- Hello, everyone. We would love your feedback on "Conversations at the Perimeter." Let us know what you like and what you'd like to hear more of. Go to perimeterinstitute.ca/podcastsurvey to share your thoughts. Thanks so much. (light music) - Hey, everyone. And welcome back to "Conversations at the Perimeter." I'm Colin here at Perimeter Institute, as always with Lauren. - Hi. - And we are so glad to be bringing you the conversation that we had with Shep Doelman.
Shep is the leader of the Event Horizon Telescope, or EH, a global collaboration of scientists on every continent that gave us humanity's first ever glimpse of a black hole. - Now, chances are you've already seen the images captured by the EHT. In 2019, the collaboration unveiled an image of the super massive black hole in the M87 Galaxy, and in 2022 they imaged the black hole at the heart of our own Milky Way galaxy.
Shep tells us how these incredible discoveries were made through the collaboration of hundreds of scientists around the world, half a dozen telescopes, and of course, incredible amounts of ingenuity. - Yeah, it really is amazing to hear Shep describe not only the power and the mystery of black holes, but also the monumental global effort that went into seeing them for the very first time.
And Shep has such a sharp sense of humor and a knack for storytelling, this conversation just flew by for me. - Shep also assured us that in black hole science, the best is yet to come. He tells us about the next generation EHT, which will expand the earth-based telescope array to observe black holes in even more detail and future projects that will include space-based observations and even capturing movies of black holes in action.
It's a fascinating ride and we felt so fortunate to be a part of this conversation. So, let's step inside the perimeter with Shep Doelman. - Shep, thank you for being here at "Conversations at the Perimeter." - It's a pleasure to be here. - You and I have talked a number of times before on Zoom calls where we each have just been a little a cube on a tic-tac-toe board, but this is the first time chatting in person and there's a question I've always wanted to ask you. What's a black hole?
- What is a black hole? So if you ask different people, they might have different viewpoints on what a black hole is. I mean, quantum physicists will want to dive into information theory. I'm an astronomer, so I live kind of in the real world and my idea of a black hole is that it's a condensation of matter that's so dense and in such a small region that it creates an event horizon around it. And that's a point where light can't escape.
Even if you travel at the speed of light, you can't escape the gravity of that black hole. That for me is a black hole. And what's more, these black holes we know exist in the universe. So, they're something we can study. And it's not just a theory, it's not just something on a piece of paper. It's something we can see with advanced instruments.
- And you know what, Shep, today I was getting ready to come to work and I have to tell you, I was talking to my two and a half year old son and I told him, "Guess what? Today I'm gonna talk to someone named Shep Doelman and we're gonna talk about black holes." And he really loves digging with his shovels. And he told me, "Mom, I've seen a black hole when I was in the forest."
So, you know, I think even these really young kids, they have a picture come to mind when they hear about a black hole, how much of that picture that we have, as soon as we just hear that phrase, how much of that is really true? - Well, it is true in that like when you dig a hole in the forest, maybe the one that your son is thinking of, you can put things in it, you can forget about them, you know?
So, we think of a hole as being something where you can store things or it's out of sight, out of mind. And a black hole really is like that. When things fall into the black hole, when they go through the event horizon, there's really no causal connection left to our universe. They're gone forever. So, it's really a hole that you can't withdraw anything from in the future. So in that sense, your son has it exactly right. It's the universe's big pocket.
It's something that you put something in, you can't take it out again. - Is there anything misleading about what we might picture when we hear black hole? - I study black holes for a living. We observe them, but black holes exist in literature. They exist in even music. They exist in art. So, a lot of the things that we know about black holes come from the culture in which we live.
So, it's perfectly fine to think about black holes and interpret them in your daily life in a way that makes sense to you. And if you talk, again, to a quantum physicist, they'll have a different way of looking at it. If you talk to an astronomer like me, I'll be thinking about, you know, the hot gas that swirls around the black hole that allows us to even see that there's a black hole there. So, everyone can think about black holes in the way that they want to.
When you get down to it, there are some formulas, there are some equations, there are some real world, telltale signatures of black holes. But I really enjoy the fact that they have an existence beyond the theory, beyond the observations. I embrace that. - How long was it before black holes moved from purely an idea, a theory, to something that you know is out there? - Black holes have a deep history.
When we made our first image of a black hole using the event horizon telescope that I'm sure we'll talk about, we felt a deep connection with that history. I like to phrase it in this way, that we have a 100 year handshake with Einstein, that we are living in an era where if Einstein were here, he would be part of our team. There's a deep visceral connection to all the people who came before us and studied this. And it begins with general relativity.
It begins with Einstein in 1915 coming with this idea that gravity was different than Newton had theorized. That there was a different way of thinking about gravity. It was a deformation in space time, and things would move in that deformed space time. And then the question is, well, how do you know that that's the right new theory? Well, it explained things like the perihelion shift of mercury.
When mercury orbits the sun, it changes its orientation a little bit, it gets a little kick that general relativity predicts that Newton's gravity would not. So, it explained that right away. And then the next thing that happened was Karl Schwarzschild, in the trenches of World War I, solves Einstein's equations and he comes up with this idea of the Schwarzschild radius. This is where the event horizon is.
And Einstein is so tickled by this solution, by this scientist who's serving in World War I. He presented to the Prussian Academy of Sciences. And for many years, that was just a theoretical mathematical oddity. No one really thought you could make a black hole. And indeed Einstein went to his death, convinced that nature would never allow you to make a black hole. There would be something that would prevent it.
Things would be orbiting the black hole so fast that the centrifugal force would prevent the collapse into a black hole. And now, of course, we know that they do exist. There was work by Oppenheimer and Snyder in the 30s that really showed you could condense something beyond the event horizon. And astronomers began to get the inkling that there was something out there looking at Cygnus X-1, a black hole that's devouring another star.
And the signature, the radiation signature from that was such that it's hard to explain it unless you have a black hole that is devouring another star. And then the story got even weirder in a sense because we began to see the centers of galaxies glowing so brightly that only the conversion of gravitational potential energy, a matter falling in and turning that into radiant energy, which a black hole can do, was the only explanation.
And all of a sudden you could have black holes that were millions of times the mass of our sun, billions of times the mass of our sun, at the centers of these galaxies. So, the evidence began to become overwhelming, but we had never seen one, we didn't have the angular resolution, we didn't have the instrumentation that would've allowed us to really see it. And that's what we've been working on for the past 20 years.
So, from Einstein to Schwarzschild, you know, all the way through like thinking about quantum effects around black holes from Stephen Hawking and Bekenstein, all the way through to what we're doing now, which is observing black holes, it's been a wild ride and it's hard to believe this has all happened in such a short amount of time. - So, can you tell us a little bit about the event horizon telescope and how it works, how it's achieved this?
