Speaker 1: Imagine a future one hundred maybe two hundred years from now.
Speaker 1: In space, manufacturing has come a long way, and we
Speaker 1: can now build colossal structures using resources collected from the
Speaker 1: Moon and the asteroids. First interstellar ship has been built
Speaker 1: and is getting loaded up with supplies for a long
Speaker 1: trip to Alpha Centauri. It's now time to pick the
Speaker 1: crew who will be the ambassadors for humanity should we
Speaker 1: meet intelligent life in the neighboring Solar System. How many
Speaker 1: people will we send, how should we pick them, What
Speaker 1: dangers will they face en root and what will their
Speaker 1: lives be like during this journey. In our last episode,
Speaker 1: we talked about the rockets that could carry us to
Speaker 1: distant stars. Today, we're going to talk about the squishier
Speaker 1: side of things, focusing on some of the human stuff
Speaker 1: you'd have to deal with on an interstellar journey. Welcome
Speaker 1: to Daniel and Kelly's Extraordinary Universe. Hi.
Speaker 2: I'm Daniel. I'm a particle physicist and the longest flight
Speaker 2: I've ever taken was fourteen hours.
Speaker 1: Hi. I'm Kelly Wiiner Smith. I studied parasites in space,
Speaker 1: and I think the longest flight I've taken was twelve
Speaker 1: I've been down to Brazil. I haven't really kept track
Speaker 1: of how long my flights were. Where were you going?
Speaker 2: I went to an absolutely ridiculous slash amazing boondoggle conference
Speaker 2: in Fiji on the island of Morea, where the University
Speaker 2: of California has a research station, and we were there
Speaker 2: to talk about dark matter, of course, So I brought
Speaker 2: my daughter and we did a lot of snorkeling and hiking,
Speaker 2: and we rode horseback of the mountains and tried to
Speaker 2: keep the horses from eating pineapple plants. And it was
Speaker 2: an amazing time. But wow, the flight was long.
Speaker 1: What made it a boondoggle?
Speaker 2: Why do you need to go to a tropical island
Speaker 2: to talk about dark matter?
Speaker 1: Don't That's what makes it a Yeah, I gotta be honest.
Speaker 1: Ecology has a lot of that too. It's like, why
Speaker 1: do you need to go to the glorious rainforest to
Speaker 1: answer questions about frogs when you've got frogs in the US.
Speaker 1: But I get it. We like go into beautiful places.
Speaker 2: Yeah, it's one of the perks of being a scientist
Speaker 2: is getting to travel to weird, random places to meet
Speaker 2: with your colleagues.
Speaker 1: That's true, that's true. I love getting to see new places.
Speaker 1: I often get invited to places that I never actually
Speaker 1: really wanted to go to, but once I get invited,
Speaker 1: I'm like, yeah, I want to go to Slovakia, and
Speaker 1: I love Slovakia. Broadoslava was beautiful.
Speaker 2: Well what's your experience like on these long flights, because
Speaker 2: I always feel like, oh, fourteen hours, no big deal.
Speaker 2: I'll just watch a few movies and then like two
Speaker 2: movies in, I'm like, wow, get me off this plane,
Speaker 2: and then like four movies in I'm gonna kill myself.
Speaker 2: And then by the time I land, I'm like, hmm,
Speaker 2: that wasn't so bad.
Speaker 1: I hate it. I have a very similar experience. I
Speaker 1: can't sleep. I try to sleep, I can't sleep. I'm
Speaker 1: not comfortable. Every once in a while, I'll get lucky
Speaker 1: and there'll be no one else in the row and
Speaker 1: I can just like lay down and at least then
Speaker 1: I feel kind of rest ish or restoids. I know,
Speaker 1: I hate it too, And then I always feel kind
Speaker 1: of angry at the people in first class because they've
Speaker 1: got like a much nicer setup. But you know, what
Speaker 1: are you gonna do.
Speaker 2: You're not gonna spend ten thousand dollars for that flight,
Speaker 2: that's right. Yeah, no, But if I was an astronaut
Speaker 2: and I was going to the Moon or to Mars
Speaker 2: or to Alpha Centauri, I might want the engineers to
Speaker 2: build in a seat that can fully recline. What do
Speaker 2: you think?
Speaker 1: Heck, yes, you do have to have a completely different
Speaker 1: mindset to really enjoy super long trips. Like Jim Lovell
Speaker 1: and Frank Borman were on a Gemini trip around the
Speaker 1: Earth and I think they were up there for something
Speaker 1: like two weeks, and it was a really tiny space
Speaker 1: and at least on airplanes, like, yeah, the bathroom is small,
Speaker 1: it's super inconvenient. I hate it. But it's got a
Speaker 1: door and the Gemini didn't. And so Frank Borman tried
Speaker 1: to go all twelve days without having a bowel movement,
Speaker 1: and I think he made it like eight days or something,
Speaker 1: and then he was like, Jim, I can't wait anymore.
Speaker 2: I'm about to make a delivery.
Speaker 1: Oh gosh. Yeah, So anyway, it could be worse.
Speaker 2: So you're saying that the cutting edge super distant travel
Speaker 2: is less convenient and less comfortable than like economy flights
Speaker 2: across the country. That doesn't make any sense to me.
Speaker 1: Well, you know, you've got to pay for all of
Speaker 1: the space that you send up there, and it's super expensive.
Speaker 1: And I mean, let's be honest, anybody who's told you
Speaker 1: get to go to space is going to put up
Speaker 1: with whatever you give them, and so they're definitely going
Speaker 1: to go. But there was a recent SpaceX trip where
Speaker 1: there were complaints about the bathroom also, and I think
Speaker 1: it was the Dragon capsule. Restrooms in space are just
Speaker 1: hard to pull off.
Speaker 2: Well, I think this is another case of like my
Speaker 2: over optimistic rose colored glasses when it comes to space travel,
Speaker 2: imagining that the problems we have with like airplane flights
Speaker 2: are not going to be even worse on space trips.
Speaker 2: They're somehow all going to be comfortable and get along
Speaker 2: and the food is going to be amazing like it
Speaker 2: is on Star Trek. Right. That's why I was excited
Speaker 2: that today we're going to dig into like the reality
Speaker 2: of a potential interstellar trip. What's it going to be like?
Speaker 2: Will there be doors on the bathrooms? How far back
Speaker 2: will this eat recline? And will they have anything besides
Speaker 2: peanuts and pretzels?
Speaker 1: Well, let's dig in and find out. So this is
Speaker 1: part two of our interstellar travel series. We talked about
Speaker 1: the kinds of rockets that get you to space in
Speaker 1: the last episode, and today we're talking about the squishy
Speaker 1: human side of things, and so we asked our listeners,
Speaker 1: can humans survive interstellar travel? Why or why not. Here's
Speaker 1: what they had to say. Humans could survive interstellar travel
Speaker 1: with terraform spaceships, and over multiple generations, they could get
Speaker 1: somewhere interesting.
Speaker 3: There are so many unknown issues with closed ecosystems in
Speaker 3: order to produce the food that we need in the
Speaker 3: form of plants, et cetera, that I'm too sure that
Speaker 3: we've solved all the problems necessary in order to have
Speaker 3: a long duration interstellar travel with.
Speaker 4: Our current technology. I don't think it's possible, but maybe
Speaker 4: with advances in propulsion and radiation shielding and artificial gravity
Speaker 4: from propulsion, that might be possible.
Speaker 5: One human couldn't survive because we haven't sought in suspended
Speaker 5: animation yet. But if you're talking about generations of humans,
Speaker 5: if as human we've sorted all the problems of sustaining
Speaker 5: reproduction and nutrition and health, I wonder whether the risks
Speaker 5: of the dangers posed by cosmic rays will actually be
Speaker 5: less in deep space. We do only then have to
Speaker 5: worry about the problem of re entry into the new
Speaker 5: stellar system.
Speaker 6: I think generally it's possible, but you have the problem
Speaker 6: that when you go fast you have cosmic rays that
Speaker 6: are really high energy, and if you go slow, it
Speaker 6: takes forever. So it's a tradeoff and you're lose in
Speaker 6: both situations.
