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Matthew Bothwell, "The Invisible Universe: Why There's More to Reality than Meets the Eye" (Simon and Schuster, 2021)
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Interviewer Gregory McNiff
Welcome to the New Books Network welcome to the New Books Network. I'm your host Gregory McNiff, and I'm excited to be joined by Matthew Bothwell, the author of the Invisible why There's More to Reality Than Meets the Eye. The book was published by One World Publications in the United States in December of 2021. Dr. Matt Bothwell is a public astronomer at the University of Cambridge and a science communicator who gives astronomy talks and lectures on almost any area of astronomy and makes regular media appearances, including local and national TV and radio, as well as podcasts. When he is not doing research, Matt is an observational astronomer who uses a range of state of the art observing facilities to study the evolution of galaxies across cosmic time. As you'll see, he's well versed in all fields astronomy, cosmology, and everything in between. So why I selected the Invisible Universe is because it explains in plain terms that most of reality cannot be seen with our eyes, even though it shapes everything we observe. The book shows how scientists learn to, quote, see the universe using tools beyond ordinary light, such as radio waves, infrared radiation, and gravity itself. It's a clear, thoughtful guide for readers who are curious about science but don't have a technical background. I think the Explanations are wonderful without simplifying them. There's maybe an equation or two, nothing to be afraid of. And it's really just a wonderful overview of cosmology and astronomy. And Matthew makes a distinction there that really offers a great insight into the fields and the scientific progress and where we're going with that. Matt, thank you so much for joining us today.
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Matthew Bothwell
Yeah. How's it going? It is great to be here.
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Interviewer Gregory McNiff
Thank you, Matt. I'll start with my standard question. Why did you write the Invisible Universe? And who is the target audience?
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Matthew Bothwell
I guess this is a slightly pass answer to why I wrote the Invisible Universe. I started writing it in around April of 2020 and it's kind of because I had nothing else to do. Right. Like the rest of the world, I was trapped in my house on my own, doing not very much at all. I've been wanting to write a book for a couple of years before then, and it was really a case of, if I don't do it now, this is the greatest excuse ever, Right? If I don't do it now, this is never going to get done. So it was a mix of having wanted to write a book for a while and also the pandemic giving me an excuse in terms of who the target audience is. I really wanted to write it for people that just had no knowledge of astronomy at all, for complete beginners. There was a bit of conflict with my editor about that because he very correctly raised the point that complete beginners that know nothing about astronomy don't necessarily want to pick up a book about astronomy. I think I managed to win the argument. So the book really doesn't assume anything. So it's designed to not patronise people, but take complete beginners who really don't have any kind of physicsy astronomy, sciencey background and take them all the way to the coal face of cutting edge research. Basically, that's what I tried to do. Hopefully it was somewhat successful.
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Interviewer Gregory McNiff
Oh, absolutely. No, like I said in the intro, I think you did a wonderful job of condensing a fair amount of information and history in a very thoughtful manner. I want to jump right in here. In the opening chapter, you note that most of the universe is completely invisible. Why can't we perceive the universe through visible light alone? I mean, why don't we just build a bigger, more intense, more powerful telescope? Is it just a linear, you know, just bigger lens and more set, or what's the impediment there?
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Matthew Bothwell
Yeah, that's a great question. And to some extent, yeah, you say like, you know, why can't we just build a bigger and bigger telescope? And in some sense we do. We do try and build bigger and bigger optical telescopes to see the light we see with our eyes in a better and better way. But I think it's almost better to back up a little bit and just think about why is visible light visible light. So what we call visible light, what we think of as normal light, if you like, is really just an accident of evolution. We live around sort of a standard orangey star. And the wavelengths of light where the sun is brightest are the wavelengths of light that we evolve to be able to see. The kind of obvious biological reasons. But it turns out that is just a tiny, tiny sliver of the whole electromagnetic spectrum. I open my book with this analogy, which I've used before, which is, if you think about the wavelengths that we can see, the reddest light we can see is about 700 nanometers.
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Interviewer Gregory McNiff
Ish.
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Matthew Bothwell
The bluest light we can see is about 350 nanometers. So that's about a factor of two in wavelength. And any musicians will hear a factor of two in wavelength and think, okay, well, that's an octave. If you're sitting in front of a piano, you play a middle C, and then you play a C1 octave higher. Those notes will differ by a factor of two in wavelength. And so in the book, I draw this analogy and say, well, we can sort of see one octave's worth of light. The entire electromagnetic spectrum that astronomers make use of these days from radio waves all the way down at the low energy side, all the way gamma rays on the high energy side is about 65 octaves. And so we can see one of those 65 octaves. Right. So visible light is just this tiny, tiny, tiny little fraction of all the information that's out there. And we'd be sort of crazy not to make use of all that extra information.
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Interviewer Gregory McNiff
Absolutely. And I want to talk to you about how we do that and the specific tools. But could you define light and why you suggest the speed of light is, quote, so slow, which I think is certainly different than what we normally hear about light being, well, nothing being faster than light, as far as we know. There might be some discussion on quantum there. But could you briefly talk about light and why you suggest the speed of light is so slow?
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Matthew Bothwell
Yeah, sure. So what is light is. I don't know if that's an easy question or a hard question. So it's a. I think it's an easy question if I keep the explanation simple, right? And we don't get into quantum philosophical weeds. So light is just the excitation of the electromagnetic field. Right. So the universe contains an electromagnetic field. And where it's excited, that comes in the form of a photon or a wave, if you want to think about it that way. And these waves of electromagnetic radiation travel around the universe. They're given off by hot things like stars, and then they travel around. Why is the speed of light so slow? And yeah, I sort of call the speed of light slow in my book. I think mainly to get a rise out of people because I think it's quite funny. Funny thing to say, like slow and fast relative terms. Right. I think what I wanted to do was just reframe light from more of a cosmic perspective. We think the speed of light is very fast, but only because we're so tiny compared to the universe. Right. The speed of light can go about seven times around the world in a second. That's unbelievably fast. Right. It makes the speed of sound look like it's standing still. But if you, for example, take a map of the solar system and look at the light rays coming out of the sun and you press play, naively, you might expect them to start flying through the solar system in a kind of science fiction sped up way, but they don't. They crawl through the solar system. If you look at that on your screen, it's like a pixel by pixel crawl. And from a cosmic perspective, light can take millions of years to travel between the galaxies. And in a way that's kind of lucky, right. If light was really, really fast, light wouldn't be able to teach us about the past in the way that it does. If the speed of light was a thousand times faster, then light from the distant universe would only be telling us about the kind of the recent decades. Because light is so kind of cosmically slow and takes these millions and billions of years to travel around the universe. The signals we get from the distant universe tell us about the deep past of the universe. So, yeah, it's kind of lucky that light is so cosmically slow, if you think about it that way.