- This is just about my favorite thing to talk about, but so when you think about observing a black hole, it's totally counterintuitive. Something that's designed by nature not to emit light, that swallows all the light. How do you go about viewing it? So, when you think about taking a picture of a black hole, which is what we did with the event horizon telescope, I wanna first talk about why they glow. So, all this matter is falling into the black hole, let's say the center of a galaxy.
And as it falls in, it encounters this cosmic traffic jam. It's trying to get into a very small space. And so it backs up, it collides with the gas that came before it, and it soon heats up to hundreds of billions of degrees. So, in a paradox of their own gravity, black holes glow extremely brightly, especially at the centers of galaxies where there's so much gas. So, we have this intense flashlight illuminating from all directions, this event horizon, and the light gets bent around it.
So in about 1916, Hilbert asked, "Well, how big would this ring of light be around the event horizon?" He came up with some clear formulas and Max von Laue in 1921 confirmed that. And then a bunch of simulations were done in the 70s and then later in the 2000s that showed, given a super massive black hole at the center of a galaxy, you would be able to see this ring of light. And the dimensions of that ring would tell you how massive the black hole, if Einstein's theory was correct.
So, in one measurement you could measure the mass of the black hole and confirm Einstein's theories. And then we had to ask, well what wavelength of light is the right wavelength to look at? Because this thing can glow at all different wavelengths, in the optical, in the x-ray, ultraviolet. And it turns out that you wanna be able to see all the way to the event horizon. And in the optical you probably can't do that. It's probably optically thick.
You'd see like a cloud of emission outside of the event horizon. But with radio waves, you can see all the way to the event horizon.
So, now the event horizon telescope, so now we know what wavelength to look at it in and we know that we can see this ring and we decided that we could do this in the radio waves, but we needed a telescope that was as big as the earth because the size of the objects you can see on the sky is basically the wavelength of light at which you're observing, divided by the size of your telescope. A very simple formula.
So, if you're looking in the radio, maybe a few millimeters of wavelength, you need to see the nearest black hole, Sagittarius A star in the center of our galaxy, or M87 at the next distant galaxy. You need to have an angular resolution that's about 50 microarcseconds. Okay, and what does that mean? This is equivalent to being able to read the date on a quarter if you're in Los Angeles and the quarter's in New York, or equivalently, it's being able to see like a tangerine on the moon.
So, we had to devise a telescope that had the greatest resolving power of anything ever done. And the way we did it is we took telescopes on different sides of the earth, we recorded lights from the black hole, stored it on hard disks, and then brought those discs together to a central facility and we played them back and we were able to form a telescope as big as the distance between the telescopes. So, by linking telescopes across the earth, we made a telescope the size of our planet.
And when you think about it, what we're doing is pretty much the way an optical telescope works. An optical telescope is a perfect parabola and it's a highly reflective surface light from an object bounces off that. And it all comes to a focus and that's where you put your camera, okay? And it's the shape of that lens that gets all of the light to that one focus at the same time.
And what we do with the Event Horizon Telescope is we take these recordings of radio waves from the black hole, we bring them to a supercomputer and we play them back and align them perfectly. So, we replicate what an optical telescope does with its mirror in silicon. We delay the light and play it back so it perfectly aligns. And that gives us this earth-sized telescope. And even that's not enough, 'cause you need many telescopes around the globe.
So, it's not just two telescopes, but in the first instance of the Event Horizon Telescope, we took eight telescopes, observed simultaneously, and that was just enough to make the first image of a black hole. - It seems like an almost impossible undertaking. How was this idea even conceived? Did you have a eureka moment one night and wake up and think we could make a telescope the size of planet Earth? It's almost crazy. - Yeah. It is like mind boggling when you think about it.
And I do pinch myself occasionally, not just because it was a very interesting project, but because we got to do it. As with many ideas, this has been burbling for a long time on the theory side, as I mentioned, back in the early parts of the 20th century, people have been thinking about how big a black hole might appear to be on the sky. And then there were many simulations done in the 70s and the 2000s to show what it might look like.
And at the same time, this idea of radio interferometry, of linking telescopes around the globe, was in full flower. So, we had already begun to look at longer wavelengths with less angular resolution on the sky, at galaxies, at stars. And we had come to understand that this was a way of getting the most extreme angular resolutions possible from our planet. What we did was we just took it to the next level.
We said, we can see all the way to the heart of the black hole at short wavelengths, and we can make the electronics now work at these short wavelengths, which had been harder to do prior to the Event Horizon Telescope and everything will converge and we'll be able to make this image of a black hole. So, it was really an advancement of the technology with an idea that had already been around for a while that made this possible.
- So, it really had to happen when it happened because the technology hadn't caught up with the ideas until fairly recently? - Yeah, it was really technologically based, like a lot of the ideas were there and it came at just the right time. And as with all things like this, you need a few crazy people who are willing to champion this and risk their careers on it.
So, one of the first things we did was we said, even with this short wavelength, even with the Milky Way Galaxy, there as a prime target, even with a few telescopes around the globe, we're still short on sensitivity. Given the instrumentation that we had in the early 2000s, we would not have been able to detect the super massive black hole at the center of the Milky Way Galaxy. So, we began to develop this very wideband system.
So, instead of just recording a small sliver of the radio spectrum, we broadened that to record many frequencies. And that took about four years to develop. But once we had that, the increase in sensitivity was dramatic. That proved to be the enabling new capability. And then in 2007, we took the systems to Hawaii, California, and Arizona and we looked at Sagittarius A star. For the first time we discovered event horizon scale structure around a black hole.
So, we knew all of a sudden that there was something really small and that we could move towards real imaging. So it was that moment in 2007, 2008, when we realized that the Event Horizon Telescope could succeed. We had the technology, we had the theory, but now we had the actual measurement that there was something really small there. And that set us on the path. - And I'm curious too about the number of telescopes needed. You said you had eight to make that first image.
So, with the technology that you had at that time, how much would've changed if you had had seven or if you had nine, how much does this change? And also how much more complicated does it become as you add more telescopes? - Yeah, what a great question. So, is eight telescopes enough? So, we did our first experiments with three telescopes and we knew that wasn't enough. We could tell there was something going on there.
It was a great discovery that put us on this path, but we couldn't make an image and we decided to just get as many telescopes as we could and that when we had enough, we'd be able to analyze the data and then this image, if it was there, would emerge. But there really is a piece of the puzzle that set us at this level of eight telescopes. I told you before that we needed more sensitivity and we increased our bandwidth and that was true.
