Dan Snow's History Hit - The Discovery of the Universe

Episode Date: March 3, 2020

The universe has always been there, kind of, but it took intelligent life on earth billions of years to start to grapple with its nature. Carolyn Collins Peterson is a science writer who charts the progress of astronomy through the observatories used throughout history, from the earliest such as Stonehenge, to places like Birr Castle with its Leviathan telescope used by Herschel. As always the compressed timescale of the major discoveries in astronomy left me amazed. in just a few generations we have gone from squinting at the nearest celestial bodies to sending manmade objects beyond our solar system. For ad free versions of our entire podcast archive and hundreds of hours of history documentaries, interviews and films, including our new in depth documentary about the bombing war, please signup to www.HistoryHit.TV Use code 'pod6' at checkout for six weeks free.

Hi everybody, welcome to Dan Snow's History Hit. Now, you'll have to forgive me, I'm fascinated by the history of science. I don't know much about science. I was hoping my kids would grow up to be scientists, but they're as useless as I am. They know a lot about Boudicca. They know a lot about the final attack of the Imperial Guard at the Battle of Waterloo, let me tell you that much. They know about the world's first integrated air defence network, instituted by RAF and Dowding before the Second World War, but they don't know diddly about science. So they are sadly mirroring my strengths and weaknesses. Anyway, enough about my failure of parents. I love science and it's been a wonderful opportunity on this podcast to

occasionally launch into stories about the history of science. This episode is one of those. Caroline Collins-Peterson is a wonderful broadcaster science writer in the US. She's written a book about the discovery of the universe, how intelligent life for years gazed up unknowingly at these pinpricks in the dark night sky. And in the course of really just a few generations, we have learned a gigantic amount about the nature of this universe. We've even sent man-made objects, humans, to nearby celestial bodies. And in the case of the Voyager missions,

outside our solar system itself. It's so exciting. So it's lovely to have a chat with Caroline Collins-Peterson about astronomy, its beginnings, some of the extraordinary early work that was done by civilisations like the ancient Greeks.

And then it's more recent history as well. So it was a real treat. You can go to History at TV. You may have heard me mention this now. It's like Netflix, but it's for history. You can sign up with the code POD6, P-O-D-6, and you get six weeks free of charge. Yes, you do.

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All this tradition of ours, our school history, our songs, thank you so much for coming on the pod, Carolyn. I'm glad to be here. I know virtually nothing about astronomy, pre-Herschel, pre-18th century enlightenment, but you go all the way back, don't you? Well, if you want to go back to the very first time people looked up into the sky, that goes probably a little back to the first time some cave person looked up. But scientifically, I think you really have to look back towards maybe a few thousand years ago when people were looking up at the sky and trying to understand what those objects were. And as opposed to just being gods or goddesses or objects of admiration, what exactly they were, because they could notice their motions and try to figure out what were making those motions. So well into prehistory, I think. When did people start systematically trying

to map the heavens? Well, it really goes back to people like Hipparchus in ancient Greece, who tried to make some of the first maps of the sky. And obviously, he's looking at the brightest stars, he could only see what he could see with his naked eye. So a lot of that is really limited by what you can see with the naked eye. It wasn't until we started getting telescopes and cameras and high-resolution instruments that we could start seeing things that were fainter than what could be seen by the naked eye. And when did that come in? Well, the first telescopes were, obviously, Galileo started using the first telescope. It was invented just before he started using it. So that was around 1610. And that magnified the view by about three times,

by about three powers. And then after that, it was kind of a race to see who could build the biggest and best telescopes that you could see farther and fainter. And today now we see things well down, you know, many, many magnitudes fainter than we can see with the naked eye, using things like the Hubble Space Telescope, for example, for optical astronomy. What were the first things that Galileo was able to see? Well, he was noted for studying a number of things. Obviously, his first drawings were of things like Jupiter and its moons. And so Jupiter and its moons were a big discovery for him. And that's what led him to show his bosses basically at the church, oh, these things are moving. These are separate worlds. They have their own moons. And so Jupiter and its moons, I would say, were his first big

discovery. He also studied the sun. He studied stars the best he could with the telescope that he had. Now you have to remember, he built his own telescope and these were pretty crude by today's standards. Speaking of building telescopes, I've always loved the stories of the Herschels, you know, brother and sister staying up all night making their telescopes. How difficult was that process? Well, in the beginning, they were polishing metal

and metal has its own problems with tarnishing and that sort of thing. So they'd be repolishing these mirrors over and over again. When we graduated to using glass, you had to make sure that your piece of glass was not cracked. It wasn't breaking around the edges. It didn't have flaws or bubbles when the glass was poured. And then you go through the whole polishing process, which for a small amateur type telescope can take several days or weeks of very, very careful polishing. You have to use special grit to do this. And it's not very different.

