Podcast: Play in new window | Download
Subscribe: RSS
Astronomers talk about all the amazing discoveries they’re making but sometimes, it turns out, they were wrong. After decades and centuries of discoveries, how have they changed their minds?
This episode was made possible by the following Patreon members:
Jordan Young
Stephen Veit
Jeanette Wink
Siggi Kemmler
Andrew Poelstra
Ed
BogieNet
Brian Cagle
David Truog
Gerhard Schwarzer
David
Nicholas Cunningham
THANK YOU! – Fraser and Dr. Pamela
Transcript
(This is an automatically generated transcript)
Fraser Cain [00:01:19] Astronomy Cast episode 700. The Things We Got Wrong. Welcome to Astronomy Cast for weekly facts space during the cosmos, where we help you understand not only what we know, but how we know what we know. I’m Fraser Cain. I’m the publisher of Universe Today. With me, as always, is Doctor Pamela Gay, a senior scientist for the Planetary Science Institute and the director of Cosmic Quest. Hey, mama. How are you doing?
Pamela Gay [00:01:42] I am doing well. I am still recovering from American Thanksgiving. I know you got Thanksgiving out of out of the way back in October, but we’re a little behind down here.
Fraser Cain [00:01:55] Well, I mean, I am now experiencing American Thanksgiving in situ. I am surrounded by Americans experiencing Thanksgiving. Well, well, we just huddle up and watch Apple TV shows. But but now I think we’ve gotten through the other side of this, and now life’s going to return to normal. Is something else really big and consumerist between now and the end of the year. So everything should be fine.
Pamela Gay [00:02:17] I need to get Santa hats for the skeletons in the yard.
Fraser Cain [00:02:20] There are Santa hats on on the cactus is here. It’s hilarious. Yeah. People put like, you know, you’ve got some little saguaro cactus and someone’s put multiple Santa hats on each one of the little heads of the cactus. Yeah, it’s it’s no.
Pamela Gay [00:02:35] One giant googly eyes to put on cacti like you can or just like, giant eyes out of felt that you can slide over the needles without harming the. Yeah. Oh, this so needs to be like a midnight hack.
Fraser Cain [00:02:49] That sounds good.
Pamela Gay [00:02:50] I need teenagers.
Fraser Cain [00:02:53] Astronomers talk about all the amazing discoveries they’re making, but sometimes it turns out they were wrong. After decades and centuries of discoveries, how have they changed their minds? And I think I want to clarify, because when you pitch the story, I’m like, when we were wrong or when astronomy was wrong, and it was clear when, yes, it was when astronomy was wrong.
Pamela Gay [00:03:14] And we reported on it.
Fraser Cain [00:03:17] And we reported on it. Yeah, yeah. So we’re wrong by proxy. Exactly, exactly.
Pamela Gay [00:03:22] We never make mistakes.
Fraser Cain [00:03:24] Yep, yep. All right. So, you know, you’ve got a bunch in your mind. I know I will be able to throw some in addition, on top of that, where do you wanna start?
Pamela Gay [00:03:34] Planetary formation. Okay. Just. We don’t know how it works.
Fraser Cain [00:03:41] Sure, but what was the original idea for how planetary formation worked?
Pamela Gay [00:03:45] So when we started this show. Well, so the original idea going way back was you have a solar nebula, and this part was still fine. Still fine? Where? Where a collapsing molecular cloud fragments into solar system blobs. Size varies with solar system collapses down, begins to spin. Because it’s spinning, it flattens just like pizza dough. And in this disk of swirling material in the core where it’s densest, you get a star. Further out, you get planets and everything forms where it is. With the rocky planets forming and staying near the star, the gassy planets forming and staying in the outer parts of the solar system, and then icy junk. It’s the migratory stuff that decides it needs to come in and make a light show now and then.
Fraser Cain [00:04:42] Right? And so where we have planets now is where the planets form. They scooped up the material within their region, and you got a planet. And where there wasn’t enough material, you didn’t get planets or material was stolen. And so in the last couple of decades, how has this picture changed?