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Interviewer Gregory McNiff
Yeah, absolutely. I think I will probably mis. Paraphrase, but you have. The farther we look, the further we look backwards, so to speak. And it's fascinating. Yeah, exactly how we can, I guess we can almost get back to the Big Bang and have pretty thoughtful understanding of how we think roughly. The big bang transpired 13.8 billion years ago. And light is definitely a big part of that. I should ask you could you define the electromagnetic spectrum. And briefly, I guess I realize that's probably another whole book in and of itself.
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Matthew Bothwell
No, no, sure. So the electromagnetic spectrum was a fairly late discovery, right? It didn't come until towards the end of the 19th century. The discoveries that led up to it, right? The pieces of the puzzle, if you like, were the discovery of. Well, I was going to say the discovery of light. That's not really discovered, right? You just open your eyes and there it is. The discovery of the infrared part of the spectrum by William Herschel, who was. He was looking at the sun and he noticed that beyond the red end of the spectrum. He did the Isaac Newton kind of experiment, right, where you take the sunlight and you split it up with a prism. And he noticed beyond the red end of the spectrum there was an increase in temperature. And so he figured out there was some invisible stuff in sunlight which we now call infrared. And then a few years later, someone else noticed that if you put certain chemical experiments beyond the blue end of the spectrum, they speed up. And so he's figured out, well, there must be some invisible stuff in the spectrum beyond the blue that's affecting chemistry. And we now call that ultraviolet. And then for a while it was a bit confusing, right? Light started off as this fairly simple thing, and then Newton showed it was made of colors. And then it turns out there's strange invisible stuff going on either side. And then it was a guy called Maxwell, a Scottish scientist, like, genuinely one of the most brilliant scientists that's ever lived that unified all of these different types of phenomena. And what Maxwell said was, well, if we call light an electromagnetic wave, like literally a wave made of electricity and magnetism, then waves can have varying wavelengths, right? Like wavelengths of sound can change. And a high note and a low note have different wavelengths. You said, well, what if there's an equivalent for light? And the equivalent of a high note for light is like blue light, and the equivalent of a low note for light is red light. And it turns out you can just keep on adjusting those wavelengths, stretching or compressing them way beyond our eyes can see. And you end up with a modern view of what we call the electromagnetic spectrum, which starts with radio waves, where the waves can have wavelengths of like kilometers. And then you shrink the waves and eventually the radio waves become microwaves and then infrared and then very, very briefly visible lights as it passes through our visible spectrum. And then as you shrink and shrink, they go to ultraviolet and X ray and then eventually gamma rays, which are these incredibly short wavelength, high powered bits of Light mainly coming from exploding stars and so on. But it's all part of the same tapestry. That's the point. All these disparate phenomena, it's all just light, but it's just light of varying wavelength.
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Interviewer Gregory McNiff
Excellent explanation, not surprisingly. Matt, just follow up here. You write, other than familiar visible light, infrared is the only part of the electromagnetic spectrum that our bodies are naturally able to detect. How, if we can't detect it visibly, how do we detect infrared light?
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Matthew Bothwell
Yeah. So infrared our bodies can detect as heat. Right. People often call infrared radiation heat radiation. If you stand next to your radiator, it's a very cold day in the UK right now. My radiators are blaring because it's frosty outside. I can feel the heat coming off my radiator right now. And what I'm feeling is that infrared radiation being put out. Put out by my heating system.
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Interviewer Gregory McNiff
Perfect. Could you talk about the birth of spectroscopy and why that was so important to quote, seeing the universe beyond our visible. Beyond, you know, our. I guess, an optical telescope.
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Matthew Bothwell
Yeah. So spectroscopy is just what the scientific term for splitting light up into its wavelengths. And I guess if you want to go all the way back, the birth of a spectroscopy is probably Newton, right? Like, he figured out that you could take a beam of sunlight and pass it through a prism and get a rainbow. And there's a little wrinkle to the story which listeners might hope will. Forgive me a tangent. People often say that Newton discovered that light contains this rainbow. But of course, we had known for hundreds of years before Newton that you can split light up into a rainbow using a prism. Right. People didn't know that since ancient times, you make glass and it turns light into a rainbow. But what people always thought was that the glass was imparting the colors onto the light. The idea was that light was pure, then it was impurities in the glass were creating the colors. And Newton had this brilliant experiment where he split light into a rainbow using a prism, and then he put another prism into the path the other way around, and it recombines the colors into white light. And that really showed. Right. The colors are there, inherent in the light. And that's the same thing that we do these days when we do modern spectroscopy. We take light from a planet or a star, star, or some kind of interesting astronomical source. We split the light up into its constituent wavelengths, and that just reveals a lot more information. And the analogy I used is that if the light from a star that's arriving is like a book or something, just like, looking at the color of that light would be like reading the title of the book. Spectroscopy actually lets us read the book word by word and just extract every single bit of information that's in that star.
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Interviewer Gregory McNiff
Oh, that's fantastic. Follow up question to that. Can you talk about the importance of the spectral line in seeing the universe?
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Matthew Bothwell
Yeah. So the spectral line is really where spectroscopy shines, if you don't mind a terrible pun. So basically, inside a star, for example, let's imagine that we're looking at a star. I think stars are a really good example because there was a writer in the 18th century used the idea that we'll never understand the composition of stars as a way of talking about the fundamental kind of limit of science. Right. It was almost like this apocryphal. You know, you may as well try and learn what the stars are made of, because it's completely impossible. And thanks to spectroscopy, we can actually learn what the stars are made of. And it's thanks to these things that you said, spectral lines. So every atom inside our star is going to have sort of, you know, protons and neutrons in the middle of the atom, what we call a nucleus, and electrons around the edge. And the electrons around the edge are going to sort of capture specific wavelengths of light. So if we imagine the star shining and energy coming out of the star and there being like an atmosphere of gases around the star, all of the atoms in that stellar atmosphere are going to capture specific wavelengths of light, thanks to the electrons orbiting around their nuclei. And so when the light arrives here on Earth at our telescopes and we spread the light out into its spectrum, and instead of seeing a continuous smooth rainbow, we see a rainbow with dark stripes in. And these dark stripes are holes in the spectrum, what we call spectral lines. And they are at very, very particular wavelengths. And so carbon, for example, will have a particular pattern of these dark stripes, almost like a fingerprint. Carbon will have one, and calcium will have one, and copper will have one. And when we take the spectrum of a star, we can look at these specific fingerprints and figure out what that star is made of. So we do that with the sun, and we can figure out that the sun is made of hydrogen and helium mostly, but also there's oxygen in there, there's carbon in there, there's calcium in there. And that's all because we can see these patterns of dark shadows inside the fingerprint of those atoms.