Without that extra bandwidth, this would not have been possible. But in addition, there was a new facility that was just emerging called the Atacama Large Millimeter Array, or ALMA, for short. And it was a new facility in Chile and it consisted of roughly 60 dishes, each 12 meters diameter. If we had recorded data from one of those dishes, we might have been able to pull this off.
But we realized that if we got all those dishes in one area to act as a single dish, if we could add all the signals from those 60 dishes, we would have effectively a gigantic dish. And that would increase our sensitivity, again by a factor of 10. So, we took our time and we developed a whole system over about seven years to phase up or combine all of those telescopes together. And while we were doing that, other telescopes were made ready.
So when ALMA was ready, we had seven other dishes and then we kicked off our observations in 2017. we had amazing weather, I mean just absolutely fantastic weather. And it was a combination of having ALMA, having the wide bandwidths, having seven other dishes, and having this amazing weather that put us at just the right moment, just the right time. People say, "Were you lucky?" I think we were fortunate, but fortune favors the prepared and we had spent almost two decades preparing for this.
So when the time was right, we had everything in place and then we were able to make the image. - I remember shortly after I first started working here at Perimeter, this is eight or nine years ago, I was talking to your colleague, Avery Broderick, who works here, and we've chatted with him on the podcast. And he told me, I actually thought he was a little bit out of his mind at the time.
He said, "We're gonna take the world's first image of a black hole, and mark my words, when we do it will be on the front page of the 'New York Times' above the fold." And I said, "Okay, Avery." Sure enough, in 2019 you have a press conference. You issue the image of the M87 black hole. And not only the front page of the "New York Times" above the fold, but all of them, all the major newspapers, it seemed to be, had them right on the front page.
And I'm curious, A, I should have trusted Avery, he knows this stuff better than I do, but also why do you think it captured people's imagination. There are breakthroughs in science that get relegated to page C19, but this one captured the world's imagination.
- True. When we came down the morning after this announcement on April 11th of 2019 and we saw the "Wall Street Journal" and the "New York Times," "Boston Globe," every major newspaper had this picture above the fold, as you say, it really rocked us back on our heels because we had been so focused on getting this image. We'd been so focused on some of the materials that would explain it to the public that we hadn't really thought about where it would land. Right?
Or I hadn't thought about where it would land. I knew it was gonna be big, but the visceral connection with the curious public, and the curious public is they ask the best questions. Like they're really curious, right? And the connection was dramatic. So, we were surprised. I was surprised anyway.
I mean you might have predicted there'd be some play in the media, but you know, I got into cabs and I would say, "Hey, what do you think about that black hole business?" Not letting them know that I had anything to do with it. And they would say, "Oh yeah, it's amazing." You know, and they would start explaining how it was done, you know, and I would say, "Really?" And they were like, "Come on, get with it. I mean this interferometry stuff, it's here, it's now."
You know, so people were very invested in understanding the result, but your question was why? And I think it's due to a few different factors. One is, people are always interested in monsters and there's no bigger monster than a black hole that sits at the center of a galaxy devouring everything that comes near it. All throughout history, Greek mythology, there are these monsters and we're just fascinated with them.
And to be able to see one that you've only heard about before and has been the subject of sci-fi movies, that captured everyone's imagination just to know that it was out there. That's the first thing. The second thing is, black holes are unique in that once you fall into one, you can never get out again. It's a knot that you can't untie, that is scary. So in addition to being a monster, it's also especially scary.
And to know that there's really something out there that's a portal from our world to a place where you can never return from, that captured people's imagination too. And then I think a really important aspect of it was that we did it as a team. There was early work that put all of this on solid footing, you know, on the theory side, also at the early experiments that I told you about.
But to make the image, required connecting people from around the globe, you know, sidestepping borders, all the things that normally divide us as humans. We brought the best people with the best expertise, no matter where they came from, we brought them together to form this team. We used telescopes around the globe and then we used the earth itself, the geometry of our planet as part of the telescope. I mean, you can't get a more kumbaya moment than this, right?
Everybody working together, everybody contributing, the planet itself forming the scaffolding of our telescope and then addressing one of the greatest mysteries that we have ever really contemplated. And then coming with a success. All of that I think just gave people a sense of wellbeing, of knowing that humans could pull together to do something truly extraordinary.
And now that we're faced with things like, you know, the pandemic and we're faced with the climate change, and we're faced with hunger, and all these things that we're gonna have to deal with on a global basis, this is a beacon, this is an exemplar of how we can come together as people to tackle the really big questions. - And your role on this very big team is the founding director of this project. How do you describe your role?
- I led many of the early experiments that showed this was gonna be possible. And that was with a small team. And that for me is probably the thing I'm most proud of. The thing, you know, these early experiments where we had no idea if this was remotely possible and working with a small group of colleagues and seeing for the first time that there was this event horizon scale structure, scientifically, that was the greatest moment I have felt in my career. And that motivated me greatly.
But, my role later grew to be organizing this global effort and while in the early stages I derived most satisfaction from the results, like looking at a graph and seeing, yes, we've seen something that's only like 30 microarcseconds across, it's like amazing. But later ,I began to realize that I was deriving as much satisfaction from organizing this effort, from putting this team together, from getting the theorists together, the instrumentalists together.
And I view it a little bit as herding cats. So, my role was really to get everyone together, to focus us all with a common vision and see it through to the end. That was the most important part. - In 2019, that first image that was released, that was the M87 black hole. Since then you've also unveiled an image of the Sagittarius A star black hole. Can you tell us about those two? Why those two and how are they different? How are they similar? How did you choose them?
- Well, so you're asking how did we choose Sagittarius A star and M87? And in a sense they chose us. We can't engineer the universe, right? We can engineer our telescopes, we can engineer our instrumentation, but we can't engineer the universe, right? It turns out that there are two sources.
Sagittarius A star in the center of the Milky Way and M87, 55 million light years away at the center of the Virgo A galaxy, that are massive enough and close enough that they present a ring of light, this lensed photon orbit around the black hole that we can hope to image. So, we knew going into this that Sagittarius A star was our primary target, and M87 whose mass was a little bit less well-defined was likely our secondary target.
And we observed both of them in 2017 with the Event Horizon Telescope. Why are there only two? That's a mystery. Why aren't there more? That's a mystery. Are there others? Undoubtedly there are others and new instrumentation that we're developing will likely bring other super massive black holes into range of our planet-sized telescopes. We'll be able to make measurements of other galaxies and other black holes. But these two were special because we knew that we had a shot at imaging these two.