Speaker 7: It depends on how far away the other stars. If
Speaker 7: the star we're trying to get to is there one
Speaker 7: that we're going to share our clouds with in about
Speaker 7: a million years or so, then that's much more achievable
Speaker 7: than a star on the other side of our galaxy.
Speaker 8: I say no because the first two mens who leave
Speaker 8: Earth going to interstellar space will not be alive because
Speaker 8: it takes approximately twenty two to twenty five thousand years
Speaker 8: to exit our solar system. And that opens up the
Speaker 8: question about children in space to continue to journey, because
Speaker 8: the adults who begin the journey will not live to
Speaker 8: exit our solar system.
Speaker 9: So no, if we allow for human reproduction all root,
Speaker 9: which is a big if, humans would encounter significant survival challenges,
Speaker 9: not the least which is that our physiology is ill
Speaker 9: equipped to handle zero gravity and excessive radiation exposure in
Speaker 9: the vein of we do not know what we do
Speaker 9: not know. There are likely other factors that terrustrial living
Speaker 9: either provides for us or protects us from that we
Speaker 9: would faithfully and tragically encounter on the interstellar voyage.
Speaker 10: We can imagine traveling to other solar systems, but can
Speaker 10: we deal with all the questions radiation, food, power sources, generationships.
Speaker 10: We just don't know enough at this point.
Speaker 2: Those are super fun answers, And if you find yourself
Speaker 2: speaking back to the podcast with your own answers, then
Speaker 2: send us those answers and we'll put them on the
Speaker 2: pod so that everyone else can hear what you have
Speaker 2: to say. Just write to us to questions at Danielankelly
Speaker 2: dot org and we will share your insights with the world.
Speaker 1: Looking forward to hearing from you. And we've been very
Speaker 1: excited to have more women sharing their responses lately, so
Speaker 1: let's keep that up. Go women.
Speaker 2: Well, do you think our listeners also have rose colored
Speaker 2: glasses and they're underestimating the difficulty of traveling to space
Speaker 2: or do you think they have a realistic sense.
Speaker 1: We have a really nice range of people who are
Speaker 1: super optimistic, and I would maybe say not quite reasonably so,
Speaker 1: and then people who are maybe a bit more down
Speaker 1: on the enterprise than is necessary. We've got a lot
Speaker 1: of variability. I think it depends a lot on the
Speaker 1: timeframe that you're willing to consider for this question.
Speaker 2: All right, well, let's dig into the problem why space
Speaker 2: travel is so much harder than airplane trips, or if
Speaker 2: it's just airplane trips times a thousand, tell us what
Speaker 2: basically are the obstacles here to traveling in safety and
Speaker 2: comfort to another solar system.
Speaker 1: Well, as you pointed out in the last episode, space
Speaker 1: is vast, and so if we're going to Alpha Centauri,
Speaker 1: that is four light years away. So with current technologies,
Speaker 1: we're talking about eighty thousand years. That's a lot of
Speaker 1: human generations.
Speaker 2: That's a lot of movies to watch.
Speaker 1: Wow, oh my gosh. Yeah, maybe in the next one
Speaker 1: hundred years Marvel will make enough movies to get you
Speaker 1: to Alpha Centauri.
Speaker 2: I think there might be enough fast and furious movies
Speaker 2: to make sure.
Speaker 1: I would not make it to Alpha Centauri fast and
Speaker 1: furious movies. I would rather push myself out the airlock.
Speaker 2: But our he no, you're missing out, You're missing out.
Speaker 2: Fast and furious is fantastic because they don't take themselves seriously.
Speaker 2: Like every movie they have an even more ridiculous stunt.
Speaker 2: They're like, oh yeah, how about a space shuttle. Okay,
Speaker 2: how about a submarine on the ice with a torpedo.
Speaker 2: It's ridiculous and fantastic and really creative. I watch a
Speaker 2: lot of terrible movies, and there's always something new in
Speaker 2: the Fast and Furius that makes me go, whoa that
Speaker 2: it was cool. So yeah, don't overlook them.
Speaker 1: Okay, all right, I'll take another look at the Fast
Speaker 1: and Furious series. I didn't imagine I would say that
Speaker 1: phrase today, but there you go.
Speaker 2: But I don't think we want to travel the stars
Speaker 2: fast and furious. I think it's kind of more like
Speaker 2: slow and calm is the way to go.
Speaker 1: That's what I would like, and with no explosions or
Speaker 1: anything like that. So you said that we could get
Speaker 1: to Alpha Centauri in forty years if you can travel
Speaker 1: at ten percent the speed of light. Yeah, So we're
Speaker 1: going to talk about a range of different options. What
Speaker 1: if you could get there fast if the technology works out,
Speaker 1: and what if you need to get there over the
Speaker 1: course of multiple generations. So you need to have a
Speaker 1: generational ship sometimes called an arc and this field has
Speaker 1: a good sense of humor, so sometimes they call the
Speaker 1: study archaeology also, yeah, which I love.
Speaker 2: That is very cool.
Speaker 1: All right, So one human thing we're going to need
Speaker 1: to overcome is this whole money situation because the cost
Speaker 1: of a project like this is probably going to be
Speaker 1: massively prohibitive. So you talked about how much mass would
Speaker 1: be needed to hold the propellant, and that for chemical
Speaker 1: rockets the tank would have to be as big as Jupiter.
Speaker 2: Yeah, and then you also need to somehow find that fuel.
Speaker 9: Yeah.
Speaker 2: Right, basically you have to use Jupiter as your rocket. Yeh.
Speaker 1: Many layers of problems here. But you know, if you're
Speaker 1: talking about bringing humans that are awake, you're also going
Speaker 1: to need space for recreation areas, space for schooling, space
Speaker 1: for medical facilities, places to grow food. The International Space
Speaker 1: Station is the most expensive human made object ever and
Speaker 1: it's clocking in at about one hundred and fifty billion
Speaker 1: dollars and it usually holds seven people uncomfortably.
Speaker 2: So this is going to cost a lot of money.
Speaker 2: But we're basically just going to ignore the financial side
Speaker 2: of the question.
Speaker 1: We are, yes, right, So let's assume that money is
Speaker 1: no longer an object. Yea, yeah, hey, that's right. Humanity
Speaker 1: has decided we absolutely must do this. Okay, what kind
Speaker 1: of problems are the humans going to encounter? As you
Speaker 1: might remember from our conversations on Mars and the Moon,
Speaker 1: space has a lot of radiation that is bad for humans.
Speaker 1: It has two kinds of radiation that are not very
Speaker 1: common here on Earth, and that scalactic cosmic radiation and
Speaker 1: solar particle events. And these are bad for equipment and
Speaker 1: for people. And I'm kicking over to Daniel tell us
Speaker 1: about galactic cosmic radiation and solar particle events.
Speaker 2: Yeah, so the Sun puts out a lot of light,
Speaker 2: but it also shoots out a lot of other stuff.
Speaker 4: You know.
Speaker 2: They're protons, they're electrons. Basically, it's just spewing plasma. We
Speaker 2: call this the solar wind, and it's moving at high speed.
Speaker 2: So these particles are dangerous because any one of them
Speaker 2: hits your body, tears through it like a little tiny bullet.
Speaker 2: You can rip apart DNA, you can destroy cells. It's
Speaker 2: not good. One random one you're probably fine, But you
Speaker 2: take enough of these you're getting cancer. And down here
Speaker 2: on the surface of the Earth. We don't worry about
Speaker 2: this because while the solar wind is hitting the Earth,
Speaker 2: the atmosphere protects us. It's an enormous, very thick, very
Speaker 2: massive blanket. And the whole idea is that when you
Speaker 2: go out into space, you no longer have that atmosphere,
Speaker 2: so you have to replicate that with shielding. Galactic cosmic
Speaker 2: rays are a whole other question. They're basically radiation from
Speaker 2: other stuff in the galaxy, like the combined radiation from
Speaker 2: other stars and from black holes and from other weird
Speaker 2: stuff we've never even figured out, like there are particles
Speaker 2: that are so high energy. There's nothing in the universe
Speaker 2: we know of that can make particles go that fast,
Speaker 2: and yet we see them. So there's like really fascinating
Speaker 2: physics mysteries there. But from a human survival point of view,
Speaker 2: you don't want these super duper high energy particles hitting you. Basically,
Speaker 2: space is filled with tiny bullets, and you got to
Speaker 2: go up there with a bulletproof vest.
