Welcome to episode 500 of Astronomy Cast. To celebrate this momentous occasion, we’re going to look back 500 years into the past to see what we learned about the Universe. And then we’re going to look 500 years into the future.
Astronomy Cast celebrated their 500th episode on Sept 15-16, 2018. We broadcast from our celebration, in front of a live audience! And we debuted our new theme music by composer, fan and friend David Joseph Wesley!
We usually record Astronomy Cast every Friday at 3:00 pm EDT / 12:00 pm PDT / 19:00 UTC. You can watch us live on here on AstronomyCast.com, or the AstronomyCast YouTube page.
If you would like to support Astronomy Cast, please visit our page at Patreon here – https://www.patreon.com/astronomycast. We greatly appreciate your support!
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
This episode is sponsored by: Super Chewer
Podcast Transcription provided by GMR Transcription
Fraser: Astronomy Cast, Episode 500: 500 years into the past and the future. Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. I’m Fraser Cain, publisher of Universe Today. With me, as always, live here in Edwardsville, Dr. Pamela Gay, the Director of Technology and Citizen Science at the Astronomical Society of the Pacific and the Director of CosmoQuest. Here we are live in Edwardsville for Astronomy Cast episode 500. 500 episodes. Pamela, how’s it going?
Pamela: I’m well, how are you?
Fraser: I’m good, good. This is the second day of our 500th episode fun here in Edwardsville with a bunch of our closest friends. Did a bunch of events yesterday, a bunch of events today, more coming. Live stargazing –
Pamela: That was last night.
Fraser: That was ye – last night, I remember I was there. And yeah, it’s been so much fun. We’re sort of nearing the end of all of the stuff we’ve got planned, right?
Pamela: Well, that just means we’re gonna have to do another 500 episodes and do this all over again at 1000, right?
Fraser: Yeah, of course, 1000. It only – it only took us 13 years to get to here, so I’m in for another 13, no problem.
Pamela: I don’t know about you, but I’m gonna be at least 26 more years before I can retire, so, 150, we can do it.
Fraser: Yeah, that sounds good. All right, so let’s get onto this week’s – this week’s episode. So, welcome to episode 500 of Astronomy Cast. To celebrate this momentous occasion, we’re gonna look back 500 years into the past to see what we learned about the universe and then we’re gonna cast our minds forward and speculate on what we’re gonna see up to 500 years into the future. All right, Pamela, so let’s start with the history portion of this episode, so here we are – I’m gonna have to do some quick math, I haven’t even done the math here. So, 2018 – so would that be 1618?
Pamela: It would be 1518.
Fraser: 1518. Yeah, my math’s terrible.
Pamela: So, it turns out if you look up what was the most important even in 1518, it was an outbreak of dancing sickness. And Strasbourg people were dropping dead from dancing too hard. So, apparently it was a kind of interesting, but not very scientific year in 1518 and we would need to wait for the science to begin. So, let us start by setting the stage. In 1518 we were roughly 1500 years after Ptolemy. So, people were living in a land where everything went around the Earth, where asteroids were not known, where comet were strange demons that possessed the sky, where science was just starting as the Renaissance begins to sweep through Europe.
Fraser: The planets went up to Saturn.
Pamela: Now, for us and our story of astronomy, things would begin to get interesting in 1543 when Copernicus first publishes his heliocentric theory of the universe.
Fraser: And did you actually – have you actually seen sort of the history of how this went with Copernicus? He didn’t make a big deal of it, just posted a fairly quite paper that said oh, by the way, I think the sun is at the middle of the solar system and then published it, not I wanted to get into trouble.
Pamela: Well, and if you read more he was also kind of into Apollo and Apollo was the deity of the sun and so there was a lot of Apollo having to do with this. And I’m mostly good with that, my favorite moment in science was explaining to Richard Hatch that the asteroid that tried to take out Chelyabinsk, Russia was an Apollo-class asteroid. No one laughed. No one laughed.
Fraser: But the thing as well is that the thing with the Copernican model was that it didn’t match reality as well as the Ptolemaic model. So – so even though he got the big picture stuff right, the fact that the sun is in the middle of the solar system and not the Earth. Ptolemy prediction about the movements of the plants actually worked out a lot well because they had been thought through over and over again and were needlessly complicated to be able to do that. So, let’s continue our story forward until we’ve got a much better sense of how the solar system worked.
Pamela: Oh, the 1500’s were an active time where people were finally starting to try and think scientifically. As I said, we’re in the age of the Renaissance here. So, fairly soon, 1572 we’re still talking within a human lifetime. Tycho Brahe, he discovers a supernova in the constellation Cassiopeia, this was the first time that we’re starting to make these modern observations. We have lots of super old observations, especially by the Chinese and by the Native Americans who carved things in things, but the reason that I bring up Tycho Brahe in particular, is because he noticed the supernova because he was outside night, after night, after night, after night, after night, all the nights, he was out there observing very, very precisely the astrometric positions of the planets.
And Kepler who was a kinda indoor kind of a guy, was able to take all of Brahe’s observations and start testing all of the mathematics of the models against Brahe’s observations. And this is the important part, now, so we have Brahe outside making his observations and now we have Galileo starts getting involved in 1609. So, Brahe’s out there literally measuring things against metal things in a slot. So, he – no lenses are harmed or enjoyed at this point in science. Now, it would be 1609, roughly 30 years later, or 20 – roughly 40 years later, I can math. I took a pain pill before doing this, I mentioned this earlier, I’m going to mention it again for the people who are listening on the podcast.
And with the use of a telescope to look at the stars, it started to change what we were able to do. It started to change how we thought about science. Because prior to that it’s all about the sphere, we had the moon was a perfect sphere and then Galileo looks at it and goes nope, mountains. We had everything goes around either the sun or the Earth, depending on whose argument you’re listening to, he looks at Jupiter, things are going around Jupiter. Galileo basically took a whole lot of science that was based on philosophical arguments and noped it with the beginnings of observational astronomy.
