Science Friday - Big Ideas In Physics, Saturn’s Rings, Soylent Green. Sep 23, 2022, Part 1

Episode Date: September 23, 2022

Biden Declares The COVID-19 Pandemic Over. Is It? During an interview with 60 minutes last weekend, President Joe Biden said “the pandemic is over.” “The pandemic is over. We still have a problem with covid, we’re still doing a lot of work on it. But the pandemic is over. If you notice, no one is wearing masks. Everybody seems to be in pretty good shape, “ Biden said at the Detroit auto show. This comment has prompted some dismay from the public health community. The World Health Organization hasn’t declared the pandemic over just yet. And the criteria to declare a pandemic over is nuanced and cannot be declared by the leader of a single country. Ira talks with Katherine Wu, staff writer at the Atlantic, about that and other top science stories of the week including a new ebola outbreak in Uganda, the latest ant census, and Perseverance’s rock collection.  Diving Into The Biggest Ideas In The Universe Can mere mortals learn real physics, without all the analogies? Dr. Sean Carroll, Homewood Professor of Natural Philosophy at Johns Hopkins University and author of The Biggest Ideas in the Universe: Space, Time, and Motion, says yes—if you’re willing to accept a bit of math. Carroll says that he dreams of a world in which ordinary people can have informed ideas on physics, and might argue about the latest black hole news as urgently as they might debate a sports team’s performance in last night’s game. His new book starts with some of the basics of motion that might be taught in an introductory physics class, then builds on them up through concepts like time and black holes. Carroll joins Ira to talk about the book, exploring where physics equations leave off and philosophical concepts begin, and the nebulous world in between. To read an excerpt of The Biggest Ideas In The Universe: Space, Time, and Motion, visit sciencefriday.com. Was Soylent Green Right About 2022? In the spring of 1973, the movie Soylent Green premiered. The film drops us into a New York City that’s overcrowded, polluted, and dealing with the effects of a climate catastrophe. Only the city’s elite can afford clean water and real foods, like strawberry jam. The rest of the population relies on a communal food supply called Soylent. There’s Soylent Red, Soylent Yellow… and a new product: Soylent Green. The year the film takes place? 2022. And spoiler alert: Soylent Green is people. While the 2022 the film depicts is—thankfully—much darker than our current situation, the message still holds up. When the film premiered, Rachel Carson’s Silent Spring and the Clean Air Act were very much in the country’s consciousness. 50 years later, warmer temperatures, soil degradation, and social inequality are more relevant than ever. Joining Ira to talk about the importance of Soylent Green 50 years later is Sonia Epstein, associate curator of science and film at the Museum of the Moving Image in New York City. Also joining is soil scientist Jo Handelsman, director of the Wisconsin Institute for Discovery in Madison, Wisconsin.  Saturn’s Rings Might Be Made From A Missing Moon Saturn’s rings are one of the most stunning, iconic features of our solar system. But for a very long time, Saturn was a ring-less planet. Research suggests the rings are only about 100 million years old—younger than many dinosaurs. Because Saturn wasn’t born with its rings, astronomers have been scratching their heads for decades wondering how the planet’s accessories formed. A new study in the journal Science suggests a new idea about the rings’ origins—and a missing moon may hold the answers. Co-author Dr. Burkhard Militzer, a planetary scientist and professor at UC Berkeley, joins Ira to talk about the surprising origins of Saturn’s rings. Want to know more? Listen to this previous Science Friday episode about Saturn’s formation.  Transcripts for each segment will be available the week after the show airs on sciencefriday.com.  Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Iraflato. Later in the hour, diving into the biggest ideas in the universe with physicist Sean Carroll and how an exploding moon may explain the origin of Saturn's rings. But first, during an interview with 60 minutes, President Joe Biden said something that understandably made a lot of headlines. The pandemic is over. We still have a problem with COVID. We're still doing a lot of work on it. It's what the pandemic. is over. If you notice no one's wearing mask, everybody seems to be in pretty good shape. This comment has prompted a lot of response from the public health community. The World Health Organization hasn't declared the pandemic over just yet. How do we know when it's over? Joining me now to talk about that and other science news of the week, Catherine Wu, staff writer at the Atlantic. She's based in New Haven, Connecticut. Welcome back to Science Friday, Katie.