Speaker 1: I am always so impressed by how eloquent you are
Speaker 1: when I put you on the spot, Bravo. So we're
Speaker 1: going to need to shield against this kind of stuff.
Speaker 1: And it's not just a problem for human bodies, it's
Speaker 1: also a problem for our machines. Did I tell the
Speaker 1: story on the show before about Terry Vertz and Samantha
Speaker 1: Christofferetti when the ISS had a false alarm?
Speaker 2: Oh? Tell us?
Speaker 1: All right, So you've got Terry and Samantha in space
Speaker 1: on the International Space Station and an alarm starts going
Speaker 1: off and Terry's not immediately sure what this alarm means,
Speaker 1: but Samantha has memorized all the alarms and it's an
Speaker 1: ammonia leak. And on the US side, ammonia is used
Speaker 1: to cool the space station is also toxic. So the
Speaker 1: protocol for what you do when there's an ammonia leak
Speaker 1: as you run over to the Russian side, you close
Speaker 1: the first hatch, you take off your clothes. You close
Speaker 1: the second hatch with you on the other side, you take.
Speaker 2: Off your clothes. Why do you have to take off
Speaker 2: your clothes as just make it more fun and dramatic.
Speaker 1: Well, yeah, I mean one, sure, but also that ammonia
Speaker 1: could cling to your clothes and you don't want to
Speaker 1: bring it over to the Russian side. So you got
Speaker 1: to hope the Russians have some undies they'll be willing
Speaker 1: to loan you, and so they ran over. They closed
Speaker 1: the first hatch, but they didn't smell the ammonia. And
Speaker 1: this is an important sort of lesson about how humans respond,
Speaker 1: like it sort of doesn't matter what protocols you put
Speaker 1: into place. When one human is looking at another human
Speaker 1: and they're both like, am I going to really see
Speaker 1: you naked? Right now? They decided to just skip that
Speaker 1: step and they went in with all of their clothes
Speaker 1: over to the Russian module. It did turn out it
Speaker 1: was a false alarm, and the reason you go to
Speaker 1: the Russian module is because they use glycol to cool
Speaker 1: their side, which is not as toxic, and so if
Speaker 1: the leak was coming from anywhere, it was the US
Speaker 1: side anyway. It was later determined that the most likely
Speaker 1: reason that this alarm got switched on was because the
Speaker 1: computer had been hit with galactic cosmic radiation, which messed
Speaker 1: with the equipment and started setting off alarms. You could
Speaker 1: have cancer, cognitive declines, your machines could start breaking down.
Speaker 1: So this is a problem we need to take seriously.
Speaker 2: Yeah, this is actually really fascinating from an engineering point
Speaker 2: of view. You know, what's happening is that these particles
Speaker 2: are passing through your equipment. Sensitive bits of it are
Speaker 2: mostly made out of silicon, and when a high energy
Speaker 2: particle passes through, it leaves a trail of ions, you know,
Speaker 2: it like kicks electrons and leaves holes, and this is
Speaker 2: how these things work also, right, they like separate the
Speaker 2: holes and the electrons, and so all this equipment can
Speaker 2: get like a false bit, like you can have a
Speaker 2: zero in your memory and then they can turn into
Speaker 2: a one or something, and so these kind of cosmic
Speaker 2: ray bitflips are real concern and like massive data centers
Speaker 2: worry about this also, but they have a lot of
Speaker 2: error correction and so they have like duplications and cross
Speaker 2: checking to basically remove this. So you can either have
Speaker 2: a lot of duplication or you can try to make
Speaker 2: get radiation hard by shielding it. The even folks who
Speaker 2: are using diamonds instead of silicon, because diamond has a
Speaker 2: lot of the same electrical properties, but it's radiation hard.
Speaker 2: You can grow diamond, it's much more expensive and there's
Speaker 2: not a huge industry for this. But like at the
Speaker 2: large hadron collider, there's very intense radiation near all of
Speaker 2: our sensitive detectors. So every couple of years, we've got
Speaker 2: to pull it out and swap in a new one
Speaker 2: because it's basically ruined.
Speaker 1: Wow.
Speaker 2: So, yeah, electronics are very sensitive to high levels of radiation.
Speaker 2: And if you are relying on your electronics to keep
Speaker 2: you alive and an eighty thousand year journey in all
Speaker 2: of your grandkids and great grandkids, then yeah, you want
Speaker 2: those things to work.
Speaker 1: Yeah. And so the shielding could come in the form
Speaker 1: of things like water, like you could store your water
Speaker 1: supply on the outside. Would that help with galctic cosmic
Speaker 1: radiation too, Daniel.
Speaker 2: Yeah, with various kinds of it. Yeah, okay, but mostly
Speaker 2: you basically just need high Z mass, like you need
Speaker 2: atoms with a lot of protons and neutrons between you
Speaker 2: and the radiation.
Speaker 1: Got it. I've also seen proposals for scraping the regolith
Speaker 1: off the Moon and padding your interstellarship with it. That
Speaker 1: would be complicated, but it's a solution.
Speaker 2: That would be pretty cool because then your ship looks
Speaker 2: like a rock, you know, yeah, like floating through space,
Speaker 2: like masquerading as an asteroid or something.
Speaker 1: Well, another complicated problem we're going to need to solve
Speaker 1: is what do you do about no gravity.
Speaker 2: Right, But the takeaway from the shielding is an important one. Right.
Speaker 2: It makes our ship big and massive and heavy, and
Speaker 2: that makes it expensive. Right, But fortunately money is no
Speaker 2: hurdle for.
Speaker 1: Us, so cool, that's right. In space manufacturing might help
Speaker 1: with this a lot. So you know, you could, like
Speaker 1: I mentioned, go get the regulis from the surface of
Speaker 1: the Moon, but also you could go to the asteroids
Speaker 1: and extract water from the asteroids. In that way, you
Speaker 1: don't have to pay to boost it from Earth. But
Speaker 1: one way or another, it's going to be an expensive,
Speaker 1: massive project.
Speaker 2: Yeah, all right, So problem number one is radiation.
Speaker 1: Yes, and problem number two is going to make the
Speaker 1: design of our vehicle even more complicated. And problem number
Speaker 1: two is that there's no gravity in deep space. So
Speaker 1: we know from astronauts on the International Space Station and
Speaker 1: the space stations that came before that when they are
Speaker 1: essentially in free fall and feeling the equivalent of no gravity,
Speaker 1: that their bones start breaking down, their muscles start breaking down.
Speaker 1: And the gravity on Earth and the fact that we're
Speaker 1: constantly moving around and submitting our bones and muscles to gravity,
Speaker 1: and then the pressure of our bodies as we run
Speaker 1: around that makes our bones and muscles strong. That's like
Speaker 1: a que Our bodies need to keep these things toned.
Speaker 1: Without those cues, they just start to decay because you're
Speaker 1: not using them, so bodies start falling apart. Additionally, we
Speaker 1: see declines in vision, and we think that's because the
Speaker 1: fluids in our bodies without gravity to pull them down,
Speaker 1: sort of accumulate near our heads and change the shape
Speaker 1: of our eyes. There's also some evidence that there could
Speaker 1: be some cognitive declines. Basically, we're gonna want some gravity
Speaker 1: when we're living out our lives on a ship, and folks.
Speaker 2: Out there might be thinking, well, you know, we're adapted
Speaker 2: to life on Earth, but if we spend it long
Speaker 2: enough in space, maybe our bodies are just going to adapt.
Speaker 2: Maybe we don't need those bones and those muscles because hey,
Speaker 2: we're all floating around to the Blue Danube anyway, right,
Speaker 2: Why do we care about degradation of our bones and
Speaker 2: our muscles if we're just floating in space.
Speaker 1: Yeah, so that's a great question. We don't actually know
Speaker 1: that we could survive long term. So the longest anyone
Speaker 1: has ever been in space, I think, is four hundred
Speaker 1: and thirty seven days. That was Valeri Polyi call. So
Speaker 1: we don't even have like more than a year and
Speaker 1: a half of consecutive time in space. We know that
Speaker 1: astronauts lose something like one percent of the density of
Speaker 1: their hip bone per month, and we don't know if
Speaker 1: that tapers off eventually. But if you imagine trying to
Speaker 1: have babies in space, hold.
