the birth itself happens extremely rapidly. So catching something in action while it's being born is really quite hard, practically impossible. So what we are really seeing is after this over massive black hole has formed from direct collapse. And it ends up kind of in this parent galaxy in a very transient state. So most of the black holes in our universe, including the one at the center of our galaxy, do not outweigh the stars. The stars outweigh the black hole by several orders of magnitude. And this is completely the opposite. And so that's a transient phase that these galaxies then snap out of, because the stars start to grow and assemble, and we reach where we are now with most galaxies.
So after first having a diet of almost all gas where it gets born, it falls into this bigger galaxy and it's still eating a diet of mostly gas, not so much popcorn or stars, because most of what's there is, is gas. Yeah. Makes a lot of sense. Yeah.
And I think as you mentioned, right. One thing to clarify is a lot of the light that we are seeing from the black hole, right, is gas that is being pulled in and gobbled by the gravity of the black hole hasn't quite crossed the event horizon yet. Because remember, we are not going to get any signals once you cross the event horizon. So everything that we are seeing is by is from gas that is being sped up, sped up close to the speed of light, and it gets really hot and it starts to glow. So that's the light. The dying gasps of gas are what we are seeing. That's revealing the presence of this black hole.
Great. So it's interesting. Black holes I feel, have gotten a reputation as kind of the bad guys of the universe. They're scary. They eat things you can't come out afterwards and so on. You mentioned that they all they're also good things, first of all, about studying black holes, because it's basic science we learn can be used for all sorts of great technology here on earth. But I wanted to ask you if they're also if they've also gotten an unfairly bad reputation in a more direct way. In, we see that pretty much all galaxies have a big black hole in the middle. Do you feel that the role they play in regulating star formation and so on is ultimately also helpful? Like, for example, do you think that life on earth would have actually happened in the first place if there were no black hole in the middle of our galaxy or.
No, I think that's a great question. I think aside from the fact that, you know, there are all these downstream practical applications, you know, black holes are really enigmatic because in many ways they also represent the edge of what we can ever know, the edge of knowledge. So there are limits of what the human mind can really figure out. But originally, black holes were thought to play a really marginal role in galaxy formation. But I think in the last two decades or so, we've understood that they are actually fundamental to shaping the visible matter in galaxies. So one could say that we may not actually be here if there wasn't a black hole that had regulated, modulated the formation of stars in the Milky Way. And so I think now we believe that they play a starring role, you know, from the margins to center stage.
So even though you don't want to fall into a black hole and get eaten and they're scary, you're saying in a way, we owe our existence to black holes, because if if there were no black holes in the middle of our galaxy, this, this area of space that we might have been uninhabitable.
That's right. I mean, I think we would not have had the stellar nurseries and the stellar distributions and hence the planets around those stars that could have given rise to life as we know it.
All right. So thank you to the black holes for giving us the opportunity to have this conversation. And that was well, we're not done yet because I want to make sure that, okay, I hope the black holes heard this. I appreciate it enough that they don't eat us. So I want to I want to, give you guys a chance to ask, any, any fun black hole questions that you have. Let's start over here.
Hi, Luke. Melissa. Amsterdam. I have a question. Did all your vast research and knowledge give you any insights or a different opinion about us as humankind? Did it change your perception about who we are as human beings and really curious to to hear that?
Yeah. I think that, you know, studying cosmology in general and black holes specifically, really instincts, sort of instills a sense of cosmic humility because, you know, why should we who have, you know, an organ the size of a cantaloupe, a gelatinous thing out here? Be able to figure all of this out and understand, you know, our place in the universe and how this physical universe, which we have again, the good fortune of looking back in time, you know, looking out into the universe is uniquely allowing us to look back in time and piece together this beautiful cosmic story that we are part of. So I'm a bit of a romantic. So for me, you know, it's just really moving that we have these capacities. And I feel really grateful and humbled to be alive at this time. When you have all these convergences of, you know, the sophistication of human ideas, our skill in building technologies and, you know, the collision of these sort of ideas, instruments, computation that allows us, allows us these insights at this time. Yeah, I think that it makes you feel very grateful and humble.
Yeah, but but not just humble. I think also empowered because I feel we humans have been the masters of underestimation, right? Not only did we underestimate the size of our cosmos and our opportunities again and again, making the mistake of thinking that everything we knew was everything that existed, just to find that that was just part of a much grander structure. You know, a planet, absolutely a galaxy, a supercluster, a universe, etc. but we had also underestimated our own minds and our ability to understand, you know, we black holes, right? We're not arguably discovered first with a telescope, but with a pencil. People like Einstein and Schwarzschild and even Laplace. And the idea that by that, by thinking with these brains that had been evolved to pick bananas and so on, we could unveil.
I know it's I think, you know, it's this weird, as you said, you know, simultaneously feeling very significant and insignificant at the same time, significant because of these capacities that we never even imagined. I don't think Copernicus, for example, would have ever even imagined in a hallucinogenic dream state that we humans would make these satellites the Voyagers that would actually leave the solar system, because at that time, the solar system was the universe, right?
Yeah, absolutely.
So. So never underestimate yourselves.