Great to be here again. Thanks for having me. You're welcome. Well, obviously many public health experts disagreed with the president's assessment, right? But how exactly do we determine when the pandemic is over? It is a great question with a very unsatisfying answer, unfortunately. I think the tricky thing with pandemics is there isn't even a totally universal definition of pandemic. We just have this fuzzy sense of, you know, it's a disease that is affecting the world on a global scale, pandemic, pandemos, all people. being affected by something. That has certainly been the case, but it's not like we say, oh, as soon as cases of X disease crest over, you know, Y number, there's a pandemic. And then once we go

back below Y number, we're done. It is definitely not that clear cut. There's no super clear cut demarcation. And you're right. The WHO could lift the state of emergency. The U.S. could lift its own. But it's not up to one person. And even if it were, unfortunately, I don't think it would be the president. of a single country. Sorry, Joe Biden. You know, but I think the president was on to something there when he said, no one's wearing a mask anymore because you do see very few people wearing masks. Yes, this is true. And I think some of the discussion that's going on right now is, you know, when do we sort of start acting like the pandemic is over? Because if we're sort of using the

psychological concept here, you know, when do things feel like they've returned to normal, arguably that has happened. Is that enough to say the pandemic is over? But it's kind of tricky here. A lot of experts have pointed out this week that the better question is maybe not if we're saying the pandemic is over or not, but what do we do about it? COVID is still a problem? Is this even the right question to be asking? Rather than debating the semantics, how are we going to live with a virus that is still killing hundreds of people just in the U.S. alone every single day? Well, while we're still on the infectious disease discussion. Let's talk about Ebola because there's a new outbreak reported in Uganda. Tell me what's going on there. Yeah, so officials this week reported

that there has been one confirmed death and several others that they're looking into. This is being caused by the Sudan Ebola virus species, which is one of the six species of Ebola virus known to humans. And this is really concerning. You know, Sudan and Uganda are two of the countries that have had several outbreaks in the past few years. And this is yet another one that's being added to the list. So should we be concerned about it spreading through Africa and possibly around the world? I think we should be concerned, but it is certainly not time to panic. I think what's important to keep in mind is that this species of Ebola virus, the Sudan species, is just one of six types of Ebola.

It is not the same species that caused the 2013 to 2016 epidemic in Western Africa, which killed more than 11,000 people that was caused by a different species called Sayyir. But one reason to be concerned is the treatments and vaccine that we have developed against Ebola were all developed against that Sayir stream, which means that the Sudan Ebola virus, we may not have as many tools. So right now it's pretty important for the rest of the world to be invested and to send as much aid as possible. Let's move on to your next story, but we're going to still stay with pathogens. And this one is found in frogs.

A new research study links a fungal infection in frogs to a spike in malaria cases in humans. How does that work exactly? Yeah, this is a fascinating story. And Marin McKenna had a great piece about this in Wired for anyone who wants to learn a little bit more. But what's going on here is this is a really fascinating story about how just food webs are so interconnected and there's a really interesting domino effect going on here. So basically, let's remember that malaria and humans is caused when mosquitoes carrying the parasite that causes malaria, the mosquitoes bite us. They introduce the parasite into our blood.

Frogs are one of many animals that eat mosquitoes. And so when their populations decline, mosquito populations can boom, and that can be bad news for us if those happen to be mosquitoes that carry malaria. And that is possibly what's going on here. In Costa Rica and Panama, this fungal pathogen, nicknamed BD, has really been annihilating frog populations there. It's actually caused more than 90 amphibian species to go extinct in the past few decades. And if it's devastating these frog species in Central America, that is a big problem for us, because we no longer have this natural form of mosquito control. Wow, yeah.

And there's another surge, I understand, of a similar fungal infection on the horizon. Right. So BD has a sister called B-cell, and both of these are pretty problematic in the same way. You know, they infect frogs and other amphibians. They get into their skin, and that can actually cause heart failure. Scientists haven't yet figured out a really good way to stop the spread of this fungal pathogen, which means we could see a lot more loss of frogs and related spielia. species in the very near future.

Oh, I hate hearing this kind of news. Let's talk about some really interesting news, and that's an abundance of ants. This week, the latest ants census came out. Who knew there was one, right? 20 quadrillion ants on the planet Earth. How do you wrap your head around that number? I honestly can't. I can barely picture a couple hundred ants, which is a really great point that Sabrina

Imbler made at Defector this week. I mean, that is a trillion ants multiplied by 20,000. Like, I can't do that kind of math in a way that allows me to picture a pile of 20 quadrillion ants. But that is so cool, right? That means there's 2.5 million ants for every single one of us humans here on Earth. And if you sort of weighed all that, it would be 12 megatons of carbon, which would outweigh all of the wild birds and mammals on earth put together. And how do you find out how many ants there are? Well, Ira, you count them one by one by one. I'm joking.

I mean, but that is it. Hate to be that grad student. That is part of the answer, though, right? It's kind of like how we do the census in the U.S. You go to a certain part of the world, you know, or the country, depending on the scope of your census. you count how many individuals are there and you sort of extrapolate out. So the people who did this study just compiled a ton of data from many, many, many studies that have been done over decades

looking at different countries, different geographies, different types of ecosystems, trying to get a sense of the density of ants in different parts of the world and extrapolating out. And what I think is actually amazing is that that 20 quadrillion estimate, they call it a conservative estimate. So there could be way more ants that we're dealing with, we just haven't seen yet. Wow, you know, we always talk about how many termites there are, and we know there are a lot of termites, but we never think about how many ants there are,

and we need to pay a little more attention, a little more respect then. Oh, I think so. Ants are amazing. They can do so many things we can't, and if they outnumber us by this much, they definitely deserve our respect. Speaking of abundance, it turns out, now this is a great segue,

that Mars rover perseverance has a pretty sizable rock collection and some potentially very important ones, right? Yeah, so this rover has been hanging out on Mars for a little while now, collecting rocks slowly from all over the crater in which it landed. And what is pretty cool is this crater, Jazeera crater, there used to be water in it billions of years ago. And so if Perseverance is doing its job, it's going to be collecting these rocks. The hope is that those rocks will make it back to Earth some time in the next decade or so. and scientists here will be able to study them and get a sense of what was going on in that lake, what was going on before the lake arrived?