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Interviewer Gregory McNiff
Does the mix of the elements in there help us date the star? Is there any way to determine its age?
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Matthew Bothwell
It can do yeah. So younger stars, or at least stars that were born earlier on in the universe, will be more pure. They'll be more just hydrogen and helium. The more heavy stuff is in a star, the later it was born in the universe, pretty much. Astronomers are very lazy. We have a much more simple periodic table than chemists. Right. So chemists use the periodic table that you might remember hanging on your high school chemistry lab. Astronomers are much easier. We have hydrogen and then we have helium, and then we call everything else just metals. So I was terrible at chemistry. I always used to set things on fire. So this makes my life much easier. And so, yeah, the more metals that we have in a star, and that means there have been more sort of previous generations of stars that came before it.
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Interviewer Gregory McNiff
Perfect. And I think we get the lighter elements, like you said, hydrogen, helium from the Big Bang, and maybe some lithium. And I think there might be some barium in there.
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Matthew Bothwell
I'm not sure, but no, I think. I think, yeah, hydrogen and helium and a small sprinkling of lithium is all the Big Bang made. And then everything else was made by stars.
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Interviewer Gregory McNiff
Perfect. So we are, in a way, stardust. Is that.
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Matthew Bothwell
Yeah, exactly. Very, very famously. Right. We're made of stars. But I do think it's worth. That's almost become a cliche, and it's almost worth actually genuinely trying to internalize it. Right. Because it's very easy to say, oh, we're made of stars, but to look at your hand and genuinely think, every single atom in my hand was once inside a star, like, that's just. I don't know, that's. That's kind of mind blowing to me.
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Interviewer Gregory McNiff
Yeah. There is this cosmic connection with the universe that. Yeah, mind blowing. Exactly the right word. I want to ask you about a statement you have relatively early in the beginning, and I probably should start the interview with this. You write everything glows in the universe. What do you mean by that?
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Matthew Bothwell
Yes, everything glows is. Yeah, it sounds a bit sort of hippie spiritual. Right. I promise. I mean this in a scientific way. So essentially, there's a phenomenon in physics called black body radiation, which I think is. I remember learning about this when I was doing my physics degree, and I remember, I think, thinking it being. It was taught in a kind of. Kind of confusing way. Like, even the term black body radiation, it's not very obvious what that means. Like, essentially, everything in the universe that has a temperature above absolute zero, which is to say everything in the universe, because nothing's really at absolute, gives off radiation according to your temperature. And the rule is, the hotter you are, the shorter wavelength radiation you give off. And so stars, for example, say, like our sun has a surface temperature of about 6,000 degrees ish, more or less. And if you sort of, you know, you go to your physics textbook, you figure out what wavelengths will be given off by something at about 6,000 degrees, and that turns out to be kind of like orangey yellow lights, which is why our sun looks orangey yellow. And if you go back to the same equation and you plug in, for example, about, you know, 37 degrees, I'm talking in Celsius, right. I'm being European. So if you plug in your body, what's. What's body temperature In Fahrenheit?
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Interviewer Gregory McNiff
About 98. I should know this. 98.6.
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Matthew Bothwell
Let me just put you on the spot.
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Interviewer Gregory McNiff
Yeah.
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Matthew Bothwell
You know, you put in body temperature, basically, and then you, you know, you do your math and you will figure out that the light being given off by a body that is the temperature of your body is about 20 or 30 microns. That's in the infrared. And indeed, if you look in infrared glasses, like night vision goggles that the police use to find people hiding in bushes and so on, you can see people glowing at that wavelength. So, yeah, we often think, if you think of taking a piece of metal and heating it and heating it and heating it, and then it starts glowing red, hot. The truth is, it doesn't start glowing. It was always glowing. But before it was glowing deep into the infrared. And then as it got hotter and hotter and hotter, the light it was given off got shorter and shorter and shorter wavelength, and eventually it gets hot enough that you can see the light it was given off, but it was always glowing.
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Interviewer Gregory McNiff
Awesome. I want to ask you about the first infrared telescope in space. I think it's IRAS, or Infrared Astronomical Satellite.
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Matthew Bothwell
Yes, IRAS was a game changer. So it launched in 1983. It was an all sky survey instrument, which is a slightly different telescope than listeners might be used to. So if you think of something like the Hubble Space Telescope, the most famous telescope of all time, Hubble's job is to point at whatever you tell it to point at. So like, if you're a galaxy person, you tell it to point at a galaxy. You take a nice picture of a galaxy, you learn about that galaxy. Or if you're a planet person, you might take a spectrum of a planet and then try to learn about the planet that way. Iras's job wasn't to point at things. It was just to sort of take a broad survey of the sky. Think of like Google Earth or something, right? Like Google Earth just scans the whole surface of the Earth. IRAS scanned the whole sky in infrared wavelengths. And it was really the first time that we learned about what the universe looks like in the infrared. Because the infrared light that IRAS was seeing can't get through the atmosphere. The only way to see that infrared light is to go to space. So the sort of mid-80s was literally the first time we got this new window to the universe. And it discovered all kinds of really cool things. We found these very red galaxies. That's why, you know, they have so much dust in them, obscuring their star formation, that they're almost invisible to the naked eye. It also found one of the biggest puzzles that IRAs revealed was that these whole series of stars were normal stars to the light we see with our eyes, Right? If you just look at it, it's a normal star. But it turns out they were really, really, really bright in the infrared. Like way brighter than you would expect in the infrared. And it turns out the reason for that is that they have baby solar systems glowing around them. And those baby solar systems were glowing really brightly in the infrared. And it's a really cool thing in astronomy. Every time we open a new window to the universe, like IRAS was, this new infrared window to the universe, you just see these amazing new things that you would never have expected.
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Interviewer Gregory McNiff
Yeah, no, absolutely. It comes across in the book. And yeah, I mean, it feels like we're still in the early stages. I know you talk about we only quote, see or understand 5% and I want to talk about the other 95% in a little bit. But before that, one thing I found cool is you have a chapter on star formation. You write, the birth of stars is normally a secretive affair. Young stars are born cocooned deep inside shrouds of gas and dust, which are optical telescopes can't penetrate. But infrahead, I'm sorry, but infrared behaves very differently to short wavelength optical light. Invisible light can travel where visible light cannot. The reason for this is a physical phenomenon known as Rayleigh scattering. If I have that pronounced, if I'm pronouncing that properly, could you explain what that is?
