Speaker 1: Hey, Daniel, do you believe in luck? Do you think
Speaker 1: you're a lucky person? I'm not sure. I guess I'm
Speaker 1: pretty happy with how things have turned out. Oh yeah,
Speaker 1: But was that luck or was it inevitable? I'm sure
Speaker 1: there was a lot of randomness involved. I guess I'd
Speaker 1: have to study the multiverse to see how often Daniel
Speaker 1: gets to be a physics professor. But wait, is that
Speaker 1: the lucky outcome. Wouldn't the lucky outcome be the one
Speaker 1: where you get to be a movie star or a
Speaker 1: billionaire or maybe a billionaire movie star physics professor. That's
Speaker 1: a lot of titles there. It might cause the universe
Speaker 1: to collapse on itself, physicists always ending the universe. We
Speaker 1: might have caused it, but it doesn't mean it's our fault.
Speaker 1: That sounds like a logical contradiction. Wouldn't that also collapse
Speaker 1: the universe into a puff of logic? Hi am Jorhanmay,
Speaker 1: cartoonists and the creator of PhD comics. Hi, I'm Daniel.
Speaker 1: I'm a particle physicist and a professor at UC Irvine,
Speaker 1: and I'm doing my best to understand the universe without
Speaker 1: collapsing it. You're doing your best. I feel like your
Speaker 1: best is not enough, like I guarantee is not enough.
Speaker 1: Maybe you should look into that before doing it. I'll
Speaker 1: check with my legal department. I'll do twice my best
Speaker 1: time of that still not enough. Ending the universe twice
Speaker 1: is still ending the universe. Maybe it's like negative signs.
Speaker 1: You know, if you do it twice, it comes back.
Speaker 1: But then are you going to be a physics professor again?
Speaker 1: Are we going to be that unlucky? Maybe when everything
Speaker 1: snaps back, that's when I get to be a billionaire.
Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain
Speaker 1: the Universe, a production of iHeartRadio, where we try our
Speaker 1: best to make sense of this crazy universe. When you
Speaker 1: look out there in the cosmos and try to understand
Speaker 1: the way things are, the way things might be, and
Speaker 1: how it all can possibly make sense. We do our
Speaker 1: best to cram this incredible, giant, fantastical universe into our
Speaker 1: tiny little primate brains and squish it all around until
Speaker 1: it makes sense to us and hopefully makes sense to you. Yeah,
Speaker 1: it is an amazing universe, or maybe an amazing multiverse,
Speaker 1: or might be more than one universe out there, But
Speaker 1: at least the one we're in. It seems pretty amazing,
Speaker 1: pretty awesome to explore and to ask questions about, and
Speaker 1: to wonder about the logic of it. Yeah, as we
Speaker 1: look out into the universe, we wonder why is it
Speaker 1: this way and not some other way? Why are we
Speaker 1: in this part of the universe and not some other
Speaker 1: part of the universe? Are we lucky that we ended
Speaker 1: up here? Was it just a fluke or is it
Speaker 1: pretty common our experience of the universe? Is the universe
Speaker 1: guaranteed to be logical? Daniel? Do you think is it
Speaker 1: logical that the universe is not logical? Yeah? A guarantee
Speaker 1: itself rests on logic, and so if the universe is illogical,
Speaker 1: then it cannot provide any kind of guarantees at all.
Speaker 1: Philosophically speaking, we don't know why the universe makes sense
Speaker 1: to us at all, Like, why is it even possible
Speaker 1: to describe it in terms of pretty simple mathematical stories.
Speaker 1: We don't know, But we do know that it seems
Speaker 1: to work, and it works really really well. Well, the
Speaker 1: universe is random, right at the quantum level, things are random?
Speaker 1: Is random the same as logical. Well, that's a really
Speaker 1: interesting point. Because even if quantum mechanics is random, it's
Speaker 1: still also logical, Like quantum mechanics makes very specific predictions
Speaker 1: for the probabilities of different things to happen, even if
Speaker 1: it doesn't actually pin down what will happen. So quantum
Speaker 1: mechanics being random doesn't mean it's like crazy, you're out
Speaker 1: of control. It still makes very specific predictions about what
Speaker 1: can and cannot happen and the probabilities of those things happening.