And what I'd like to say is if I was on a desert island with two black holes, these would be the ones I'd want, right? Because Sagittarius A star is in our backyard. It's our own black hole. But what that means is that it's very faint. It's eating very timidly. So, it glows with just like a faint luminosity. And it's a kind of black hole that is probably at the center of most galaxies out there.
'Cause most galaxies are kind of like the Milky Way Galaxy, small, non-descript, run-of-the-mill, working day black holes that just go out there and do their thing. So, we're able to see Sagittarius A star because it's so close. So, it's one kind of black hole. M87 is a monster. M87 is so powerful that it energizes a jet of material that likely leaves from the north and south pole of this spinning black hole. And this jet is so powerful, it pierces the entire galaxy.
It goes for tens of thousands of light years from the center of the galaxy. You would not wanna be in the way of that jet, right? You wouldn't wanna live too close to that black hole. - Why, what would happen? - It would create conditions that life would never have existed there, right? It would just like vaporize everything. So, what what I'm getting at is that M87 is a different kind of black hole. It's a black hole that's accreting enough matter that it glows very, very brightly.
And so, it gives us a window on a different kind of galaxy. So, what's really wonderful about being able to look at Sagittarius A star and M87 is it gives us an idea of how to study two different kinds of black holes. One black hole that's faint, one black hole that's eating a lot, one black hole that's in a large elliptical galaxy, that's M87, one that's in a spiral galaxy. So, it gives us two different flavors of these black holes. And that's very interesting from an astronomical perspective.
- When you describe the differences between M87 and and Sag A star, like how vast are these differences in terms of power and size? Can you give us a sort of a more terrestrial comparison? - Well, one way of saying it is a Sagittarius A star weighs about 4 million times what our sun does.
So, you would think that if there's a stellar phenomena, if there's a energetic phenomena associated with a star, that you'd be looking at something that's 4 million times brighter, okay, if it scales with mass. But, it turns out that Sagittarius A star is surrounded by such a tenuous gas, such a thin vapor, that even though it's accreting what's around it, it's insufficient to really glow beyond what a normal star would show.
So, there are these stars where the star is being devoured by a black hole. They're called X-ray binaries. So two stars, one of which has gone supernova, is turned into a black hole and then is devouring this other star. Sagittarius A star doesn't really emit more energy than one of those star pairs. That's really extraordinary. You have this behemoth, this 4 million solar mass black hole, and it's the most timid of giants.
So in that sense, Sagittarius A star, the black hole there, is very faint, very quiet. It represents a part of the evolutionary life cycle of a super massive black hole in which it's just not perturbing what's around it too much. M87 on the other hand, is devouring much more, probably a hundred thousand times a greater rate than Sagittarius A star for its mass. And so, it is extremely luminous. It's probably billions of times more luminous than Sagittarius A star.
And it ejects this jet that goes for tens of thousand light years. So not only is it bright, but it's also dynamically disrupting what's around it in a way that Sagittarius A star is not. So, they're very different from that perspective, just in levels of energy and in the phenomena that surrounds them. - And are any of these differences things that we can see when we compare these images?
- In a way, yes, and in a way, no. I hate when people do that, like yes and no. So, when you get very close to the black hole, even though there are some differences, Einstein's gravity determines what you'll see. The space time around the black hole is so warped that even though you have M87, which is accreting at a much higher rate than Sag A star, you see the same ring of light.
And when you look at Sagittarius A star, you see this ring of light, you're seeing the geometry of space time and no matter how you light it up, whether with a bright flashlight, which is M87, or a dim flashlight, which is Sagittarius A star, all the light gets bent into this ring and that's what captures your attention. If you look at things in the time domain though. So, imagine we fast forward a few years, we're going to engineer something called the next generation Event Horizon Telescope.
And the goal is to make movies of black holes, to capture the dynamics, to capture the action around the event horizon. There you'll see something different. Sagittarius A star, because it's 4 million solar masses entrains the matter around it to orbit about every half an hour. So, every half an hour things will move around Sagittarius A star. So, during an evening of observing, you will see a change shape. It will shimmy while you're watching it. M87 is six and a half billion solar masses.
And the dynamical time scale is related linearly with mass. So, the same orbit will take three weeks for M87. So if you look at M87, it will not be changing moment to moment during a night of observing, while Sagittarius A star will be madly spinning. - Even though M87 is the more active, hungry of the two? - Even though on a larger scale M87 is more luminous, it changes much more slowly when you take a picture of it.
So, when we moved to taking motion pictures of black holes, then you will see the movies for Sag A star and M87 be completely different. - So, you've mentioned the next generation EHT, what is that? How does it expand upon the original EHT? - So you ask yourself, well how can we do better? The Earth is only so big, so how do you take the next step? And, I would add that I think it's the human condition to always be restless.
And it's not just for scientists, we wanna do the next thing, but also the curious public. After a while they start asking, okay, so you've made the image of a black hole, what's next? When you think about it, people are really curious about these things and they're not content with what you've done just recently, what have you done for me lately? Yes, you imaged a black hole, yawn, you know, what's next?
(Lauren and Colin laughing) And I get that because people are naturally curious, they push in the same way that scientists do. So, if we're gonna take the next step, we do have to make movies of black holes because this will showcase the difference between M87 and Sagittarius A star. So, I'll give you just a little bit of motivation. The size of the ring around these black holes doesn't change much if the black hole is not spinning or if it's spinning as fast as it possibly can.
These are very important parameters for theorists and observers because if you have a spinning black hole, then you can get these jets that erupt from the north and south pole like the one we see for M87. And if it's not spinning, as we suspect the black hole in the center of the Milky Way is, you don't get these jets. And indeed around Sagittarius A star, we don't see these jets, not yet anyway. The motion of matter around the black hole is exquisitely sensitive to spin.
So let me put it this way, if the black hole at the center of our Milky Way Galaxy is not spinning, it'll take matter about half an hour to orbit the black hole. If it's spinning at its full potential, it would take four minutes. So, you'll be able to see just by looking at a movie if the black hole is spinning or not. So, it gives you a whole new dimension into the fundamental parameters of black holes. So now you ask, well how do we make a movie?
And the the answer is, you wanna be able to engineer your Event Horizon Telescope so that from moment to moment you are able to make a snapshot image of let's say Sagittarius A star and stitch those together into a movie. We were able to make the image of M87 pretty much immediately because it doesn't change moment to moment.
So, we were able to take all the observations from a single night of observing as the earth turned and all the telescopes had different look directions and they filled in this earth-sized virtual lens, we combined all that data to make a still image. For Sagittarius A star it's much more complicated because it's changing its appearance during a night of observing.