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Matthew Bothwell
Yeah, so. So Rayleigh rally. I actually don't know. I've only ever seen it written down. So I'm gonna say, I'm gonna say rally. Scatter.
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Interviewer Gregory McNiff
Go. It would not be the first time. Rally Scattering.
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Matthew Bothwell
Okay, I, I don't know. It's a toss up. I'm gonna say rally, but I think I could be wrong. Who knows? So, yeah, so Rally scattering is the phenomenon where any light passing through, like a gas or something like that is going to be scattered. So imagine playing pinball, right? You launch your pinball up from the bottom and it doesn't just sail around and then plonk back at the bottom, back of the, you know, at the base of the game, there are these like pins and obstacles and you launch your pinball and it will ricochet around the different obstacles. And that's kind of what makes it a game. Well, light behaves in kind of the same way. A photon of light coming through an atmosphere, like some gas is going to sort of ricochet and ping off the different, like molecules of gas in the air. The reason this is interesting for physics is that the amount of scattering, the amount that A light ray is jostled and pinballed around, depends on the wavelength. And the way it works out is that shorter wavelengths, so like bluer light gets scattered more. And that's for example, the reason that the sky is blue. So white light from the sun hits the top of the atmosphere and the longer light in the spectrum, that kind of like red, orange light comes straight through. And the short wavelength in the spectrum, the blue stuff, gets scattered, gets pinballed around and ends up essentially being smeared all over the skies. So if it's a nice sunny day, I'm in the uk, right? So I'm looking out my window and I can just see gray. But you know, if you imagine that it's a nice blue sky above you, that's because of the Rayleigh scattering. It's the short parts of the spectrum being smeared around the sky. And the same is true when we look in space. So stars form in these dusty clouds of gas scattered around galaxies. Dust is very good at blocking and scattering light. So when you look at a star forming cluster, so think of like the Orion Nebula or something, the constellation Orion is very familiar, right? And down below Orion's belt there is a cluster of stars, a patch of gas. It's a stellar nursery where new stars are being formed. If you look in optical light, you can't really see anything. And that's because the dust that's screening all those newborn stars is scattering and blocking all of your light. But you go to the infrared, and if you remember the rule we said before with Rayleigh scattering, the longer wavelength you have, the less you get disturbed by this Rayleigh scattering. Infrared light, because it's longer wavelength, can just waltz straight through the dust and actually see the stuff underneath. It's not scattered as much. And so it actually works as a probe to be able to see these newborn stars.
- [29:27]
Interviewer Gregory McNiff
Oh, fascinating.
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Matthew Bothwell
We use this here on Earth as well. Like firefighters when they go into a burning building will use infrared goggles to try and see through the smoke and the gas to try and see the trapped people.
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Interviewer Gregory McNiff
Yep. Nope. Great example. I want to we talk about star formation. I want to go back to the very beginning here. And can you talk about the role of the Cosmic Background Explorer in helping us detect cmb, Cosmic microwave background?
- [29:55]
Matthew Bothwell
Yeah, sure. So the cmb, we might have to go back even further, right? So we can reach there. But that's the end of quite an interesting story. The story is all about this debate over how the universe began. So if you go back more than 100 years that everyone Sort of generally thought that the universe was sort of static and unchanging. Then Hubble in 1929, Edwin Hubble, one of the most famous astronomers of the 20th century, in 1929, Hubble saw the universe expanding and growing. And as soon as you see the universe expanding, you think, well, it kind of stands to reason that you needed something to start this expansion off, right? And so the idea came about that maybe the universe wasn't static and eternal and just sitting there. Maybe there was some kind of beginning to the universe, and it's all been expanding out since then. And that's, of course, what we now call the Big Bang. But the question was, well, if the universe started with a Big Bang, there should be this sort of evidence around of the Big Bang. The way the argument goes, essentially, is that if the universe did start with a Big Bang, then it must have been all sort of squidged up at the start of time and taking all the stuff in the universe, all the matter, all the energy in the universe, and squidging it up near the big Big Bang. That would make the universe, when it was young, really hot and dense. Then that hot, dense universe grew and expanded and became the kind of cold and empty universe that we live in today. And so if the early universe was really hot and dense, as the Big Bang theory predicts, we should be able to go and see the afterglow of that hot, dense state. And so that's what Kobie finally saw. So COBE was a satellite that was launched in 1989. So COBE was a satellite that launched in 1989, tasked with finding little ripples in this early light, what we now call the cosmic microwave background. So the cosmic microwave background, or the cmb, because it's easier to say, was actually discovered in the 1960s. But what we didn't discover after that was any sort of any structure, any patterns in the CMB. So in the 1960s, astronomers spotted this afterglow radiation from the Big Bang, and that sort of settled the debate. We figured out that the universe had to have started with a Big Bang. And then astronomers wanted to study the cmb, this cosmic background radiation, to get a picture of what our universe looked like when it was really young. And so they built all these kind of microwave telescopes and put them all over the Earth. And they put them on hot air balloons and sent them above the atmosphere to get a better look. And they eventually painted this picture of what the very, very early universe looked like. And it was just exactly the same in every direction. It essentially looked like the early universe was just put in a blender and just completely smoothed out. And that, you know, that was fine to start with. You know, the takeaway was just that, okay, well, just, I guess the early universe was very sort of smooth. Like one part of the early univers was very similar to another part of the early universe. But then, as the decades rolled by and our telescopes got better, the CMB still looked completely smooth in every direction. And it almost became to be a problem, right? Because the universe we live in today is not smooth. It contains all kinds of interesting stuff. Like us, right? Like stars and planets and galaxies and people. We're kind of interesting lumpy structure. The universe that we live in today is a very lumpy, structured place. And lumpy structure has to come from somewhere. You can't start from a perfectly smooth universe and end up with interesting lumpy structure. Those lumps have to be there in small parts, but we just couldn't see them. And it genuinely got to the point in the 80s when people thought the Big Bang was in crisis because there was no sign of this lumpy structure that we knew had to be there. And we solved it by going to space. So this satellite, cobe, is what sort of saved the day eventually. We launched COBE in 1989, and it found these ripples, this lumpy structure, in the patterns from the early universe that proved that what we were seeing was the universe's baby picture and did evolve over billions of years into the universe we see today.