Speaker 1: Right although technically acquantic to quantum physics, like a pink
Speaker 1: unicorn could technically appear in front of me out of
Speaker 1: the boob right now, or in front of any of
Speaker 1: us right now, right and that would be logical. According
Speaker 1: to physicists, that would be logical, even though it would
Speaker 1: also be fantastical. And that's something we're always trying to
Speaker 1: understand about the universe. We see what happens to us,
Speaker 1: we wonder was that just a random, lucky fluke, or
Speaker 1: is that the kind of thing we expect to see
Speaker 1: in the universe. And there's this overriding principle in science
Speaker 1: called the Copernican principle, which argues that our experience is
Speaker 1: not weird, that everywhere in the universe is the same,
Speaker 1: and nothing is special anywhere, and so when we look
Speaker 1: out into the universe, we tend to try to explain
Speaker 1: what we see without resorting to lucky chances and random flukes.
Speaker 1: But lucky flukes is why we're here, Daniel, Lucky flukes
Speaker 1: are the best. Well, every individual person, of course, has
Speaker 1: an almost astronomically tiny chance of ever existing with all
Speaker 1: of their constituent details. But what we don't know is
Speaker 1: what are the chances of any person existing? You know,
Speaker 1: one of the deep questions in the universe is what
Speaker 1: are the chances for life evolving, for intelligent life to evolve?
Speaker 1: Are we unusual or are we common in the universe?
Speaker 1: And we'd like to be able to explain our existence
Speaker 1: here without resorting to a one in a trillion chance
Speaker 1: of all of this is happening. Well, it seems like
Speaker 1: there's a sort of a fine line between illogic and
Speaker 1: unlikeliness or as you said, improbability. Yeah, that's right, and
Speaker 1: often we can tell the difference, you know, we have
Speaker 1: just this one example of our lives and the part
Speaker 1: of the universe that we can see. And often we
Speaker 1: look out into the universe and we see stuff that
Speaker 1: seems weird, that seems like a weird coincidence, and we
Speaker 1: want to try to explain it. We don't want to
Speaker 1: just like brush it under the rug and say, hm,
Speaker 1: that's random, seems weird. I guess sometimes you just get lucky.
Speaker 1: We'd like to understand if there's something else going on,
Speaker 1: something deeper behind it. But you know, there isn't always
Speaker 1: an explanation, like, for example, the sun in the moon
Speaker 1: take up about exactly the same space in our sky,
Speaker 1: which allows for very dramatic eclipses, and that's just a coincidence.
Speaker 1: Sometimes coincidences happen, but sometimes they do have deeper explanations
Speaker 1: that we can look for. Yeah. So one way we
Speaker 1: try to explore the logic of the universe is by
Speaker 1: coming up with situations in our minds or that maybe
Speaker 1: we get hints at out there of events or things
Speaker 1: that seem to break the logic of the universe. And
Speaker 1: these are paradoxes. Yeah. One very famous paradox is the
Speaker 1: Fermi paradox, which says where are all the aliens? You know,
Speaker 1: if the galaxy is really really old and actually filled
Speaker 1: with stars and planets, then maybe it should also be
Speaker 1: filled with aliens, and why haven't we seen any of
Speaker 1: them yet? Why haven't they sent us messages? This is
Speaker 1: called the Fermi paradox because if you accept all of
Speaker 1: those assumptions, then we should have heard from aliens, and
Speaker 1: yet we haven't. So paradoxes are fun because they make
Speaker 1: you re examine those assumptions to say, well, we haven't
Speaker 1: heard from aliens, then which of those assumptions must be wrong?
Speaker 1: And what does that tell us about the universe. Well.
