DKEU Listener Questions Volume #3

Daniel and Kelly answer listener questions about soil on Mars, the double slit experiment, and adaptations for surviving on the Red Planet. See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

  This is an iHeart Podcast. Guaranteed Human.

• 0:04Kelly Weinersmith?

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• 0:35Speaker 02

  Hey, I'm Niall Rogers. This fall, I'll be driving across the country, meeting some of today's coolest and most fascinating artists. We'll explore the stories before the moments that changed everything, because every musician remembers the moment where it all began. Experience Before the Moment, a Lincoln original series, on the iHeart Radio app, YouTube, or wherever you get your podcasts.

• 1:13Kelly Weinersmith?

  Hello, friends. One of my favorite parts of co-hosting this podcast with Daniel is that it's given me the chance to meet and interact with a bunch of you. I've really enjoyed learning about your backgrounds, your interests, and some of you have cracked me up in some of the emails. You're a funny bunch. And in particular, I love getting your questions. Y'all ask some incredible questions, and often they're questions I had never thought about before. And Daniel and I love that we get to find answers to questions that keep you up at night. So today, Daniel and I are going to tackle three questions that we've received from listeners. And we take the responsibility of finding answers to your questions quite seriously. So after we have an answer to these questions recorded, we

• 1:55Kelly Weinersmith?

  check back with the listeners to see how we did with the answers. Essentially, we let y'all grade us. And if we fail to give a clear answer, we're gonna try again. And in this way, you all can help us learn how to explain things even more clearly. So thank you. If you want to send us a question, you can either join us on our Discord channel, or you can send us an email at [email protected]. We hope to hear from you and welcome to Daniel and Kelly's Extraordinary Universe.

• 2:38Daniel Whiteson?

  Hi, I'm Daniel. I'm the part of a physicist and I love getting your questions.

• 2:43Kelly Weinersmith?

  I'm Kelly Wiener Smith. I study parasites. And as you already know from the opening, I love getting your questions, too.

• 2:50Daniel Whiteson?

  Do your kids ask you science questions you can't answer, Kelly?

• 2:54Kelly Weinersmith?

  Oh, yeah. So my daughter asked me a good science question that I sent to you the other day. So I know the right people. And every once in a while, she will ask a question that's like at a very deep level of why. And I won't know the answer and she'll stump me sometimes. But she also doesn't like talking to me about biology too much because she knows, which is such a bummer. But

• 3:17Daniel Whiteson?

  Is that because your answers are too long? Is that why?

• 3:20Kelly Weinersmith?

  Exactly why. That is exactly why. Yeah. Oh, yeah. Do your kids ask you questions you can't answer?

• 3:26Daniel Whiteson?

  They do sometimes ask me questions I can't answer, but they always stop me after a few sentences. And Hazel's favorite line is like, I didn't ask for a college lecture.

• 3:37Kelly Weinersmith?

  I mean, your dad's a college professor. That's what you're gonna get.

• 3:41Daniel Whiteson?

  And your mom, too. So what do you expect?

• 3:47Daniel Whiteson?

  But it's fun. I love their questions. And I love the challenge of trying to answer it within that teenager attention span of like, six seconds.

• 3:54Kelly Weinersmith?

  It certainly forces you to be succinct and clear. It's good. It's good practice.

• 3:59Daniel Whiteson?

  Yes, exactly.

• 3:59Kelly Weinersmith?

  But it's not naturally how I roll. But that's okay, because we have at least 20 minutes to answer each one of these questions. So we can go ahead and get into a nice bit of detail. Our first question is, you know, exactly the kinds of amazing questions that I hadn't thought of ahead of time, but I love getting a chance to think about. So the first one is about, you know, soil on Mars and what makes soil. And I just thought this was such a fantastic question, but I didn't know the answer. And so it's also a great chance to bring a friend on the show.

• 4:29Speaker 03

  Hello, Daniel and Kelly. After two Mars episodes, a question or two popped in my brain. Mars does not have soil now, but if there was life a long time ago on Mars, could there be soil deeper down in the ground? Also, if there used to be life on Mars, could that have created oil deep on the ground?

• 4:52Speaker 03

  Can single cells produce oil? Or do we need at least bigger life than that? Thank you for the podcast. Kind regards, Yoast.

• 5:00Kelly Weinersmith?

  Okay, so this sounds like a geology question. And lucky for me, I have a geology friend. He was my quarantine buddy in the pandemic. So we're bringing on to the show Callan Bentley, who's an associate professor of geology at Piedmont, Virginia Community College. And he's co-author of the free online textbook Historical Geology. Callan, what's up?

• 5:20Speaker 04

  Hey, thanks for having me. I'm glad to be here.

• 5:23Kelly Weinersmith?

  We're happy to have you here. So I read this question and I remembered that I had a conversation with you once about what's the difference between regolith and soil? And I think I remember you just sighed and walked away.

• 5:39Kelly Weinersmith?

  It was something like, my sense was that, oh, that's just jargon. But so what can you tell me? What is the difference between soil and just dirt and regolith?

• 5:48Speaker 04

  Yeah, so dirt doesn't really have a scientific meaning, but regolith does and soil does. And the difference between them is that soil has organic matter in it, which we call humus here on this planet.

• 6:02Daniel Whiteson?

  Not to be confused with the delicious dip with tahini in it.

• 6:05Speaker 04

  That's right. That is humus. And there is a difference of one M.

• 6:11Speaker 04

  Here on Earth, humus gets added from the top. So basically, like this time of year, the leaves are dropping off of many of the trees in the northern hemisphere. And that's basically a rich source of organic matter. And that drops onto the soil. And those leaves fall apart or they get tugged underground by earthworms and basically get mixed in with the rock fragments and mineral grains that make up the other sort of solid bulk of the soil. It's important to realize that soil actually consists of, you know, solid stuff, but also a lot of empty space, which can be filled. With either air or water, depending on whether you're in a drought or it rained recently, or how deep you are in the soil. So, you know, if you went and looked at the Apollo astronauts

• 6:56Speaker 04

  footprints on the moon, those are in regolith because there's no organic matter on the moon. We don't know about, you know, sort of the constituents of Mars as well as we know about the moon because we haven't been there and picked up samples and, you know, brought them back and, and, you know, we've done a few sort of remote experiments. But the sort of mechanism of folding organic material into the, you know, putative Martian soil would seem to be lacking. And so, at least in the present day. Now, if it existed in the past, you know, that's, that's, I suppose, a possibility. If Mars had a thicker atmosphere in the past and a more pronounced greenhouse effect, you know, perhaps there was life there in the terrestrial realm at that time that could

• 7:39Speaker 04

  produce organic material and add it to the regolith and turn it into soil. And it is indeed possible, as the, the listener asks, that those old soils could be buried under subsequent sedimentary layers, perhaps with zero organic content. We have examples of buried soils here on Earth. We call them paleosols, and there are a lot of examples of them. They have various characteristics that are signatures of the conditions under which they formed, just like sedimentary rocks contain signatures of the circumstances under which the sediments accumulated.

• 8:12Daniel Whiteson?

  So you make soil on the surface and then it can get buried. And so you're saying if you had life a long time ago, you would have made soil. And then if life all died out, you continue to make layers and that buries the old soil into, is that paleo soil?

• 8:25Speaker 04

  Paleosol. So they dropped the I. Yeah, soils are a little bit weird. They call the soils themselves by these names that all end in S O L S, like Aritasols and Jealousols and I don't know, a bunch of them. Soil scientists are really into classifying things. They've like organized all of the planet Earth soils into like 19,000 soil orders and/or soil series. And then those are grouped into like a dozen or maybe 14 soil orders. Honestly, it's not my area. Area of expertise. The main thing that seems to be a driver for my sort of basic level understanding is that the climate really controls what sort of soil you get in a given area.

• 9:07Speaker 04

  So soils and deserts tend to be really jacked up in terms of their evaporate mineral content because water gets whipped through them, carrying material in solution. And then that gets precipitated as the water goes into the atmosphere. So they tend to be very hard and calcareous. Soils in the tropics tend to be really clay rich because the most common mineral in the crust of the planet, feldspar, rots under warm, wet conditions and it makes clay. So you get these bright red iron oxide stained, clay rich tropical soils.

• 9:38Kelly Weinersmith?