So, there we need to make a motion picture camera and we have determined through a bunch of simulations that if we double the number of dishes, if we go from about 10 dishes now to about 20 dishes, that will give us enough coverage in this Earth-size lens so that every five minutes we'll be able to make a new image and we'll stitch those together to make the first motion picture of the Sagittarius A star black hole.
So, when we think about the next generation instrument, we think of a few things, adding more telescopes, that's the first. Broadening the bandwidth even further to make it more sensitive, that's the second thing. And then observing at a higher frequency than we currently do. Right now, the Event Horizon Telescope observes at 230 gigahertz which limits our angular resolution.
But by going to 345 gigahertz and recording that simultaneously with 230 gigahertz, this will give us more angular resolution, fill in the Earth-sized virtual telescope even more and allow us to make movies. So it's those three things, more telescopes, more bandwidth, and more frequencies, that will transform the EHT into a motion picture camera. - And when you're adding those 10 new telescopes, you have to choose 10 new locations where they're gonna be.
Can you tell us a bit about that process of how you choose where to put the new telescopes? - So, it turns out that there are a couple of different factors. One is you can ask yourself, if I could put a telescope anywhere on the planet, where is the place that starts filling in the holes that I currently have in the Earth-sized virtual lens? And you can think that there's some places where you don't have a telescope now, and if you put one there, you would immediately get sharper images.
So, we go through many simulations and we've identified some key sites around the globe that will be very important to populate with telescopes. But then you have to ask yourself, well, I don't wanna put it in the middle of nowhere because there's no power, there's no communication, there are land rights issues, et cetera, et cetera.
So, there's a balance to be struck between where you might be able to put a telescope, where there's already some infrastructure, and where the ideal place for this new telescope is. So, we're playing that game now. We're going to sites in Mexico, going to sites in Chile, going to sites in the western United States. I just came back from Tanzania where we're thinking about putting telescopes in that country because it fills in very nicely this Earth-sized virtual lens.
And we're looking at local universities that can help us. We're looking at local infrastructure where we can use some of that for power and communications for these telescopes. And we've come with a two-phased approach. The first phase will be to add about five new telescopes and that will allow us to make movies of M87 and then we'll add another five or eight telescopes in phase two which will allow us to make movies of Sagittarius A star.
And it's been a blast going to different places around the globe and surveying these new sites. You feel a little bit like an explorer with your pith helmet and you know your adventure pants, you know, going to these these far flung places. And it's a new dimension for us because with the Event Horizon Telescope, we used telescopes that were already in place.
We brought bespoke specialized electronics to these sites so that together they could do something that no one telescope could do alone, but we used existing telescopes. Now we're thinking expansively, where do we put new telescopes around the globe that don't have telescopes right now? And that is very interesting and exciting. - We've received some questions from elementary school students for you and Ria has a question about Sag A star. - Hi, my name is Ria and I'm from grade seven.
And will Sagittarius A get bigger or smaller over the coming years and what would be the consequences if it gets bigger? - Wow, Ria, that's a great question and it's a very intuitive question too because black holes digest all the gas around them and they do grow because nothing can ever escape from a black hole. It's always gaining weight, it's never on a diet, right? When you think about that. But it turns out that Sagittarius A star is in a phase right now where it's eating very, very slowly.
I think the way to say it is that if Sagittarius A star was a person, the way it's eating is equivalent to that person eating a grain of rice in a million years. - Oh my God. - That is the level of starvation. I may have that wrong. I know it's a grain of rice in a human for a very long amount of time. I think it's about a million years. It's not gaining weight at an appreciable level. So, over the course of like a human time scale, we won't see Sagittarius A star grow at all.
But if it were to grow, we would see the ring of light surrounding it increase in size, we would see the time it takes matter to orbit the black hole increase. So it would wouldn't take half an hour, it may take 40 minutes or an hour to orbit the black hole. If we're growing appreciably, we would see it with the Event Horizon Telescope. Unfortunately, neither Sag A star nor M87 really is growing fast enough for humans to see it.
Maybe a million years from now, our ancestors will say, "Hey, Sagittarius A star has grown," but we won't. - And talking about the NGEHT and what may come after it, there's another question from a student named Jackson. - Hi, my name is Jackson and I'm in grade eight, and my question is, how detailed do you think the images of black holes will be able to get? - Oh, what a great question, Jackson. And that's what consumes us all the time, right? - Thought you'd like that one.
- The only thing we think about is how sharp can we make these images? So, lemme put it to you this way. We've seen this ring of light and it's a little fuzzy, I'll be the first to admit that. But the reason it's fuzzy is not that we made a fuzzy picture, it's that we are at the absolute limit of what astronomers can do.
We've seen this ring, it's a clear ring, but we're at the limit, but we're motivated to take an even sharper picture because we think that that ring is actually a compilation of an infinite number of rings. We see some of the light gently bent around the black hole, that's what we call the n equals zero ring. But there's some light that does a U-turn around the black hole and that creates an even thinner sub-ring closer to the actual photon orbit and within that larger ring.
And then, there's some light that does a full loop to loop around the black hole, that creates an even thinner ring. And when you think about it, there's an infinite nested number of rings that go closer and closer to the true photon orbit. And if we could see past the n equals zero ring. This ring that we've already seen, and we could resolve the very, very thin ring just interior to that.
That ring so closely holds to Einstein's equations that we'll be able to, in a single stroke, read off the spin of the black hole, look for deviations from Einstein's theory at a much deeper level than we can now. So, we're actively focused now on being able to see that and we think that with the Next Generation Event Horizon Telescope, we'll be able to see that first inner ring and make our image of Sag A star and M87 sharper by many factors, right?
So, we're aiming at exactly what Jackson is thinking about and then we can think even more expansively and ask, can we make a telescope larger than our planet? And there we're thinking about launching a satellite so that the size of the telescope would be about the distance between telescopes on the Earth, but the distance between telescopes on the Earth and a distant satellite. And that will allow us to see these infinite nested rings using a different technique, using space interferometry.
So, it's all very exciting. - Is that the next, next generation EHT? - Yeah, yeah. Well, so we have different names for these things. The Next Generation EHT is on the Earth. And then we have this event horizon explorer concept, which takes a satellite, launches it into like a mid-Earth orbit or a high-Earth orbit. And that will give us the anger resolution necessary to begin to see these inner rings with high degrees of clarity. So, that's where we're going probably after the next decade.