Fraser: I mean, the thing that’s really fascinating about Brahe was as you said, no telescope lenses were done. He had this amazing instrument that was sort of like a sextant that was a big metal structure and he could measure angles and he was able to essentially map out of the positions of the stars and the planets, and especially the planets every night, night after night, after night, with a level of accuracy that had never been accomplished by any astronomer before him. And it was this dump of data that Brahe has presented to the astronomical community that gave, as you said, Kepler the tool that he needed to be able to understand what was going on. And the key discovery that he made was that it’s not all circles. Because this was the assumption that everybody had made, that yes, the Earth is – the Earth is in the center of the universe and all of the planets – the sun’s going around, the planets are going in circles and to make the reality match the observations that had been made was that the planets were going in little circles around the bigger circles and that how it all lined up.
It was when Kepler looked at the data and said wait a minute, they don’t have to be going in circles, they could be going in ellipses, that suddenly you suddenly get a better explanation of the motions that we see in the heavens.
Pamela: And this was a complicated process for them to get to because they had to keep overcoming their personal biases. And bias gets all of us now and then, so in this case the things that they were struggling against is that they thought the stars were kinda close and if the earth is going around the sun and the stars are kinda close you expect to see the stars moving relative to one another as you go around the sun. The same way our motions may appear to have the trees move back and forth against background mountains, nearby houses moves against background skyscrapers. This constant change in alignment, change in perspective due to the Earth’s motion wasn’t something that was happening and the only way that they could explain that we’re not seeing the stars positions change as the Earth moves, is if the stars are immensely further away than anyone had ever imagined before.
So, they had to expand our universe in their brains and they had to get rid of this idea of a perfect circle and ellipses are mathematically harder, so you also have to explicative it and add the extra terms to make it an ellipse.
Fraser: So, in between the time when Brahe had made his observations and Kepler had done the math to figure it out, Galileo was the first person to take this new technology, this telescope and point it at the sky and start to observe the heavens to see what he could see to actually make observations. And that also was a really defining point of modern astronomy.
Pamela: And it always amazes me how all of this was pretty much going on all at once, but in very different parts of Europe. You have Kepler up in the land of the Protestants and you have Galileo annoying The Pope. So, Kepler was working on his first and second laws of planetary motion the same time that Galileo’s publishing his initial observations. And it was in 1619 that Kepler brought everything together in his Harmonices Mundi and I will translate that for you, it was his Harmony of Worlds book with all three laws. And next year is the anniversary of that, so from 1619 to well, 2019 we have 500 years to celebrate – 400 years to celebrate.
Fraser: Yeah, whose math is falling apart now?
Pamela: Yeah, I know. I took a pain pill.
Fraser: Oh, you’ll just keep playing that this whole episode.
Fraser: I should take one too and then we’ll be the same. No one’s going to be driving this ship. So, with Galileo he got all the first early big discovers because he was the first person to point that telescope to the sky.
Pamela: Oh, yeah.
Fraser: He saw that Venus makes a crescent. He saw that, of course, discovered the moons of Jupiter, discovered the rings of Saturn, although he thought they were the ears of Saturn, pointed a telescope at the moon and saw all of the craters and the mare’s, the seas of lava. And pointed his telescope into the Milky Way and saw that it was full of stars, that it wasn’t just some cloud that was up there in the sky. All of these fell to Galileo and it was just such low hanging fruit. I mean, I guess, to think that nobody had really done these kinds of careful observations. Anyone of us would have gone wait a minute, look at the sky, what does it look like?
Fraser: But the thing we have to remember is they really didn’t have machine tools back then. And they didn’t have lasers for collimation and so these are individuals who are hand grinding their lenses, hand aligning everything. And they’ve got wood and forges and stone, and it wasn’t the dark ages, it was the Renaissance, but it was – for making future discoveries, it was who can build the better instrument by hand. And so, now they start to reach this amazing new era of the gentleman scholar, the human being who’s able to afford the leisure time to build that great observatory or just good enough observatory. Christian Huyghens was going to come next in 1656, where he is able to finally make sense of Saturn’s ears and go no, no, no that is a ring that is passing around Saturn.
And he also noticed that Saturn too, has – well, it’s fourth moon, Titan.
Fraser: So, and last night when we did the star party portion of this 500th episode of astronomy cast, there was a whole bunch of telescopes set up and they – in those telescopes, we were able to see the rings of Saturn and Titan. And in some of the more powerful ones we were able to see another moon, I don’t know which moon it was. It was Reah, okay. So, we were able to – so, that view that we were able to see in those telescopes last night was roughly the same view in the smaller telescopes that were just seeing Titan. That was essentially the view that Huyghens was making to be able to see his first observations and make those detailed discoveries about Saturn.
Pamela: But we were still seeing so much better because Huyghens wasn’t quite able to make out the gap in the rings. He was just able to go oh, rings. He – he was the first one to start noticing these fine features. He went on to realize that Mars wasn’t just a solid colored disc, it was a disc that had variations in colors. He went on to figure out that – well, actually, it wasn’t Huyghens actually it was another Saturn related human, it was Cassini that then went on to one up Huyghens and in 1666 realized Mars has polar ice caps. Now, up until then, they hadn’t even really figured out Earth that well, so we’re looking at 1666, they knew America existed and I’m just going to leave it at that.
And they know that there’s polar ice caps on Mars, how amazing is that?
Fraser: And again, this sort of matches in the largest telescopes we could see last night at our star party, you could just make out those polar ice caps on Mars. And with the – with the largest telescope I was able to make out the Cassini division in the rings of Saturn names after Cassini.
Pamela: And now you’re jumping ahead to 1675 and totally bypassing the work that Newton did.
Fraser: Well, I thought we’d come back around after I shared the capabilities.
Pamela: Okay fine.
Fraser: Right, and so, Newton, of course, in that exact same period revolutionized the telescopes by inventing an entirely new kind of telescope. When I guess he wasn’t stabbing his own eyeball with a needle to see –
Pamela: With a knitting needle.