  So Mars has red soils like that. Is there any similarity there or am I just reaching?

• 9:44Speaker 04

  There's definitely oxidized iron in the, what I would call regolith in sedimentary rocks of Mars. So yeah, that's a similarity that the iron there reacted with oxygen. And under what circumstances that occurred, I couldn't tell you whether that was in the open air, you know, whether it was submarine or whether it was, you know, in a freshwater system or whether it was underground due to groundwater flow or, you know, there's a lot of possibilities there.

• 10:09Daniel Whiteson?

  How much do we know about the surface of Mars? I mean, I know we've had rovers there for decades and they like pick up rocks and they drill into them, but how far like down have we dug into Mars?

• 10:19Speaker 04

  Not far. Yeah, there was an attempt a few years back to, you know, basically drill the deepest hole yet dug on Mars in the service of installing a seismometer so we could listen for Marsquakes.

• 10:32Daniel Whiteson?

  Love that word, Marsquakes.

• 10:34Speaker 04

  Yeah. And I don't think it got very far. I think it got stuck and so it was sort of an abortive kind of thing. Kelly's nodding, so maybe she's more familiar with the, the history of that.

• 10:44Kelly Weinersmith?

  I think it was more than one problem. One, I think things were more compact than they had expected them to be. So it's harder to get through. And then also it was having trouble gripping and staying in one spot. It got only a fraction of, of the goal of the depth that it was shooting for. It's just hard to work in space.

• 11:00Daniel Whiteson?

  My Wikipedia research tells me that the deepest hole on Mars is nine millimeters deep, which is not very impressive.

• 11:06Kelly Weinersmith?

  Oh man. So if there's soil on Mars, probably it's just bacteria. That that's adding the like life-y component to it. Is there anywhere? There's probably nowhere on Earth where it would be just like that. Probably anywhere else you'd also find like nematodes and stuff.

• 11:21Speaker 04

  Well, yeah, not anymore. There certainly would have been paleo environments on Earth when it would have just been microbial, and those would have lasted for a very long time for, you know, the first several billion years of Earth history. You know, some of those microbes would be prokaryotic, of course, and then eventually eukaryotes show up as well. But yeah, probably it would be unicellular, if anything, big if.

• 11:43Kelly Weinersmith?

  Could having just unicellular organisms result in oil? Or do you need bigger stuff to get oil?

• 11:49Speaker 04

  Oh, wait, wait, we're going into oil now? I thought we were talking about soil. So have we dropped the S?

• 11:54Daniel Whiteson?

  You dropped the I and went to sols. Now we're gonna drop the S and go to oils, yeah.

• 12:00Speaker 04

  Okay, so with with oil, the story is a little different. It's a little more complicated. So when I think of soils, I'm thinking of terrestrial regolith with organic material being added from the top and then gradually getting mixed in. But the organic content would decrease the deeper you go.

• 12:18Daniel Whiteson?

  Hold on, did you just say terrestrial regolith? That means regolith on Earth?

• 12:21Speaker 04

  Um, yeah. Thank you so much for asking that clarifying question about the words I'm using. What I meant was not underwater, not in the ocean. So I meant on the land. All right. So, you know, my default setting would not be to call marine sediments by the name soil. I would call them sediments. And they might have a high organic content or they might not. But that is not what I'm saying when I'm talking about soils. I'm talking about land-based settings. So that's what I mean by terrestrial.

• 12:49Kelly Weinersmith?

  But you said terrestrial regolith. You used the R word.

• 12:53Speaker 04

  Originally, it would have been regolith, right? And then eventually, sometime in Earth history, it started becoming soil through the addition of this magical ingredient of humus.

• 13:02Kelly Weinersmith?

  This clears up an argument Daniel and I had in the past. Thank you.

• 13:06Daniel Whiteson?

  Turns out you can turn regolith into soil just by adding humus or humus.

• 13:11Speaker 04

  You could add, yes, you could do the job with humus or other forms of humus.

• 13:16Daniel Whiteson?

  Dahini is like magic, really. It's life-giving.

• 13:19Speaker 04

  The scientific community argues, you know, at meetings, like at geological meetings, like the Geological Society of America, there are periodically sessions about the terrestrial biosphere during the Cambrian. And what they're not saying there is the biosphere on Earth. They're talking about the biosphere on land. So we have a much better geologic record about what was happening in the oceans, because that's a place where sediments tend to get deposited and tend not to get eroded. Whereas the land is a place where sediments tend to get eroded and tend not to get deposited, at least in the long-term sense. We do have terrestrial, and here again, I mean land, deposits of sedimentary rocks,

• 14:02Speaker 04

  but they are far less common, fewer and further between than marine sediments.

• 14:07Kelly Weinersmith?

  We were gonna get back to oils.

• 14:09Speaker 04

  So that's basically what I was saying for soils, okay? And yeah, basically, we don't know when the humus started getting added. People argue about that and they look at various, you know, biotracers, geochemical signals, things like that. As far as oil, oil is a liquid hydrocarbon cocktail that is formed due to cooking algae, cooking phytoplankton, all right? So I'm using algae here in the most inclusive sense. But basically, you know, phytoplankton photosynthesizing in the upper sunlit portions of bodies of water, usually the ocean, but potentially also, you know, large lakes and things like that. They capture energy from the sun doing photosynthesis. They lock that up in their organic molecules.

• 14:55Speaker 04

  Then they kick the bucket and they die. And if they avoid getting eaten, then they fall down and their little dead bodies accumulate on the bottom of that body of water. They are likely to accumulate there if there's not a lot of things that are grazing them, trying to eat them, and oxygen levels are relatively low. So if you bury this organic-rich

• 15:17Speaker 04

  Stuff and you warm it up, then you can cause chemical reactions to take place that produce the stuff that we call oil and the stuff that we call natural gas, which again is a cocktail of a bunch of different ingredients. But in the case of natural gas, they are in the gas state, not in the liquid state. So with accumulating that phytoplankton here on earth, you know, there's certain conditions that we need to kind of go through to get that stuff and get it down to the bottom of the ocean. And then it has to be buried and then it has to warm up to the right temperature. So before we started our podcast today, I made a cup of coffee and that's about the right temperature that you need to warm up your dead phytoplankton in order to get them to produce oil. If you don't

• 16:02Speaker 04

  heat them up enough, they don't make the oil. And if you heat them up too much, it basically reacts away and makes other compounds that are not capable of flowing and being pumped out of the ground. So the happy place for oil production is around 100 degrees Celsius. Okay. The temperature of an espresso.

• 16:19Daniel Whiteson?

  This sounds kind of complicated and not so easy to arrange. How is it that we have so much oil on earth?

• 16:24Speaker 04

  Well, we would have more if it wasn't so darn complicated. And, you know, we have some, but we don't have an infinite amount. So it's these circumstances might sound really far fetched and unlikely to occur, but they have occurred. And if they hadn't, you know, we would probably be living very, very different lives.

• 16:45Kelly Weinersmith?

  So Mars used to be warmer because it had flowing water at one point. Was it that warm?

• 16:51Speaker 04

  So what I'm talking about is not the temperature at the surface. And if, if the temperature at the surface was 100 degrees C, you wouldn't have flowing water. You'd have, you know, water vapor, right? Or, you know, the transition between those. What I'm talking about is burial conditions. So deep in the earth and, you know, there's usually some amount of overburden, some amount of pressure of overlying sedimentary layers weighing down on this sort of pressure cooker, where these phytoplankton are getting simmered. And that's the right condition to produce the oil. Then if that is up near the surface of the earth, here on earth, if it flows out at the surface, then a couple of things happen. One is it can de-volatileize. And so that will release the stuff that kind

• 17:33Speaker 04

  of keeps it low viscosity and it tends to get more gooey and sticky and tar-like at that point. And ultimately, the high levels of oxygen in Earth's atmosphere will react with those leaking petroleum deposits on the surface. And ultimately, you know, they will release their energy through reaction with oxygen. But in a way, that's not conducive to humans capturing that energy and putting it to work. So there are places where that occurs. And you, you know, probably have heard of the La Brea tar pits, or the beaches at Carpinteria in California. Those are places where petroleum is actively leaking out onto Earth's surface

• 18:12Speaker 04

  naturally. All right. But in order to utilize oil, what we do is we try and find places where that hasn't occurred, but where it has pooled in the subsurface. So Daniel, if you thought it was complicated before, there's actually another step, which is that we need to take the oil out of these nice, warm source rocks, and then move it into someplace where it will pool in an accessible sort of setting. And so, you know, ideally, that would be some sort of subterranean trap, we call them. And one of the most common ones is a fold in the rock layers that goes up in the middle, a so-called anticline. And if you have a sort of sandwich of less permeable and more permeable and less permeable rock layers,

• 18:57Speaker 04

  such as shale, sandstone shale, then that provides a nice little, and then you fold it into like a rainbow shape. The sandstone can soak up lots of oil and natural gas, and the shale basically keeps it from leaving that arch. So because oil is less dense than water, it rises to the top of the arch, but then it can't rise any higher. The overlying shale acts as like a ceiling and keeps it from, you know, escaping.