- [34:24]
Interviewer Gregory McNiff
Fascinating. Later on in the book, you talk about why observing the universe at longer wavelengths is so effective. Could you expand on that?
- [34:36]
Matthew Bothwell
Yeah, I think it's just. It's because there's so much stuff out there that you can only really see at long wavelengths. So if you look at the history of satellites that we've launched into space with these infrared telescopes on them, starting with IRAs, but then onto Spitzer and then Herschel, and then, of course, the latest and greatest one that I'm sure listeners would have heard of, the James Webb Space Telescope. They have just revealed so much to us in the universe that we just had no idea about from looking at shorter wavelengths. So one, for example, is that there's a whole class of galaxies in the early universe that are just like the biggest, the most powerful, the most efficient factories for stars. And they're essentially invisible to normal telescopes. We had no idea they were there until we observed the universe at these long wavelengths and saw these ridiculously luminous beacons from early universe. These sort of unbelievably powerful firework shows of star factories. And, yeah, we would have no idea that they were there if it wasn't for these long wavelengths. So everything from those, you know, those amazing hidden galaxies to these baby solar systems that I mentioned that Iras saw to the cmb, like, all of that is thanks to long wavelength observations.
- [35:54]
Interviewer Gregory McNiff
Perfect. I want to move to a chapter I found really fascinating, I suspect most people do, is black holes. Matt, how do we see or detect black holes? And could you give us a little history there? It seems like we got the theory right, and here I'm talking about Schwarzschild and maybe Ray Kerr. Before we actually had visible proof of
- [36:14]
Matthew Bothwell
a black hole, we did. So black holes are a. They fall straight out of Einstein's field equations, basically. So there's a fun piece of history here. So, like, Einstein came up with his theory of general relativity, and this was in 1915, and Einstein himself thought that his equations were just too difficult to solve. But it was only a few years later that this brilliant theoretical physicist mathematician called Karl Schwarzschild was able to solve Einstein's equations and come up with different descriptions of objects that can exist in the universe thanks to Einstein's theories. And one of them was this very strange thing that we now call the black hole. So Schwarzschild was able to show that one solution to Einstein's equations was this sort of infinitely small, infinitely dense dot of spacetime. That seems sort of ridiculous, and I'm not totally sure. Maybe we should ask a historian of science. I don't know if Schwarzschild thought that these things physically existed, or they might have just been like a novelty that fell out of the equations. But this was like 1920s, I think, and it was going to be decades before anyone actually saw one of these things.
- [37:34]
Interviewer Gregory McNiff
Perfect. And then could you talk about how we actually detect black holes?
- [37:39]
Matthew Bothwell
Yeah. So black holes are famously black. It's sort of their defining feature. Right. So what a black hole is. So I talked about a black hole being a solution to Einstein's field equations. It doesn't really describe how you get a black hole in the real universe. What a black hole is for a sort of an observational astronomer, is a collapsed, dead, massive star. So a very, very big star, sort of 15, 20 times heavier than the sun. When they are at the end of their life, the outer parts of this star explode away, and the inner core of this star squishes down smaller and smaller and smaller. And it turns out there's so much gravity compressing the core of the star that there's just no force in the universe that can stop it collapsing down, essentially infinitely small. And so you end up with this infinitely small point that still has the mass of a star attached to it. And it turns out when you do that, the escape velocity of this object, like how fast you have to go to escape, the gravity, becomes faster than the speed of light, which means that even light approaching this little heavy speck in space will get swallowed up. So that's how they get their name, black holes, which you would think means they are impossible to detect. Right, because black holes are black, and space is quite famously black. How do you detect something black on black? Well, the way astronomers detected the first black hole was that they found a binary system which is sort of two objects orbiting around each other, where one of the objects was a black hole and the other one was a normal star. But what they saw, in effect, was a star orbiting around nothingness. They saw this star whizzing around and around and around. They're very, very close, tight, fast orbits that they just couldn't see any sign of a companion. And they did their kind of gravitational maths and just asked, well, if this star is whizzing round, how heavy does its companion have to be? And the answer is it has to be really heavy, indeed heavy enough that we should absolutely see it. And there was just no trace there in any telescope at all. It was a very powerful source of X rays, though. And I think that was the piece of the puzzle that made people realize, well, what's going on here is that this has to be a black hole. And this was the 1960s. So this is decades after they were first theoretically predicted. And then eventually we saw them in the real universe.
- [40:05]
Interviewer Gregory McNiff
Interesting. Matt, I want to move on to pulsars. Why do you describe them as the universe gift to physics?
- [40:12]
Matthew Bothwell
Yeah. So pulsars are a very cool thing, so discovered very famously by Jocelyn Bell here in Cambridge. Pulsars are a Cambridge invention. The reason they're the universe's gift to physics is because they spin with just extraordinary regularity. So I'll explain what a pulsar is. First of all, I was talking before about how a very massive star gets the end of its life and the outer bits explode away, and then the core shrinks down, and there's no force in the universe that can stop it collapsing down to a single. And that's how you get a black hole. Well, it turns out if the star is a little bit smaller, like, say, 10 times heavier than the sun, not quite big enough to make a black hole. The process goes kind of the same. The outer bits of the star explode away. The core shrinks down. But because our star now is a bit smaller than the one that we were talking about 10 minutes ago, there is slightly less gravity to that core. And it turns out there actually is a force in the universe that can stop our slightly smaller star collapsing down into a black hole. And that's called neutron degeneracy pressure. So, essentially, neutrons, the things in the center of all the atoms, including the ones that make up your body, neutrons don't like being squashed together too much. And when you try to squash neutrons together, they kind of push back. So if we imagine the core of our star shrinking and shrinking and shrinking under gravity, eventually it gets to the point where all the neutrons are packed as tightly as they possibly can be. At that point, they start pushing back. And because our star's only medium size and gravity is kind of a bit weaker than it was before, with our black hole, it essentially stops there, and you end up with a ball of neutrons. So this is what we call a neutron star. It's essentially the core of a star squashed down to something about. About the size of Cambridge of just a few, a few miles across. One of these things, they're unbelievably dense. A teaspoonful of neutron star would weigh as much as a mountain. They are just the extraordinarily physically extreme objects. And what makes them the universe's gift of physics is that many of these neutron stars are spinning, and they have very strong magnetic fields. And the combination of the spin and that magnetic field makes sort of energy shoot out of the north and south poles, a bit like a lighthouse. And so as these pulsars spin and rotate around, you really can imagine them like rotating lighthouses with these beams sweeping around the universe. And if one of these beams intersects the Earth, we will see it flashing on and off. Like, if you imagine that you're a ship in the ocean late at night, you'll see a flashing as the lighthouse beam sort of sweeps over your ship. That's literally what we see from Earth. We can look into the galaxy. We see a flashing, and that is a pulsar beam passing over us. And when we time how quickly these pulsars go around, they are just extraordinarily precise. Like, some of them are very, very fast. They all, you know, they can spin tens or even hundreds of times per. And then we keep track of how quickly they rotate and they're just stable to more than billionths of a second accuracy. Right. I think It's a number one followed by 15 zeros sort of accuracy. They are far, far more accurate and stable than an atomic clock. Which means essentially the universe has provided us with just networks of hundreds of atomic clocks spread around the universe. It's the kind of thing that if you were a Star Trek kind of civilization, we would want to put them there to do experiments. And the universe has just given them to us. It's kind of amazing. So one experiment that we did with them a couple of years ago was to measure a type of gravitational wave. So gravitational waves, another prediction from Einstein's theory. You can write down Einstein's equations and turn them into an equation for a wave which predicts out the. The space and time background to our whole universe will ripple and wash just like the ocean. And you can detect this if you look at pulsars across the Milky Way galaxy. You can see this coordinated sweep of timing errors changing as a big gravitational wave sweeps across the galaxy. A little like if you imagine sort of looking out into a harbor if you couldn't see the ocean because it was dark, but you had a series of buoys, or I think buoys Americans call them, with lights on, and you see a sweep of them kind of going up and then down. You could say, well, there's a wave going through that harbor. We do the same thing with the gravitational wave as it sort of sweeps across the Milky Way and makes all the pulsars shift in a coordinated way. Yeah, they're amazing things.