Fraser: Yeah, a knitting needle to see how his eye worked, figuring out how rainbows worked, all this stuff. He invented the reflecting telescope which was again, almost all the telescopes we were using last night were these Newtonian reflector telescopes. Essentially the same design that Newtonian – that Newton had figured out 400 years ago.
Pamela: Now, what you should start to be seeing with all of this is we have hand in hand people who are going, I’m going to observe all of this stuff and people – often the same people, saying I’m going to math all this stuff. It was Galileo who figured out momentum, he figured out friction, it was Newton who figured out that gravity is what is causing Kepler’s Laws to Kepler’s Law. And so, we’re starting to build this modern version of astrophysics where it’s math and observation coming together to map out reality. And this is how it’s going to continue happening going back and forth. 1687 we have gravity, once – well, okay, we already had gravity, let’s face that. That came out like within a gazillionth of a second of the universe forming.
Fraser: Right, but Newton at least started to figure out how gravity worked.
Pamela: And once we have gravity as a complete theory, you start to be able to figure out highly elliptical orbits, start figuring out how bigger planets are able to screw up the orbits of littler things, and this starts changing how you think about motions in our solar system. And in 1705, Haley, of Haley’s comet, is able to start figuring out that these bright, streaky tailed objects that we sometimes see, there’s a green one you can see with binoculars right now. These are repeating objects, at least in the case of Haley’s comet.
Fraser: But the thing that I love about Newton’s discovery about gravity is that he looked at – and, of course, the stories of that he dropped an apple, who’s to say whether it really, really happened, but he thought about the way an apple falls from a tree and knew that that was the same thing that was causing the moon to go around the – around the Earth and to make that logical leap. I wouldn’t think of it, but Newton’s a very smart person. But just to –
Pamela: And creative.
Fraser: And creative. And so, to realize that the moon was falling into the Earth, but it was also moving sideways and so it was missing, and it was just constantly falling and missing, and falling and missing. And it is this – and this is why it’s this universal theory of gravity that tied all of these pieces together and served as the bedrock for hundreds of years of observations and understanding about the universe from that point forward.
Pamela: And – and during this period is where we start having all of your amateurs, people not too distant – different from those of you in this room. I see at least one person who built his own telescope and I think ground his own mirror. And it was these individuals who were building their own telescopes and as they skipped from one known star to one known star, they were finding fuzzy objects in between and mapping them out. And this is where we had Messier, this is where we had the Herschel’s, this is where we had an explosion of catalogs that began to allow us to realize our heavens are more than just points of light. And it’s also when we had our first planet that would be demoted. This was – I am, as some of you know, team Ceres. In 1801 –
Fraser: Did you catch Uranus?
Pamela: Well, okay, I was gonna skip Uranus because well it was just Herschel doing his Herschely thing. In 1781, Herschel found a planet. He was a – by training a composer, an oboist, he led the orchestra in Bathe and yeah, he found a planet in his spare time as you do.
Fraser: Yeah. Yeah, right. And the crazy part of that is that Uranus is just visible with the unaided eye if you know where to look and you’ve got really good vision. So, it didn’t necessarily require Herschel to discover it. Anyone back at that time with the right vision would have – could have seen it in the right conditions, but it still took somebody with a telescope to see it and confirm it and –
Pamela: And the amount of stubborn required to do it by eye because the vastness of the sky and it moves slowly.
Fraser: But – and it’s the same process that’s going now, we’ll talk about Neptune in a bit, Pluto, all of the dwarf planets that are out there. All of the Kuiper belt objects and, of course, the search for planet nine to this day. It’s all the same technique. Scanning the plain of the ecliptic, searching for anything that is moving slowly.
Pamela: And for Herschel, he was already looking for things that were moving, he was looking for comets and Uranus just refused to grow a tail. Now I will point out that if you took Pluto and you put it where Mercury is located it would happily grow a tail. So, take that.
Fraser: We’re – we are not getting into that fight here. That was episode one, that was 500 episodes ago, we’ve let that – we’ve left that in the dust. But then you were talking about Ceres.
Pamela: Yeah, so 1801, we find this – not we, we were not alive. Piazzi discovers this new, small world that was located between Mars and Jupiter and this is where people start looking at the ratios of the distances of the planets and hey this is cool, but it didn’t stay cool for long. Because we just kept finding new objects, after new objects until they eventually decided to demote Ceres.
Fraser: Awe, and this is – of course, they found a bunch more of these asteroids. I think there was eventually four majors ones – five major ones and they realized that they couldn’t just keep calling them planets because that would just freak people out. No, seven planets in my solar system and not gonna have eight or nine or 12 or 13 – again, we can’t escape this argument. But, yeah, this technique of expecting that there’s going to be a planet in the outer solar system, observing thanks to the interactions of gravity, thanks to predictions made by Newton, helped astronomers find the next planet.
Automated Voice: This episode is brought to you by Superchewer. For a limited time get 50% off your first month of Superchewer on a six- or 12-month plan. Visit Superchewer.com/astro and enter promo code astro at check out. Superchewer is a monthly subscription box from the good folks at BarkBox, it brings my dog Eddie six new items every month. This new to us box is filled with Superchewer fluff-free toys that make play last longer. Eddie isn’t a chewer or shredder, but he’s a tugger and gutter. I can’t tell you how many times my 65-pound floofball and I have tug-o-warred limbs off toys, leaving him an entry point to get fluff out and everywhere. Now we have all the play and none of the carnage. Along with two toys come two meaty treats and two bags of treats I use for training.
This month’s meaty treats smelled like an amazing stick. Everything is from the US and Canada, is all-natural and is designed by dog people, for dog people, and my dog loves it. For a limited time get 50% off your first month of Superchewer with a six- or 12-month plan. Visit Superchewer.com/astro and enter code promo code astro at checkout.