Speaker 1: Another famous paradox is the grandfather of paradox. Right, This
Speaker 1: idea that if you go back in time and you
Speaker 1: somehow prevent your grandfather from giving birth or making your
Speaker 1: father or mother haven't, then that creates an illogical consistency
Speaker 1: because then how could you have existed to them prevent
Speaker 1: your grandfather from doing that. That's one of the most
Speaker 1: famous logical paradoxes, right, And that's like something that doesn't
Speaker 1: make sense logically, but it could maybe happen. Well, we
Speaker 1: don't know if that could maybe happen exactly. That's one
Speaker 1: of the paradoxes inherent in time travel. It's the kind
Speaker 1: of thing that makes people wonder like, well, what are
Speaker 1: we overlooking? Is there something in time travel which would
Speaker 1: prevent that from happening. And there are various ideas about
Speaker 1: cosmic censorship that might prevent paradoxes from cropping up if
Speaker 1: you could actually achieve time travel. So you're right, it's
Speaker 1: a really interesting idea and it focuses your thinking on
Speaker 1: the issues to say, well, what can we do to
Speaker 1: prevent this paradox from happening, because, as you say, the
Speaker 1: universe seems logical, and so anything that creates a contradiction,
Speaker 1: a logical contradiction, we don't think that that could exist.
Speaker 1: The universe can't exist in two states that disagree with
Speaker 1: each other simultaneously. Yeah, so there is another interesting paradox
Speaker 1: out there. Then maybe the challenges the logic of us
Speaker 1: being here in the first place, or at least of
Speaker 1: our son being here in the first place. Yeah, asked
Speaker 1: the question basically of why we're not looking up into
Speaker 1: our sky and seeing a different kind of star than
Speaker 1: the one that we have, or stars plural. So today
Speaker 1: on the podcast, we'll be asking the question what is
Speaker 1: the Red Dwarf paradox? The real Red Dwarf paradox is
Speaker 1: why don't more people watch the show The Red Dwarf.
Speaker 1: Is that a show? I've never seen it? Is that
Speaker 1: a show? Oh my gosh, it's like one of the
Speaker 1: most hilarious can't be science fiction shows ever. I've never
Speaker 1: heard of it. Where does it er? I think it's
Speaker 1: on the BBC, but you can find it online. Is
Speaker 1: it really hilarious show? Sort of in the vein of
Speaker 1: Hitchhiker's Guide to the Galaxy. Definitely not hard science fiction. Well,
Speaker 1: the paradox maybe, is how come I've never shown I mean,
Speaker 1: I've seen several seasons of Doctor Who. There you go, Yeah, well,
Speaker 1: maybe it only exists in another multiverse, and that's proof
Speaker 1: that I came from another universe. You do seem out
Speaker 1: of this world, Daniel, you mean out of my mind.
Speaker 1: But so, the Red Dwarf paradox apparently is a thing.
Speaker 1: I had also never heard of this, the paradox or
Speaker 1: the show before coming into this episode. But it's sort
Speaker 1: of like a thing that physicists talk about, right. It
Speaker 1: is a thing that physicists and biologists and basically everybody
Speaker 1: who's curious about why we ended up on this rock
Speaker 1: around this star. Fundamentally, we're always asking the question, is
Speaker 1: our experience unusual? Do we have to resort to shrugging
Speaker 1: our shoulders and saying, well, I guess we were just lucky,
Speaker 1: or is there a reason that our experience is this
Speaker 1: way and not some other way? And in this particular case,
Speaker 1: we're wondering about why our star is one of these
Speaker 1: yellow stars instead of a red dwarf star. Well, this,
Speaker 1: like you said earlier, this sort of seems similar to
Speaker 1: the Fermi paradox, which is sort of this idea that
Speaker 1: we should have been contacted or seen aliens right now,
Speaker 1: but we haven't, given the size of the universe. But
Speaker 1: I feel like those are not really logical paradoxes, right Like,
Speaker 1: strictly speaking, it's not a logical there's no logical contradiction here.
Speaker 1: It's just like an unlikeliness. Yeah, that's true. I mean,
Speaker 1: the set of assumptions, when you combine them, suggest that
Speaker 1: it would be very unlikely for us to not be
Speaker 1: contacted by aliens. So either we're just unlucky or there's
Speaker 1: some other reason one of the assumptions that goes into
Speaker 1: it is wrong. And so you can always explain these
Speaker 1: things away and say, oh, well, maybe it's just one
Speaker 1: a million chance, and that's what it is. But you
Speaker 1: can also sometimes make progress by digging into those assumptions
Speaker 1: and saying, is one of those wrong, let's take another look.