Speaker 2: On, wait, I'm gonna imagine it. Hold on. Hmmm, yeah
Speaker 2: that seems gooey.
Speaker 1: Yeah, yeah, that is such a dive response. The gooeyness
Speaker 1: is not a problem.
Speaker 2: Man, But now you're in space, you have like weird
Speaker 2: balls of goo.
Speaker 1: It's oh, imagine trying to do a C section in
Speaker 1: space with like the blood floating around your head anyway unpleasants.
Speaker 2: Or imagine like a diaper explosion, you know, like loss
Speaker 2: of containment in space. I don't know about that loss
Speaker 2: of containment. You've had that experience, you know what I'm
Speaker 2: talking about. We've all had the like Transatlantic flight with
Speaker 2: loss of containment of the diaper like ooh, no, I.
Speaker 1: Did right when a plane was taking off. My had
Speaker 1: a blowout on my lap and we couldn't get up
Speaker 1: for thirty minutes, and oh man, nobody liked me. And
Speaker 1: it brought a change of clothes for her, but not
Speaker 1: for me, but she sat on my lap anyway. All Right,
Speaker 1: these problems can only get more difficult in space. So
Speaker 1: we don't know, for example, that women's hips will be
Speaker 1: able to survive childbirth, and we just generally don't know
Speaker 1: if you can survive a lifetime. But maybe you can.
Speaker 1: So let's say that you can. Let's say that not
Speaker 1: only can you survive, but you can also go through
Speaker 1: reproduction in zero gravity, which again I think is highly unlikely,
Speaker 1: but we don't have a lot of good science for that.
Speaker 1: There's a lot of reasons why you'd want at least
Speaker 1: a little bit of gravity, and you know, a lot
Speaker 1: of them have to do with things like using the restroom.
Speaker 1: So we talked a little bit about how that's unpleasant.
Speaker 1: At the start of the show.
Speaker 2: My gooey imagination is filling in the details for me.
Speaker 1: Yes, oh oh yeah, you're really into Guey today. It's
Speaker 1: only going to go downhill from here. When I was
Speaker 1: researching a city on Mars, every space vehicle that I
Speaker 1: read about had a story about escapees, where the escapees
Speaker 1: were like bits of feces that kind of floated out.
Speaker 1: It's hard to keep things clean. Everything is more of
Speaker 1: a pain in the rear end. If you have just
Speaker 1: a little bit of gravity, Surgery gets easier, restrooms get easier,
Speaker 1: farming gets easier. We're almost certainly going to need at
Speaker 1: least a little bit of gravity just to like hold
Speaker 1: our stuff down and make our lives easy.
Speaker 2: And if you hope that your descendants or whoever is
Speaker 2: arriving in the distant Solar System is going to be
Speaker 2: able to get off the ship and walk around on
Speaker 2: this new alien planet, they're going to have to have
Speaker 2: some bones and muscles, right, So it makes sense to
Speaker 2: maintain that capacity on the trip.
Speaker 1: Absolutely. So not only are we going to have this
Speaker 1: massive object, but this massive object needs to have at
Speaker 1: least some areas that are spinning to create artificial gravity,
Speaker 1: so that you've got some of that force keeping your
Speaker 1: body strong or helping the brown trout swim down the
Speaker 1: river in the right direction.
Speaker 2: All right, So we've talked about radiation and that might
Speaker 2: be a solvable problem with enough shielding, and we talked
Speaker 2: about gravity might be a solvable problem if we have
Speaker 2: acceleration or something spinning or something like that. So so far,
Speaker 2: I'm feeling kind of optimistic about how our kids' kids, kids' kids'
Speaker 2: kids might be able to walk off the ship and
Speaker 2: stand on a planet around Alpha Centauri. So let's take
Speaker 2: a break, and when we come back, Kelly's going to
Speaker 2: tell us about how that's all an impossible dream.
Speaker 1: I'm not trying to be negative today.
Speaker 2: The facts that we're going to get into though, all right,
Speaker 2: So we're back and we're talking about whether we could
Speaker 2: survive an interstellar trip, whether it's a good idea to
Speaker 2: build an arc where people can have their babies and
Speaker 2: their babies babies babies can one day visit an alien
Speaker 2: solar system, or whether these problems are insurmountable. We've talked
Speaker 2: about radiation, We've talked about money, we've talked about gravity.
Speaker 2: Now Kelly tell us about knowledge. Why do we need
Speaker 2: to make sure knowledge doesn't decay along the way we.
Speaker 1: We've already talked about how difficult it is to store
Speaker 1: knowledge in computers, or at least how careful you need
Speaker 1: to be to protect it from radiation. But another problem
Speaker 1: you're going to have is that the farther you get
Speaker 1: from Earth, the longer the communication delay. So if people
Speaker 1: are living on Mars, for example, there's a minimum three
Speaker 1: minute communication delay, just because it takes a long time
Speaker 1: for the message to go from Mars to Earth and
Speaker 1: then from Earth to Mars when you're ready to respond.
Speaker 2: I think that's really fascinating because you know, the Earth
Speaker 2: is not small, but it's small compared to the speed
Speaker 2: of light, So you can have what feels like an
Speaker 2: instantaneous phone call with somebody in Tokyo, right, and the
Speaker 2: lag is imperceptible. But then once you go to the
Speaker 2: Moon or to Mars, like now, it really ruins what
Speaker 2: it feels like to have a conversation.
Speaker 3: Right.
Speaker 2: You can ask a question, you got to wait like
Speaker 2: six minutes to hear the answer. That's like not a conversation,
Speaker 2: it's more like writing letters back and forth.
Speaker 1: It is. Yeah, I mean, I think even on the
Speaker 1: Moon you can have a close to real time conversation,
Speaker 1: maybe a little bit of an awkward delay. But when
Speaker 1: you get to Mars, it's a minimum of three minutes,
Speaker 1: a maximum of something like twenty to twenty two minutes.
Speaker 1: But when you're starting to get to Alpha Centauri, it's
Speaker 1: just going to keep extending, extending, extending, until at some
Speaker 1: point you're not communicating anymore.
Speaker 2: So for example, if you like need it support, you're like, hey,
Speaker 2: my MacBook is crashing. You don't want to wait four
Speaker 2: years for the answer to be like, turn it on
Speaker 2: and off again.
Speaker 1: That's right, it's not helpful anymore. At that point you've
Speaker 1: probably figured.
Speaker 2: It out, hope, so, or you're all dead.
Speaker 1: Yeah, And I mean that also means at some point
Speaker 1: you're gonna stop benefiting from any new knowledge that is
Speaker 1: created on Earth because it's gonna be hard to get
Speaker 1: it to you and probably at some point impossible to
Speaker 1: get it to you. But it also means if somebody
Speaker 1: has an illness that you don't have anyone on the
Speaker 1: ship who's an expert in that you're on your own
Speaker 1: the surgical procedure that you're doing. You better hope you
Speaker 1: downloaded a good YouTube video for it, because nobody's gonna
Speaker 1: walk you through it in real time. You really are
Speaker 1: on your own.
Speaker 2: Yeah, you can't look things up unless you bring like
Speaker 2: all of human knowledge with you somehow download Wikipedia onto
Speaker 2: your ship's computers. I mean that seems that could be
Speaker 2: a good idea anyway, doesn't it.
Speaker 1: No, absolutely, yes, for both entertainment purposes and you know,
Speaker 1: knowledge purposes. You should bring as much information with you
Speaker 1: as you can. That would absolutely be worth the storage space.
Speaker 1: In my opinion, what.
Speaker 2: Do you think takes more storage space? Like Wikipedia or
Speaker 2: all the Fast and Furious movies?
Speaker 1: Are you taking Wikipedia in every language?
Speaker 2: Ooh question?
Speaker 1: I don't know.
Speaker 2: We better though, yeah, including the Scottish one. That the
Speaker 2: Scottish one turns out to be totally made up.