Pamela: So, once we found Uranus, Uranus just did not behave the way it was supposed to, and so people started mathing it. Now, there are arguments among astronomical historians over to exact – over exactly how this story went. I’m not going to get into those arguments, but I will say that Johann Galle observed Neptune in 1846 and brought us yet, one more planet that was still not quite behaving the way our early pre-computer, pre-database, pre-mathematical models of all sorts of computational complexity, Neptune appeared to not be fully behaving, so they kept looking.
Fraser: Right, right. And do we want to fast forward to that part or do we want to cover some of the other objects?
Pamela: And so right now we’re at a point where we have – we’re finding in 1877, Phobos and Deimos orbiting Mars, were starting to understand the atom better and better in the late 1800s. It was only in the late 1800s that we started to have the electromagnetic force, we started trying to realize what photons are doing, the wave-particle duality arguments. All of these things that we’ve done entire episodes in Astronomy Cast during the past – how many have we done?
Pamela: That sounds about right.
Fraser: Yeah, apparently that’s not the right number, there’s 537 with the question shows.
Pamela: Mine – 539.
Fraser: 539? Okay.
Fraser: Yeah. So, this – forget it, we made a terrible mistake, we should have done this 39 episodes ago.
Pamela: You know we should have fixed this back in 2006.
Fraser: The Gall – what was it the Julian calendar in the – right?
Pamela: Oh, that was more than 500 years ago, you’re going back too far now.
Fraser: Yeah, we could have followed that same method. Just redone the math. So, I think one thing that I think we slightly skipped over and it’s more core to Astronomy itself, is the understanding that the light coming from stars can be broken up into – like a rainbow into it’s individual chemical components. They were able to set things on fire here on Earth, see what kind of light that gave off, then look at stars and compare the light and realize you can tell what a star is made of by the kind of light that it gives off and the way you can break that up. This is, of course, spectroscopy and it is the – the swiss army knife, the most important tool that a lot of astronomers have at their disposal.
Pamela: And the crazy thing about how they did this originally, so they – this wasn’t the first time that light got put through a prism. Herschel put light through a prism, it was just sunlight, he discovered infrared radiation this way because he put his thermometer outside the visible rainbow and it still went up in temperature which told him it wasn’t actually in the shade, it was in the infrared radiation. Now, unfortunately, we didn’t develop cameras, photographic techniques until after we developed the spectrograph. I say unfortunately because we weren’t able to record any of those first spectra that helped us understand that well, stars are just hot balls of gas. And so, in the 1860’s spectroanalysis began and we started figuring out both in the lab and at the telescope what things are made of one spectra at a time.
Fraser: So, now we’re like closing into the 20th century of history and it’s kind of amazing to think that here we are only 100 years later, a lot of the major discoveries that we’re going to talk about next. That they’ve only unfolded in 100 years – less, we are – we just lost our banner there. We are – so much of our knowledge, so much of human history’s been around and yet a lot of the modern ideas that we have about astronomy are brand new compared to the history of science and the history of humanity. It’s amazing.
Pamela: And one of the things that up until I was prepping for this episode really bothered me, is people have been saying my entire adult life that we’re in a brand-new renaissance of astronomy. And then I thought about it while prepping this show and realized the renaissance were a couple hundred years old and I’m not and so it’s valid that for the couple of decades that I can say I’ve been pretending to adult, we’ve been continually in a renaissance of astronomy. This is due to all of the amazing computational abilities we have, but this is just building on the early renaissance of the entire last century as we started to get photography, as we started to mathematically understand quantum mechanics, relativity, and be able to realize that our universe is more than just our galaxy. And that those fuzzy nebulas we see in some cases are star farming regions and in other cases are complete other galaxies.
Fraser: Yeah, I mentioned this past I have a – I have a planisphere from the 1930s and it has the Andromeda nebula in it. And so, people even then thought Andromeda was a nebula and not a galaxy. They weren’t entirely certain. Where do you wanna pick up the history here?
Pamela: Well, I think we’re now at the point we have to start grouping discoveries.
Pamela: And what gets me is it’s just over 100 years ago back in 1914 that rocketry for the purposes of launching things towards space versus launching things at other people, as missiles and arrows.
Fraser: Or fireworks.
Pamela: Or fireworks. Robert Goddard in 1914, started launching rockets, liquid-fueled rockets. And at the time that he started doing this we started dreaming of space telescopes. So, we’re now hitting the modern era where we have people beginning to think about airflight and we get this mixing of the brand-new field of aerospace. And the people we are reaming of the stars and science fiction all coming into this great new era of creativity. And if you go back and you read some of the older works, you have Ray Bradberry in particular telling stories of Mars based on Shaperelle’s discovery of the canals where he imagines amazing civilizations and vast forests, and – well, wow we were wrong, but it’s amazing to dream through these writer’s eyes.
Fraser: And, of course, it was the Mount Wilson observatory that was created by Wilson to try to find evidence of the canals on Mars.
Pamela: That was Lowell Observatory.
Fraser: The Lowell Observatory, yeah, I’m sorry the Lowell Observatory to find evidence of the martians last stand try to prevent the climate change on their planet as their oceans and seas were drying up and they were building these vast canals on the planet to try and herd all the water to their –
Pamela: He was just writing science fiction about our planet, wasn’t he?
Fraser: Yeah, exactly maybe, but had built a very powerful telescope to try and prove this evidence.
Pamela: Now, as we move forward, we’re hitting at this period, also the age of – well, computers and in this case, I mean the women working at Harvard College Observatory. Doing mathematics wasn’t considered something that men did, it was women sat down and did all that long, hard, tedious calculations. Which gets me when they’re now like math isn’t for girls, no math was actually originally for girls. It was the original science for us.
Fraser: Math is for computers and computers are girls, right?