It wasn't very different in the past to do that. Today, with the very large telescopes, they're polishing mechanically, they're computerized. They can polish these right down to a perfect figure as long as they're doing it properly. So it's a process that takes quite a long time. When do states start looking into space rather than sort of eccentric individuals? It was sort of a gradual process. I mean, there was always a state or a city or a municipality interest in being able to tell time by using the stars. So in that sense, you could have gone back well to, you know, before the Roman Empire, when people needed to have some way of telling time. In modern, in more modern times, and I'm saying more modern, meaning perhaps, you know, after the Renaissance, the medieval times,

you had states like your country, basically building places like Greenwich Observatory to be able to use the stars to be able to tell time. Paris did this. There was a big observatory in Edinburgh. India, China, places like that were building observatories. And these were strictly time-telling so that people at sea would be able to know what time it is as they're coming in. Navigation was another big issue. It wasn't just time-telling. You had to be to be able to navigate by star and in that case you see cultures going back you know a couple thousand years several thousand years being able to use the stars to navigate that's a good point is is that one of the leading practical applications because it's c accurate celestial readings are the difference between life and death um the practical applications if i understand understand your question correctly, are that you're basically looking at the stars to do a number of things.

One of them is navigation. Another one is time telling. Another one is being able to create a calendar of the year, for example, so that people noticed very, very early on, several thousand years ago, the sun rises at certain places along the horizon. It sets at certain places. It goes through the cycle of rising farther north, farther south throughout the year. And that was, you know, the earliest way that they were able to create calendars. So take me through the development of telescopes from, say, the Enlightenment onwards. Well, it's really kind of difficult to say. I mean, you had people like Herschel creating what are the homemade telescopes, but these were giant. I mean, his were fairly large, several meters across.

And so it really was sort of a, I mean, I think I say in the book, it was sort of a rich person's obsession for a while. But as people were using these to do more and more science, I think that really interested the academics at the universities, the places of higher learning in it, because they were very interested in understanding how the universe worked. And so I think that was one of the major impetuses was to just to get an understanding of, you know, where Earth is in the universe, what these things are that are moving across the sky, how they work, what they're doing. And we really didn't start seeing modern astrophysics as a science until the late 1800s. And that was, there were a couple of centers of learning for

that. There was, Europe was one of them, particularly in Paris. The Paris Observatory was very much interested in turning the observatory into a laboratory of the sky. And then George Ellery Hale in the United States got onto this idea, and he'd always wanted to see more laboratory work being done. So the observatories he began building, particularly Yerkes, became these laboratories where you had laboratory instruments to study the chemical makeup of objects in the sky. And that caught on around the world. And we have essentially the science of astronomy, the study of objects in the sky, and then

the science of astrophysics, which is the study of the physics of those objects, how they work, what they do, what their activities are, how they evolve, that sort of thing. And that's relatively recent within the last couple of hundred years. What are the big things we're currently trying to see in space? Well, there's several holy grails. We were just talking about this last night in an interview. One of them is something called the epoch of reionization, which is a time very early in the universe when the first stars, essentially the first stars began to shine. And pinpointing a time for that within the first few hundred thousand, few hundred million years of the universe when this happened is very important. And there are several signatures, several ways to

observe that. And people are looking at it across a range of optical wavelengths, as well as radio frequencies, ultraviolet, infrared, basically across the electromagnetic spectrum. Another thing that's really caught a lot of interest in the last few years is detecting gravitational waves. And I do talk about that somewhat in the book. There are several gravitational wave detectors. There are two here in the United States. There are others in other countries, China and Europe. And they want to be able to figure out exactly what's causing these gravitational waves, which are very barely detectable on Earth. They're very, very tough to detect. And now that they figured out a way to do this and the methods to do it, they're detecting them rather pretty much on a weekly basis now. Collisions of black holes, collisions of neutron stars, these very, very massive objects