• 19:22Daniel Whiteson?

  This is like a geological Rube Goldberg machine.

• 19:25Speaker 04

  Yeah, man, it is. And so people have tried to shortcut this, you know, in some places where they've, you know, said like, hey, we've got these tar sands up in northern Alberta. They're full of petroleum, but it hasn't yet escaped the source rock. But we can make it escape by grinding up those things and then boiling them essentially. And then we can let the oil out and then we can burn the oil. But that takes a lot more energy investment. And so that really Only becomes viable economically if oil prices are really high, like higher than $150 a barrel.

• 19:57Kelly Weinersmith?

  So I bet they'd really like to have oil on Mars, though. And if you're already spending all that money to get to Mars, maybe you're willing to spend as much as it takes to get the oil out. Is it hidden in difficult places? Or does Mars just not have the right conditions?

• 20:10Speaker 04

  I mean, I think Mars does not have the right conditions. So if we think about the various things that are necessary, like, did Mars have oceans in the past? Yeah, maybe, probably. Did those have life in them? That seems like it's a little less likely. Did Mars have a sufficiently active surface environment to bury sediments, you know, enough subsidence in these areas where you'd get organic sediments buried? Mars certainly doesn't have plate tectonics, which is what crumples those sedimentary layers up into those folds that concentrate the oil. But maybe there would be some other equivalent trap on Mars. It does seem like, though, each of these things is far less likely on a planet like Mars than it is on a planet like Earth.

• 20:53Daniel Whiteson?

  How likely do you think it is in general? We took a random planet and I said, there are oceans and there was microbial life. What are the chances that it has oil on it? Are we talking like one in two, one in two million?

• 21:05Speaker 04

  Insufficient data, Daniel. Insufficient data. So we do not know the the the parameters of these different exoplanets. But like, one of the things that's necessary here on Earth to bury the phytoplankton in their little graveyard at the bottom of the sea is you need to have something to bury them with, right? So you need to have sediments. Well, where are those sediments coming from? They're coming from terrestrial, and again, I mean, land source areas here where rocks are being weathered, and they're shedding off particles, big and small. But if you have a planet that's completely aqueous, where it's it's got no land, then what is going to bury those things in the first place? There's no source for sediments other than like chemical precipitants from the ocean itself. So there's no way I could put a number on how likely it would be.

• 21:48Speaker 04

  I appreciate the question. It's worth articulating, but I cannot answer that.

• 21:52Kelly Weinersmith?

  We have focused on single cell organisms because we got this great question that focused on single celled organisms. On Earth, is all of our Oil from algae? Or is it also from like dinosaurs and stuff? Because that would be cooler.

• 22:06Speaker 04

  Okay, so it's not from dinosaurs and stuff. So dinosaurs and stuff are terrestrial organisms. They live on the land. They wander around on the land. When they die, they're very unlikely to be preserved in the fossil record. You know, we are very attracted to dinosaurs. We go to museums to see their fossil remains. But the reality is that they are far, far, far, far less common than marine organisms, particularly marine invertebrates. So the fossil record is strongly biased towards things that live in the ocean, things that don't have backbones, things that lived a long time ago, like during the Paleozoic. Dinosaurs, you know, were limited to a relatively brief window of geologic time. And also, the fossil record is biased towards things that have hard parts,

• 22:50Speaker 04

  such as bones or shells or teeth. Dinosaurs do have bones, of course. But, uh, you know, three of those four are kind of stacked against dinosaurs basically entering the fossil record in the first place. Usually when a dinosaur dies, its flesh rots away because it's out here in the open atmosphere where there's lots of oxygen that wants to react with all the carbon in its body.

• 23:14Speaker 04

  And that's if it doesn't get eaten or scavenged, right? So what we really want is circumstances where, you know, a dinosaur maybe, uh, you know, died, bloated with gas, a flood washed it out to sea, then out at sea it popped, and then its skeleton and its remains could join the oil-forming process. But that is really unlikely because that's not its natural habitat. No, it's not dinosaurs. But basically, it's anything organic that could enter these low-oxygen settings where sediments will then bury them and they'll get warmed up to the right temperature. Let me maybe at this point invoke an organism that you may have heard of or may not have, the conodont. Do you guys know what conodonts are?

• 23:58Kelly Weinersmith?

  No.

• 23:59Speaker 04

  Okay, so for a very long time geologists are trying to figure out how old sedimentary layers are. And we figured out that the fossils in those sedimentary layers change through time. So for instance, you find dinosaurs in some layers, you find trilobites in other layers, you find woolly mammoths in other layers still, right? So there is a time progression to the geologic record where the fossils change in a regular and predictable way. This is awesome on many levels. It's a record of past biological evolution on our planet. But it also is kind of a tool for figuring out how old the sedimentary layers are. And when coupled with other tools such as isotopic dating, say of a granite dike that

• 24:42Speaker 04

  cuts across a trilobite bearing shale, you can then figure out by dating the dike how old the shale must be. The shale must be older than this igneous rock that cuts across it, right? So we've been using this principle of relative dating by fossil succession for centuries now to figure out how old sedimentary rocks are. Leonardo da Vinci even practiced this. All right, so these fossils are most useful when they are distinct and recognizable, when they're very cosmopolitan and widespread all over the planet, not limited to some particular habitat or landmass or island or whatever. And when they are limited to a brief period of geologic time. So those three characteristics make for a good index

• 25:26Speaker 04

  fossil. Cockroaches are lousy index fossils because they've been around for, you know, hundreds of millions of years. So you find a rock with a cockroach in it, no big deal, it doesn't really tell you that much. But conodonts are powerful index fossils. So they are these little Things shaped kind of like teeth or spiked balls, or they look like sadistic ice skates or something like that. They are made out of a mineral complex called hydroxylapatite, and they're found in sedimentary rocks the world over, from the Cambrian period of geologic time up through the Triassic or Jurassic, sometime in the Middle Mesozoic. And people were like, hey, these things are awesome.

• 26:09Speaker 04

  You can really use them to tell these rocks apart, but they're different ages. We had no idea what they were, right? So they were just these things that we could find, these entities. And we were like, OK, they're useful, but we don't know what they are. And recently, they found out that they're part of the head region of an eel-like critter. So a very small, little, thin fish, where the other parts of its skeleton are not hard enough to enter the fossil record. But they found one of these rare fossil occurrences where we've got the soft tissues preserved, the muscle blocks and some of the skin, the eyeballs, they've got great big eyes. So they look to be like sort of gill support structures or something related to the mouth, but not traditional teeth like you or I have. And these things are really neat

• 26:53Speaker 04

  because they can not only tell us time, but they change color when they get different temperatures. So a geologist at the United States Geological Survey, Anita Epstein, figured out that you could use the color of conodons to figure out if the rocks had gotten to the right temperature to generate oil. So they would basically go from sort of a yellow color to an orange to a burnt umber kind of orangey brown to a gray brown to black. And you could figure out exactly the temperature they were cooked at. And that could tell you whether the rocks at that depth got to be the right temperature for oil production. A pretty neat trick. They call it the Conodont Alteration Index. And there's a nice little article on Wikipedia

• 27:38Speaker 04

  you can read if you're interested in exploring that more.

• 27:40Kelly Weinersmith?

  So when people are trying to figure out where oil is, if they find one of these things and it's the right color, are they like, OK, now we need to dig in this area a lot more? And that's like an indicator that you're in the right spot?

• 27:50Speaker 04

  Yes. And if it's the wrong color, don't bother.

• 27:53Kelly Weinersmith?