Pamela Gay [00:05:04] Well, in in the 1990s, we started realizing there are worlds orbiting other stars. The first discovery was actually of basically rocky objects going around and around a pulsar. Then we had discovery of 51 peg, having a. Object half the size of Jupiter, with less than half the orbital radius of Mercury going around a young star, not two. Hugely different from our own sun, and according to all of our understanding of all of the solar systems that should be out there, this should not be an option. And as we found more and more worlds throughout the 90s and 2000s, we kept finding things that did not match our own solar system. And so new models were needed that allowed things to migrate. And once astronomers got to thinking about planetary migration, they also gave a good hard stare at our own solar system. And they were also starting to worry about things like, why was there an era in the past that appears to have significantly more cratering than other epics in the past? So why was this one set of a billion years particularly violent? And a group of researchers gathered together in the city of Nese, France, built this idea that you could have massive amounts of planetary migration where worlds could migrate both inwards due to, dynamical friction and absorbing material as they went. Or you could have gravitational rearranging with the notion that at some point in our solar system’s history, Saturn and Neptune were nice and politely in resonance with one another and started flinging Uranus and Neptune and many other things all about the solar system.
Fraser Cain [00:07:18] And so, I mean, this is the nice model, not the nice model niece. And this model is not the nice model. Oh, no, she’s named after the place in France. And I mean, I think where the revolution came was with the development of next generation telescopes, both on the ground and in space. So on the ground we have alma. And alma is this incredibly sensitive instrument that’s looking in the microwave. And it is sorry in the submillimeter sorry, almost. This incredible instrument is looking in the submillimeter. And it is seeing through the gas and dust into newly forming planetary systems. And we’ve got these images, dozens of newly forming planetary systems where you see the the collections where new planets are forming. And now suddenly, instead of just having one solar system that we know of, that we have it all mapped out. Now we see dozens of these things at various stages and different configurations, allowing them to compare and contrast the different models and say, oh, I. In fact, this nice model planet migration makes a ton of sense. And then we’ve got this whole new revolution in in planet hunting telescopes, Kepler, which died too soon, and Tess, which are showing us how many of these hot Jupiters there are out there. It’s not a one time 51 pack. There is a there are dozens, dozens, hundreds of these hot Jupiters. So clearly migration is one of the dominant processes that are happening in solar systems.
Pamela Gay [00:08:52] But it turns out even the nice model is incomplete. With the nice model, it’s super easy to create a solar system that has, for instance, all of our Kuiper Belt objects with their wild and crazy elliptical and very inclined orbits. But it’s very hard to create all the Kuiper Belt objects, all of the Trojans that are on fairly circular orbits, Trojans we can get to via Jupiter, centaurs, though centaurs in the plain of our galaxy on fairly circular orbits just don’t fall naturally out of the nest model. And then when we start looking at the mass distribution of these objects, it again makes even less sense. So there’s something completely missing. And then we’re finding solar systems that are developing on timescales that don’t make any sense to us. Where with with the nice model and the solar nebula model, you have this young star turning on slash cleaning with light pressure, the solar system around it. And when you start comparing the timescales that we’re now finding that stars turn on and the timescales that massive planets form, we need a way to get more material into the inner solar system of these forming systems faster, or those gas giants just can’t creep fast enough to explain their size.
Fraser Cain [00:10:35] And so what’s the mechanism that’s been developed for this there?
Pamela Gay [00:10:40] So they’re now starting to think, and this is where where I’m personally very much of the we don’t really understand planetary formation school of thought. But the thing that’s making the most sense is that just like galaxies sometimes form in a sudden collapse of a massive amount of mass, perhaps solar systems form in a much faster collapse. And we had previously thought, and if you have a faster collapse, you feed them more matter and faster.
Fraser Cain [00:11:12] Yeah. And I think this is the part that was really surprising to astronomers is how fast this process seems to go. Like the thought was it would take a million years that the planet would slowly drift around in this region, slowly accrete material bigger and bigger, have impact. But now it looks like it’s it happens in tens of thousands of years, maybe thousands of years, maybe hundreds of years that it just comes together so quickly. Yeah, like a instant collapse into a planet. And then you’ve got this clearing out. And I think that’s really exciting because now you don’t have so much tension between the activity of the star. You have the mass turning into the planets in their appropriate places almost as quickly as it’s possible to happen. And I think that gives us a lot more latitude for the planets being able to form before the star is able to kick everything out.
Pamela Gay [00:12:03] And so we’re now at this point where we see people, instead of saying that solar systems are formed with an accretion disk model, that they’re instead formed with a collapsed disk model. And I, I have to admit. I kind of feel like both will be an answer, because it keeps turning out that both is always the answer in our universe.
Fraser Cain [00:12:25] And also dust.