in the universe. And it was only within the last few dozen years that we've been able to come up with the technology to do that and make it work. Land a Viking longship on island shores, scramble over the dunes of ancient egypt and avoid the poisoner's cup in renaissance florence each week on echoes of history we uncover the epic stories that inspire assassin's creed we're stepping into feudal japan in our special series chasing shadows where samurai warlords and shinobi spies teach us the tactics and skills needed not only to survive but to conquer whether you're preparing for assassin's creed shadows or fascinated by history and great stories listen to echoes of history a ubisoft podcast brought

to you by history hits there are new episodes every week. This is nothing to do with history, but I've got a passion. I love stories about searching for planets in the so-called Goldilocks zones. That's a very big, very big search in planetary astronomy, in exoplanets is what they call. And it's very difficult to do in a lot of ways. I mean, although you do have amateurs, you know, attempting to do this now and making discoveries, but to really find the most number of them, you have to do these large surveys of the sky using special instruments to do it. And the biggest issue is that the planets are very dim. And of course, they're next to these very bright stars. And so you have to separate out that signal from this tiny little planet. It might be a Jupiter sized planet, but it's still tiny to us in relationship to the star

from the light of the star. And so there are several methods that people use to do that. And they are finding, I believe that there is something like 5,000 or 6,000 exoplanet candidates. And then once they find these candidates using the Kepler data or other methods, then they have to do follow-up observations to see if these really are stars or if there's some other transient event causing the observation that we have. So an idiot like me assumes that Hubble is so much more effective than telescopes here on Earth. Do Earth-mounted telescopes still have a role? Oh yes, they do. Oh my goodness. When you talk to people at places like Gemini or the European Southern Observatory, they

basically are crowding in on Hubble's territory in terms of being able to get good resolution and good images. They are hampered by our atmosphere, and so they do have to correct for that, which is why we have something called adaptive optics and laser guide stars and the sort of technology that allows them to correct for the aberration of our atmosphere. Hubble still is the gold standard for a number of observations you just can't get from Earth, like ultraviolet, high-resolution ultraviolet, and some infrared. And that will be the case until it stops operating, essentially. What's the story of astronomy over the last few hundred years? Is it a story of steady advance or dramatic leaps forward?

Well, I think it's actually a little bit of both these days. In the beginning, it was big leaps forward and understanding. And again, as I mentioned earlier, we had our mark two, mark one eyeballs

to depend on in the beginning. That's all we had. And so whatever we got was limited by those. As soon as we put a telescope to the eye, that changed everything. So that was the first big leap forward. Big leaps followed after that when you had bigger telescopes. And there was a history of building bigger and bigger and bigger

telescopes. The problem with some of them was they were bigger and bigger, but they were more susceptible to wind, to tarnishing, to a number of problems, until changes in telescope technology allowed people to build telescopes indoors to put them on more steady mounts, that sort of thing. When you could mount a telescope very strongly and not have it be jittered by the wind or something like that, when it was protected from heat and cold, then you could start mounting instruments like cameras and spectroscopes and that sort of thing to it and start getting high resolution imagery and data from your telescope. So that was a big deal. In recent, I would say within the last century and a half,

it's really been a steady progression of discoveries. Yes, there have been these big leaps forward, but not in the same way that they were guided by the technology of the past. So we saw things like the discovery, the observation of a supernova almost in real time with supernova 1987A, and we watched them in other galaxies. Or the discovery of the first exoplanets, that was a big one as well. So you see those, but those are all dependent on a steady progression of technology improving. And we're at a pretty good rate of technology improvement

right now. I am really excited to find out what people come up with in the future. And a lot of it is really dependent on how we manipulate data and how we analyze that data and how we come up with ways to understand the information that we've been finding. You mentioned the supernova. How old is that light? Well, that star that exploded was on the order of about 170,000 light years away. So it took 170,000 years to get here. So way older than the evolution of Homo sapiens. Yeah, that's about right. Very, very early ancestors. They wouldn't have seen it, obviously. We got to see it. But yeah, the universe, one of the things when takes things to travel, the light to travel that