  OK. And Mars will have none of this. So we're, we're out of luck there, but that's awesome.

• 27:58Daniel Whiteson?

  My last question is, do all these names that they give to soils and rocks, whatever, do these actually make sense? Or is it a big pile of nonsense, the way it is in astronomy with arbitrary dotted lines that date back to like some old man in robes in 1700s who gave something the wrong name?

• 28:16Speaker 04

  I mean, I'd love to tell you that it all makes perfect sense, but you know, like the English language, the geological lexicon has adopted words from other traditions, other languages. I really like thinking about the origins of these different words. I think conodont, I'm sure that breaks down into something like cone shaped tooth in terms of its etymology. But geology is very rich with words from French, Italian, Scottish, even Indonesian. Bahasa Indonesia has contributed major words to the geological lexicon. And I love that sort of melting pot aspect of the science. It's very appropriate for the Indonesians

• 28:57Speaker 04

  to have a word for a volcanic mud flow, a laharr, but you wouldn't expect that to originate from Scotland. But it's very appropriate for the Scots to come up with words like esker and tarn, which describe glacial features. So it tells you something sort of almost anthropological about the, the place where these words originate.

• 29:16Daniel Whiteson?

  There's like sediments of words that build up over time.

• 29:20Speaker 04

  Yeah, that's a good way of thinking of it. And probably some of these words are almost like index fossils, right? Where they come into fashion for a while, they're used, and then you can only find them in the deepest, dustiest pages of the literature.

• 29:32Kelly Weinersmith?

  Which is where we love to explore. All right. Well, thank you so much, Callan. This was super helpful and we're going to send your answer to Youst and he'll tell you if he feels like his question was answered.

• 29:42Speaker 04

  Right on. Okay. Good luck, everybody.

• 29:44Daniel Whiteson?

  I love talking to geologists. They rock.

• 29:47Kelly Weinersmith?

  I bet Callan's never heard that before.

• 29:48Speaker 04

  I'm sure.

• 29:51Speaker 03

  Hi, Callan, Daniel and Kelly. Thank you for those rock solid answers. I'll put my plans for oil company on Mars on hold now. Thank you.

• 30:02Kelly Weinersmith?

  All right. Well, I am so glad that Youst felt like he got his question answered. And so now let's take a break and we'll move on to a question from Scott, who unfortunately is from California. We don't all get to pick where we're from.

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• 31:36Daniel Whiteson?

  All right, we're back and we're answering questions from listeners like you. If you have a question about the universe that nobody you know can answer, send it to us, we will answer it for you. We'll be right back to everybody. Send us an email to [email protected].

• 31:52Kelly Weinersmith?

  We'll try to get you an answer. Not all questions have answers, but we will do our best. But I guess there's no answer is also a kind of answer.

• 32:00Daniel Whiteson?

  Mm-hmm, yeah. The answer nobody knows is unfortunately the answer to most questions. And today, we have a thorny question from Scott from California. He's asking about a famous physics experiment that leads to all sorts of tricky philosophical wrinkles.

• 32:14Speaker 05

  This is Scott from California. I have a question about the double slit experiment. I am imagining a probability wave of a particle approaching the first barrier that has the slits in it. As the wave approaches that first barrier, I'm assuming that the universe has to make a decision about whether the particle is going to hit the barrier or go through a slit. That is, the wave function would collapse and the particle would find itself hitting somewhere on the barrier, or perhaps find itself right where a slit is. If it finds itself right where a slit is, does the wave function then instantly uncollapse, such that it goes through both slits simultaneously? This question has been bothering me for a long time, so I'm really looking forward to getting an answer. Thank you so much.

• 32:57Kelly Weinersmith?

  Oh, man, Scott, that is a great question, and I have vague memories of the double slit experiment from freshman year of college, but I guess that's 20 years ago now. Oh, my gosh. So, Daniel, refresh my aging memory. What's the double slit experiment?

• 33:15Daniel Whiteson?

  Yeah, I think it's useful to nail down exactly what we're talking about, so we can figure out how best to answer Scott's question. This is a famous experiment that's been done in many ways with changing interpretations over time. So, the first version of this experiment was done with light. You have some source of light, a light bulb, or a laser, or whatever, and you shine it on some barrier. And most of the light is absorbed, but you have two little slits in the barrier, and where those slits are, the light can go through. So now, on the other side of the barrier, you have these two little narrow slits, which act like sources of light themselves, right? Almost like you have two little light bulbs right there. And then the light that comes from these slits hits some screen, and that's where you're observing it. What you see on the screen is not just like light from the two slits, you see an interference pattern.

• 33:59Daniel Whiteson?

  You see that in some places, it's dark, even though the light hits it, and other places, it's very bright. And that's explained by light being a wave and cancelling out in some places and adding up in other places. So, the first earliest version of this experiment showed us that light had these wave-like properties, because it interfered with itself on the screen.

• 34:18Kelly Weinersmith?

  Okay, I'm following that, but I feel like I also have a vague memory of physicists talking about light as a particle. Yeah, what's going on there?

• 34:27Daniel Whiteson?

  So, now, it gets weird. Remember, the crucial explanation for why do we have interference is that we have light coming from both slits, right? Each one is like a little source, and sometimes their waves go up and the other one is going down, and sometimes they're both going up, so they add up. But the crucial thing is you have two sources, which is why Of interference. So then slow the experiment down. Now we know light is actually made out of little packets. It's not like a continuous stream, right? When you turn on your flashlight, it's actually shooting out little packets of light. These things we call photons. And so you can make this experiment more interesting by slowing it down and saying, what happens if we only have one photon in the experiment at a time, right? Instead of huge numbers of photons which are interfering with each other, what happens if you have a single photon? And then you see something very strange,

• 35:11Daniel Whiteson?

  which is the interference pattern builds up gradually on the screen. So one photon comes through and it lands in one spot. Another photon goes through, it lands in a different spot. And then the third one in another spot. But if you do a million of these, it adds up to give you the same pattern you saw when you illuminated it with a huge amount of photons all at the same time. So the confusing thing there is, and I can see Kelly's face is going huh?

• 35:36Kelly Weinersmith?

  Yep, what?

• 35:37Daniel Whiteson?

  Is what's doing the interfering? Because in the earlier version, I explained that the interference pattern is coming from having two sources. But if the one photon is in the experiment at a time, what is it interfering with? That's the big puzzle.

• 35:51Kelly Weinersmith?

  Is the answer gonna be quantum entanglement or something? Why do you all always make this so complicated?

• 35:57Daniel Whiteson?

  The answer is definitely quantum mechanical, though not entanglement. What's happening here is that the photon is not like a little particle that has a specific path and it goes through this slit and then hits the screen. The photon has a probability to go through one slit or the other slit, or to get absorbed by the barrier. Right? We don't know where an individual photon is gonna go. And it's that uncertainty, that probability, that's doing the interfering. So remember that picture I painted in your mind of light going through the experiment and coming out of the slits as little sources and then interfering with itself? You can use that exact same picture, except instead of thinking about it in terms of light, think about it in terms of probability for one photon. So you send that photon against the barrier.

• 36:40Daniel Whiteson?

  It has a probability to hit one slit or the other slit. That probability passes through both slits, right? And then that probability interferes with itself and creates a probability distribution on the screen in the Back. Then the universe has to pick, okay, where is this photon actually going to go? So I can put it somewhere on the screen and it draws from that probability distribution. And it puts one photon. So that probability distribution guides each individual photon. It puts more where the probability distribution is high. In other words, where the interference pattern is bright and fewer where it's dark. So that gradually it builds up the same interference pattern you saw when you shone the light brightly.

• 37:21Daniel Whiteson?

  So you just replace the concept of light waves with probability waves and all the same math works.

• 37:27Kelly Weinersmith?

  Awesome. I think I had been imagining when we were sending a particle through the slits that we had directed it to one slit in particular. Not that it could have gone through both, but it's not like I had the probability stuff in my head. So I still, yeah, anyway, makes sense now. Awesome.

• 37:41Daniel Whiteson?