- [44:57]
Interviewer Gregory McNiff
I want to move on to radio astronomy and particularly how it helped us map the Milky Way galaxy. Can you explain how radio astronomy works and particularly the. The role of hydrogen there and how, like I said, we're able to map the Milky Way galaxy?
- [45:13]
Matthew Bothwell
Yeah, sure. So radio astronomy is quite near and dear to my heart, I think, if only because it's really the first time that astronomy went beyond the optical. Right. Astronomy is the oldest science. We've been doing it for thousands of years. But it was only in the 1930s that we developed the ability to study the universe using radio waves. So radio waves are, if we go back to the electromagnetic spectrum we were talking about before, they're the far end of the long wavelength, low energy kinds of electromagnetic waves. And there are all kinds of different sources of radio waves. So black holes shine very strongly in radio waves. But another source of radio waves is just clouds of hydrogen gas. And that is important because the universe to like a First approximation is basically only made of hydrogen. We were talking before about how the Big Bang made hydrogen and helium and tiny little smidge of lithium and not much else. And over billions of years of cosmic history, stars have been generating these heavy metals like carbon and oxygen and the stuff that we're made of. But still the universe is mostly only made of hydrogen. And that's kind of a problem for astronomers because we want to study the stuff that the universe is made of. But hydrogen is pretty invisible to our telescopes. A cloud of hydrogen just sitting out there in the darkness of space. It doesn't shine, it doesn't block light. You know, if we just look at it with your eyes, it just looks like nothing at all. You see straight through it. But it turns out that hydrogen clouds, hydrogen atoms do spontaneously emit radio waves in a way that we can detect. And this is this very famous 21 centimeter radio wave signal, which I think anyone that's watched Contact, I'm pretty sure they talk about the 21 centimeter radio wave signal in Contact. The whole universe glows with these 21 centimeter wavelength radio waves. And it's all thanks to Hydrogen.
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Matthew Bothwell
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Matthew Bothwell
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Matthew Bothwell
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Matthew Bothwell
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Interviewer Gregory McNiff
Related to the radio astronomy, you talk about the Square Kilometer Array being the most advanced radio telescope in the world. But you also say it's the most ambitious telescope project the human race has ever attempted. Why do you say that?
- [48:44]
Matthew Bothwell
So the Square Kilometer Array is amazing. It is genuine, like something out of science fiction. So. So radio telescopes, like I said, we've had them for about 100 years. They started back in the 1930s, and we realized early on that there is a trick we can do called interferometry, where the trick, it essentially goes. Rather than building a telescope 20 miles wide, which is impossible, no one could build a telescope 20 miles wide. What you can do instead is take two telescopes and put them 20 miles apart and cleverly combine the signals from these distant telescopes. And if you like, mathematically combine the signals in the correct way, they will kind of act like a telescope 20 miles apart. And the more telescopes you add to your network, you make a big array. You can just link them up and make a huge thing. So there's one called ALMA down in South America that has sort of 60ish of these antennae, these telescope antennae, and Alma's doing amazing things. It's seeing distant galaxies in the early universe and it's seeing baby planets in formation. So the project of the Square Kilometer Array is to do that, but on a much, much grander scale. So to take hundreds of thousands of individual antennae and spread them across thousands of miles of Australia and South Africa and link them all together to make a telescope with a collecting area of a square kilometer. So that's why it's called the Square Kilometer Array. It's unbelievable. When it's finally finished, I think these sort of late 2000s, early 2000s, it's going to be just tens of thousands of times faster and more powerful than anything that's come before. It basically makes every other radio telescope ever built look like a toy. It's costing a couple of billion euros. So it's just incredibly ambitious. It's going to be so. Yeah, it's going to be very exciting when it's finished.
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Interviewer Gregory McNiff
Matt, just if you could speculate for a minute what type of, I guess, discoveries. What, what do you think this might be able to tell us? The Square Kilometer Array, once it's finished?
- [50:52]
Matthew Bothwell
Yeah, it's a good question, but it's hard to answer. But I think, I think telescopes often, they, they do two different things, right? They clear up existing problems, but they also reveal new things. Right? To, if you don't mind me indulging in the Donald Rumsfeldism, there are, you know, there are known knowns and there are unknown knowns, or there are known unknowns even there are unknown unknowns. Right. So there are things that it's certainly designed to work on. So we talked about how clouds of hydrogen emit these radio waves. Well, existing telescopes can only see them out a little way into the universe. Right. What would be a long way for a non astronomer, but, you know, a few hundreds of millions of light years where we can't see these clouds of hydrogen way back to the early universe. And that's where a lot of the interesting stuff is going on. So the Square Kilometer Array is going to push our ability to see hydrogen. You know, the kind of the fundamental pristine stuff of the universe way back to the early universe. For the first time, it's going to be able to sort of study how the first stars formed. We think there's a period called the Dark Ages, which is right after the cosmic background radiation, but before the time of the first stars and galaxies when the universe was made of just nothing but nothing but gas kind of assembling itself. And the square kilometer rate is going to let us learn about what happened at these very, very early times. So there's so many exciting problems it's going to help us solve. I think the most exciting stuff is going to be just the brand new stuff that it throws up. Like every time we've built an amazing state of the art telescope, we just find new things that we didn't expect. And I think that's what I'm most excited about. Like what is the Square Kilometer Array going to reveal that we just didn't see coming?