Was there even life there at some point that deposited little chemical signatures that we can pull out in the present? Yeah, because scientists were saying that's a very important place. That's probably one of the most important places that Perseverance has visited. Absolutely. And here's the question. How do we plan to get the rocks back to Earth then to analyze how important it is? It's a great question. And luckily, the rover will not have to do that job.

It's already been working very, very hard. But we're going to be launching two spacecrafts in 2027 and 28 whose specific jobs will be to grab those samples and bring them back to us. Think of them as the freight trucks going between Earth and Mars. Well, if you're saying we're going to launch them in 2027 or 28, they've got to go there. They've got to take a while to get there, get the rock. and then bring them back. So we're talking what? Ten years.

The goal is 233 to have them back here on Earth. Wow. Well, it has been a big week on Mars, especially for NASA listening in on what's going on there because NASA released audio of a meteoroid hitting Mars recorded by its rover insight. Let's listen to that. I swear that sounds like water dropping.

I was going to say, It's like that was a soap bubble maybe popping. All right, okay. So it's cool sound, but can we learn anything from it? Yeah, so that was not a soap bubble. Those were space rocks crashing into Mars. This is the first time that Insight has conclusively picked up those sounds and that scientists have really analyzed them

and been able to say, wow, that's the sound of something from outer space impacting the surface of Mars and creating craters. These were impacts that happened while the pandemic was raging here on Earth in 2020 and 2021. And the great thing is, if we start to understand what happens when rocks impact the surface of Mars, that gives us some, well, insight, ha-ha, into what happened with all those craters that are all over Mars that happened in the past. You can sort of think of craters as a fossil record almost for the surface of a planet. And the Martian surface is especially susceptible to these kinds of impacts. It's pretty near the asteroid belt. The atmosphere is thin.

And so if we get a better understanding of all those craters, we're basically reading Mars' history book. Yeah, well, that sound collected on Mars is something we won't have to wait 10 years to analyze. Definitely. We're just eavesdropping. Thank you, Katie, for taking time to be with us today. Thanks so much for having me. Catherine Roo, Staff writer at the Atlantic. She is based in New Haven, Connecticut.

We're going to take a break, and when we come back, physicist Sean Carroll tackles the big ideas in physics. This is Science Friday. I'm I, Refleto. You think you understand how the world works, but do you really, really understand it? I mean, what would you say were the central ideas that shape our understanding of the universe? And how complete are those ideas? Dr. Sean Carroll is the Homewood Professor of Natural Philosophy at Johns Hopkins in Baltimore, and author of the biggest ideas in the universe, space, time, and motion, and he argues, real physics shouldn't be just the realm of PhDs and grad students. It should be understandable

to all of us so we can all wrap our heads around this stuff. Sean, welcome back to Science Friday. Thanks very much for having me, Ira. Nice to have you. How did you decide what big ideas should be included and what should be left out? You know, I think it's pretty obvious as soon as you open the book. the big difference is that there are equations in this book. And Stephen Hawking famously told us that every equation cuts your sales in half. But, you know, my attitude is that everyone knows what two plus two equals four means. And that's an equation. It's not that hard.

And it's just a matter of degree to get up to the harder equation. So we go through all of classical mechanics, you know, a la Isaac Newton, and then relativity, special relativity, the twin paradox, things like that, all the way up to general relativity. and black hole. So you really know at the end of the book what a black hole is and why they're predicted by Einstein's theory. So how is your book different? Because as you say, Stephen Hawking has written about this and other physicists have written about this. What was your idea about how your book would be different? I thought that there was a gap between popular level treatments of physics, which I myself am a big fan of and have both read and written throughout my life.

And then there's textbook treatments of physics that assume that you're going to take years, of courses and that you're really dedicated to it. And if someone wanted that little bit of quantitative understanding, but didn't want to do all the problem sets, that didn't want to spend years and years getting there, then there was not a lot of resources for that person. So I don't think it should take you years to understand things like general relativity. So that's why I thought that this was a gap in the literature.

I know that I've had to read this stuff over and over and over again, over my career just to understand it. Yeah, I mean, it's not easy because when we don't use the equations, we tell stories, we use metaphors, we use analogies. And those are great, but they're never exact, right? They're never capturing exactly what is there. So people talk about how curvature of space and time warps things, and then they want to say, well, was time running at a different speed close to the Big Bang?