  It's crucial that you don't know in advance which slit it goes through, that you have the possibility for it to go through both slits. Because then the other version of this experiment is, well, what if we check? What if we put a little detector like a camera or something that can tell whether the photon went through slit A or slit B? Then what happens? Well, then the universe picks which slit it went through because you put a detector there. So you've collapsed the probability. Instead of allowing for the possibility that the photon goes through either slit, you now force the universe to pick which slit it goes through. So then the interference pattern disappears and you just get photons going through one slit or the other slit and you get a geometric shadow instead of an interference pattern. Because there isn't probability coming out both slits because you forced the universe to pick.

• 38:24Daniel Whiteson?

  And now it just sends a photon to one slit or the other slit. This is this bizarre process. We don't fully understand of how possibility becomes reality when the quantum meets the classical.

• 38:35Kelly Weinersmith?

  It still absolutely blows my mind that just measuring it changes the pattern that you get on the back wall. Like, is it just shy? And like, you know, what is the, what is the leading theory for why observing it changes things?

• 38:48Daniel Whiteson?

  It's not something we understand very well, and this is called the measurement problem in philosophy of physics. It's really a puzzle. I mean, we have this quantum theory that says things at a quantum level follow these equations of probability, and that's the Schrodinger equation. And they can have weird properties like not having a specific location, but instead having a probability to have several locations, or having probability to be spin up or spin down. You can maintain a superposition of different possible outcomes, different possible properties for yourself. That's what a quantum object can do. But we know that classical objects can't. Like, when you have a screen, the photon either hits here or there. It doesn't like half-hit here and half-hit there. Or when you flip a coin, it's either heads or tails. It's not like

• 39:32Daniel Whiteson?

  half-heads and half-tails. So we have these two different worlds, the quantum world where you can have superpositions, and the classical world where you can't. And we don't really understand the transition between them. It's confusing, because everything in the classical world, like quarters, and me and you, are made up of quantum things. So the leading theory is sort of nonsensical. The leading theory, called the Copenhagen Interpretation, says that, all right, you have quantum stuff, and it can have multiple possibilities, and it can do all sorts of crazy, wave-like things, like interfere with itself and its own probability. But then, when you interact with a classical object, like an eyeball, or a detector, or a screen, then the wave function collapses, and the universe has to pick. It says, instead of this whole spectrum of possibilities, you just pick

• 40:15Daniel Whiteson?

  one. And that allows us to have classical outcomes, like, hey, it's up, or it's down, the photon is here, photon is there. This collapse theory doesn't really work, because, number one, it violates like basic quantum mechanical rules, like quantum information is never lost. And also, it's not really well-defined. Like, when I said, "A quantum object meets a classical object," I wasn't clear on, well, what is a classical object, exactly? Because, as I said earlier, all classical objects are made of quantum objects, and that's the puzzle. Nobody can define the barrier between quantum and classical objects. So we don't really understand it. We don't have a great explanation. It's one of the biggest open questions in philosophy of physics.

• 40:56Kelly Weinersmith?

  Still so much left to do.

• 40:58Daniel Whiteson?

  Still so much left to do. Exactly. So let's get to Scott's question. And Scott is thinking about what happens when the photon is approaching that barrier. And I think that he's imagining that either the photon hits the barrier and is absorbed, or hits one of the slits and goes through. And I think Scott is thinking that maybe the universe collapses it at that moment, when it either hits the barrier or goes through a slit, because it sort of encountered some big classical object. And then he's confused about how later we can say it maybe went through both slits. And is there some uncollapse? Like, how do you get multiple possibilities through that barrier? I think is essentially Scott's question. And the answer is that hitting that first barrier doesn't collapse the wave function, because you've still left multiple possibilities.

• 41:43Daniel Whiteson?

  It can go through slit one or go through slit two. So both of those possibilities propagate forward. So the short answer is the first barrier doesn't collapse the wave function, unless you have a detector there that's saying like, hey, did you go through slit one or slit two? Because you allow the possibility of multiple slits, you allow the quantum mechanical properties to maintain, and for there to be a superposition of two possible outcomes. And so then both of those possibilities go through the slits, and then you get the interference from those two possibilities.

• 42:13Kelly Weinersmith?

  Great. So if it collapses at the two slits, instead you get a totally different answer.

• 42:17Daniel Whiteson?

  Yeah, if you collapse it at the two slits, which you can do, if you put a little detector there and you say, I want to know which one it went through, then you get a totally different answer, exactly. You get a different pattern on the screen. And crucially, you can't uncollapse. Like, when you collapse the wave function, you go from here, the whole bunch of possible outcomes, to now there's just one. And you can't ever uncollapse it. You've lost information, which is why it's so confusing. We've said on the podcast before, like, you can't lose quantum information. It can't be deleted from the universe. But this collapse theory does violate that principle of quantum mechanics. And people out there might be like, hold on, aren't you contradicting yourself? Yeah, absolutely. And this is one reason why we haven't really figured this problem out. Like, we had this best explanation we have violates other things we know about the universe.

• 43:01Daniel Whiteson?

  So it's like a work in progress.

• 43:03Kelly Weinersmith?

  Yeah, this is one of the really fun things, I think, about podcasting with a physicist. I hadn't realized there were so many works in progress. But it's exciting that there's so much left to discover. So I feel like I understood that. But let's go ahead and test ourselves and ask Scott, if, uh, did we actually answer the question that you were asking? And if so, was the answer clear?

• 43:22Daniel Whiteson?

  That's right. Or did we just collapse his brain? Okay, so it's my pleasure to welcome to the podcast Scott Goldman. Scott, thanks so much for writing in with your really fun question.

• 43:32Speaker 05

  Yes, thank you.

• 43:34Daniel Whiteson?

  So tell me, you heard me and Kelly talk about the double slit experiment and what happens to the wavefront as it hits the first barrier and interferes afterwards. Tell me, did that make sense to you? What questions do you have remaining?

• 43:45Speaker 05

  So it makes sense to me. I guess it all comes down to one question, and that is every time a particle is shot at that double slit, the barrier with the double slit in it, there's a probability wave that comes to that barrier, it goes through both slits, interferes with itself, and when it gets to that detector screen, the universe at that point then, I guess, has to make a decision where it hits. My question is, does every particle that is shot at that barrier with the double slits go through and then hit

• 44:26Speaker 05

  the detector screen? Or do some particles not hit the detector screen because they actually hit the barrier somewhere instead of going through the two slits?

• 44:36Daniel Whiteson?

  Yeah, great question. The answer is the second one. Not every particle makes it through, but, and there's always a but, every particle has a probability of making it through. So there's sort of a lot of different outcomes. One outcome is you make it through one of the slits and you end up somewhere on the screen as a dot. Another possible outcome is you don't make it through at all. So imagine that probability wave approaches the first barrier or the one with the slits in it. Some of the probability wave makes it through and interferes with itself and gives it a probability to hit the back screen, but a lot of it, as you say, hits the barrier. So then when you force the universe to roll the dice and say, what is the outcome for this particular particle? A lot of them are going to hit the barrier. In most of the descriptions of this experiment,

• 45:19Daniel Whiteson?

  they sort of ignore that part because that's not so interesting. We pay attention mostly to the ones that go through because those are the ones that do the interfering. But yeah, a lot of them, if you ask, like, hey, what happened to this particular particle? The answer would be that a lot of them hit the barrier and don't make it through.

• 45:33Speaker 05

  Okay, so that's the part, I guess, where I'm having Trouble understanding because I'm imagining this probability wave approaching the barrier. And then when it gets to the barrier with the slits, the universe has to decide like, oh, am I going to hit the barrier? Or no, I didn't hit the barrier. I happen to, I'm, I'm gonna be right in this little space where there's a slit. But then it goes through both slits.

• 46:03Daniel Whiteson?

  Right. Yeah. So the universe doesn't necessarily have to decide there, right? What it can do is have several possible outcomes. The wave approaches the barrier and now there are three possible outcomes. You go through one slit, you go through the other slit, or you reflect or maybe get absorbed, depending on the nature of the barrier. So the probabilities sort of fragment there, but they don't have to collapse, right? They only collapse when you insist you know. But if you don't insist, you know, you're like, well, I'm just going to allow the universe to keep doing its thing. I'm gonna keep that within a black box or keep my eyes closed for that part of it, the equivalent. Then it can continue to propagate all three possibilities that it reflects back or that it goes through one slit or that it goes through the second slit.

• 46:44Daniel Whiteson?

  It can maintain all of those and it's maintaining the uncertainty that allows it to make that interference pattern.