Pamela Gay [00:12:27] And also dust.
Fraser Cain [00:12:28] Right? Yeah. Which to you later on, I’m sure.
Pamela Gay [00:12:31] Yeah.
Fraser Cain [00:12:32] Yeah, yeah. Okay. Well, I think that’s great. All right. What’s the next mystery that astronomers were kind of wrong about?
Pamela Gay [00:12:41] I feel like long gamma ray bursts really need some attention.
Fraser Cain [00:12:47] Because what is a long gamma ray burst?
Pamela Gay [00:12:50] So. So we discovered back in the 1960s that various regions of our sky just feel the need to flash out gamma ray energy in a way that to a detector that simply goes detection. No detection. Not where detection looks rather like our enemies are launching nuclear weapons, which is bad that. With further study over the past many decades, we’ve now been able to go not just where burst, but also how long, what frequency, and all sorts of different details. And we’ve begun to realize that gamma ray bursts broadly appear to come in short duration and long duration. And and for the longest period of time in the early 2000s, the argument was, these long ones must be some sort of a supernova event. And this came from our ability to find leaves thanks to telescopes like Swift go from. There’s gamma ray bursts in this giant area of the sky to flipping over X-ray detectors and go, okay, the x rays are coming from the smaller area looking with an optical detector and then seeing, oh, it’s actually this thing right here and figuring out there’s something that looks like a supernova going on. And so we’re going to say a special fraction of supernovae are pointed directly at us and causing gamma ray bursts. So that’s where we started the story.
Fraser Cain [00:14:32] And so that’s what that’s what we used to think was that the gamma ray burst was, was that the beam was directed at us.
Pamela Gay [00:14:41] And that was the only special thing.
Fraser Cain [00:14:44] Right? Okay.
Pamela Gay [00:14:45] So yeah. Yeah. But the problem with that, we don’t see enough things exploding. If that’s if that’s all that’s going on. Right. So so we, we know there’s a certain number of supernovae that go off every year. We know what kinds most of them are. We know how many gamma ray bursts go off and we can match them. And if you assume that the things producing supernovae and gamma ray bursts have a completely random orientation on the sky, a random spin rotation of the thing that goes boom, you can calculate what fraction of supernovae should be giving off gamma ray bursts. And in the number of gamma ray bursts seems to be significantly too low. So then people started arguing. Well, these must be specially super rotating supernovae. But then the question becomes, why are these spinning so differently from everything else?
Fraser Cain [00:15:52] And I think it’s really important to sort of make that distinction. The difference between a supernova and a gamma ray burst is like the gamma ray bursts are just ludicrously bright. That they are. We are seeing them so bright from half a universe away compared to regular old boring supernova which explode with a, you know, mediocre amount of enormous energy.
Pamela Gay [00:16:17] They only give off as much energy as the solar system, and they’re within, whereas the gamma rays are like, I shall be the brightest thing in the sky. This.
Fraser Cain [00:16:24] Yeah. Yeah. Yeah. Gamma ray burst will give off as much energy as the entire galaxy for a while. Like it’s off the charts, while a supernova merely gives off the entire light of a, you know, a sun for 100 years or something like some long amount, but it’s just next level. And so, like, how did this, I guess, what made this story or this. Yeah, more complicated. So we started to get a sense that there was actually a lot more to this than we knew.
Pamela Gay [00:16:54] Well, folks started to notice things like when you look in detail at some of the gamma ray bursts that have been close enough that we could start doing that, it was realized, well, this one over here kind of looks like there was a binary star involved. So there are some people that are saying perhaps what we’re seeing is star goes supernova. If it has a companion star like a neutron star. So a stellar remnant as a companion, the mass feeding on to that will create a disk that generates jets. So maybe that can explain some of them. And it’s those jets that are gamma rays. And the physics for that worked super well. And it starts to explain why we see the numbers that we see. And so we’re starting to see papers that are like, okay, is this due to binary star systems. But we’re still trying to figure this out. And there there is also this weird thing that we’re starting to realize where when you use different kinds of gamma ray telescopes that may examine more or less of the gamma ray part of the spectrum. The split between we’re going to call this a long gamma ray burst, and a short gamma ray burst appears at a different time. So with some data, with some telescopes, it’s like anything longer than two seconds probably has a supernova involved in the system that’s going gamma ray other telescopes. It’s point eight seconds. So this tells us we have a lot to figure out about what is what is the full distribution of light across all the colors coming out of these things. And how do you explain that? Why is why is it producing different colors at different times for different periods of time? And. Is it one kind of thing or many kinds of things? We still have a lot to figure out, and I think what we have learned, just like with planetary formation, is we thought we knew what was going on. But the universe is more creative than we are and our understanding is incomplete and was wrong.