And if you look at the equation, the answer is easy. It's no, it was not running at a different speed. but if you don't look at the equations, you kind of got to trust people, and that's never quite as satisfying. Yeah, you say in the introduction to the book, my dream is to live in a world where most people have informed ideas and passionate opinions about modern physics. Do you think that's possible to get to a place where people might discuss the latest theories as deeply as they analyzed last night's baseball game? Well, you know, there are people out there who do have passionate opinions about these things, and they don't always have the understanding to back it up.

So I both want those opinions to be more widely shared and for them to be more informed so that the discussions are more interesting. You know, I think that physics should have a similar status in society as history or economics or movies or whatever, things that we go and argue about at a very, very passionate level. Do you think then that physics, as it is taught to people, is just too oversimplified. No, I don't think it's too oversimplified. I think there's absolutely a place for the simplifications. And like I say, I do it myself.

But it's not the only thing. So it's not that I'm saying that other attempts are wrong or bad or inadequate, but there should be a richer ecosystem. We have enough books and online resources out there that we should be catering to all different levels of interest. I imagine my own 16-year-old self would have loved books like this. you go a little bit deeper than one more picture of a bowling ball and a rubber sheet trying to explain general relativity.

You start off with things that people might remember from high school with mass and acceleration. And do you believe that that is such a central principle that if you understand that and how that is working, that might be enough for a lot of people? Well, I really do believe that everyone will have a different level into which they want to dive, right? And I think some people are going to be just in love with the first half of the book where we're talking about the basics of classical mechanics, Newtonian physics, just appreciating the fact that momentum is conserved, that if you have an object out there in outer space where there's no friction or air resistance or whatever, it keeps moving at a constant velocity. That's a really deep thing that it took hundreds and hundreds of years for scientists to figure out. So appreciating that at a deep level is very, very important and is an accomplishment.

And then there's going to be other people who want to get to the tensor calculus at the end of the book where you're like, what does it mean that Einstein says space and time are curved by matter and energy? What does that literally exactly precisely mean? You can get it here. As you get further and even deeper into the book, that chapter or those ideas that deal with time, I think that confuses so many of us. I mean, we think we know what time is, right? But then we have scientists saying, no, your conception of time is all wrong. Well, it's a tricky one.

And it's not as if there is something out there in the universe called time. And we're just trying to figure out what it is. There's a word called time. And we're trying to figure out how to best deploy it in understanding the universe. And it turns out, post-Einstein, that what you used to refer to as time means different things in different circumstances. There's the time that the universe feels, so it's the time that individual people within the universe feel, and there's different aspects to them all.

Yeah, and what exactly is time? Einstein wrote people like us who believe in physics know that the distinction between past, present, and future is only a stubbornly persistent illusion. Well, and that's why I wanted to not just do a dry rehearsal of all the equations and concepts of physics, but also talk a little bit, take seriously, the philosophical questions that they raise, and sometimes they, that really impacted how we think

about the physical ideas. So what is time? Is the universe eternal? Are all different moments of time equally real? Or is only the present moment real? You know, these are hard questions to answer definitively, but the reader will at least come away knowing what the possibilities are. Let's get into the philosophical side then. I know you just started a new position at Johns Hopkins. it sounds like it sort of spans in between physics and philosophy. Would that be an accurate take? Yeah, I think that's exactly accurate. I mean, one of the great things about this position is that I got to invent the name for it,

and I named myself a professor of natural philosophy, hearkening back to the time of Galileo and Newton and their friends who didn't distinguish between science and philosophy. It was all the same to them. It was all a single endeavor trying to understand the natural world, as well as we possibly can. So people who would be interested in things like this include not only philosophers and physicists,

but the right kind of mathematician or neuroscientist or biologist who's really just saying, what are the fundamental principles by which nature works? That's a set of questions that it requires both philosophical and scientific tools to try to answer it. You know, that's good to hear because I've always thought that one of the mistakes we make in high school, for example, is that we teach students to be like scientists. We give them

those inclined planes. We do chemistry with stuff they're never going to use, right, but for 90% of them. But we never teach them how to appreciate science or where it fits in. And it sounds like that's what you're trying to do. Well, that is absolutely part of it, both understanding the context, the bigger picture into which where science fits in. But also, like, just trying to do better science. You know, one of the things that you realize when you dig into science and philosophy at the same time, is that they have kind of complementary skill sets. Scientists, bless their hearts, they're just not very patient.

They often know what the right answer is because they've done the experiment. And so if you ask them, well, why is that the answer? They'll give you some very half-baked reason that just doesn't hold up logically, but they know what the right answer is. So that's good enough for the work that they're doing. And I think that if you want to go beyond our current understanding, then sometimes you have to be a little bit more patient, a little bit more careful. That's what philosophers are really good at.