• 46:49Speaker 05

  So some of the probabilities go through the slit. And then when it gets to the detector screen, at that point, it decides whether it actually made it through or hit the barrier?

• 46:58Daniel Whiteson?

  Mm hmm. Yeah, exactly. It doesn't have to collapse when it hits the barrier.

• 47:02Speaker 05

  Oh my gosh, sorry.

• 47:04Daniel Whiteson?

  Yeah, no, that's, yeah, it's, it's amazing. It's sort of crazy. But the way to think about it is that it's allowing some of that probability. You can also think of it another way. You can think, um, you know, the probability, most of it gets zeroed out and only those two little narrow slits of probability remain. But there's still uncertainty there. There's still, you don't know which way. And so that's what allows for the interference. And I think a lot of people are confused by that. They're like, well, why doesn't the barrier collapse the wave function, right? Right. And you can think about it that way also. And you can, for example, add detectors to the barrier so that the only possibilities for the particle are that it goes through a slit or hits the detector. And that doesn't collapse the wave function completely.

• 47:48Daniel Whiteson?

  That just says, if it hits the barrier, then I want to know. If it doesn't hit the barrier, there's still uncertainty because it could still go through either slit and then you'll still get the interference pattern. So that scenario, you could sort of partially collapse the wave function. You'd be like, if it hits the barrier, I want to know. Otherwise, I'm going to allow for the uncertainty to propagate through both slits. So there's an infinite number of confusing and amazing ways to do this experiment. All right. Well, I hope that helped you understand. Thanks so much for asking the question. Thank you.

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• 49:46Kelly Weinersmith?

  And we're back. Our final question of the day is a question from Lewis on Discord. And here is his question.

• 49:54Speaker 05

  Hi, Daniel and Kelly. I was wondering, what kind of adaptations might we make to humankind, whether genetic or bionic or anything, um, to help us to live on a place like Mars? Thanks. Looking forward to hearing your answer.

• 50:16Kelly Weinersmith?

  All right. Oh, my gosh. There's so many problems on Mars. Which ones should we try to solve?

• 50:21Daniel Whiteson?

  I'm excited that you're optimistic about this. I thought your answer might be like, it's impossible. Give up.

• 50:25Kelly Weinersmith?

  I mean, uh, the back of my mind is saying that, but, but I'm gonna, let's try to have some fun. Let's start with the problems that could kill us. And so those problems are probably radiation, partial gravity and depressurization. So I think those are the top three. What do you think, Daniel? Are those the top three worst problems on Mars?

• 50:45Daniel Whiteson?

  Those sound pretty bad. Yeah. And I think I'd love to hear solutions to those. And this is great because it gives you an opportunity to demonstrate your optimistic side instead of just throwing cold water on humanity's prospects.

• 50:56Kelly Weinersmith?

  Oh, man, I hope that doesn't mean this is gonna be a bad answer. Cause it's not in my skill set to be optimistic. Okay.

• 51:02Daniel Whiteson?

  Let's see.

• 51:03Kelly Weinersmith?

  All right. Let's hold off on the depressurization problem till the end because the initial set of solutions that I have are not really good for depressurization. So one problem is radiation. So as we've discussed on a couple of other episodes, space has different kinds of radiation than we typically encounter on Earth. So you have solar flares and solar particle events, and these are like shooting protons, boop, boop, boop, boop, boop. You can die right away from something like radiation sickness, uh, just shuts a bunch of your organs down all at once, or you can get cancer, which will kill you slowly. Also, we have galactic cosmic radiation. Not a hundred percent sure where it comes from. Could be from exploding stars and black holes, but we don't really know. Right, Daniel?

• 51:41Daniel Whiteson?

  Yeah, exactly. Yeah.

• 51:43Kelly Weinersmith?

  All right. So the galactic cosmic radiation tends to be bigger, like charged ion particles. Uh, I saw this one paper. It was an old paper from like the seventies, but they got a gel that was meant to be sort of like the human body and they shot an iron ion through it and it blew a hole the size of a human hair, which like, does, I mean, usually like, oh, size of a human hair. That's used to indicate something small, but like, I don't want holes the size of a human hair in my brain. Like, that's no good.

• 52:11Daniel Whiteson?

  No, and that's a great image because it reinforces the message that these things are not like little fuzzy quantum objects that somehow interfere with you. They are basically space bullets, right? Space is shooting bullets at you. And we have a bulletproof vest here on Earth, right? Our atmosphere is protecting us. It's absorbing all that kinetic energy. And we're lucky. And so, yeah, how do we deal with life on Mars without our atmospheric bulletproof vest, Kelly?

• 52:34Kelly Weinersmith?

  The easiest solution is probably something related to shielding, but radiation, well, space makes everything complicated. But one way radiation is complicated is because of something called spallation. So when galactic cosmic radiation hits your habitat, it hits particles that it then breaks into other kinds of particles that are also radioactive and now rain down on you in what's called a nuclear shower. See, Daniel, you asked me for a solution, and I'm giving you reasons why it's worse. My pessimism is winning. All right, I'm backing up. Okay.

• 53:02Daniel Whiteson?

  Wait, so you're saying if I walk around Mars with like an umbrella of some very heavy duty material to protect myself from radiation, it's actually just going to generate like showers of radiation underneath the umbrella?

• 53:13Kelly Weinersmith?

  Depending on what the umbrella is made out of, yes. So there are some particles that are better at absorbing things. I don't think anything's really great at absorbing galactic cosmic radiation without breaking up, but could bury your habitat in regolith, which we've talked about before. But, you know, human bodies can repair some damage, and some of us are better at repairing damage than others. And so let's assume that part of the solution is you're burying your habitat in regolith, but you could also specifically send to Mars people from Earth who are more radiation resistant. And to be honest, I don't know how we pick those people yet, because like, we don't have a lot of experience with space radiation, but presumably there's variation in this trait. So you could send

• 53:57Kelly Weinersmith?

  more radiation resistant people up to space, and at least for the first generation, that might help. Maybe.

• 54:04Daniel Whiteson?

  Because they're like less likely to get cancer, they have some sort of like genetic predisposition? Like biologically, how does that work? What is it about some people that makes them like more rad proof than others?

• 54:16Kelly Weinersmith?

  Yeah, no, great question. Who knows, right? Here's Kelly. We don't really know. And so that there are some people who are like, well, you know, we can pick people who are more radiation resistant. And then we could figure out what it is about them that makes them more radiation resistant. And then we could try to use genetic engineering to tinker to make the next generation more radiation resistant. And like through this combination of crew selection and genetic engineering, we can create people who can survive better in space. Here's a tiny little bit of pessimism really quick. Uh, I won't linger too long, but you know, most of the important human traits are not controlled by like a gene that you can tinker with. So like our genetic engineering of humans that has gone best so far has involved tinkering with genes that don't get passed to babies

• 55:00Kelly Weinersmith?

  and dealing with diseases that are caused by like a mutation in one spot. So if radiation is controlled by a hundred genes, you could tinker with all those genes. But the other problem is that genes usually don't just do one thing. So when you tinker with all those 100 genes, you might be messing up other stuff too. So actually, let's go ahead and say that's not the best solution. And now, because I have a physicist on the show and an optimist, maybe, I'm going to kick to you. So let's imagine that we are living in an environment where we had, where money is no problem. And we have as many nuclear, portable nuclear power plants as we could possibly need. Could you use electricity in some way to protect your habitat from space radiation?

• 55:42Kelly Weinersmith?

  I know it's energetically expensive, but like, could we super cool, like what are, what are our solutions here?

• 55:47Daniel Whiteson?

  Yeah, well, these things are mostly ions, right? And so these, they are charged particles and those charged particles can be repelled or redirected by electric fields. But they're very, very high energy. The good thing is the very high energy ones are rarer. So while it'd be much more challenging to redirect the high energy ones, they are less common. The rate falls very, very quickly with energy. But yeah, it would cost a huge amount of energy. Really, the better way to do it is a magnet, right? Rather than relying on their electric field, because that's what the earth does. The earth has a magnetic field and we deflect a lot of this stuff. There actually is a fun proposal to put a huge magnet between the sun and Mars

• 56:28Daniel Whiteson?

  to create like a magnetic shadow for Mars to deflect these particles. And I asked a friend of mine, who's a planetary scientist, who has actually worked on like Mars missions. And he says, quote, "This is literally the dumbest idea I have ever heard." I almost fell out of my chair when I saw someone presenting it.