Fraser Cain [00:19:12] I mean, what’s kind of amazing when I sort of think back at the very beginning and I’m sure we have a show, but this is like gamma ray bursts. There was a thing called gamma ray bursts, and then it got split into two. And so you had short gamma ray bursts and long gamma ray bursts. And it really looks now like the short gamma ray bursts are due to colliding neutron stars, you know, or a neutron star in a white dwarf or a neutron star or a black hole. Some kind of collision. While the long gamma ray bursts are these biggest stars in the universe exploding a supernova. But then we’re getting in. Now, just in the last couple of years, we’re getting these things being broken, sliced even more. Like maybe you’re getting these short gamma ray bursts into neutron star, neutron star, neutron star, white dwarf. White dwarf. Right. Black hole. Right. You’re getting this this sub categorization. And then you’re getting the same thing with the gamma ray bursts. And we’re seeing these really weird and kind of interesting scenarios that mean there’s probably something even more complicated going on than just big star go boom that you’re seeing based out of a boom near another star, big star go boom, because it gobbled up a different star. Like, like, yeah, things are getting weird. And and so as always, I think, like, I feel like that is the story that we hear, that it’s always so common. Right? Is that the thing that we thought was a was one classification, when you really understand it better, suddenly gets split up into all these little pieces. And so again, I think it’s, you know, back with the planetary migration concept, it is the revolution in in observation techniques. We have better gamma ray observatories, better X-ray observatories, better ground observatories, even, you know, neutron neutrino observatories are being brought on worldwide collaborations between astronomers able to turn their telescopes on the same target at the same time. And this what was this monolithic mystery has become a pile of little mysteries. Each one is a little better solved than the monolithic side of things. And so I agree, it’s it’s a really fascinating journey. All right. I think one of the big ones that you’ve been thinking a lot about is this did the supermassive black hole or the galaxy come first towards galaxies, collections of small pieces that came together. Do they. Yeah. Monolithically take us back to sort of early astronomy cast days. Think back to younger you.
Pamela Gay [00:21:34] What did man what.
Fraser Cain [00:21:35] Was your synthesis of the science at the time?
Pamela Gay [00:21:38] Well, I mean, what what we’d been taught and what many who don’t follow that part of the literature still hold on to because I don’t think we’re loud enough sometimes, when things change, is this idea that galaxies either form in the wholesale collapse of a giant pocket of material into a galaxy, so different sized pockets of material create different galaxies, or or you have little tiny things form that have to merge together to get big galaxies. And we were really taught it was either or. And the answer is, as always, both where we are now finding giant galaxies in the early universe that could only have formed via massive collapse of giant blobs of material. But then we see there’s still small stuff today. We see things merging today, growing today. And so it’s really looking like with stars, you had this distribution where massive things were fewer, tiny things where multiple dynamics kicked in, smaller things kept merging, so they took up less. Basically, when you’re a whole lot of little things, the probability of collisions is much higher than when you have a small number of big things. So like in solar system formation, we’re like, oh yeah, it started out with a gazillion planetesimals and they just kept colliding until we got planets. Well, it’s now looking like we had a gazillion tiny galaxies, and they just kept merging until we ended up with big things. And so both the answer is both. And then like we totally are confused currently on the timescales and the order of operations for, for supermassive black holes.
Fraser Cain [00:23:44] But like this is one of the most vexing problems for astronomy and cosmology. To the point that quest. Right. Like this is like up until this point, all you had was Hubble Space Telescope being able to occasionally see lensed galaxies at the very limits of its optics. This mystery was unfolding at a place that that Hubble couldn’t see, that none of our telescopes on Earth could see that there was there was hints, but they’re just like enough to give questions, but not enough to give answers. And so the whole purpose of Webb was to just help answer this question. And so here we are now, a year and a half into full operations and operations of this telescope. And we are getting these answers. And as you said, it turns out the answer is more complicated than anyone expected. It’s not a simple, you know, you know, dwarf galaxy merger folks. You were right. Giant collapsed region, folks. You were right. No, it’s it’s a mixture of both. And so we’re seeing these dwarf galaxies, and yet we’re also seeing these giant galaxies that seem to have merged come together too quickly than anyone expected. And so wonderfully, the reality is more complicated and more interesting and more nuanced than anyone had ever believed.