Yeah. So what kinds of books outside of the normal realm do you tell your students to read if they want to understand philosophy and science? Well, there are a group of people who work in what are called the foundations of physics or the foundations of biology. And these are people who really are fundamentally interesting. interested in science, but in a way, using a methodology maybe, that will never get them hired as professors in physics departments or biology departments, so they become philosophy professors.

There are people like David Wallace and David Albert and Jananne Ismail, my new colleague here at Johns Hopkins, who are really analyzing the basic structures of the world in a very careful philosophical way. And so it's actually, I think, a beginning of, of a renaissance for this kind of work. That's why it's very exciting for me to be here. And, you know, we're starting up a little forum on natural philosophy. And we hope to inspire others to take up this way of thinking about the universe. Natural philosophy, isn't that what they used to call science before it was science? Yeah, you know, it's philosophy, but philosophy in dialogue with the natural world. That's what science is. So if there is this shared space

between physics and philosophy? Are the things that we sort of think as nebulous ideas in philosophy that might be testable and provable scientifically? Oh, yeah. You know, when people talk about the foundations of physics, for example, let's take quantum mechanics as an example.

We've been arguing over the foundations of quantum mechanics since the 1920s when quantum mechanics came on the scene. You know, Einstein and Bohr famously had a series of debates about exactly this. And, you know, generations change and times change and the physicists of today are less interested in those most fundamental questions about the nature of quantum mechanics. Philosophers are interested in them. And they've

developed, you know, in concert with the physicists, different ideas have been developed that literally do have different experimental implications. So again, there's not a bright line between the thinking that philosophers do and the experimenting that physicists do. It's all people trying to understand the universe. This is Science Friday from WNIC Studios, talking with Dr. Sean Carroll, author of the new book, The Biggest Ideas in the Universe, Space Time and Motion. You know, I was always impressed by Richard Feynman's idea that if you, you know, really want to appreciate nature, and he used to talk about this as a flower, you know, I can appreciate a flower more than an artist because I know how a flower works. I know what makes it, you know, the insides of it work. Are there parts of physics that you can teach your students or get them to appreciate nature more by knowing the physics or the biology behind it?

Well, absolutely. And furthermore, there's ways to make them appreciate the physics more by understanding the philosophy behind it. You know, I'm teaching right now at Hopkins seminar on topics in the philosophy of physics. And we were talking about the arrow of time, the difference between the past and future and how it relates to entropy and things like that. And some of my students who are physics majors came up to me and said, you know, my physics professor told me this and this and this. And I'm like, yeah, that was not very good. We can do better now in this class. Are they shocked to hear that physics professors and physicists can be bogus?

I don't think so. I mean, maybe it depends on the individual. But I think that at this point, you know, once you're a couple years into your, undergraduate career, you don't think that your professors are infallible, right? You've seen that there's a couple of mistakes they make along the way. We're all human. That's to be understood. And you can be a really, really good scientist without understanding any philosophy whatsoever or without even being especially careful about the foundational aspects of your field. But if you want to be careful, then you're going to be disappointed when you go back and listen to some of the things your

professors have told you. Yeah. The, think that science, a lot of science, starts out as philosophy that is put forth and then scientists say, hmm, that may be a good idea. Let's look into that. Well, I think that what happens is that when problems become better defined, they will often move from the purview of philosophers into the purview of physicists. You know, philosophers really spend a lot of their time struggling with problems that are just not very clear what the right way to ask them is, much less what the the answer is. You talk, for example, about consciousness. And David Chalmers famously formulated the hard problem of consciousness. How is it that we have a first person feeling for what it is

like to experience something? And that's hard to answer at a scientific level, but as science advances and as philosophy advances, we get more and more ideas about how to do exactly that. Do you get into the philosophy and the physics of when there was nothing and how you could get something out of nothing? We're going to. I wrote a paper about that. Why is there something rather than nothing? And I'm hoping to get to that in the class. But there's so many good things. Who knows how far we're going to get? Yeah. Well, what other good things? Can you give me a list of other good things that you like to talk about? Well, I've narrowed for the course that I'm teaching. I've narrowed it down to three big topics. One is, like I said, the arrow of time, its relationship. to entropy and disorderliness and the second law of thermodynamics, but also its relationship to cosmology in the universe as a whole, which leads into the second topic, which is the multiverse,

the anthropic principle, questions that arise when you have many, many observers in a universe, how do you make predictions, how do you compare it against data, how do you use that in a good scientific way? And then finally, the classic obvious thing about the foundations of quantum mechanics, What really happens when you make a measurement in quantum mechanics? Are there many worlds? And once again, how do you deal with the fact that there are many worlds? And we might be living in one of many, many copies of the reality that we experience. Do you get into at all whether we'll actually ever be able to understand the universe?