Speaker 1: There's no Scottish wikip Wait what There.
Speaker 2: Is a Scottish Wikipedia, but it's mostly written by a
Speaker 2: guy who just invented what he thought Scottish should sound like.
Speaker 2: Oh my god, yeah, it's bad.
Speaker 1: I am regularly amazed by the amount of time that
Speaker 1: humans are willing to put into messing with each other.
Speaker 1: That must have taken a long time.
Speaker 2: Oh he thought he was doing something good. No, he
Speaker 2: was like, hey, nobody else has done this, and I
Speaker 2: know how to do it right, so my goodness, the
Speaker 2: best intentions. Anyway, you should read that story. It's hilarious. Okay,
Speaker 2: but anyway, what is the impediment though, to just bringing
Speaker 2: all of human knowledge with us and saying like, all right,
Speaker 2: we're gonna be cut off from the mothership or we're
Speaker 2: not going to get the latest advancements in quantum computing
Speaker 2: at the same moment. Maybe they can beam them to
Speaker 2: us as they come in who are a little behind.
Speaker 2: But why can't we just bring it all with us.
Speaker 1: You can bring a ton of knowledge with you, but
Speaker 1: you know, if you set me down next to a
Speaker 1: bunch of textbooks on quantum computing, I could do nothing
Speaker 1: with that information. Like I mean, maybe after a couple
Speaker 1: generations I could. But this ties into the next problem
Speaker 1: that we're going to deal with, which is you have
Speaker 1: to pick whatich humans you send with you, and what
Speaker 1: kind of knowledge they have, and how many of them
Speaker 1: you get. But I'm guessing you had another limitation in mind.
Speaker 1: Was it how many hard drives you'd have to bring?
Speaker 1: Or should I stop trying to guess what you're thinking.
Speaker 2: No, I think that your point is valid that you
Speaker 2: can bring a bunch of knowledge, but just having that
Speaker 2: knowledge isn't enough. You need people who can digest it
Speaker 2: and people who can put it to work. So you're
Speaker 2: essentially saying, make sure you bring enough physicists on board.
Speaker 1: You know, you guys are good for a lot of stuff.
Speaker 1: I don't know how many practical problems. Also, you have
Speaker 1: to worry about like hygiene interstellar trip, but you should
Speaker 1: bring a couple cleanly physicists probably, Yeah.
Speaker 2: I think the real problem here is that you need
Speaker 2: a breadth of notice, right, And so there's a question of,
Speaker 2: like what is the minimum size of a community that
Speaker 2: has enough technical knowledge and expertise to basically run independently
Speaker 2: of Earth, Because it's not like two people, it's not
Speaker 2: ten people. And I'm guessing that's where you're going to
Speaker 2: go next, is like how big a community you need
Speaker 2: not just have the knowledge, but also to like have
Speaker 2: healthy babies.
Speaker 1: Yeah, so I'm going to be focusing on the healthy
Speaker 1: babi's part, but this occupation's part is really important, and
Speaker 1: it's very hard to have a concrete answer for it
Speaker 1: because it depends on what you're willing to live without.
Speaker 1: I heard once that there's something like one hundred thousand
Speaker 1: medical specialties, and that number seems unreasonably large. But let's
Speaker 1: even say there's like a thousand medical specialties. Okay, you'd
Speaker 1: probably want one person from each of those specialties, or
Speaker 1: like duplicates of all of those people, but you also
Speaker 1: need janitors and plumbers and engineers and farmers, and there's
Speaker 1: just so many different kinds of people you would like
Speaker 1: to have there, but you might not be able to
Speaker 1: have everyone you want there. Like, you know, you probably
Speaker 1: couldn't have three of every remedical specialist if there are
Speaker 1: one hundred thousand kinds, So you're gonna have to sort
Speaker 1: of pick and choose and decide what you're willing to
Speaker 1: do without.
Speaker 2: I think there's also an interesting interplay there between are
Speaker 2: you just trying to survive the trip or are you
Speaker 2: trying to bring the seeds of a future civilization with you?
Speaker 2: Because think about just like pencils. Okay, you need a
Speaker 2: lot of pencils on an eighty thousand year journey. Maybe
Speaker 2: you could just stock a bunch of pencils, right, bring
Speaker 2: a bunch of pencils, or like light bulbs or whatever,
Speaker 2: and you might be able to survive the journey and
Speaker 2: not use up all the light bulbs and pencils. But
Speaker 2: once you get there, you might still want light bulbs
Speaker 2: and pencils in a thousand years. And so what you
Speaker 2: need to do is bring like the manufacturing capacity to
Speaker 2: produce all of the goodies that we expect for a
Speaker 2: certain quality of life, or to severely restrict the goodies
Speaker 2: that you're expecting these people to live without. So you
Speaker 2: really need to bring like your entire manufacturing supply chain
Speaker 2: and pipeline with you if you're going to seed a
Speaker 2: civilization on the other end of this, not just like
Speaker 2: visit Alpha Centauri and turn around and come back.
Speaker 1: Yeah, so let's jump for a second to a conversation
Speaker 1: about what you bring with you. So, yeah, you would
Speaker 1: want to maybe bring all the manufacturing stuff to make pencils. Additionally,
Speaker 1: we should have invited Katrina on the show briefly, because
Speaker 1: you're going to want to make sure, for example, you
Speaker 1: have a diversity of microbes, But how do you know
Speaker 1: which ones to bring?
Speaker 2: You just bring all the poop on Earth. That's the
Speaker 2: easy solution, that's what she would say.
Speaker 1: Okay, but a lot of that poop on Earth has parasites,
Speaker 1: And while I don't want to live in a world
Speaker 1: without interesting parasites to study, I think most people would,
Speaker 1: although I prefer parasites that aren't infecting people. But anyway, so, yeah,
Speaker 1: you got to figure out what kind of microbes and
Speaker 1: that requires knowledge that we don't necessarily even have yet.
Speaker 1: What kind of microbes do you want to bring with you?
Speaker 1: But you also need to bring medicine, but medicine expires,
Speaker 1: and eighty thousand years is a long time, so you're
Speaker 1: probably going to want to bring the equipment that you
Speaker 1: need to make more medicine. And there are some designs
Speaker 1: for three D printers that will print medicine on demand,
Speaker 1: but you need to make sure you've got the raw
Speaker 1: materials for that.
Speaker 2: Yeah, exactly. It feels like you're cutting that very tip
Speaker 2: off a very complex pyramid of manufacturing and civilization, and
Speaker 2: it's going to rumble eventually. It feels very difficult to
Speaker 2: maintain the same level of civilization if you're not bringing
Speaker 2: the whole pyramid with you. And it turns out the
Speaker 2: pyramid is huge, right, Like, just to make a pencil
Speaker 2: requires an enormous manufacturing capacity and lots of different specialties.
Speaker 1: Our global supply chains are amazing. We rely on them
Speaker 1: for so many things. That pencil takes a million people.
Speaker 1: Thing came from somewhere in one of these days. I
Speaker 1: want to figure out, was it a Milton Friedman essay?
Speaker 2: I do no holpu with't Malcolm Gladwell, because you can't
Speaker 2: trust anything in these.
Speaker 1: We're on the record now, all right, let's go ahead
Speaker 1: and just accept that there's a lot of stuff that
Speaker 1: you're going to need to bring if you want to
Speaker 1: keep your standard of living reasonably high, and also a
Speaker 1: lot of stuff that you're going to need to bring
Speaker 1: or be able to build so that you can replace
Speaker 1: parts of your ship as they break down over time
Speaker 1: in the very harsh environment of space. So now let's
Speaker 1: jump to biology, the good part. Let's get to the
Speaker 1: good part.
Speaker 2: All right, Are we talking about parasites? Minimum number of
Speaker 2: parasites to bring to allisantaries?
Speaker 1: Unfortunately, No, I couldn't figure out a way to really
Speaker 1: shoehorn parasites and more than once.
Speaker 2: I'm ready for it though, when you ring it up,
Speaker 2: I'm ready for it.
Speaker 1: Okay, good, But how.
Speaker 2: Big a group do we need, like biologically to keep
Speaker 2: our community healthy and to make sure we don't all
Speaker 2: suffer from some genetic defect that like one guy has
Speaker 2: on board? How big a population do we need?