we see. And so when you're looking at something like the sun, you're seeing it, that image is basically eight and a half minutes old. And the farther out you go, the further back in time you're looking. And that's always kind of a mind bender for people. When you look back at the ancient Greeks, are you struck by how primitive their astronomy now seems? Or are we all just still taking our first baby steps? I think we're still a lot like them. I mean, they were pretty sophisticated in their thought processes. They just didn't have the data that we do. And that's not really, that's just a reflection of the technology of the time they were in. In many ways, we are far ahead of them because of the knowledge that we have. But in other ways, we look at something like a black hole, for example.

We still wonder what's going on inside the black hole. We can certainly speculate. Oh, we wonder about it, but we have no way of knowing. And I don't know if we ever will find out a way, but we always wonder. And we always try to find out ways to maybe figure that out from the outside. So those are the kind of baby steps that we try to take. Another one is to look back at the formation of our solar system. We have a very good idea of how it happened, of a series of steps and events that happened, but the minute details are still kind of beyond us. And so we look at the formation of other planetary systems to try and understand what happened in our own, which is why we're looking at all of these different kinds of planets, trying to find Earth-type planets. Where did they form close to their star or far away from their star?

It was kind of a surprise to me, for example, to learn after a number of observations that giant Jupiter-type planets don't always form way out in the solar system like where ours is orbiting. It probably formed very close to the sun and migrated out during a period early in the solar system's history. That's kind of detail that we're finding out. So in that sense, those are baby steps, but we're learning to take bigger and bigger baby steps as we get more data about how these places, what their activities are, how they form, and how they evolve.

Who's your favorite astronomer? Why is that? That's a really good question. I have to kind of think about Herschel, actually. You know, he's out there in the countryside, essentially at that time, trying to observe through all those clouds and repolishing and polishing his mirrors and building bigger ones and sketching and observing and supposing about what he's seeing out there, these little fuzzy things, what are they?

And he's sort of, to me, the example of just dogged perseverance to try and find out what's going on in the sky. And I really am impressed with that. And of course, there are a lot of modern ones. The person who really first got me involved with astronomy, aside from my dad, he and I would go out and observe together, was Carl Sagan. And he really inspired me to go out and start sharing astronomy with the world, which led me to creating a lot of, I work with museums and planetariums and science centers. We create content for them to get shows out there to explain to the general public exactly what we're learning in astronomy.

And that, so I owe a lot of that to him. And there are, there are men and women throughout history that I, that I've read about that I think if we didn't have them in our history, we wouldn't be anywhere near where we are in astronomy today. Okay. Now inspire me. I take the kids out. I go out, we look for the bear, we look for the North Star. Tell me, how can I improve? What do I need to look for? Well, I always tell people to go out there with a star chart and learn the constellations because those are a roadmap to other things in the sky. If I tell you, go out and find the Big Dipper, and then from there you can find the North Star,

that also gives you a framework for when you go out and get a telescope, being able to find some fairly interesting galaxies in that area with your telescope. Also with a pair of binoculars, which is fairly inexpensive and easy to get, you can go out and look at double stars in that same area. So really learning the roadmap of the sky is the most important thing that I tell people to do first. And it also is just very a lot of fun to try and figure out why those constellations are there, the history of those constellations. Why did somebody see a Big Dipper there and someone else in the world saw a bear and someone else saw a plow and someone else saw something else?

I find it really, really inspiring to study the different constellation, outline pictures and stories that different cultures have. But also, there's just nothing more fun, really, than on a nice good night, when you're nice and not too uncomfortable, to just go out there and lay up and look at the sky and just think about what you're seeing. I could not agree more. What's the name of the book? It's called The Discovery of the Universe, A History of Astronomy and Observatories from Amberley Press. Excellent. Thank you very much for coming on the podcast. Sure.

I feel we have the history on our shoulders. All this tradition of ours, our school history, our songs, this part of the history of our country, all were gone and finished and liquidated. One child, one teacher, one book, and one pen can change the world. He tells us what is possible, not just in the pages of history books, but in our own lives as well. I have faith in you. I hope you enjoyed the podcast.

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