Not really. You know, I think that there's a whole set of questions in the philosophy of science that are these kinds of meta questions, right? epistemology and metaphysics questions. Why is science possible at all? What is the best way to do science? How do we formulate hypotheses? How do we change theories from one to the other? How do we update our beliefs on the basis of evidence? These are all great questions, and there should be a whole other course on them, and there are courses on exactly those questions. And so what's your next book going to be about? You're thinking about that, taking this idea one step further, or turning your courses into a book idea? There's so many books that need to be written. But,

But happily, I have my immediate future planned out for me because the current book, the biggest ideas in the universe space, time, and motion, is volume one of a three-volume set. So there's that right. Oh, is that right? Right. Well, we'll look forward to it and look forward to having you back. It's always a pleasure. It's always a pleasure to be here, Ira. Thanks for having me.

Sean Carroll, Homewood Professor of Natural Philosophy at Johns Hopkins University, author of the biggest ideas in the universe, space, time, and motion. You can read an excerpt of the book on our website, Science Friday.com slash physics ideas, and you can tune in to his podcast, Mindscape, to hear some more of those ideas. And another book recommendation for readers interested in reconsidering the way we study and talk about science.

Our SciFri Book Club pick for October. Next month, the club is reading Braiding Sweetgrass, Indigenous Wisdom, Scientific Knowledge, and The Teachings of Plants by Robin Wall Kimmerer. You can find out more and enter to win a free book. All on our website, sciencefriiday.com slash sweetgrass. That's science friday.com slash sweetgrass. After the break, revisiting a classic 1973 science fiction film,

Soiling Green, and why it has aged so well. Stay with us. We'll be right back. This is Science Friday from W&MIC, studios. Hey there, podcast listeners. I were here with a simple request. If you're listening to this podcast learning something, enjoying yourself, please go to sciencefriday.com slash support to make a donation. Our work and this podcast depends on public support from listeners like you. You know that. You're here listening, which means you find our programming valuable. Any amount

makes a difference, even two bucks. But the lasting gifts are the ones we can count on sustaining donations which we can rely on every year. So please go to sciencefriady.com slash support to make your gift. Again, that's science friday.com slash support. And thanks. This is Science Friday. I'm I'm Irfledo. Those of us of a certain age can remember the first showing of the movie, Soilent Green. It premiered in 1973. The film drops us into a New York City that's overcrowded, polluted, and is dealing with the effects of a climate catastrophe. Only the city's elite can afford clean water and real foods, delicacies like strawberry jam. The rest of the population relies on a communal food supply called Soylent. There's Soylent Red, Soilent Yellow, and

and Soylent Green. What is Soylent Green? Spoiler alert. You got to tell them. Silent Green is people. Yes, people are eating people. And in what year is cannibalism the norm? 2020, of course. Our friends at the Museum of the Moving Image in New York are doing a special showing of Soyland Green this Sunday at 3 p.m. introduced by Bill Nye. Yes, It's part of an ongoing series at the museum called Science on Screen. So we're revisiting a conversation we had on the show this April about the importance of the film and the prescient parallels to the age we live in, featuring Sonia Epstein, curator of science and film at the Museum of the Moving Image in Queens, New York,

and Joe Handelsman, soil scientist and director of the Wisconsin Institute for Discovery in Madison, Wisconsin. Welcome back both of you to Science Friday. Thank you. Great to be here. Great movie. Great movie, isn't it? Yeah, yeah. It is.

All right, Sonia, tell us, give us a bit more of a rundown of the plot of this film. Sure, so this is a Richard Fleischer film, which some people might know his other famous kind of science film, Fantastic Voyage, which he made in 1966. But the plot, you know, it's based on a book called Make Room, Make Room. And as you say, it's set in a very overpopulated New York City of 2022, and it follows a police detective who is at work trying to discover the roots of the Soylent Corporation that is, you know, basically one conglomerate that is in charge of all the food production in the city. And there's a sort of pertinent quote for this conversation about, you know, guards their farms like fortresses. This detective, played by Charlton Heston, is trying to unravel a murder that is somehow related to the Soylent Corporation. And film and art, right, Sonia, is there often a reaction to what's happening in the world. What was going on in the early 70s that may have inspired Soylent Green?

Yes, this film was released in 1973. Silent Spring, the book that a lot of people credit was sort of the start of the environmental movement by Rachel Carson. was published about a decade earlier. But in 1970, specifically, there was the Clean Air Act that was passed by the EPA and also the first Earth Day. So by 1973, certainly the environment was a big part of people's consciousness, connection between population and its effects on the environment, and also the book, The Population Bomb, had come out a few years earlier in 1968, I believe. And so, as I said, you know, the effects of a growing population on the environment and awareness of greenhouse gases, as you see in the film, that was all, you know, kind of in the public consciousness very much at the time. You know, Joe, in the film's 2022, there's almost no soil or agriculture land left.

We're thankfully better off than in the film. But you're right about the loss of soil. We are in sort of a state in our current world heading in that direction. Absolutely. The film is so clairvoyant. It was so predictive of things to come in terms of climate change and as well as loss of soil. We're losing soil about 10 to 100 times faster than we're producing soil. And so that puts us in a near crisis.