- [52:43]
Interviewer Gregory McNiff
Wow, definitely looking forward to that in terms of, I guess, seeing things we didn't expect. I want to move to dark matter and you label this chapter Cosmic Ghost Story and you write much of this book deals with things which are invisible because they don't emit light at wavelengths we can see. You cite newborn stars, but you say dark matter is so invisible we still haven't got a glimpse of it at all and can only guess at its existence because we see the effects it has on the normal matter that surrounds us. As far as we can tell, dark matter is a kind of quote type 2, invisible, completely dark across the entire electromagnetic spectrum. How do we detect dark matter? And is there any way we can see it in a direct manner at some point?
- [53:32]
Matthew Bothwell
Yeah, it's a good question. So we have an awful lot of indirect evidence for dark matter. I'll go on a tangent if you don't mind, to kind of explain, to talk about this so if we go Back to the 1820s, 1830s, one of the most pressing problems in astronomy was explaining the weird behavior of Uranus. So Uranus was discovered in 1783 by William Herschel, like, completely by accident. He thought it was a comet to start with. And then astronomers had to persuade him he saw a planet. And then in the years following Uranus discovery, I say we. I wasn't alive in the 1780s, right? We astronomers, we astronomers tracked its orbit and noticed it was speeding up and slowing down in strange ways. And so astronomers realized, well, there has to be an eighth planet, right? There has to be something out beyond Uranus, pulling Uranus around, making it speed up and slow down, even though we can't see it. And then the race was on. And then we found it. And of course, that's Neptune. But the point was, we saw Uranus, and we saw Uranus behaving in a way that was very, very strange and not according to our rules of the universe. And we said, okay, well, there has to be some invisible thing out there causing this strange behavior. And of course, there was, and that was the planet Neptune. That's kind of what's happening today. So when astronomers look all the way around the universe, we see things behaving really strangely in a way that we can't really explain unless there's heavy, invisible stuff pulling things around. So galaxies are the most famous one. This is how dark matter kind of exploded onto the public stage. If you look at a galaxy like our Milky Way, the galaxy we live in, our Milky Way is spinning around, goes around Once every about 200 million years, more or less. Is Monty Python famous in America? They have a galaxy song. They say it goes around once every 200 million years. And they get all their numbers exactly right. It's fantastic.
- [55:37]
Interviewer Gregory McNiff
Oh, wow. They are very, very well known in America.
- [55:41]
Matthew Bothwell
Okay, good.
- [55:42]
Interviewer Gregory McNiff
Yeah.
- [55:43]
Matthew Bothwell
So, yeah, so in that case, to quote Monty Python, the galaxy goes around every 200 million years. But it turns out our Milky Way and basically every other galaxy in the universe is spinning way too fast. And the only way to explain how fast these galaxies are spinning is if there's invisible stuff pulling them around faster. Think of Uranus being pulled around by invisible stuff that turned out to be Neptune. There is some stuff pulling galaxies around that we can't see. But the difference is with the to the Neptune story is that we just can't see this stuff in any wavelength we look in every single kind of light that's. That we know of. And there's just no sign of Whatever is pulling galaxies around. So we say it's dark matter. So dark just meaning because we can't see it at all. And matter just because it's, it's stuff, it has weight, it has gravitational attraction, so it's invisible stuff, it's dark matter.
- [56:43]
Interviewer Gregory McNiff
Perfect. You talk about three revolutions in astronomy, the first one being Galileo, the second one being the discovery of radio waves by Karl Jamsky when he switched on his radio antenna. You refer to the third grand revolution in Astrani happening very specifically at 4:50am on September 14, 20, 2015 with the detection of gravitational waves. Could you talk about LIGO and how that was able to detect these waves and how significant that was?
- [57:12]
Matthew Bothwell
Yeah, absolutely. I will say I was playing a bit fast and loose for saying there are sort of three revolutions. I think an astronomer colleague, after I published the book, came to me and said, well, I really think you should have included spectroscopy as a sort of similar sized revolution. Which I thought was like, you know, I thought they had a very fair point. But anyway, yeah, so the point I wanted to make in the book is that the detection of gravitational waves was a genuine just revolution, game changer, sea change, whatever you want to call it, compared to what came before. So the reason I think, you know, Galileo's telescope was a huge revolution because from ancient times, you know, Babylon and ancient Greeks all the way through to the Italian Renaissance, astronomy was only done with your naked eye. Then Galileo invents this new tool. Oh no, sorry, he didn't invent it. Right. Hans Lippershey invented it. Galilei used this new tool to study the sky. And that was just a huge step change in our ability to understand the universe. Then again, in the early 20th century, Karl Jansky's discovery of radio astronomy, that was another huge step change in our ability to understand the universe. And I think a similar size step change was the discovery of these gravitational waves. So I mentioned them very briefly before when we were talking about pulsars. So just to dive in a little bit deeper, what a gravitational wave really is, it's a wave of space and time itself. And to even sort of process that sentence, you have to be thinking about the universe in kind of an Einsteinian way. So Einstein's theory of relativity describes the sort of the background fabric to our universe, the space and time of the universe itself, as this sort of stretchy bendy fabric. Right. And that's an update to what we thought before, like kind of the Newtonian view of the universe is that empty space is basically a blank canvas upon which objects move around. And Einstein said, no, it's not a blank canvas. It itself is this kind of stretchy, bendy medium. And then he went on to describe gravity as the sort of the stretching of this stretchy, bendy medium that we call space time. And another. Another consequence of Einstein's theories is that this stretchy, bendy medium we call spacetime can have waves in it. Think of like a wave in a trampoline or something. And these ripples of spacetime itself is what we call a gravitational wave. And so any. It turns out that any accelerating object will make a gravitational wave. Right. So anytime anything accelerates, it will ripple the fabric of the universe itself. And so, for example, two black holes spiraling around each other right before they crash together will send out these enormously powerful ripples in space and time that were detected for the first time in 2015 by this incredible instrument LIGO in America.