Speaker 1: You mean, it's sort of like a tool to examine
Speaker 1: our assumptions about the universe, or as someone else might
Speaker 1: come complete guesses. Yeah, but it's a basic part of science.
Speaker 1: You know, anytime you think you have an understanding of
Speaker 1: the universe, you then think about what the consequences are.
Speaker 1: You know, if the universe is this way, then I
Speaker 1: should be able to prove it by seeing this thing.
Speaker 1: And if you don't see that thing happening, then you wonder, well,
Speaker 1: what's wrong with my idea of the universe? When we thought, oh,
Speaker 1: the universe would make more sense if it had Higgs
Speaker 1: Boson in it, let's go look for it, and we
Speaker 1: found it. Now, if we hadn't found it, then we
Speaker 1: would have to go back and re examine those assumptions
Speaker 1: that suggested it does exist and wonder which one of
Speaker 1: them were wrong. All right, Well, this red dwarf paradox
Speaker 1: basically just real quickly in a nutshell. It kind of
Speaker 1: asked the question that you asked earlier, which is, why
Speaker 1: isn't our star a red dwarf. Our son is a
Speaker 1: nice yellow or white I guess technically white ball of fire.
Speaker 1: It's not a red, it's not a dwarf, and so
Speaker 1: that's kind of what the paradox is about. Yeah, that's
Speaker 1: about it all right. Well, as usually, we were wondering
Speaker 1: how many people out there had asked themselves this question,
Speaker 1: why isn't our son different? Why isn't it a red dwarf?
Speaker 1: So thanks very much to everybody who participates in this
Speaker 1: segment of the podcast, and we would love to hear
Speaker 1: your voice out there. Those of you who have been
Speaker 1: listening for a while but haven't yet chimed in, please
Speaker 1: write to us to participate to questions at Daniel Horge
Speaker 1: dot com. So think about it for a second. Have
Speaker 1: you ever asked yourself on a nice sunny day, why
Speaker 1: our star isn't red? Here's what people had to say.
Speaker 1: I feel like thybe it's too big, big to be
Speaker 1: a red dwarf. That's it. I really don't know the
Speaker 1: answer to this one. I would just imagine that it
Speaker 1: doesn't have enough mass to either collapse into itself a
Speaker 1: form a black hole or become a red giant. I
Speaker 1: don't know all a son didn't follow his diet and
Speaker 1: has eaten a lot, so it's too big to become
Speaker 1: a red dwarf. I think the main reason our star
Speaker 1: isn't a red dwarf is just because it's something has
Speaker 1: to do with like the amount of mass it has
Speaker 1: in the beginning and when it begins, because some stars
Speaker 1: go supernova and some stars just white doors. I don't know,
Speaker 1: I get mixed up. Maybe our son is not old
Speaker 1: enough to be a red dwarf. Maybe it still has
Speaker 1: a lot of fool to be larger and right, dar,
Speaker 1: I don't think that our star is supposed to be
Speaker 1: a red dwarf. I think that it may someday be
Speaker 1: a red dwarf given enough time, But I think that
Speaker 1: it's not quite yet reached that phase of stellar evolution.