Pamela Gay [00:25:03] And this is your reminder scientists don’t know everything. We want to know everything. And along the way, our our data isn’t always as good as it needs to be to tell us the actual truth about the universe, and the details we fill in on our own often simplify things far too much.
Fraser Cain [00:25:25] Yeah, so.
Pamela Gay [00:25:26] Yeah, it’s complicated.
Fraser Cain [00:25:28] And it’s funny, though, because you got to take a stab at it. Like you can see from scientists though, like like we’re seeing this thing. We’re trying to figure out how this works based on what we know. This is how it probably came together. And then it’s that based on what we know. And then we learn a bunch of new things like, oh, this is more complicated than we thought. This is more nuanced. This has more shades of gray. This is a more complicated story than we believed. And yet the answer is so much more satisfying. And it’s it’s always wonderful to hear that. And I wish we could figure out some way in advance to know, oh, here’s some stuff that seems simple. It’s expected to be complicated, right? And it’s, you know, it just it always surprises.
Pamela Gay [00:26:09] That both and is the thing that always gets me. It it used to be that people argued, well, either our understanding of gravity is incomplete or there’s dark matter and now there’s room for both and and so both just. All the different sciences collaborate to get us where we are.
Fraser Cain [00:26:30] Yeah, totally. Super fun. It’s interesting, like, you know, this is sort of what astronomers were wrong about. And like, I wonder, like, what were they right about white dwarfs.
Pamela Gay [00:26:41] We were really, really good with white dwarfs. We understand white dwarfs.
Fraser Cain [00:26:46] I mean, even black hole event horizons. Right? Like once you open your eyes and telescope image. Yeah. Yeah. The speed of light. Me being the speed of gravity. Like it wasn’t till the kilonova that we got that final confirmation. So, you know, there’s a lot of really interesting predictions that were made. And even in our time in doing this job, that those predictions have proven out in ways that are really satisfying.
Pamela Gay [00:27:13] Gravitational waves. We finally proved.
Fraser Cain [00:27:16] Gravitational waves exist. Yeah. Yeah, yeah. Man, there’s so many things that that we could go the other way around and say, what were astronomers right about? Yeah, I love it.
Pamela Gay [00:27:26] Compact objects were really good with compact objects.
Fraser Cain [00:27:31] All right. Well, maybe that’s another show at some point. Oh, thanks, Pamela.
Pamela Gay [00:27:34] Thank you. And thank you so much to all of the folks out there in our audience that donate through Patreon and, and make everything go. So this week I would like to thank in particular James Roger, Sam Brooks and his mom, Sean Martz, D, Nat Detweiler, Kimberly Reich, Jesus, Trina, Paul D Disney, Jeff Wilson, Tim Gerrish, Michelle Cullen, Janelle aka Veronica cured Dwight Elk, Gabriel Galvin, Benjamin Davies, Brian Kilby, Jordan Turner don’t blame me Paul Esposito, Bob Czapski, Ruben McCarthy, Robert Hundley, time Lord, IRA Ryan Thorson, Jason. Kerr, Kadokawa. Christian Goldy, Daniel Donaldson, Frank Stewart, Jeff McDonald and Lee Harborne. Thank you all so very much, and thank you for forgiving me on my pronunciation.
Fraser Cain [00:28:37] And thanks for helping us get to 700. Yeah yeah yeah it’s amazing. Thanks everyone and we’ll see you next week. 701.
Pamela Gay [00:28:48] Yep. Bye bye. Astronomy cast is a joint product of the Universe Today and the Planetary Science Institute. Astronomy cast is released under a Creative Commons attribution license. So love it, share it, and remix it. But please credit it to our hosts, Fraser Cain and Doctor Pamela Gay. You can get more information on today’s show topic on our website. Astronomy. Cars.com. This episode was brought to you. Thanks to our generous patrons on Patreon. If you want to help keep the show going, please consider joining our community at Patreon.com Slash Astronomy Cast. Not only do you help us pay our producers a fair wage, you will also get special access to content right in your inbox and invites to online events. We are so grateful to all of you who have joined our Patreon community already. Anyways, keep looking up. This has been Astronomy Cast.