• 56:46Kelly Weinersmith?

  Okay. I feel like this person would be good friends with me as a fellow pessimist.

• 56:52Daniel Whiteson?

  I know. And I asked him to elaborate and he says, quote, "There are so many reasons it's stupid. You have to somehow make a giant magnet. You'd have to put it on a ginormous spaceship and keep it in orbit around the Lagrange point." And he goes on to point out that not all of the radiation comes directly from the sun. So the shadow wouldn't even protect you. And a lot of the radiation are UV photons, which do not have a charge and will not be deflected by magnets or electric fields. You really need the combination of a magnetic field for your whole planet, not just a shadow. And you need an atmosphere to absorb the stuff that isn't charged. So yeah, physics doesn't have an answer for this one either.

• 57:28Kelly Weinersmith?

  Oh, man. Okay. Well, let's move on to the next problem. I don't have an answer, really.

• 57:36Kelly Weinersmith?

  And then, of course, there's all the ethical things that we just completely glanced over with genetic engineering. So that that is something else holding this all back. All right, so then the second problem is partial gravity. So Mars has 40% of the gravity we find on earth. We know that astronauts who experience no gravity when they're in free fall lose muscle mass, bone density. And that might explain why they start losing some of their vision, or some of them, not all of them. Because the fluids, you know, were adapted to have gravity pulling our fluids back down. So when we don't have that like benefit. Fluids tend to go up and they like push on our brain and they might be changing the shape of our eyes. So 40% gravity, would that solve the problem? We don't know. Like some of those problems, maybe bones and muscles, for example, that

• 58:20Kelly Weinersmith?

  could possibly be solved by like putting on really heavy weighted outfits that sort of make it so that you're carrying around as much weight as you'd be carrying around on earth. That might help keep everything nice and strong. I don't know if that's going to help with like fluid related problems or like anything else in your body that's associated with partial gravity. But you could, and I've seen proposals for this, create banked racetracks to create artificial gravity. And you could, I don't know, maybe sleep in those and that might be enough. And then I also have seen proposals for what are called sucky pants or sucky sleeping bags. And they, they create a different kind of pressure and it pulls the fluids down. And so you could like sleep in these or wear these. They're

• 59:05Kelly Weinersmith?

  like, you have to tune them well, because sometimes when they turn them on like too fast or too strong, the fluids rush out of your brain and people like pass out, which is not great. And they don't look super comfy. But so there are some technological solutions.

• 59:20Daniel Whiteson?

  But to be clear here, you're saying that we know there are problems in zero gravity. And now we're asking like, is 40% gravity enough? Like, do we still have those problems in 40%? And then what can we do about solving that additional bit, right?

• 59:33Kelly Weinersmith?

  Yeah, right. So I am assuming that 40% is not going to solve all of our problems. If it does, then great. We don't need any extra help. If we do need extra help, here are some things we could do.

• 59:44Daniel Whiteson?

  But who wants to live on like a banked racetrack their whole life? That doesn't sound like a fun place to hang out. Or maybe only part of the time you need to be on the racetrack?

• 59:51Kelly Weinersmith?

  Yeah, we don't know. Maybe you could sleep on the racetrack and that would be enough. But I, we don't know.

• 59:57Daniel Whiteson?

  Well, what about something like more inherent? Is there something we can do inside the body, you know, like to modify the structure of our bones or change some fundamental process inside of us that'll just make us more naturally suited to that kind of environment? I'm thinking like really science fiction craziness here.

• 1:00:14Kelly Weinersmith?

  Science fiction craziness. Okay, so, right, so one of the questions would be like, does our current genetic makeup include enough variability where we could tinker with things in the right way to make us survive better in these environments? And so, you know, maybe there are, for starters, people who have bones that are thicker than others and would maybe do better in an environment like this. And if we can figure out why they have thicker bones, maybe we could tinker with the DNA of future generations, which is a phrase that makes me shudder just thinking about it. But anyway, we could do that, maybe, and like thicken up their bones, so that maybe it wouldn't matter if they're in an environment where you would expect bones to atrophy because they were

• 1:00:56Kelly Weinersmith?

  already stronger to begin with. Like, maybe that'll be enough? I really don't know. For this one, I kind of come up at a loss. With radiation, I felt like it was maybe a little easier to imagine.

• 1:01:06Daniel Whiteson?

  Well, my question is like, who's working on this stuff? Like, can you do any kind of ethical research here in terms of like bioengineering humans? Or are people doing like bioengineering on rats and dogs and stuff, or just sort of theoretical? Is it possible to do research in this area?

• 1:01:22Kelly Weinersmith?

  So with new CRISPR technology, it's easier for us to tinker with genetic information. So to like, cut bits out and replace it with other bits that we want. And we have used that to help out with some diseases. So for example, sickle cell anemia, by tinkering with some genes using CRISPR Cas9, we've been able to like, make people's lives way better. So we are getting better at using some of these techniques in humans, which is a big step, I think. And so we're getting a little out of sight of my expertise. I think the first time that technique was used on babies in a way that it would be transmitted across generations was done in China, and they got thrown in jail for that because the whole international community was like,

• 1:02:07Kelly Weinersmith?

  no, no, no, no, no. We were not okay. None of us are okay with this. You jumped way too far ahead. And so I think that research is gonna not move forward, I hope, for a while.

• 1:02:17Daniel Whiteson?

  And if I could press on that for a moment, like, I've always wondered, is there a CRISPR Of why it's okay to breed humans by selecting your mate, but not by editing their genome? Is the only answer just like, well, this is a dull enough strategy that you can't like feel too bad if you mess up and you know, your kid doesn't have the genetics you wanted or something? Like, is it just the power of this technology to create horrendous outcomes?

• 1:02:41Kelly Weinersmith?

  I think it's a couple of things. So one thing is that we as a species have a lot of experience with mating and having babies and seeing how that turns out. But when you start tinkering with things at the genetic level, things don't always go the way you think they're going to. You know, you think you understand a system, you tinker with it, and maybe that child will have catastrophic issues they'll have to deal with for their whole life because you decided to tinker with their DNA.

• 1:03:07Daniel Whiteson?

  But just to play devil's advocate, the same thing can happen when you choose your mate. Like, for example, if you're in a small community and you choose to select your partner inside your community, you open them up to possible conditions that come from small genetic populations. You know, like, I'm an Ashkenazi Jew. I know that Tay-Sachs syndrome would have been a real risk if my partner was also an Ashkenazi Jew.

• 1:03:31Kelly Weinersmith?

  Yeah. And so I don't think Zach would mind me admitting that he's a carrier and that I had to get that test because that was a real risk for us. But I think that is why we try to have genetic testing so that you can be aware of these potential issues and make decisions based on that to avoid these worst case scenarios. And so I think we would say we don't want to stop people from marrying and having children with the people that they love, but we do whatever we can to minimize the negative impacts of that. I think trying to improve a bad situation you find yourself in is very different than trying to tinker to get something better that you would ideally have. And so I, and I think that leads to the second problem with genetic engineering is that there's this concern that people who can afford to tinker with their kids

• 1:04:16Kelly Weinersmith?

  are going to end up having like what often gets called in the press as like designer babies, and that we're going to further see inequality sort of exacerbated by, by this kind of thing.

• 1:04:28Daniel Whiteson?

  Right. Like, I want my kid to be a long jump champion. So I'm going to give them this genetic package, which costs a million dollars or whatever. Yeah, that does seem like terrifying. I'm already terrified to make any sort of decisions for my kids. Like, oh, we're going to this high school or that high school, or you have to eat this way or that way. And I wonder about the consequences for the rest of their lives. So, yeah, I'm glad to not have to have made some genetic decisions.

• 1:04:50Kelly Weinersmith?

  Yeah, well, and we should have like, you know, maybe, maybe one day we'll have a bioethicist on the show to talk about this stuff. Cause it's complicated and I feel like the more you think about it, the more you're like, oh, but it would be great if we could do that. But it would be catastrophic if we could do that. And like, you know, there are people who spend their whole lives thinking about this much in much more detail than I did.

• 1:05:07Daniel Whiteson?

  Yeah, and the technology will be available eventually. And then we're going to figure out like what to do about that. But yes, let's have an expert on who actually knows how to think about this stuff.