Speaker 1: All right, A lot of interesting answers here, I like
Speaker 1: the one about the Sun not following a diet, yeah,
Speaker 1: or the one about it not being old enough. But
Speaker 1: I am disappointed nobody brought off Superman. I mean these answers,
Speaker 1: what does Superman have to do with the Sun being
Speaker 1: yellow or red? You don't know. I don't know, Yeah,
Speaker 1: you don't know. Some basic mythology about Superman. I spent
Speaker 1: all my time watching the show Red Dwarf instead of
Speaker 1: reading Superman comics. Well, there you go. That's a multiverse
Speaker 1: I don't want to live in. So tell us what
Speaker 1: a Superman have to do with red stars. Yeah, it's
Speaker 1: a basic part of his mythology. So in the original comics,
Speaker 1: he grew up in a planet with the red sun,
Speaker 1: and so when he comes to Earth, he has all
Speaker 1: these superpowers because our son is not red, it's yellow,
Speaker 1: and somehow that gives him his superpowers somehow. Wow, you
Speaker 1: just yadda yadded over all the crucial elements of it. Yeah, somehow,
Speaker 1: you know, like how physicists do somehow the Higgs boson
Speaker 1: is created in architectors. That's exactly what I wrote in
Speaker 1: the paper. Yeah, that was it basically. I mean, you
Speaker 1: use more words and formulas, but there's not much difference
Speaker 1: between Action comics in the Journal of Physics. I'm sure
Speaker 1: that Action Comics hired some physics consultants to work out
Speaker 1: the details, and there's somewhere in there archives there are
Speaker 1: formulas explaining how the yellow sun gives Superman his special powers.
Speaker 1: What does that mean that Superman doesn't have those powers?
Speaker 1: In the dark. Well later on, it's sort of it's
Speaker 1: sort of like he acts like a battery, kind of
Speaker 1: like he needs to recharge, he needs to sunbathe they
Speaker 1: to get his superpowers. I see. So kryptonite isn't his kryptonite.
Speaker 1: It's sunscreen. That's his kryptonite in the long run. Yes, okay, fascinating. Well,
Speaker 1: let's dig into this red dwarf paradox and how it
Speaker 1: might affect Superman, I guess, or all of us, because
Speaker 1: it'd be great if we were all Superman and women. Well, actually,
Speaker 1: what the redware paradox suggests is that most of the
Speaker 1: universe is basically Superman, because one thing that's really interesting
Speaker 1: about the universe is that most of the stars out
Speaker 1: there in the universe are red stars, not yellow like ours.
Speaker 1: All Right, well, let's dig into this topic and this
Speaker 1: red dwarf paradox, and it's starts with the basics. What
Speaker 1: is a red dwarf star? Daniel, So, a red dwarf
Speaker 1: is just a kind of star. Remember that a star
Speaker 1: is a huge ball of gas and it's squeezed down
Speaker 1: by gravity, so at its core it's hot enough and
Speaker 1: dense enough for fusion to happen, which is where the
Speaker 1: light comes from and why the star burns at the
Speaker 1: temperature at the core, and therefore the temperature at the
Speaker 1: surface depends on the mass of the star. The more
Speaker 1: gas you have, the higher temperature and pressure you have
Speaker 1: at the core of the star, and so the higher
Speaker 1: the temperature at the surface, and so the different color
Speaker 1: of the star. Remember that everything in the universe glows,
Speaker 1: and how it glows depends on its temperature. Our sun
Speaker 1: is a surface temperature of five or six thousand degrees kelvin,
Speaker 1: and so it tends to glow in our visible spectrum.
Speaker 1: Bigger stars are hotter, and so they tend to be bluer.
Speaker 1: Smaller stars are colder, and so they tend to be redder,
Speaker 1: and so a red dwarf star is a smaller, colder
Speaker 1: star that tends to be redder than our star. M
Speaker 1: I guess maybe can you explain why smaller means lower temperature?
Speaker 1: Is it because when you're smaller, you don't have as
Speaker 1: much fusion, if at all, inside the core of the
Speaker 1: gas cloud. There's definitely a close connection between the size
Speaker 1: of the star and its internal temperature, and that's just
Speaker 1: because of gravity. Like more mass means more gravitational pressure,
Speaker 1: which means higher temperature. We once topped our way through
Speaker 1: that thought experiment of like taking a big blob of
Speaker 1: gas and squeezing it down. Squeezing it down heats it
Speaker 1: up because you're basically applying pressure which pushes on all
Speaker 1: those molecules, turning them around to focus them back towards
Speaker 1: the center. You imagine like a big box containing cold gas.
Speaker 1: As you can strict that box, you're pushing on all
Speaker 1: the molecules that would have otherwise escaped, so you're giving
Speaker 1: them more and more energy. So as you squeeze down
Speaker 1: harder and harder, you're speeding up all those molecules, you're
Speaker 1: making them hotter and hotter. So a bigger blob of
Speaker 1: stuff has more gravitational pressure, which means a higher temperature.