So, first will be the NGHT on the Earth, then we'll be expanding into space. So, if you thought that building an Earth-sized telescope was hard, just try launching something into space to do the same thing. I mean everything is harder in space. Launching the atomic clocks that are necessary is very, very difficult. Getting the data back from space is very, very difficult. Knowing the precise orbit is very, very difficult. So, everything gets harder when you launch a telescope into space.
But, we think we have a handle on a lot of the fundamental concepts. So, we think this really is possible in the same way that we thought the Event Horizon Telescope was possible. I wanna add one thing. So, you asked before about how the Event Horizon Telescope works, and we do use telescopes at different parts of the globe. We record the light and we combine that light to create a telescope as big as the Earth itself.
But, a key part of it is that we have atomic clocks at each of these locations because when the radio waves come in from the black hole, you can think of them as crests and troughs. Troughs coming in from the black hole, these radio waves. We need to be able to align the radio waves that we record at one part of the earth, exactly with the radio waves we record at another part of the earth.
So, we need an atomic clock so we can time tag all the radio waves that we get at both these locations so we can line them up perfectly. If we don't have a really stable atomic clock at both these locations, then you can think of it as like the waveforms would be jittering back and forth. If they're stable, then we can line them up perfectly and that's how you make this Event Horizon Telescope work.
So, getting one of these atomic clocks into space and not disrupting it or not breaking it during launch or something like that, that is quite a challenge. - There's just so many pieces that clearly have to fall into place to give us that one image of a black hole. And I'm just curious, how many failed images did you see that you might have expected? I might see it today and then it just didn't look like what you expected?
- Well, I love that question because in this business you have to embrace failure. Failure is your companion. Failure is not a problem. If you're not failing early on, you're not really doing your job. So first, I'll address your question about the images, but first I want to go back to 2006. In 2006 we tried to make our first detection of event horizon scale structure for Sagittarius A star.
And we went to Hawaii and we put specialized instrumentation on the Caltech Submillimeter Observatory, which is a telescope on the summit of Mauna Kea on the big island of Hawaii. And we also put this same kind of instrumentation on a telescope in Arizona, the SMT, the Submillimeter Telescope. And we failed. Everything seemed like it was working correctly. All the instrumentation seemed like it was going well, but we didn't get any detections, nothing worked.
Even when we steered the telescope towards very, very bright objects, we thought for sure we would see it. We didn't see anything. And we spent months pouring over the data. It turned out that a little piece of metal had fallen into the superconducting junction of the telescope in Hawaii. So, we were receiving the radiation from the black hole, but the wave form was jittering back and forth because that little piece of metal was ruining all the phase of our waveform.
So, it was vibrating in there and causing the whole waveform to move back and forth. We were doomed from the start. And it was only afterwards, like months later, that we realized the problem. And then we had to dust ourselves off, pick ourselves up, get our heads in the game again, we were horribly, you know, saddened by this. And the next time we went out, which was in 2007, we added another dish in California to make the whole array more robust.
We triple checked everything 'cause we learned from what had happened and then we succeeded that year in discovering horizon scale structure around Sagittarius A star. So, failure is important and you have to be resilient, but also learn from it. On the images, for M87 in 2019, we were very fortunate because the signal was so strong that you could even look at the raw data and you could see there was something that was ring-like.
I'll never forget, I was at a dinner at a conference and one of the postdocs who was deeply involved in the analysis of the data, his name is Amachek Vilgas, he came and he showed me the freshly calibrated data and I think there's somewhere in the internet, there's a picture of the two of us just like looking at this computer screen. Like, oh my god, I think I'm like pointing. Like that's it, and Amachek is beaming, right?
And that was the moment where we realized, even though we didn't have an image, that there was something so crystal clear that we were seeing this ring of light around the black hole. So, for M87 we were lucky and fortunate. Fortunate, not lucky, that nature provided us with this very, very clear signal that we could see with the instrument. So, there weren't too many false starts.
We did separate the team into four separate imaging groups because we wanted to make sure that if we did see a ring, there wasn't cross contamination. So, we didn't want everyone in one room and someone says, "I think I see a ring" and then someone else says, "Oh, me too, I also see a ring." And pretty soon everyone says they're seeing a ring. So, we kept four groups totally separate. We gave them all the data, but we didn't let them talk to each other.
And then in July of 2018, we all came together at the Smithsonian Astrophysical Observatory in Cambridge and each group showed their image and you could see immediately that we had four rings. And that was the moment when we all realized this signal is so clear that even four different teams that are working with different algorithms, different approaches, all found the same structure. That was when we realized that we had a discovery of great magnitude on our hands.
- What was the mood in the room at that point? - Pretty subdued. No, no, it was like, we were like going crazy. It was absolutely a joyful celebration and the fact that we had all done it with different methods, right? And we all got to the same point. That was really something. I like to think of that as being like a beer stein moment. Like, we were clinking our beers, we were like drinking. It was a moment of real comradery.
The champagne moment was really unveiling the image and it's a very important distinction because even though we had this great result and we were convinced it was right, we spent another six months doing everything we could to make that ring go away. Because if you're going to come with a great result like that, you have to be your own worst critic. So, we tried to model it with two bright sources on the sky. We tried to model it with a filled disc with no shadow.
We tried to model it with elliptical rings, not circular rings. We did everything we could to fit the data in a way that would not have corroborated Einstein's theory. And it was only after we had ruled everything out with high statistical significance, then we realized that we had something that all astronomers, all physicists, everybody would look at and agree, this is a very robust result.
It's an amazingly important and indispensable part of the scientific process, being your own worst critic, because you will fool yourself. You are the easiest person to fool. So, splitting us up into teams, red teaming this over the course of six months, that's what gave us confidence.
And then I would say even then waiting until we had Sag A star, waiting until a completely different object in a different part of the sky, different mass, also showed this ring structure, that now has beyond any doubt showed us that the Event Horizon Telescope has seen what Einstein predicted 100 years ago. - Is there any limit in the Next Generation EHT, or the Event Horizon Explorer?
Could you see other black holes beside Sag A star and M87 or is there a limit to the resolution that you can get? - So, there are two ways we might increase the number of sources for which we can image the event horizon. So, one is that we'll be able to go deeper in sensitivity. So, there are some sources out there, we just need to find them and they might even be as big as Sagittarius A star, as big as M87, but they're too faint right now for us to see.
So, by increasing the bandwidth, increasing the size of our telescopes, we may be able to see those. Okay, that's one area that we're examining. And with the Next Generation Event Horizon telescope, we are predicting that we would see at least a few more of these super massive black holes.
One of the postdocs working in our group, or he was a postdoc, now he's a staff member, Dom Peche, has gone through very detailed calculations showing that we are likely to see at least a few more with the Next Generation Event Horizon telescope. The other possibility is that we could increase the angular resolution.