Pamela: Yeah, yeah. Why do you think Siri’s voice is a woman’s? That’s totally not true, I’m just making a bad joke. So, we had Henrietta Swan Leavitt in 1908 discovered Cepheid variables. We had Annie Jump Cannon doing her work on stellar classifications. We had so many amazing discoveries being made by this small group, all put together in one place and when those men went away for World War One, they got a whole lot of work done.
Fraser: So, now that idea of the Cepheid variables that you’ve got this star that is this set amount of brightness intrinsically based on the – how quickly it grows and dims or brightens and dims, gave astronomers this cosmic yardstick. A way to independently measure the distance to anywhere they could see a Cepheid variable. And suddenly they were able to notice that there were these Cepheid variables in other nebulae that actually helped them calculate the distance to these other nebulae.
Pamela: So, at this point early on in the 1900s, we philosophically think that our universe is unchanging with time, it is a steady state system where we have Einstein to consider all of these other – well, big names that those of you who took graduate school physics have been forced to use the calculations of. They put together our model of the universe and then added in stain variables, this is that cosmological constant that originally was put in to make the expansion stop.
Fraser: Because the universe is clearly – all the parts are attracted to each other by gravity they should have just gravitationally sucked into a ball.
Pamela: Or expanded away forever.
Fraser: Or expanded – drifted away from each other. Why are they there? There must be some constant force that’s keeping everything in its position.
Pamela: Well, not necessarily a force, it could be that everything just happens to be balanced out precisely.
Pamela: And it – it started with initial set of spectral observations of galaxies was made at Lowell Observatory that prior to us having the ability to measure the distances to galaxies, showed that galaxies weren’t moving in completely random rates, but on average tended to be moving away from us. If we lived in a static unmoving universe, you’d expect some of the galaxies to be moving towards us, some of them moving away, just a random buzz of galaxies back and forth and around. And when Hubbell followed up on this at Mount Wilson Observatory and started using Henrietta Leavitt’s Cepheid period-luminosity relationship to measure distances, a trend began to appear.
And it was Lemaitre who initially wrote a paper in French that worked out that our universe is expanding and made the first ever attempt to calculate the rate of that expansion. A value that we now call the Hubbell constant which may be weird, but the problem is – did I mention he published it in French?
Fraser: Yeah and we covered this last week in great detail, but maybe at some points it could be turned into the Hubbell-Lemaitre Law?
Pamela: I think so. I think in about three months we’re voting on this.
Fraser: What’s your vote gonna be?
Pamela: My vote’s gonna be yes, change that.
Fraser: Right on.
Pamela: So, now we’re entering the age of understanding our universe in expanding and needing to understand more physics and more math and now we have quantum mechanics coming into regular play. And we’re starting to understand what powers stars. At the beginning of the 1900s, people were running calculations assuming if the sun were made out of coal, how long would it last? And we’re getting numbers that had the sun couldn’t have lived as long as the mountains and that is a problem. But, then in the 1900s – in the early 1900s, we began to understand nuclear fission – fusion, alpha, beta, gamma. All of them are working on their various papers and Eddington is describing stars and it’s discovery after discovery after discovery. Thus the – we live in a renaissance of astronomy.
Fraser: The first renaissance, plus the one we live in right now?
Pamela: And then there’s the 1970’s.
Fraser: Right, was it particle physics renaissance? Anyway, so just imagine now suddenly we are in this world where we can calculate the distance of these galaxies. These galaxies as Hubbell discovered are actually moving away from us, the stars that make up these galaxies are not made of coal, they are made of – which would be weird if you think about it, they’re actually made of balls of hydrogen gas that are undergoing fusion that’s pumping out the light and heat that we see and feel. That our understanding that where we are in this universe is that we’re in a much smaller spec in a much vaster cosmos than we ever had originally imagined.
Pamela: And this is where we enter our new modern age where we finally have all of the forces – not nailed down but identified. We begin to realize there’s dark matter with the work of Vera Ruben. We didn’t figure out dark energy until 1998, that one’s a little bit more recent, but we have our modern universe. Coming out of World War Two we rearranged where the scientists live, put them into different politically defined nests of great research being done.
Fraser: Is that – are you saying that the Nazi’s for World War Two were broken up into two camps, some went to the United States, some went to Soviet Russia, and again the –
Pamela: I might be saying that, yes.
Fraser: So, I mean, this is the thing, we discovered our place in the universe and now suddenly we have the ability to actually get out there and explore this universe that we now understood more about.
Pamela: And now our discovery’s being driven by how well can we build our instruments, how much money do we have, is a major limiting factor, and where is the next great, creative mind; the next Newton, Einstein, Changar Sacer. Who’s going to come along and figure out, well can gravity get tied into anything? Is there an experiment to figure out if it’s geometric or particle? What is this dark energy thing? And so, we need that creative mind, we need that budget for the instrumentation, and now we’re moving into the future.
Fraser: Well, did you wanna – do we wanna skip the space flight portions of this history of astronomy?
Pamela: Didn’t we do a whole series about that two years ago?
Fraser: We really did, but I mean, just – I mean you talked about some of the cosmology components. I mean there were quasars discovered and only recently they figured out what those things are. Then there’s pulsars, there are dying neutron stars that were discovered as blasting radio waves. Black holes were theorized in the early part of the 20th century, observed or sort of second hand in the mid-70s with the X1 – Signus X1. And then the supermassive black holes figured out by the end of the 20th century, which then answered what quasars were. Which had been first observed decades beforehand.
Pamela: And what’s kind of amazing about all of this is now we’re starting to get into the discoveries within our adulthood and we’re kinda young. Planets weren’t known when we finished high school outside of our own solar system and now I know they’re kinda everywhere unless you look at globular clusters. We didn’t know supermassive black holes were there and then we thought they were everywhere and now they – we know that they’re wherever there’s a bulge. So, look for the bulge, look for the supermassive black hole, if it’s a disc with no bulge, no black hole. These are all new discoveries and still not firmly set in stone.