Speaker 1: Yeah, this is a really difficult question. So we don't
Speaker 1: necessarily know what kind of diversity we need. So it
Speaker 1: would be great to have people, for example, that are
Speaker 1: resistant to radiation in case we can't shield all of it.
Speaker 1: But we don't really know what genes are important for
Speaker 1: that at this point. So the more diversity you can have,
Speaker 1: the better. You also want people who are not closely
Speaker 1: related to each other, because we all have some genes
Speaker 1: that are carrying the code for negative traits. So you know,
Speaker 1: it could be sickle cell anemia or something like that,
Speaker 1: where if you get two versions of the gene that
Speaker 1: cause the disease, you're in a lot more trouble than
Speaker 1: if you just have one.
Speaker 2: I wonder, from an evolution air point of view, if
Speaker 2: this is a scenario where you actually want to be
Speaker 2: susceptible to radiation because it induces a higher mutation rate
Speaker 2: in your babies. And that might mean that you lose
Speaker 2: a bunch because like they have bad mutations, But you
Speaker 2: also might like invent some new weird like spacefaring, hearty
Speaker 2: human that can like I don't know, extrude pencils from
Speaker 2: some new orifice or something you're useful. I don't know, Like,
Speaker 2: is there a possibility there that more mutation might actually
Speaker 2: be beneficial?
Speaker 1: So mutation is a mechanism through which you get more
Speaker 1: genetic diversity, and some of that could be good. I
Speaker 1: think our expectation would be statistically, you'd probably get a
Speaker 1: lot more things breaking than a lot more things resulting
Speaker 1: in pencils coming out of your nose at appropriate times
Speaker 1: or something. And I think a lot of those mutations
Speaker 1: are going to be you know, like causing cancer as
Speaker 1: you're older, and not necessarily resulting in like really well
Speaker 1: adapted babies. But who knows, who knows? All right, So
Speaker 1: I've seen a bunch of estimates for how many people
Speaker 1: you need, and you do need to be careful about
Speaker 1: who these people are. So like, yes, we talked about
Speaker 1: you want doctors and stuff like that, but when you're
Speaker 1: thinking about the number of people you need, the number
Speaker 1: of people over sixty, it's great to have their knowledge,
Speaker 1: great to have their help, but they're not going to
Speaker 1: be contributing to having children. So you need to think
Speaker 1: about the number of reproductively aged individuals. And you need
Speaker 1: to think a little bit about the mix of people.
Speaker 1: So if you bring you know, ten thousand men, you
Speaker 1: better also have artificial wounds or something at that point.
Speaker 1: So you need to think about the makeup.
Speaker 2: Well, dig into that for a moment for us, Like
Speaker 2: what is it best gender ratio? I mean, because like
Speaker 2: a woman can't be pregnant from two men simultaneously, but
Speaker 2: a man can have multiple partners.
Speaker 1: It depends on what your goal is, and frankly, it
Speaker 1: depends on what your culture is willing to accept, because
Speaker 1: I think you don't want to send people into interstellar
Speaker 1: space under conditions that they would, you know, find abhorrent. Yes,
Speaker 1: if your goal is to just have as many babies
Speaker 1: as possible, and you've set up the interstellar ship to
Speaker 1: be able to scale, to feed and provide oxygen for
Speaker 1: a rapidly expanding population, then you could send exclusively women
Speaker 1: who got pregnant using embryos that you sent with you.
Speaker 1: There are ways to maximize the speed at which the
Speaker 1: population increases, but I don't necessarily know that the goal
Speaker 1: and root is going to be to increase numbers as
Speaker 1: fast as possible, because if you just wanted to have
Speaker 1: a lot of people, you could have just started with
Speaker 1: a lot more people. So I think you want to
Speaker 1: find a makeup where you can sustain your population numbers,
Speaker 1: and I don't necessarily know if the best way to
Speaker 1: go is fifty to fifty.
Speaker 2: Well, I think your point is a good one, though.
Speaker 2: If you want your people to be happy, then you're
Speaker 2: going to have to create an environment they're going to
Speaker 2: like to live in. And currently most people enjoy monogamous
Speaker 2: relationships or you know, one to one ratios, which means
Speaker 2: you're going to need roughly a gender balance.
Speaker 1: So I found an estimate where someone did a computer
Speaker 1: simulation and they found that you could possibly get away
Speaker 1: with ninety eight people.
Speaker 2: If ninety eight thousand or ninety eight people.
Speaker 1: Ninety eight individuals. What if every generation they mate it
Speaker 1: with whoever a computer program told them to mate with
Speaker 1: based on their genetic makeup. So this is an interesting
Speaker 1: thought experiment for a lower bound but if you're thinking
Speaker 1: about what humans are willing to accept, that's probably not
Speaker 1: going to work out.
Speaker 2: And for this study, how do they define success? You
Speaker 2: have like a population downstream that's healthy and doesn't have
Speaker 2: a lot of recessive traits that are hurting people.
Speaker 1: I forget the exact details, but it was something like
Speaker 1: after five generations, would you expect the population to still
Speaker 1: persist or would they have had inbreeding problems or something
Speaker 1: like that.
Speaker 2: Well, it's really fascinating because I've heard some of these
Speaker 2: studies that speculate the humanity might have had bottlenecks early on,
Speaker 2: you know, down to like as many as ten thousand
Speaker 2: individuals on the planet, and here we are, you know,
Speaker 2: eight billion people later doing pretty well. So it's not
Speaker 2: implausible to me that you could get down to a
Speaker 2: few thousand. Ninety eight seems kind of crazy.
Speaker 1: And there are plenty of people who will also point
Speaker 1: out that there are indigenous peoples living in populations of
Speaker 1: something like one hundred to five hundred. But what those
Speaker 1: numbers often miss is that those indigenous populations are often
Speaker 1: interacting with others and intermarrying, and so actually the population
Speaker 1: that is interbreeding is much larger than the individual communities themselves.
Speaker 1: But yeah, I've I've seen estimates that seem pretty reasonable
Speaker 1: that range from about five thousand to forty thousand people
Speaker 1: of reproductive age. The forty thousand numbers seemed a little
Speaker 1: bit more realistic to me. So it was taking into
Speaker 1: account the ability to survive five generations even if a
Speaker 1: black plague like catastrophe comes along. And so this is
Speaker 1: incorporating like what if some bacteria in our gut mutate
Speaker 1: and kills twenty five percent of us, Like you might
Speaker 1: have to assume that every once in a while you're
Speaker 1: going to lose people. So estimates range from ninety eight
Speaker 1: to about forty thousand, and really depend on the assumptions
Speaker 1: you're making well.
Speaker 2: Keeping in mind our constraints. Even if money isn't an optical,
Speaker 2: of course, in reality it is. And we know that
Speaker 2: size is an issue and fuel and all that stuff,
Speaker 2: and so if what we want to do is keep
Speaker 2: the ship small, then we want to keep these numbers low.
Speaker 2: And that was really interested in your comment about how
Speaker 2: you could keep it down to around one hundred if
Speaker 2: people accepted, you know, computer assigned dating. And I'm wondering
Speaker 2: how far we could push that, Like, could we make
Speaker 2: an even lower if we assume some sort of technology
Speaker 2: to like modify your genetics or correct issues or something
Speaker 2: that couldn't the interaction between biology and technology really change
Speaker 2: how small we could go.
Speaker 1: I hear a lot of engineers propose stuff like this,
Speaker 1: and it totally makes sense. It's true, it could work,
Speaker 1: But when ideas like this come like head to head
Speaker 1: with human behavior, they tend to fall apart. I mean,
Speaker 1: you could have five women who start the trip with
Speaker 1: a vat of freeze dried sperm from lots of different people,
Speaker 1: and you could maybe make it. But now you've got
Speaker 1: problems with well, do you have enough doctors and enough
Speaker 1: engineers and enough people to work the farm. So there's
Speaker 1: a lot of reasons why going big has a lot
Speaker 1: of benefits.