And we know there are some sources right now that we can see with the EHT that are very bright, that were sensitive enough to see already, but we don't have the angular resolution to see all the way to the event horizon. And by going to higher frequencies, let's say to 345 gigahertz, maybe even 450, dare I say it, 690, we're dreaming, right?
If you did that, then even from the surface of the planet, you'd have enough angular resolution to zoom in on some of the sources we are already looking at to potentially see these event horizon scale structures. So, we're coming at this from a number of different angles, from sensitivity, angular resolution, on the planet, in space. Everything is geared towards giving us better images of the sources we currently have and increasing the number of sources for which we can do this.
- You have mentioned that these projects are huge team efforts, and I know we have a lot of students that listen to this podcast. So, can you speak to the role that students and early career scientists play in these big team collaborations? - It is so important to talk about this. This is not a bunch of experts who have long been working on this for their entire careers, alone, bringing this result. In fact, it's the early career people.
It's the undergraduate students, the graduate students, the postdocs, the early career scientists who have put the energy that's required into this project to make it succeed. And I would go so far as to say that we would not have succeeded if we had not created an environment that made it comfortable for all of these early career students to dedicate a big portion of their lives to this.
It's one thing to have this idea early on, it's a completely different notion to work 24/7 and to dedicate yourselves as a young person to this. It was the early career astronomers that allowed us to succeed in this. So, to all the students out there, to the early career people, there is absolutely a place for you to make substantial, even formative contributions to these kinds of projects. So get involved, find something that other people aren't working on, throw yourself into it.
It will always be of great value. I can't stress that enough. - Well, on the topic of students, there's another question here. This one's from Reba and it's about general relativity, which has come up earlier and hoping we can talk a bit more about it. But Reba, take it away. - Hi, my name is Reba from grade eight, and does Einstein's theory of relativity work near a black hole? - Wow, so Reba, that is exactly one of the questions that we set out to answer with the Event Horizon Telescope.
So, the answer is we don't know for sure. With theories like this, you can only make ever better measurements. And what I would say is that we know that Einstein's theory has to break down. I said it. Okay? The reason is that we do not yet have a way of understanding how the quantum world and general relativity merge.
And we know that somewhere inside the black hole, this has to happen because inside the black hole, once you go through the event horizon, things get so dense and the gravity is so strong that gravity and the quantum world merge. Okay? So, we know there has to be a new theory that will emerge inside the black hole. We are testing for Einstein's theory, we are testing the validity of Einstein's theory around the black hole.
Currently, all the measurements we've made with the Event Horizon Telescope are consistent with general relativity. So, we have made these black holes, these super massive black holes, the most extreme laboratories in the universe. And we are testing Einstein's theory in these laboratories. So far, those theories are passing all of our tests, but as we get better and better observations, as we get more precision, we'll be able to test it even more.
Now, whether or not we'll find that Einstein's theory breaks down outside the event horizon, which is all we have access to, that's an open question. There are some theories that modify Einstein's gravity and we might be able to see some effects. So that's what I impels us, that's what motivates us to make better and better images using the Event Horizon Telescope or the Event Horizon Explorer. Reba, we're on the job. That's what I can tell you.
We're moving in that direction and we don't know where we're going, but we know that we're gonna get better and better estimates. - There's actually one more student question that I'd love to hear your response to. This one is from Vera. - Hi, my name is Vera from grade eight, and I was wondering if we could live inside of a black hole or if it's even possible? - Wow. Okay, so that is also a very interesting question. Once you fall into the black hole, something very interesting happens.
You know, the time axis and the spatial axis flip. So, there's no way you can escape the black hole. And in fact, any path you're on moves you closer to the center of the black hole. So in a finite amount of time, you will reach the center and you will be ripped apart. - Ah, okay. - So, you could live inside a black hole for a while probably, but it wouldn't be forever.
As an example, if you pass through the event horizon of M87, you wouldn't be ripped apart because the differential gravity between your feet and your head is minuscule. So, you would go through the event horizon and you would still be, if your friend went with you, you'd be chatting with them, you'd be able to have a cup of tea, you know, but you would be inexorably falling to the center. There's no way you could back out at that point, right?
So you could have a little vacation maybe, but you're not gonna be spending a lot of time before you zoom into the center and truly are ripped apart. - It's a one-way ticket. - It's a one-way ticket. Now, there are ways of viewing the universe. I mean, there are some people and some formulations that describe the Big Bang as a black hole and that we are kind of inside of a black hole.
So, there's a way in which we could potentially be living inside a space time that's equivalent to a black hole, that's more theoretical. But, if you think about just about falling into a black hole, you'd have only a finite amount of time to enjoy yourself. - And you wouldn't be able to tell anybody what it was like. - And you couldn't, yeah, no postcards from that vacation. - Right.
You spoke about the next stages of the EHT and the NGEHT as making movies of a black hole instead of still images. And I have to ask, when you mentioned movies, has Hollywood ever gotten a black hole right? - So first of all, I love a good sci-fi movie and really astronomers and physicists I think love to see what Hollywood's gonna come up with next when they depict a black hole.
I guess the closest true depiction of a black hole came with "Interstellar" because, of course, they had Kip Thorne who's, you know, won the Nobel Prize for gravitational waves consulting on that movie. And they got it just about right for a very particular kind of black hole. So, the kind of black hole they showed in "Interstellar" has a thin disc orbiting the black hole and it's lens over the top and on the bottom. So, you wind up seeing this kind of iconic ring with a line drawn through it.
But when I talked to Kip, I said, "You know, that's not quite right." And he said, "I know, right?" So, Kip knows that there was a problem with this because when you're looking at it, part of the emission should be coming towards you near the speed of light, and part of it should be going away from you. So, that disc part of it's coming towards you, like this side is coming towards you, this part is going away from you. So, part of it should be much brighter than the other part.
The part that's coming towards you is Doppler boosted, kind of in the same way that a train whistle is higher in pitch as it's coming towards you and it's lower in pitch as it's going away from you. One side, the side that's coming towards you should be brighter around a black hole. And the part going away from you should be dimmer. And in "Interstellar," they didn't do that because I think they thought that the public in the theater would not be able to appreciate why that was the case.
So, they made it uniformly bright all around. So, have they gotten it right in Hollywood? I think they've done a lot of things right, but sometimes just for cinema, they cut a couple of corners. - Was science fiction your first introduction to the idea of black holes, or was science your introduction? - Well, my first introduction was my father Nels Doelman. He was a high school science teacher.