Fraser: 1995 was the first planet that was discovered. 51 Peg in – and completely redefined our understanding of what a planet was because it was a hot Jupiter, an object that should not have been able to exist. And yet they found it and then found many others of that example. And it’s only been in more recent times that astronomers have finally been able to find climates that are more like our own planet. And even where we’re – and this is where we’re going to move into the future, we have not found an analog to Earth yet.
Pamela: We keep getting headlines saying we have, but that’s because that sells papers.
Fraser: So, let’s move into the future and let’s start to speculate a little bit. So, where we are now in terms of planetary discoveries, there are probably close to 10,000 exoplanets discovered. I forget the exact number, it changes, in fact, by the time we finish this podcast it will be another number.
Pamela: It will be five more.
Fraser: We have the test spacecraft which is launched, which is already I believe turned up something like 50 planets this morning. And I’ve heard there’s like 50 planets in the data so far. And we’re going to be hearing more about this, but when do you think we’re going to find that analog to Earth? We’re going to find that Earth-like planet, orbiting a sun-like star, within the habitable zone?
Pamela: I think it’s gonna take at least three more years, because you need that long to get three full Earth orbits around a sun-like star. So, we need something to go out there and get that full chance to see an Earth go around an Earth-like star, at an Earth-like distance, three full times. So, we need a test-like thing, a Gaia like thing out there taking data for three full years and they’re launched, so three years.
Fraser: Yeah, Keppler would have been the – the Keppler Observatory was the one that should have found it, but then it’s gyros broke down and so it was only able to do observations of red-dwarf stars, but I’ve heard rumors that those obser – that that discovery may be sooner than the three years waiting for tests to make the observatory – the existing obs – there are so many ground-based observatories that will possibly already found this other Earth that we might not have to wait for the three years for it to come up. But probably three years at the most is when we’re going to find confirmation of Earth 2.0.
Pamela: And so, the question that’s left that we don’t know is what is the probability of life forming? So, we’re getting so close to experimentally figure out all the variables in that Drake equation, which we did an entire episode on because what haven’t we don’t an entire episode on? And so, we’re down to that point o we know the star formation rates, we’re starting to understand the planet formation rates, and now what we’re now missing is all those variables related specifically to life. The one I don’t want to figure out is the how long does civilization last before it kills itself?
Fraser: Right, let me just do the math – oh, no.
Pamela: But if we can start to figure out how often has bacterial life cropped up in our own solar system. And this is where we start just realizing how many more robots we need to go send out to other worlds.
Fraser: Well, there’s three fascinating methods that are being used to answer this very scientific question of are we alone in the universe? The one is – you mentioned, you got the curiosity rover is looking for past evidence on Mars but following that is going to be the Mars 2020 rover which is gonna have the capability to find evidence of past life on Mars in various forms. But then you’ve also got SETI, the search for extraterrestrial intelligence, which is ramping up and listening to signals of – from space waiting to hear the aliens talk to us.
Pamela: You have Maddie.
Fraser: Maddie, yeah.
Pamela: The folks that are sending the messages to the aliens.
Fraser: You’ve got wade, of course, you’ve got the people who are waiting for extraterrestrial intelligence, but the – probably the most fruitful method that we’ve got at our disposal is James Webb which is going to be launching in 2021, it’s going to have the capability to directly observe the atmospheres of Earth-size worlds around other star systems and in theory it should be able to detect some of the biosignatures that will be out there in some of these other worlds and give us some kind of evidence that there could very well be life around another star system, another planet in another star system.
Pamela: And so, as we look into the future, looking back at everything we’ve done – well, the dancing sickness of Strasbourg in 1518 through to the discovery of lenses, the use of mathematics to model our reality and the idea that observation and theory go hand in hand and philosophy is really a different study that you don’t use to define the reaction – well, which equation is the right one. We have come so far in 500 years I don’t know where to begin in imagining 500 years from today.
Fraser: Right. You may not notice, but we already started. We talked about planets, about searching for this Earth-sized world.
Pamela: But I think we’re still talking about the next 20 years.
Fraser: Yeah, yeah, yeah. Start with the first – next 20 and then we’ll move – get crazy and speculative. But there was one other piece – so James Webb is going to be launching in 2021 –
Fraser: He says that with such certainty.
Pamela: It will absolutely no question launch in 2021, no doubt. But if James Webb doesn’t launch, that’s fine – it’s not fine, but we will still get the data because there is a set of enormous telescopes being built around the world right now. There is the Larson Optic Survey Telescope which is going on in Chile. There is the – the giant Magellan Telescope, the 30 Meter Telescope, and then the monster of them all, the extremely large telescope which I believe is expected to see first light in 2026, those last three observatories I mentioned, all of which will be capable of observing planets going around other stars.
Pamela: And so, we’re going to be making these direct observations. It’s – it might not be the shiny artist renditions that we see when we click on various press release and visit sites like universe today, which none of you have ever been to, right? So, what we’re going to be seeing instead is spectral signatures, we’re going to be seeing little tiny blocks in interference patterns indicating where the planets are, but we’re going to be seeing them and observing them and this is the amazing future that’s coming.
Fraser: Following those telescopes, there’s a next round of space telescopes, which, of course, are absolutely 100% going to launch. The one I’m most – there’s the HabEx which it the habitable exoplanet finder and that’s going to be – it’s only job is going to be to observe Earth-sized worlds around sun-like stars out there. So, we have to find them and then this telescope, which is expected to launch by 2035, course that’s not going to happen on schedule, but it will be the – it’ll be the better instrument and then following that or maybe around the same time is going to be the LUVOIR Telescope, the large, ultraviolet, infrared, optical observatory, which will be a 15 to 18-meter space telescope.
And I actually had a chance to interview the – one off the project managers for this and they believe that LUVOIR will – the capability of LUVOIR will give us a 90% answer on whether there’s life in the Milky Way.