Speaker 1: Something like Jupiter, which is also a ball of gas.
Speaker 1: It does squeeze its gas in the middle, but it
Speaker 1: doesn't radiate light like this star of Sundust, did it.
Speaker 1: It does not. You're right, there's a minimum mass in
Speaker 1: order to create the conditions for fusion. Fusion is hard. Remember,
Speaker 1: what you're doing is squeezing together two protons which have
Speaker 1: a pretty powerful force repelling them. Right, they're both positively charged.
Speaker 1: You don't like to get together, So to get the
Speaker 1: protons close enough together to fuse to make helium, you
Speaker 1: have to overcome that. So you got to squeeze them really,
Speaker 1: really hard. And so if you don't have enough gravitational pressure,
Speaker 1: you haven't raised the temperature enough, then fusion just doesn't happen.
Speaker 1: So there's a minimum threshold above which fusion happens and
Speaker 1: below which it doesn't. So Jupiter is below that threshold
Speaker 1: by like a factor of ten. In order to get
Speaker 1: Jupiter to have fusion to ignite at its core, you'd
Speaker 1: have to add like nine more Jupiter's worth of mass
Speaker 1: to get it to that threshold. Red dwarfs are stars
Speaker 1: that are just above that minimum threshold, like eight percent
Speaker 1: of the mass of the Sun. It's like the minimum
Speaker 1: amount of stuff you need to get fusion going. So
Speaker 1: red dwarfs are like basically the smallest fusion reactor you
Speaker 1: can have. So red dwarf is a star in the
Speaker 1: sense that it has fusion inside of it. If you
Speaker 1: don't make it to the threshold fusion, like if you're
Speaker 1: like point ninety ninety nine below the fusion limit, would
Speaker 1: you still glow or did you just be like a
Speaker 1: giant gas planet like Jupiter. You'd be a giant gas
Speaker 1: planet like Jupiter. You wouldn't have fusion, but you would
Speaker 1: still be kind of hot. Even just having that much
Speaker 1: mass and that pressure makes you kind of hot. Like
Speaker 1: the core of Jupiter is not cool, right, it's very
Speaker 1: high density, high temperature, just not high enough to be fusion. Now,
Speaker 1: because you're pretty hot, you are going to glow. You're
Speaker 1: gonna glow very deep in the infrared, and you're not
Speaker 1: going to be nearly as bright as stars that actually
Speaker 1: have fusion happening in them. All right, well, I'll take
Speaker 1: being kind of hot, but not being hot, although being
Speaker 1: cool it's also pretty cool. These stars are really fascinating,
Speaker 1: these red dwarfs, and they're kind of cool. As we say, so,
Speaker 1: they tend to radiate in the red region, and they're
Speaker 1: also really really dim, Like these things are not nearly
Speaker 1: as bright as our sun. As a star gets bigger,
Speaker 1: it gets hotter, and then the fusion happens faster, and
Speaker 1: so they get brighter and brighter, which is why like
Speaker 1: really big massive stars starts like one hundred or two
Speaker 1: hundred times the mass of our sun burn really brightly,
Speaker 1: very blue, and don't last for very long. They can
Speaker 1: burn out just a few million years. Stars that are
Speaker 1: about the size of our sun last for billions of years.
Speaker 1: But if a star is smaller and cooler, it doesn't
Speaker 1: burn as bright, it's much dimmer. It can actually last
Speaker 1: much much longer. So a red dwarf can last for
Speaker 1: longer than the age of the universe, or even much longer. WHOA,
Speaker 1: I guess, because it's got like the heat on low
Speaker 1: basically right, it's like it's got just enough gravity to
Speaker 1: make fusion, but not enough to like burn a lot
Speaker 1: of it, So it's just burning a little bit in
Speaker 1: the center of it like a candle, more like a bonfire,
Speaker 1: and there's something else going on like the heart of
Speaker 1: these red dwarfs. Because they're cooler, the way the heat
Speaker 1: gets mixed around in their core is a little bit
Speaker 1: different than in our star. Like at our star, a
Speaker 1: lot of the heat transfer is what we call radiative transfer.