Speaker 2: I think it's funding the mental image of that of
Speaker 2: freeze dried sperm. Why wouldn't you have them, you know,
Speaker 2: like delicate test tubes, you know, imagining like you know,
Speaker 2: liquid nitrogen flowing over them and something. Instead your words
Speaker 2: give me a mental image of like a barrel of
Speaker 2: the stuff.
Speaker 1: You started this guy theme, and I was just kind
Speaker 1: of running with it. But you're right, they'll probably be
Speaker 1: in viles in a tube of liquid nitrogen or something
Speaker 1: like that. Yeah, treat them better.
Speaker 2: Delicately, clinking glasses and stuff like that.
Speaker 1: That's right. Having technology to help with reproduction and bringing
Speaker 1: along extra genetic diversity in the form of embryos, stuff
Speaker 1: like this can really help with diversity problems. But again,
Speaker 1: each generation you're going to have to deal with the
Speaker 1: wants and desires of the humans who are there, who
Speaker 1: are going to want to find partners that make them
Speaker 1: feel complete, and who may or may not be comfortable
Speaker 1: with being told, hey, your partner isn't as genetically diverse
Speaker 1: as you might want. Sorry, this is what five generations
Speaker 1: and an interstellarship does. So you are going to have
Speaker 1: the embryo for which we provide fifty percent of the
Speaker 1: genetic information, and not everybody is likely to love that.
Speaker 1: And then what do you do when people get pregnant unintentionally?
Speaker 2: Yeah, exactly. I think that's super fascinating and it touches
Speaker 2: on another whole area of questions of like how you
Speaker 2: manage the people on board, and what laws do you
Speaker 2: have and what punishments can you do? Like you're shooting
Speaker 2: people out the airlock if they're not being the right person.
Speaker 2: It's crazy, But you know, on ships, the captains in
Speaker 2: charge and for a reason. And so anyway, that's whole
Speaker 2: other issue we could dig into another time of laws
Speaker 2: on board interstellar trips. For now, let's take a break,
Speaker 2: and when we come back, let's hear about a strategy
Speaker 2: that might make that all moot. What if everybody just
Speaker 2: sleeps their way to Alpha Centauri? All right, we're back,
Speaker 2: and we are facing all the questions for taking humans
Speaker 2: to another solar system. Radiation and gravity and greeding and
Speaker 2: knowledge and all these things require keeping people awake, having
Speaker 2: a functioning society on board, people sitting there munching on
Speaker 2: their snacks and watching fast and furious. What if, Kelly,
Speaker 2: we decide not to What if we just put everybody
Speaker 2: out for the journey. What if we can freeze them
Speaker 2: or hibernate them. You see this a lot in science fiction.
Speaker 2: Is that realistic? Where is the technology now?
Speaker 1: It's not realistic with current technology, But I wouldn't say
Speaker 1: it's absolutely impossible. You can't just put everybody to sleep
Speaker 1: as sleep is technically defined, because while you're sleeping, you
Speaker 1: still have metabolic processes happening. You're still aging. So if
Speaker 1: you were asleep, you'd still need to have like fluids
Speaker 1: put in through an IV. You need to be fed.
Speaker 1: Machines would have to roll you over. Sleeping wouldn't really
Speaker 1: cut it.
Speaker 2: It'd be like a coma, and nobody wants to be
Speaker 2: in a coma for eighty thousand years, and you can't
Speaker 2: live that long even in a coma, right. It doesn't
Speaker 2: extend your life to sleep.
Speaker 1: Right exactly. That's a total nonstarter. The next step up
Speaker 1: from that would be hibernation. And so hibernation you have
Speaker 1: a reduced temperature, you still have some metabolic stuff happening,
Speaker 1: but the metabolic activity is way down, so like your
Speaker 1: caloric needs go way down, you need less you're using
Speaker 1: the restroom less stuff like that. And there's lots of
Speaker 1: animals that hibernate. You know, You've got bear, squirrels, marmots,
Speaker 1: prairie dogs, crowned hogs. Hibernation happens a lot, but it's
Speaker 1: worth noting that one hibernation doesn't keep these animals alive forever,
Speaker 1: and sometimes animals die well hibernating, so it's not like
Speaker 1: you're one hundred percent safe when you go into a
Speaker 1: hibernation state.
Speaker 2: And can every animal hibernate? I mean bears and squirrels,
Speaker 2: they do these things themselves, but like I've never hibernated.
Speaker 2: Do humans hibernate?
Speaker 1: I would like to hibernate sometimes when it's too cold out,
Speaker 1: but no, humans do not hibernate. It's not clear how
Speaker 1: we would put humans into a hibernation like state. It's
Speaker 1: tantalizing that other mammals can do it, but it doesn't
Speaker 1: necessarily mean that if we learned the right tricks, humans
Speaker 1: could do it too. Humans do sometimes survive being very cold,
Speaker 1: so like in a very hypothermic state, and every once
Speaker 1: in a while if people have particular problems. So I've
Speaker 1: read about somebody who had rabies, and they were trying
Speaker 1: to slow down the movement of rabies and give the
Speaker 1: body some time to respond in the vaccine, some time
Speaker 1: to work. And so they essentially put the person in
Speaker 1: a very cold state to slow things down. And people
Speaker 1: can survive, but it's not like it's great for the body,
Speaker 1: and it's not like it's extending their lifetime. So you
Speaker 1: would still end up with people dying in a hibernation state.
Speaker 2: Probably all right, So we can't just knock people out
Speaker 2: with nik will. We can't just turn down the temperature
Speaker 2: a little bit so people get cold and hibernate. What
Speaker 2: if we go even colder? What if we like dip
Speaker 2: everyone in liquid helium and turn them into humansicles? Will
Speaker 2: that help? Is that possible? I mean, you hear about
Speaker 2: this all the time on science fiction and on the
Speaker 2: Simpsons for example, or Futurama. I forget which one it is.
Speaker 2: But is this just fictional nonsense or is the science
Speaker 2: moving us in that direction?
Speaker 1: Scientists are trying to move us in that direction, some
Speaker 1: of them are. So there have been people who very
Speaker 1: soon after they passed away, had their body cryogenically frozen
Speaker 1: in the hopes that at some point will figure out
Speaker 1: the cure for their disease, or figure out some way
Speaker 1: to sort of wake them back up again, or figure
Speaker 1: out some way to upload their brain to a computer
Speaker 1: once we really understand brains, so that their consciousness or
Speaker 1: something can be brought back to life.
Speaker 2: Right, they freeze them after they die. Don't you need
Speaker 2: to freeze them before they die, otherwise you're just thawing
Speaker 2: a core.
Speaker 1: I was under the impression that for ethical purposes, you
Speaker 1: do it like as soon as they're dead, and then
Speaker 1: hope you can find some way to get everything moving
Speaker 1: again to undead them. I mean, you know, people's like
Speaker 1: heart stops. You could say they're dead, but you can
Speaker 1: get them kicking again as long as you do it quickly.
Speaker 2: Interesting.
Speaker 1: I think that's the plant. But you know, if anybody
Speaker 1: has like frozen people and want to tell us about it,
Speaker 1: we'd love more information.
Speaker 2: But it's call us at FBI dot gov.
Speaker 1: That's right, that's right. Yes, I'm hoping that you had
Speaker 1: permission and signed waivers and stuff first.
Speaker 2: All right, but before we try this on humans, I
Speaker 2: imagine we're going to test this onlike frogs or kittens
Speaker 2: or something. How is that progressing?
Speaker 1: Well, So, there are some animals that freeze naturally. So,
Speaker 1: for example, there are some frogs in cold climates that
Speaker 1: have something like anti freezing their blood. So the way
Speaker 1: anti freezing your car works is it lets things get
Speaker 1: a little bit colder without actually freezing. I think that
Speaker 1: there's some combination of that happening and the cells also
Speaker 1: using some additional mechanisms to make them robust to avoid
Speaker 1: burst as water expands.
Speaker 2: Yeah, I think that is what's happening. I think for
Speaker 2: frogs what's happening also is that, like they're producing some
Speaker 2: substances and a freeze you say, which maybe prevents ice
Speaker 2: crystals from forming, and so like basically, if you dope
Speaker 2: water with this stuff, then its chemical properties change. And
Speaker 2: I think it's so incredible that water has this bizarre
Speaker 2: behavior that when it freezes, it gets larger. It's very unusual, right,
Speaker 2: most things, when you freeze them, they get smaller. But
Speaker 2: the fact that ice is less dense than water means fish,
Speaker 2: for example, can survive in the lake right because the
Speaker 2: ice is on the top rather than on the bottom.