Fraser: Right. That you’re gonna have a – you’re going to be able to see with LUVOIR, again a telescope that’s bigger than the biggest telescope that’s ever been launched, that exists on Earth, but it will be in space, it will tell us – it will observe so many worlds with such capability that if it doesn’t find life within that sphere that it can observe, that it means there probably isn’t any other life in the Milky Way. Probably isn’t any other life in the universe and that will finally be this scientific question that we will know the answer to, which is again a mind-bending possibility. And that’s, of course, 2035, so we’re only like 15 years – 18 years away from that happening.
Pamela: And here’s where I point out in ’88 we thought we were a couple of years away from that garbage collector. So, the thing that we need most in order to see this new fantastic future, is that heavy lift vehicle that’s going to be getting these new massive observatories of the future into space and this is where we need to see more money going to science, more human creativity. I’m going to keep using that phrase because that is the real thing that matters. All of this energy, both human and solar, wind, all of the actual electron moving energy, going into developing these systems, and launching these new spacecraft up to explore our solar system and beyond.
Fraser: And – an obviously people are very familiar with what’s happening with SpaceEx. They are pioneering this idea that you don’t have to throw your rocket away every time you use it. of course, they’ve now demonstrated, I don’t even know how many, I’ve lost count, dozens of times that you can launch a rocket and recover the first stage – the Falcon heavy recovered, the side boosters, they’re in the works for launching the BFR which is going to be taking off next year and flying around the moon. I don’t know, it’s the future again. But it’s not just SpaceEx, you’ve got a true in theory space race with what’s happening with Blue Origin and their plans to build reusable rockets as well. As well as what NASA’s working on with the –
Pamela: Space launch system, which is not reusable.
Fraser: Space launch system, which is not reusable. They’re taking this beautiful rocket engines, these RS25’s that launch on each space shuttle and they’re destroying them with each launch, it’s gonna be so sad. But you are going to have the most powerful rockets ever built, capable of launching the heaviest payloads that have ever been devised into space. And these are all – all of these rocket systems are going to come online over the next decade. So, again we’re not even 500 years into the future we’re still just talking the next couple of decades.
Pamela: Now if you want to imagine what society looks like 500 years from now, what do you want to see?
Fraser: Well, I mean it’s because – if the BFR – if these rockets work and you get true reusability at vast scales what it makes sense to launch into space, just becomes ridiculous. That you’re going to launch – we were actually just talking about this last night about the kinds of clouds of communication satellites that SpaceX and other groups are planning. There’s going to be multiple competing high-speed internet solutions just thanks to space and again just in the next couple of decades. Just imagine, play that forward, the infrastructure that we’re going to have in the solar system, that we’re going to have the ability to communicate across the solar system, that we’re going to have mining asteroids, bringing materials back to Earth and keeping it in space where it belongs, far, far into the future. So, it’s really – it’s about building that infrastructure and I think that’s going to be the keyword for the next 500 years is going to be infrastructure.
Pamela: And what I’m looking to is being able to stick things in to those transfer orbits so that you constantly have the ability to get from Earth to Mars, that you have the transfer orbits out to the further out worlds as well. And just asteroid after asteroid take your long journey instead of the Siberian Express, it’s the Europa Express. And imagine taking that gap year to go visit Jupiter.
Fraser: Yeah. I mean, telescopes – I mean we’re imagining things like the LUVOIR telescope, but there’s a really special place in the solar system about 1,000 astronomical unit away from the sun, where you can use the sun as a natural telescope and you can use the gravity of the sun to focus the light from distant objects. And if you positioned a telescope at that 1000AU, you could see objects like the size of the house on planets orbiting on other stars because of that gravitational lens. So again, it seem perfectly reasonable when you’ve got all this capability to launch stuff that we’ll sort of set up these telescopes out at these special points to be able to start observing worlds with high resolution.
Pamela: You just have to wait 8,000 minutes for the signal to get back.
Fraser: Right, I’m willing to wait. I’ll be on my third robot by that time.
Pamela: You might be, don’t laugh.
Fraser: Yeah, don’t laugh, it’s happening. So, now there’s a few of these really fundamental concepts that astronomers are struggling with. The big mysteries of the day was dark matter, what is dark energy? How long do you think it’s gonna take for those to be solved? Will they ever be solved?
Pamela: I suspect dark matter will get sorted out before dark energy because we’re already so close. If you look at the folks who are looking at collisions between galaxy clusters, they’re able to begin to put – well, constraints on the size and collision probabilities of the kinds of particles that could be dark matter. So, it may not be a matter that we can catch dark matter in one of these detectors we have on Earth that’s looking for them, but rather we are able to narrow it down what they are and say this invisible object would have the following observational properties, were we able to lock it in a box and observe it? I think we’re not too far from getting there. Now the more interesting thing is, dark energy, the Hubbell constant, all of this we’re finding more and more confusion between the measurements using local universe measurements and error bars, and early universe and error bars measurements and I want to believe we’re gonna figure that out in the next generation of telescopes.
Fraser: Right because you’ve got two accurate measurements, both of which are – their error bars are not overlapping, both are confirmed and yet both disagree with each other.
Fraser: Yeah, that’s’ astronomy though.
Pamela: I just enough to tell us we screwed something up.
Fraser: Right, astronomers are a little upset about this.
Fraser: Yeah, it’s a mystery. One of the – but one of the parts that I think we who grew up on Star Wars, Star Trek all of this science fiction features, we want to not be living just here on Earth, we want to have other – we want to be able to visit other star systems. And that’s one that I wonder if we will make with our 500-year time frame that we mentioned here.
Pamela: Only if we’re putting ourselves to sleep or we find a way to get into the other dimensions of space. And this is the thing, it’s – you can’t, because you have stuff that you are made of, move faster than the speed of light. You can appear to move faster away from something than the speed of light because space itself is getting bigger, but that’s not you moving, that’s more space ending up between you and that other thing you’re looking at. But there’re interesting ideas that come from quantum mechanics, particles can jump from A to B, it’s more matter if they’re wave function decided I shall be maximum here, nope I shall be maximum over here. And so, the question starts to become can we either tunnel, quantum mechanically, can we jump through other dimensions? Can we – and my intellect is going no.