- [60:09]
Interviewer Gregory McNiff
Perfect. I want to move on to dark energy, which you described as very weird and also just absolutely amazing in terms of how we've detected it. Could you talk a little bit about that and how it relates to the cosmological constant problem?
- [60:25]
Matthew Bothwell
Yeah, sure. So dark energy is indeed very weird. I think it's so weird that we don't understand it. Right. So, like, if I said we don't really understand what dark matter is, we really don't understand what dark energy is. We have a sense that dark matter is probably some particle that we haven't detected yet, hanging out in vast quantities out there in interstellar space. And it's the weight of all these particles we haven't detected. We don't know what the particle is, or we have a kind of a model for what it should be, for what we're expecting to see. Dark energy is really a case of all bets are off. So dark energy was first noticed in the very late 1990s when people tried to measure how fast the universe was expanding. So I mentioned before 1929, Edwin Hubble made this incredible discovery that the universe is expanding. The universe itself is getting bigger and bigger and bigger. And that discovery led to understanding that the universe started with a big bang. And ever since then, people have wanted to ask the question, well, how fast is the universe expanding? And in the 1990s, there was a project called the Supernova Cosmology Legacy survey that aimed to measure exactly how fast the universe was expanding. And they made this just completely remarkable discovery, which was that the universe was expanding in an accelerating way. So not only is the universe expanding, it's Expanding at an ever faster rate, right? The expansion itself is speeding up, up. And that needs some explanation. Like, if the universe is just expanding, that can be explained by saying, okay, well, it just comes from the Big Bang, right? The Big Bang happened and blew everything apart. And everything has just been moving apart ever since. But an accelerating universe, a universe that's being pushed apart faster and faster and faster, that needs something to do the pushing. And so for the last sort of 25 years or so, the question has been, what is doing the pushing? What is pushing the universe apart faster and faster and faster? So you mentioned the cosmological constant problem, and there's a really fun piece of history here. So, yeah, like I said, ever since the late 90s, we've been asking the question, well, what on earth is going to be pushing the universe apart faster and faster and faster? And the simplest version of that is what we call a cosmological constant. So what you say is that just space and time itself, like the fundamental fabric of the universe, just has some intrinsic springy pushing power to it, right? If you take a piece of universe, this little piece of universe just has some natural push built into it, and you put enough of this together and build the universe, and that will have a huge push that will accelerate the universe. The reason this is exciting and interesting is that this actually wasn't the first time it was hypothesized. If you go all the way back to Einstein, Einstein actually hypothesized a cosmological constant. He hypothesized that space and time itself might have some kind of intrinsic pushing power. The fun thing is he hypothesized this for the wrong reason. So Einstein was doing his theories of relativity before Hubble, which I always think is completely extraordinary, right? When Einstein was working on his theories, he didn't know the universe was expanding. In fact, the paradigm that Einstein was working under was that the universe is static and eternal, that the universe is sort of fundamentally one size and unchanging. And Einstein came up with this theory of general relativity, and he immediately realized there was a problem. The equations of general relativity don't want a static universe. The equations of general relativity really want a universe that's changing, either shrinking or growing. And Einstein will thought, well, this is a problem, right? He wanted to live in a static universe because that's what he thought was true. But he has these equations that implied a kind of dynamic, stretchy universe. So Einstein said, what if there is this thing called a cosmological constant, kind of its springy intrinsic Pushing power built into space and time that could act like a sort of a scaffold, like a frame to the universe and keep it static. And he was never really happy about this. It was just something he kind of plonked into his theory for just purely ideological reasons. Then a few years later, Hubble showed the universe was expanding. And so it turns out he didn't need this cosmological constant. He was a bit embarrassed. He said it was his greatest mistake ever to just sort of invent this for ideological reasons. But then 80 years later, it turns out he was right. Even when he thought he was wrong. The universe does seem to have this kind of springy pushing power to it. And the cosmological constant is like the simplest version of that.
- [65:18]
Interviewer Gregory McNiff
Absolutely. Last question, Matt. You conclude the book by noting, this is a great time to be alive. We've done so much. We're now looking outward. You cite pulsar, black hole, or gravitational wave, but at the same time, you note we only have mapped or understand 5% of the universe. You're excited about the next hill, the next horizon. And we briefly in this, earlier in this interview, talked about what maybe the Square Kilometer Array might provide, but what do you think is the next hill or the next horizon for our understanding of the universe?
- [65:51]
Matthew Bothwell
So there's so much exciting stuff. I mean, so I'm like an observational astronomer. So I think my view of this is very much in terms of the facilities that we're building and are going to reveal amazing things. And there's a handful of things that are really just coming around now that are just going to do unbelievable things. So there was a satellite called Euclid, which launched around a year ago that is making these enormous maps of the universe, and that's going to tell us things about dark matter and dark energy. The Vera Rubin Observatory, I think, is one of the most awesome telescopes of all time. What Vera Rubin is going to do is make an entire map of the sky every three days and then just keep doing that every three days for years and years and years and give us this dynamic changing movie of the night sky. And so anything that's out there that's moving from sort of binary stars whizzing around to exploding supernovae, Vera Rubin is going to spot them. You know, it's going to see all kinds of asteroids flying around our solar system and, yeah, again, reveal things that we. We had no idea about. And there's also a telescope, Nancy Grace Roman, that will hopefully launch over the next couple of years. I think it got a bit dicey for a while with the NASA funding situation, but I think all the scientists in the world are crossing our fingers. Nancy Grace Roman is unbelievable. So in terms of its resolution and its power, it's basically the same as the Hubble Space Telescope, but it's a hundred times wider field of view. So it really is like having 100 Hubble Space Telescopes all cellosaped together, which is just absolutely crazy. And again, it's going to be making these incredible maps of the universe, synergizing with Euclid really telling us how dark energy and dark matter are working on the bigger scales. I think there's just some unbelievably exciting stuff on the horizon.
- [67:46]
Interviewer Gregory McNiff
No, that's great. I mean, it sounds wonderful and hopefully it sounds like we might have some answers relatively soon on the cosmological timescale. With that, that concludes our interview. Again, the book is the Invisible why There's More to Reality Than Meets the Eye by Matthew Bothwell. Matt, thank you so much for joining us today and writing such a wonderful and really just fascinating book.
- [68:09]
Matthew Bothwell
No, it's been a pleasure chatting about it. Yeah, always happy to talk space. Thanks for having me on.
- [68:13]
Interviewer Gregory McNiff
I know. Thank you, Matt.
- [68:28]
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