Speaker 2: But also means that if you freeze, you explode, So
Speaker 2: it's this funny double edged sword of chemistry.
Speaker 1: Well, I believe there are some fish in Antarctica who
Speaker 1: can survive freezing also if they end up in that
Speaker 1: like frozen layer of ice. So the point is there's
Speaker 1: a variety of animals that can survive freezing, and while
Speaker 1: humans at this point cannot survive freezing, maybe there's some
Speaker 1: lessons that we can learn from these animals or from
Speaker 1: Tartar grades, to try to figure out a way where
Speaker 1: we could cryogenically preserve life people thaw them out and
Speaker 1: bring them back to life. But it's worth noting that,
Speaker 1: as far as I know, there's never been a frog,
Speaker 1: for example, that was frozen for ten thousand years and
Speaker 1: then brought back to life. You know, like we talked
Speaker 1: about some tartar grades that managed to be frozen for
Speaker 1: a very long time, but I think you know, when
Speaker 1: you get to vertebrate level, it's even harder to survive
Speaker 1: freezing for a very long time. So it's not clear
Speaker 1: that cryogenics will be compatible with the human body, or
Speaker 1: that it will be compatible with the human body on
Speaker 1: the time scales needed to get to alpha centauri.
Speaker 2: It's too bad we don't have the biological technology of plants.
Speaker 2: You know, seeds are incredible. I read stories where they
Speaker 2: like dug up ancient seeds and like planted them and
Speaker 2: gave them water and they sprouted, and there's like, oh,
Speaker 2: here's a date palm whose parent grew like thousands of
Speaker 2: years ago and it just sat there it totally shelf
Speaker 2: stable for thousands of years. It's incredible biological technology. It's
Speaker 2: too bad we don't have seeds.
Speaker 4: You know.
Speaker 1: Trees make no sense to me. My husband has been
Speaker 1: gardening lately and he'll say things to me about like, oh, well,
Speaker 1: you can just cut that branch off and put it
Speaker 1: in the soil and you'll get a new tree. And
Speaker 1: I'm like, that's not how life works. You can't do
Speaker 1: that to me. But it works with trees.
Speaker 2: I know. I remember saying to him, like, why can't
Speaker 2: I just stick my arm in the ground and grow
Speaker 2: a new person?
Speaker 1: That's right, Yeah, trees are wild. And so some of
Speaker 1: the most sci fi ish plans I've come across involve
Speaker 1: things like having an artificial womb with freeze dried embryos
Speaker 1: that you send.
Speaker 2: With you because embryos we can freeze and revive.
Speaker 7: Right.
Speaker 2: That's amazing.
Speaker 1: It is amazing. Yeah, and so I don't know that
Speaker 1: you can freeze them for eighty thousand years for the
Speaker 1: trip to Alpha Centauri, but you know, if you get
Speaker 1: there faster, and you can probably move much faster if
Speaker 1: you don't have squishy humans on board to worry about.
Speaker 2: Some of my best friends have two kids, and both
Speaker 2: of them came from frozen embryos. One kid is two
Speaker 2: years older, but they're actually the same age. It's just
Speaker 2: that one of them has been unfrozen for two more years.
Speaker 2: And I think about that every time I see these brothers.
Speaker 2: I'm like, you guys are actually the same age. Just
Speaker 2: one of you was frozen for two years.
Speaker 1: That is amazing. Reproductive technology is incredible, the things that
Speaker 1: we're able to do.
Speaker 2: Yeah, so you're going to put this in the maybe
Speaker 2: category that we potentially could develop cryogenic technology that could
Speaker 2: freeze humans and unfreeze them after thousands of years. It's
Speaker 2: not clear how we would do it now, but you're
Speaker 2: not going to say it's impossible.
Speaker 1: I'm going to put the cryogenic humans on the fairly
Speaker 1: unlikely Oh no, for the time frames necessary to get
Speaker 1: to Alpha Center. If you could get one of those
Speaker 1: propulsion techniques to get you there in like five years,
Speaker 1: and you just had to freeze people so they didn't
Speaker 1: get bored during the trip. Then maybe you could get
Speaker 1: away with that. But when you think about what else
Speaker 1: humans would need when you wake them up, it starts
Speaker 1: getting complicated. So you know, if those humans ever want
Speaker 1: to have a fresh egg, you also need to figure
Speaker 1: out a way to get the chickens going. You know,
Speaker 1: you also need to store the food for them. Like
Speaker 1: it gets incredibly complicated. But you know, maybe you could
Speaker 1: just bring a bunch of genetic material with you and
Speaker 1: have a lot of robots that start planting the farm.
Speaker 1: You know, a couple months before the humans are going
Speaker 1: to be gestated in the artificial womb, but now was
Speaker 1: going to raise them. Like, as a parent, it is
Speaker 1: amazing to me how much work it takes to get
Speaker 1: children to like just shower or brush their teeth. Like,
Speaker 1: there's so much nagging that needs to happen.
Speaker 2: You're out in the crowd and you look at all
Speaker 2: those people and you're like, wow, all these people were
Speaker 2: raised some parents like taught these humans how to survive
Speaker 2: and exist in a crowd, and like be functional, Like,
Speaker 2: that's so much work.
Speaker 1: Wow, it is. Yeah, culture is incredible. The fact that
Speaker 1: we've managed to get ourselves here by like policing each
Speaker 1: other's behaviors is fantastic.
Speaker 2: All right. Well, I see you struggling to not be
Speaker 2: the negative nelly and do not want to say no,
Speaker 2: it's impossible, but it seems like, yeah, pretty implausible.
Speaker 1: I would say within my lifetime, not gonna happen, right,
Speaker 1: But science often has breakthroughs that surprise me, and in
Speaker 1: a couple of lifetimes maybe it would happen.
Speaker 2: But the embryos and parental robots thing, that's a cultural issue, right.
Speaker 2: We think that technologically that might actually be possible. I mean,
Speaker 2: you might get weird humans that might kill all each other,
Speaker 2: or they might like launch nukes back at us or something.
Speaker 2: But in terms of like getting people to the other
Speaker 2: planet and growing them there, that could work.
Speaker 1: Right, It's possible that it could work. I mean, I
Speaker 1: think there's a lot of things we don't understand very well.
Speaker 1: So for example, when babies are born through a mother's body,
Speaker 1: they get slathered in bacteria that are important for the
Speaker 1: way their bodies work. They get food to the bacteria
Speaker 1: in their guts from breast milk. I think we don't
Speaker 1: really understand what would happen to humans if they were
Speaker 1: raised by robots and only encountered other babies of a
Speaker 1: similar age or other people of a similar age. But
Speaker 1: somebody should write a sci fi novel about that.
Speaker 2: Or we should just do it and see what happens.
Speaker 1: Yeah, that sounds totally ethical, totally all right.
Speaker 2: So it sounds like there's a lot of challenges to
Speaker 2: getting humans from here to Alpha Centauri. Even if you
Speaker 2: solved all the physics problems we raised in the last episode,
Speaker 2: there are a lot of biological problems, a lot of
Speaker 2: cultural problems, a lot of technological problems to solve getting
Speaker 2: the humans there safely.
Speaker 1: Yes, and we didn't touch on a lot of the society,
Speaker 1: the all the ethical problems. There's a lot more stuff
Speaker 1: we could talk about. And also I recommend ed Regis's
Speaker 1: book Starbound, which is all about interstellar travel and some
Speaker 1: of the challenges that you encounter along the way. That
Speaker 1: was an interesting read.
Speaker 2: So if somebody wants to sell you a ticket to
Speaker 2: Alpha Centauri, we're going to officially recommend maybe.
Speaker 1: Maybe yeah, I would not buy that ticket, but I'm
Speaker 1: sure other people would, and I'm sure it would be
Speaker 1: an amazing experience.
Speaker 2: Yeah, and I hope you enjoy Fast and Furious Number
Speaker 2: seven hundred and forty two on your trip.
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