Pamela: But myself is going, please.
Fraser: From 500 episodes of experience I know you would shut that down.
Pamela: But the part of me that desperately wants the free time to take part in Nanowrimo in November, it’s like I want all of those things.
Fraser: Which of the would you like the best? I want a stargate.
Pamela: Yeah, yeah.
Fraser: I want to walk to other planets.
Pamela: I – I – well, not so much stargate because there you’re stepping out onto the planet and there could be things waiting there to eat you. The original – not the original, the 1980s Buck Rogers where they had the stargates that you flew through or the Babylon Five stargates that you flew through –
Fraser: Right, that you could see what’s on the other side.
Pamela: I want a gate through space.
Fraser: Yeah, that would be awesome. A wormhole. So, well a lot of those ideas, you think that we will know what caused the big bang or what was before the big bang?
Pamela: So, I’m one of those scientists that is on the side of no. Time is an arrow that goes in one direction and there’s some mysteries that in science in our observable universe just can’t get to.
Fraser: Do you think inflation will be proven to be true?
Pamela: I’m not sure and this is because I don’t know how big our universe is. If our universe is sufficiently small and finite in size and we keep observing the cosmic microwave background better, and better, and better, one of the most amazing discoveries I don’t think we’re going to make is seeing two patches of the cosmic microwave background that are enough the same that we can say that’s the same piece of space that we’re seeing from – well, light going different directions. If the light from the eyes in the back of the head both reaching us. If we get there, that might make everything else a little bit easier, but I don’t think we’re gonna observe that.
Fraser: And that whole idea of the biset two observation that they thought they had seen primordial gravitational waves and then it turns out to me that it was dust. Now they’re building another much more powerful instrument to take another crack at seeing those primordial gravitational waves. You don’t think that these new observations will necessarily find it? Because that will, in theory, will be evidence of inflation, right?
Pamela: I guess at a certain level I am worried about how can we get all – we don’t fully have dust and magnetic fields and all this other junk in our universe mapped out. It’s at the level where people still raise questions of are these galaxies the color we think they are or is there just so much interstellar reddening that it’s screwing us up.
Pamela: We – yes, we may be able to get there someday, but not now.
Fraser: Will we integrate gravity and quantum mechanics?
Pamela: I don’t know. So, the most –
Fraser: I know that’s the answer for all for all of these questions.
Pamela: Well, so the most amazing answer to me would be that we were able to somehow show that gravity isn’t conducted by a particle, that it is actually space itself is warped by the influence of gravity just as Einstein worked to explain it and then all the other forces are like yeah, we’ve got the signs. I – gravitons are probably going to prove out, but I don’t know. That would be the more amazing result.
Fraser: Right, gravitons would overthrow a lot of the existing theories of everything.
Pamela: Or they’re required for a lot of theories too.
Fraser: Right, as you said, more theories that theorists.
Pamela: And again, there’s a difference between me saying scientifically I’m not allowed to know and me as a human being who reads science fiction saying the more interesting result would be, it doesn’t mean it’s probable it just means it would make for a cooler story.
Fraser: Are there any other discoveries that you’re thinking we will sort out? Because obviously we can’t know all the things that we don’t know and so it – when we send the Europa probe and it digs down below the ice and makes its observations. When the LUVOIR telescope comes online and make observations, when James Webb sees the first galaxies forming, all of these questions are going to pop up. But are there any questions that exist right now that you think will get sorted out into the future? I haven’t already mentioned.
Pamela: There was an illustration I saw a number of years ago that I wish I had saved better. It was an illustration that came out of one of the NASA astrobiology centers that showed a artists idea of below the ice on Europa and it had jellyfish and sea cucumbers and —
Fraser: Europian worlds.
Pamela: My first thought was how did anyone at NASA get that approved, that’s awesome. My second thought was I want that to be real. I don’t think there are space whales, I want there to be space whales, I don’t think there are space whales. Again, the one who likes science fiction versus the one who does science are competing inside me. I want – I desperately, desperately want there to be thermal vents on Europa that are teaming with life and I think we have the capacity, not necessarily in our lifetime because sterility is a hard thing to figure out, but I think that’s something in the next 500 years we’ll figure out and I hope we also have a linguistics breakthrough to go with it that allows us to better understand how to communicate with the animals on our own world and the potential life we find elsewhere.
Fraser: So, two – 500 years –
Pamela: We can talk to dolphins.
Fraser: 40 episodes a year, is that 20,000 more episodes that we’re gonna do?
Pamela: We’re gonna need more than three robot bodies.
Fraser: Well, I can’t wait to get as many of those episodes done as I can side by side Pamela. Thank you, everyone, for 500 episodes of your support and watching us. Pamela, thank you for continuing to show up every time and answer all my stupid questions. It’s been an honor and a pleasure and here’s to thousands more episodes. Thanks, everyone.
Automated Voice: Thank you for listening to Astronomy Cast, a nonprofit resource provided by Astrosphere New Media Association, Fraser Cain, and Dr. Pamela Gay. You can find show notes and transcripts for every episode at astronomycast.com. You can email us at email@example.com, tweet us @AstronomyCast, like us on Facebook, or circle us on Google+. We record our show live on YouTube every Friday at 1:30 p.m. Pacific, 4:30 p.m. Eastern, or 20:30 GMT. If you miss the live event, you can always catch up over at cosmoquest.org or on our YouTube page.
To subscribe to the show, point your podcatching software at astronomycast.com/podcast.xml or subscribe directly from iTunes. If you would like to listen to the full, unedited episode including the live viewer’s questions and answers, you can subscribe to astronomycast.com/feed/fullraw. Our music is provided by Travis Searle, and the show was edited by Chad Weber. This episode of Astronomy Cast was made possible thanks to donations by people like you. Please give by going to patreon.com/astronomycast.
[End of Audio]
Duration: 67 minutes