And in some parts of the world, it already is a crisis in terms of being able to grow crops and do all the things with soil that we normally do. And why is our soil eroding away? Well, we introduced the plow a few hundred years ago, and the plow does great damage to soil structure. So it breaks down clods and clumps and all that nice architecture that soil has naturally into single particles. And those are much more likely to blow away or wash away with wind and water than the clumps. That's probably the biggest influence. And then the way that we farm is not increasing carbon in soil.

it's not increasing the health of soil. It's just basically ripping the guts out of the soil and taking all the nutrients and leaving little behind. And that's just a function of the kinds of plants we grow for human consumption and the way that we grow them. They don't say in the movie that there is no soil up, but you can surmise that if you have to eat people, that you can't make food without soil,

certainly not enough to feed everybody. Absolutely. Yep, they were absolutely right about that. Yeah, if I may, there's actually... Just to anybody who may be inspired by this conversation, to watch the film or rewatch the film, if they've already seen it, there's a really sort of interesting montage at the start of the film that kind of speaks to what you're talking about, Joe, about the evolution of farming practices. It starts out sort of uplifting and it's about has the right brother, sort of about, you know, advances in human civilization, if you will, but then quickly sort of increases its pace and cuts to the advent of cars and industrial agriculture. culture and things like that that kind of culminate in the opening sequence of an overpopulated world and no food. And the only soil, I believe they say, that is left in the city is in Gramercy Park. And it's protected by this like, you know, crazy fortress looking tent. So just,

just to add that. Great, great messaging. I mean, in this movie, they know all the buttons to push on people at the time because we had all this anxiety. I remember about what we were putting in our bodies, weren't we, Sonia? Definitely. And interestingly, I mean, that also comes out of Silent Spring and what Rachel Carson was pointing out about the use of pesticides. But this film, this film had a science advisor who was Dr. Frank Bowerman, who was prominently featured in the credits as the tech consultant. And he was an environmental engineer from USC who was worried about population and pollution and you see people wearing masks. So definitely a lot of concern at

the time that this film, I think, engaged with purposefully. Joe, is it possible to produce food without soil? Yes, we can produce many plants and crops like strawberries and tomatoes and lettuce, a lot of the vegetable crops and some fruits. In hydroponics or in some cases, aeroponics, you may have heard of vertical farming, which is the idea of being able to stack up layers of agricultural activity in a hydroponic system even in cities so that you use very little of a footprint, but you grow plants going up instead of out. The problem is that we just don't know how, and I think it's

unlikely that we'd ever figure out how to make the staple crops of rice and corn and wheat, potatoes, some of the really high nutrient crops that we use in very large quantities in the world, either to consume ourselves or to feed to our animals, at the level. At the level of, in the quantities that we would need without soil. These plants are adapted to soil. They evolved in soil, and then we continued to breed them in soil. And so that's what they need. And soil is, it's more than just water, which hydroponics, you know, gives you water and some nutrients,

but soil is worth, it contains so much more than that. You know, Sonia, I think the movie has aged very well. You know, some movies seem to go out of their time, but I think the anxieties that were in that film in 1973 are still around us today. Definitely. I rewatched it recently. I think the only thing that looks a little kind of aged is the fact that I believe all of this was shot in a studio. So you can see some of sort of the set dressings that to our, you know, CGI accustomed eyes look a little dated. But that's also the appeal of the film for anybody who appreciates kind of set design and hand-painted things. But yeah, definitely the issues having to do with wealth disparity and equal equity and access, issues around climate change, you know, that have only been exacerbated, you know, since this film was made 50 years ago, as I'm sure you've discussed on this show, but the recent, you know, IPCC report point out.

So it is certainly one that is worth rewatching, particularly in this year. Yeah. One thing that did come true from the film is that there is a meal supplementary. called Soylent that you can buy now. And supposedly it's not made from people. I mean, what do you think, Sonia? Would you give it a try? I don't know why they named it that.

You know, it's seems like the death blow of the product before it's even on the market. Well, but would you give it a try, Sonia? Would I give it a try? You know, I, as the film, you know, there's such beauty in cooking food and hearing the crunch and the texture. So I have never been one to look for meal supplements, luckily, because I enjoy cooking and shopping and all of those things. Yeah. And one thing you stress as a soil scientist, and you talk about in your book, A World Without Soil, is that there is a solution to this issue. Can you walk us through what can be done to reverse our loss of soil? Sure. It's actually one of the

most soluble problems that we face today, which I find to be quite uplifting because we face so many environmental problems that we don't know how to solve. If we change our farming practices back to very straightforward practices of no-till farming, which means no plowing, where the seeds are drilled into the land instead of opening a plow with, open a furrow with a plow. If we use cover crops, which are crops that we plant at the end of the growing season, and they, cover the soil and anchor the soil and feed the soil over the winter until the next growing season. And then if we did intercropping, which is using multiple species to nurture the soil when we're using particularly these plants like corn, which take so much out of the soil and don't put anything