• 1:05:16Kelly Weinersmith?

  So staying on genetic engineering for a second, there are folks who argue that we need to start doing this kind of engineering now. Because it's really important that we start having self sustaining settlements on Mars as soon as we can. Because we never know when something catastrophic could happen to the earth. And it seems like a lot of catastrophic things are happening lately. So it's important that as soon as we can, we get people living on Mars in a way that can happen sustainably. And so maybe that should make all of our ethical concerns, those concerns should be dwarfed compared to the importance of keeping the human species going. I don't personally buy that argument, but you know, there, there are these emerging debates about the ethics of doing it. And how those ethics sort of change if we think that this is something we need to be doing quickly for the safety of our species.

• 1:06:01Daniel Whiteson?

  Wow, it's so hard to imagine what the future of humanity holds. It could go in so many different directions.

• 1:06:07Kelly Weinersmith?

  And because I'm a pessimist, I will go ahead and note the one final way you can get humans that are well adapted to the Martian surface, which is natural selection, which every once in a while you'll see noted in the literature as like, oh, well, you know, after enough generations, we'll have people who are well adapted to the Martian surface. And of course, that means many, many people will die and root. And it's not even 100% certain that we have the right kind of genetic variability where eventually there will be people who can survive. You know, radiation on Mars are living in 40% gravity. And so we might just lose a bunch of people. People, which sounds really awful.

• 1:06:43Daniel Whiteson?

  Also, don't you assume that you start from a pretty large population? Like, if you start from 10 people, it's unlikely you're randomly gonna have the right genetic mutation. You need to start from a pretty big population, right? Which means a lot of people are gonna die, like, big numbers.

• 1:06:56Kelly Weinersmith?

  Wow, agreed. Yes. You know, but, you know, Musk would argue with Starship, he can get a million people there in 30 years and he can, you know, keep sending people. I should clarify, Musk is not the one who has said, "We're gonna let natural selection solve the problem." He hasn't been clear on how this problem's gonna get solved.

• 1:07:12Daniel Whiteson?

  Free market somehow.

• 1:07:13Kelly Weinersmith?

  Free market, something, something.

• 1:07:16Kelly Weinersmith?

  The next thing we're gonna talk about wouldn't solve the partial gravity problem, but would solve problems related to radiation to some extent and depressurization. So the problem with depressurization is that when human bodies go from an area of higher pressure to an area of lower pressure, the nitrogen bubbles out of our blood. And if it gets stuck in your joints, it causes the bends because it hurts so much that you bend over in pain. If those bubbles get stuck in your lungs, you get the chokes, it's hard to breathe. If they get stuck in your nervous system, you get the staggers, you get these nervous system problems. But if it happens to you in space, you're just gonna get the death. Which unfortunately is what happened to the crew of Solut 1. They got exposed to the vacuum of space in the 70s.

• 1:07:59Kelly Weinersmith?

  So, how do we make a Martian atmosphere thick enough with enough pressure so that you could go outside without a space suit? And you wouldn't have to worry about your habitat depressurizing? And Daniel, I think the only solution to that would be terraforming. Could you thicken up the atmosphere and the pressure enough by... The proposals that I saw involved, like, sending nuclear weapons to the poles so that you could blow up the ice there? And that that ice would then distribute itself in the atmosphere and would thicken up the atmosphere? And that might even warm up the planets? Could that solve the atmosphere thickness problem in radiation? Or are we just nu- A planet for no reason.

• 1:08:42Daniel Whiteson?

  It's not an easy answer. Like Mars is like 1% of the Earth's atmosphere. So you'd need to increase the atmospheric pressure by a lot. And there definitely is CO2 on the poles of Mars and you could release some of it. But the problem is that if you release too much CO2, then the atmosphere becomes poisonous to humans. And so it doesn't really solve the problem. And you'd need a lot of CO2. You'd need to like scoop up some of it from Venus and transfer it over to Mars. So it's not an easy way to manufacture the kind of atmosphere you want. Ideally, you want a huge amount of oxygen in the atmosphere. So you can walk around without a suit, but oxygen is hard to make. You know, you basically need some sort of like microbes growing on Mars, eating the CO2 and producing oxygen.

• 1:09:26Daniel Whiteson?

  And my wife is a microbiologist and she thinks that would take millions of years optimistically. And, you know, on Earth, it took quite a long time. And the rocks are going to drink a lot of that oxygen before it even stays in the atmosphere. And we know that Mars is like, likes to get rusty and we don't know if you can gobble up more of that oxygen. So terraforming is not an easy solution, which is why I think this question is actually asking for another kind of solution. Like what can we do to change ourselves so we can walk around in that 1%? Like, could we engineer some sort of crazy high pressure skin? That's basically like a suit or some change something fundamental about our biochemistry? So we could just happily walk around in 1% atmosphere?

• 1:10:08Kelly Weinersmith?

  Daniel, nothing's coming to me. Do you have an answer? I mean, even if you had high pressure skin or like, what would high pressure skin be like? Like you turn your skin to metal?

• 1:10:17Daniel Whiteson?

  Basically, I just have a natural suit, you know, as part of your body. It's not really an answer. Basically, you're wearing a suit, but it's part of who you are now. So technically it might be a solution.

• 1:10:27Kelly Weinersmith?

  But like if you open your eyes or your mouth, aren't you exposing yourself to the pressure change? Like? I don't see this working.

• 1:10:35Daniel Whiteson?

  Look, I only solved the problem for a minute.

• 1:10:37Kelly Weinersmith?

  Okay, alright.

• 1:10:37Daniel Whiteson?

  I didn't do this until lunch.

• 1:10:39Kelly Weinersmith?

  Well, you got, you know, incremental. You gotta let the market something, something.

• 1:10:44Daniel Whiteson?

  Exactly. The first candidate survives until lunchtime and then they depressurize. So let, you know, we'll take, take a break and come back and solve the rest of the problem another time. Yeah, I think the answer is that it's hard, right? Pressure is important and we are just really not designed to survive in a low-pressure environment. You're right, we exchange all sorts of fluids and materials with the environment. And so sealing ourselves off from it is not really a solution. And it's hard to imagine, well, what if we somehow like inflated humans, we lived in a low-pressure environment? I'm imagining like a completely different kind of biological being, you know, where like your insides are actually at lower pressure.

• 1:11:18Kelly Weinersmith?

  I can't imagine you'd be able to do that with current genetic variability that's like available, but, but I mean, you could, I guess, like every generation, you lower the pressure in the habitat and whoever survives, you work with that.

• 1:11:35Kelly Weinersmith?

  But that would take a long time and would not be ethical.

• 1:11:39Daniel Whiteson?

  No, not even close to ethical. No, absolutely not. All right, so it sounds like we're not going to be adapted to living on the surface of Mars very soon. And even our craziest technological solutions are not really well-suited to the task.

• 1:11:54Kelly Weinersmith?

  I have to admit, I don't feel like we came up with any super satisfying answers, but let's go ahead and ask Lewis if he feels like we did the best we could.

• 1:12:02Daniel Whiteson?

  All right. I'm terrified, what kind of grade we're gonna get.

• 1:12:06Speaker 02

  Thanks so much, Daniel and Kelly. I did not appreciate quite the can of worms I was opening there. And I definitely get the message. I think I'm gonna stick around on Earth for, for a little while longer.

• 1:12:28Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.

• 1:12:33Daniel Whiteson?

  We really would. We want to know what questions you have about this extraordinary universe.

• 1:12:39Kelly Weinersmith?

  We want to know your thoughts on recent shows, suggestions for future shows. If you contact us, we will get back to you.

• 1:12:46Daniel Whiteson?

  We really mean it. We answer every message. Email us at [email protected].

• 1:12:52Kelly Weinersmith?

  Or you can find us on social media. We have accounts on X, Instagram, Blue Sky, and on all of those platforms you can find us at D and K Universe.

• 1:13:02Daniel Whiteson?

  Don't be shy. Write to us.

• 1:13:07Daniel Whiteson?

  Wait, I came in for two things. How is this $47?

• 1:13:12Kelly Weinersmith?

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• 1:14:43Speaker 04

  Everyone on board? Yeah, I think so.

• 1:14:44Daniel Whiteson?

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• 1:15:05Daniel Whiteson?

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