I remember him telling me about X-ray binaries, like Cygnus X-1, which was one of the first possible black holes. And he had some books in the library at home on general relativity. And he's a very curious person, and I had great conversations with him and that got me thinking about black holes and not really in an academic sense, but just knowing they were out there and understanding that these kinds of things existed. And that's a very nice memory.
And then thinking about science fiction, of course, then you start to think about, you know, stories you've read and stories about neutron stars, about black holes. I mean, there have been some great failures, frankly, there were some depictions of black holes as portals to like, hell, or things like this, which got very, very scary for me as a young kid. And I think when things go in that direction, it gets problematic because you can mix a lot of different emotions with a black hole.
In truth, I think that's part of their power. I mean, you can imbue them with like cultural, even like religious meaning, and that's because they are such strange objects, right? So, it's part of the whole package. They're very powerful, they're very meaningful and you can ascribe to them a lot of different attributes and that's part of what makes them so compelling.
- So, on the topic of how you went from someone interested in some of these topics to doing them for a career, Avery Broderick told us that we had to ask you of some of your earlier experiences. I think after you finished your undergraduate degree, you spent some time in Antarctica. Could you tell us a little bit about this? - Oh yeah, I did. When was that? So in 1986, I graduated from undergraduate. I went to Reed College and studied physics there. And I was a little bit burned out at the time.
Many people leave undergraduate and they're like, wow, that was intense, and that's how I felt. And I saw a poster when I was thinking about what to do next for a program where people went to Antarctica to look after all the experiments that were set up there for astronomy. And so, I applied for that and I got the position and I wound up going to Antarctica for a year. I lived at McMurdo Base on the coast of Antarctica.
I also went to the South Pole a few times to help set up some equipment there. And that gave me a really interesting perspective in a couple of ways. It showed me that you could do really interesting science at remote sites in very difficult circumstances and what it took to do it. And I kind of fell in love with the swashbuckling aspect of doing science, you know, going to a difficult place, making it work. And that has colored my entire career.
It also taught me how to deal with a lot of different people because in Antarctica you had this very interesting mix of the Navy, which took care of a lot of the construction and the meteorology and some of the day-to-day comforts at the base at McMurdo. You had the Air Force, which was doing all the flights in. You had construction workers who were building new dormitories and helping with construction of laboratories.
And you also had the scientists funded primarily by the National Science Foundation at those sites. And I got my first taste of seeing how different communities work together and that each community plays a very vital role. And you can't just be a scientist in that remote location. You can't just be someone involved with construction. You can't just be in the military. You need to find a way for everyone to work together to make that base function.
And if you wanna do science in that environment, you need to work with a lot of different people. So in addition to working in a remote site, it also taught me how to deal with people. And that has helped, as you might imagine. - That's funny, to learn how to deal with people, you go to the continent that has the fewest people on Earth, but they're all working toward a sort of common goal? - Well, that's a very interesting point.
Often it is in these extreme environments where people come together, it's not an accident. When you're just happy and you're content, you make friends and you are often with people who believe the way you do. You're often with people who think the way you do. Maybe even at work, you're with people most of the day who do the things you do.
But it's when you go to a unique environment and you are focused on a very interesting mission that requires many people come together, that's where you really need to broaden your perspective. So it's in these extreme environments, it's in these experiments where you've gotta have people coming together. And coming back to something that we talked about before, if we're gonna address the big problems that face us as humanity, we're going to have to come together.
Solving a problem like climate change is not gonna happen because a bunch of scientists get together. It's gonna happen because industry, politics, science, the general public, even like cultural, religious leaders, all come together and realize this is a problem that faces everyone. So it's in these extreme environments, it's in these turning point problems that face us as a planet. This is where people have to come together. So, I don't think it's an accident.
I think it's almost by design that we're thrown together in these unique moments. - And when we do face such terrestrial challenges of climate change and politics and everything else, why is it important for us to look at black holes, millions of light years away, that won't necessarily affect our day-to-day lives? - So, it's a really interesting point. We have so many things facing us now, why pay attention to M87? Why look at the center of the Milky Way Galaxy?
The best answer I have is that you need to play the long game in any financial portfolio. So, this will make sense to people who are saving for retirement and things like this. You need to have your blue chip stocks, which are going to do well over time. You also wanna have some more high risk element of your portfolio. Like any normal financial manager will tell you this. And it's the same thing with science. It's the same thing with business. It's the same thing with really humanity.
You need always to pay attention to the here and now. You need to pay attention to what's in front of you. Part of you needs to be thinking about the future and sometimes the far future and investing in basic research that doesn't necessarily pay off tomorrow is never a bad idea. It always pays off in the long run, always. And I think more than that, it speaks to the human condition because we're conditioned now to think about the news cycle. Every Tuesday something happens.
And if it's not this Tuesday, you forget about it. We are used to thinking about the quarterly bottom line, how is my company doing and how will I report to the shareholders? We're thinking about the next election cycle. A couple of years down the road, who will be leading the country and what kind of politics should we be dealing with? Science and the pursuit of basic research is the deep rudder in the water. It is the long game that we play.
It is what connects us across the centuries to the thinkers that came before us. It's really what defines humanity. We are not what happens this week. We are what happens over centuries. We are what happens over millennia. We are building the history that people will look back on later and say, "These people were thinking about the deepest mysteries of the universe."
If you went back and talked to Einstein and you could go in a time machine and say, "Einstein, 100 years from now you'll be able to use your phone. And using a constellation of satellites, you'll be able to pinpoint your location on the earth using your theories." As I like to say, he'd be very excited, but of course he would just say, "What's a phone?" Right? Because it's so far beyond his conception. He didn't even know what phones were back then, right?
So, he didn't realize that unless you make general relativistic corrections to the GPS system that we all rely on to get us from point A to point B in our cars, if you don't make those corrections, you're off by miles. But, he never could have known that. So, we are making the discoveries today with basic research that are not gonna pay off until maybe 100 years from now. But we'll look back and say, "Ah, that was so important to think about." And I will add one more thing.
If you only look at the things you know, if you only try to make the ideas that you currently understand better, then you're doing engineering. And engineering is amazing. I consider myself to be an engineer. In fact, my job title is engineer and I love it. But if you limit yourself to engineering what you already know, then you're missing out on the new ideas. So, you need to be asking these big questions.
You need to be looking at M87 and Sag A star because they will lead you in the directions that you have no idea about now. And many of those will not pay off, but the ones that do will be truly new windows on the universe. And that's what humanity I think should be focused on. - Well, I think that's a beautiful sentiment to wrap up on. Shep, thank you so much for this conversation. - It was a real pleasure. Thank you both. - Thanks for stepping inside the "Perimeter."
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