back in, we would probably stop erosion and begin building back our soil pretty quickly. So those are the three basic ones. And then, of course, adding more neutral. to the soil, adding compost, not, you know, throwing away all of our excess food that we do so readily in this world. But adding it back to the soil to be nutrition for the next round of crops would be very beneficial. And I want to thank both of you for going down memory lane with us today on Soilent Green. Thanks, Ira. Thank you so much. You're welcome. Sonia Epstein, curator of science and film at the Museum of the Moving Image in New York and Joe Handelsman Soil scientist, director of the Wisconsin Institute for Discovery in Madison,

and author of A World Without Soil. That was our conversation from this past April about soil in green, and if you're in New York and you want to see a special showing of the film, you're in luck. This Sunday at 3 p.m., the museum of the moving image is screening the film with a special introduction by Bill Nye. You can buy tickets at movingimage.us. You're listening to Science Friday from WNYC Studios.

Saturn's rings are one of the most stunning iconic features of our solar system, but for a very long time, Saturn, believe it or not, was a ringless planet. Research suggests the rings are only about 100 million years old, younger than some earthly dinosaurs. And since Saturn wasn't born with its rings, astronomers have been debating how they formed. and a new study in science adds a new idea about their origins. Here to tell us more is co-author of the study, Dr. Burkhard Militzer, planetary scientist and professor at UC Berkeley, based in Berkeley, California. Welcome back to Science Friday. Hello.

It's nice to have you. Dr. Mullitzer, so your team has a new idea about the rings involving an extra moon? Yes, exactly. We are proposing that the rings that we see today came about from a moon, that was early on in orbit around Saturn, and then its orbit got destabilized, and at some point it came so close to Saturn that it was sheared apart by the gravity,

and it lost most of its material, most of it ended up actually inside Saturn, but 1% is left over that formed the beautiful rings that we see today. Wow, that is really cool. I know there's another element to your study, and that explains how Saturn has this tilt to it, 26.7 degrees, also due to the moon? Not quite. The moon is related, but the tilt was actually what initiated the study. The tilt is puzzling because we think that all planets formed out of the

nebula and they all spin in this counterclockwise direction. And a few planets don't and Saturn is one of them. And it spins off, as you said, by 27 degrees, it's tilted and that you have to explain. It doesn't conform with our standard theory. And the capar power. This hypothesis was that the culprit is Neptune. So Neptune can shift its orbit a little bit, and therefore it can tilt the angular momentum or the spin rate of Saturn. So it's very strange how the object like Neptune from far away can interact with the Saturn in that way. And it only works if Saturn has this property.

And the calculations now actually show it needed an extra moon. It's like an extra handle. The moon has gravity, it's an object, so Saturn's as Neptune can sort of tilt the Saturnian system if it has these moons to hold onto. And then the moon was lost. So at that moment, Neptune lost the ability. The rings were formed, but Neptune could no longer straighten out Saturn. So Saturn was left with a tilted angle, and the loss of the moon also generated these ring particles we see today.

See yourself two mysteries at the same time. That's exactly right. So our hypothesis we're putting forward. There's no direct evidence because nobody was there to watch it 100 million years ago. But indirectly, we're solving two things with one theory. That's new. That's interesting. What had scientists theorized up until that point?

The canonical answer is, but maybe it was born that way. Ah. That was just because people didn't have any idea how the wings would be formed later. And now we actually do. But the other thing, the sort of the Cassini spacecraft, like three years ago, it flew in between the rings and the planet, and it measured how heavy the wings are. And then there are arguments that take you from a ring mass to an age, and it gave us this puzzling result that the rings are really young.

Wow. That's puzzled everyone. The people who thought, like, four billion years old, they could not explain this surprising measure. Quick quiz. How many moons the Saturn have? Quickly. Oh, there are like 60 plus we discover more, many, many. 82, I think.

Well, if you keep looking, I'm sure there will be 2 or 300. Keep looking. Keep looking. And that was a good time, actually, to look at Saturn, right? It was an opposition recently. Yeah, to be honest, I'm computer girls. I don't look at Saturn unless I teach a course. I could not answer this, Chris.

That's good. But I love your work. And I thank you for taking time to be with us today. It's a really interesting study. Thank you so much. Dr. Burkhard-Bilitzer is a planetary scientist and professor at UC Berkeley based in Berkeley, California. We have run out of time for this hour. Here's digital producer Emma Gomez with some of the folks who helped make this show happen.

Thanks, Ira. Our radio producers are Christy Taylor, Kathleen Davis, Shoshana Bucksbaum, and Rasha Arredi. Diana Montano is our experiences manager. Melissa Mayors is our office manager. Ariel Zitch is our director of audience. and I'm digital producer Emma Gomez. Thanks for listening. Thank you, Emma. B.J. Leiderman composed our theme music. And of course, if you missed any part of the program or you'd like to hear it again, subscribe to our podcasts or ask your smart speaker to play Science Friday. We'll see you next week. If you're celebrating, have a happy Rocha Shana. I'm Iroflato.