Right.
And and then we have you have a question on this side here and then and then we'll go to Jean after that. Yeah.
Hello. Thank you. Thank you for the interesting talk. I really like it. So, I liked also the analogy of the big baby, you know, so my, my question is, does this baby get old? I mean, do they grow forever or do they evaporate at some point? And then if it's so, then is it possible that then when we see them, they are already gone?
Great point. Yeah. So it turns out that, our current understanding, tells us, informs us that galaxies and black holes grow in tandem. And yes, they do grow to enormous sizes and masses. So the most massive black holes in the universe, in the nearby universe that we've detected, are tens of billions of solar masses. And in fact, many people, including myself, have speculated on, you know, what might is there physics that could set an upper limit to how big a black hole can really grow in a galaxy confined in a galaxy? So it appears that they're, you know, they're extremely, coeval in how they evolve galaxies and, and, black holes. And for the, the, the second part of your question, could you just repeat the second part of the question.
If they evaporate?
Oh, yes. Because when we look back in, when we look out into the universe, we are looking back in time. So, for example, you know, light takes about eight minutes to come from the sun itself. And these objects that I showed you, the little red dots, there are billions and billions of light years away. So what those galaxies actually look like today and what those black holes are doing today, we don't know. We just know what they look like when light actually left them billions of years ago. As for evaporating black holes, you know, Stephen Hawking suggested that very, very early in the universe, right after inflation, you could form these distortions, these punctures in space time, those are referred to as primordial black holes. But these black holes would evaporate over time with Hawking radiation and would completely disappear. However, that for black holes that we have been talking about, these supermassive black holes are even stellar mass black holes. It would take more than the age of the universe for that to happen. So these monsters are basically here to stay. However, depending on what the other invisible driving force of the universe is and its true nature dark energy, we don't know what dark energy is. So with all these dark entities, we know how they manifest in the universe. We don't know what they really are. It's quite possible. One of the outcomes. So dark energy determines the ultimate fate of our universe. One of the outcomes, potential outcomes, is that we could all end up in a big black hole. There could be a big crunch.
Yeah. So we can add that to another cool feature of black holes. There, there. The long term, rulers of our universe, because after they basically eat all the food in their neighborhood and stop growing, they just hang out there for a ridiculously long time while all the stars burn out and so on. So the last laugh is right.
Yeah.
They get the last laugh. Gingivalis.
Yeah. So, basic science, just so that we can understand is more than enough. But at the heart of almost everything we do now is quantum physics. Right? And Max referenced that, maybe there are applications here on Earth after this big crunch thing. I feel ridiculous asking this question, but what might be some of the applications that come out of our advancing knowledge about black holes that, that, that, that, that have applications like quantum mechanics at the, at the heart of all computing.
So, I mean, as I mentioned, some of the applications we have already kind of harnessed and that has to do with just understanding the nature of gravity itself. It gives us a deeper insight into gravity. And it's allowed us to launch satellites, do GPS keep track of time, time and space? So one other thing that we believe that we haven't quite understood as well is how the energy that is generated in the regions around the black hole, how the gas, for example, is transported over large cosmic scales, and the efficiency of that kind of energy generation process. So it could potentially, in the future, help us understand new ways, more efficient ways of converting mass into energy. So, you know, the course of future science, basic science is really hard to predict. So I can't quite tell you that if we find this and that's going to give you this, but what is a certainty is, is that we are going to find something and that it is going to give us many, many unimagined possible products and ways in which it is going to touch, touch our lives.
Yeah, I completely agree. And and just to add a second way in which science really helps tech, you know, there are two ways. One is the direct way. Einstein starts wondering about the theory of the nature of time, discovers E equals MC squared, and then later we realize we can directly use that to power build nuclear reactors and give green energy. Right. But another thing, which is, I think even more impactful for technology is scientists get obsessed about some seemingly weird question. And in order to study.
That question.
To me.
Right.
The scientists developed technology that would otherwise not have been developed, which turns out to be super useful. Let me just give a black hole example. So there has been a huge effort to build a black hole telescope called Lisa, which measures gravitational waves, ripples in space time of a wavelength roughly the size of the inner solar system. The idea sounds like science fiction. You put three satellites orbiting around the sun, and you send laser beams between them, and then you can measure very carefully what's going on and be like, oh, space got warped here. There must be. Maybe there's a black hole over there. No normal venture capitalist would be developing technology for how you can point a laser super accurately from one fast moving satellite to another fast moving satellite far away. But this was developed to study black holes. And then Starlink is using exactly that technology. So when you invest in basic science, you know, the returns that has for society is not only from the scientific discoveries, but I think even more often you get these crazy returns to society from the tech that the scientists discovered to study this question, which people otherwise wouldn't have developed at all. So we're out of time here. But I hope Priya has convinced you not only that black holes are very cool and not only scary, but also very helpful for us. We might not have this conversation if there weren't for the black hole in the middle of the Milky Way, but also that more and more importantly, the society's investments and and basic science are arguably the highest ROI investments we've ever done. So thank you so much again, Priya.
Thank you so much.
Thanks everyone for coming.
Thanks.