Speaker 1: Like fusion happens, and photons zoom out and the energy
Speaker 1: gets dispersed through the star towards the outside by radiation.
Speaker 1: Right these photons are flying out and so the outer
Speaker 1: parts of the star get hotter and hotter, and helium
Speaker 1: the fusion product tends to fall towards the core in
Speaker 1: our star, and that's actually a problem for our star
Speaker 1: because that helium tends to sort of put out the fusion,
Speaker 1: and so then fusion only happens on the outside of
Speaker 1: the star. But in a red dwarf it's a little
Speaker 1: bit different. Remember it's not as bright the outside of
Speaker 1: a star. What do you mean for a star like
Speaker 1: our sun near the end of its life, as it
Speaker 1: accumulates helium at its core, most of the fusion will
Speaker 1: not be happening at its core anymore. Instead, it'll be
Speaker 1: happening on the outer layers of the star, which is
Speaker 1: one reason why our sun will grow eventually become like
Speaker 1: a red giant. It'll puff out to have like a
Speaker 1: radius the size of Earth's orbit, because the fusion will
Speaker 1: be happening like in the outer layers, and the core
Speaker 1: will be the sort of cooler helium. But a red
Speaker 1: dwarf won't have that problem. A red dwarf mixes in
Speaker 1: a different way because there's not so much radiation produced
Speaker 1: at its core, so there tends to be more convection
Speaker 1: of the plasma like mixes more thoroughly, so you don't
Speaker 1: get this accumulation of helium at the core, and it
Speaker 1: can basically just sort of like burn steadily for a
Speaker 1: long time. This tends to prolong the fusion. It's another
Speaker 1: reason why these red dwarves last a really long time.
Speaker 1: And we don't know because the universe isn't old enough,
Speaker 1: but some calculations suggest that a small star like ten
Speaker 1: percent the mass of our sun could last for ten
Speaker 1: trillion years. WHOA, that's like ten thousand billion years, right,
Speaker 1: that's ten thousand billion years, or almost a thousand times
Speaker 1: the current age of the universe. Like some of these
Speaker 1: red dwarfs that were created very early on in the universe,
Speaker 1: they could be less than one one thousands of the
Speaker 1: way through their life cycles so far. By lasting, you
Speaker 1: mean like sustaining fusion at their core, yeah, exactly, because
Speaker 1: eventually they will burn through their fuel and these things
Speaker 1: will become blue dwarfs and then white dwarfs. Eventually, the
Speaker 1: life cycle of one of these red dwarves, we think
Speaker 1: ends with it basically becoming a cooler blob of heavier metals,
Speaker 1: probably helium. Sounds like the cosmic version of the tortoise
Speaker 1: in the hair there that's slow and steady kind of
Speaker 1: wins the race. Yeah, exactly. So really big stars burn
Speaker 1: really brightly but don't last for very long, and really
Speaker 1: small stars burn cooler, but they last forever almost And
Speaker 1: this is really useful when we're looking out into the
Speaker 1: universe trying to understand how recently stars were made. If
Speaker 1: you're looking at a part of the universe and you
Speaker 1: see blue stars, you see hot, bright young stars, that
Speaker 1: means stars must have been made recently. If all you're
Speaker 1: looking at our redder stars, then you know that it's
Speaker 1: pretty old because all the hot young blue stars have
Speaker 1: already burned out. So it's a really helpful lever for
Speaker 1: understanding what's going on out there in the universe. So
Speaker 1: they're like looking at TikTok only stars there. All right, Well,
Speaker 1: that's what a red dwarf is. Until the big question
Speaker 1: is why isn't our star a red dwarf? And would
Speaker 1: we all have superpowers if it were? So let's dig
Speaker 1: into that, But first let's take a quick break. All right,
Speaker 1: we're talking about the red dwarf paradox. Basically, why isn't
Speaker 1: our son a red dwarf. I feel like this is
Speaker 1: an insensitive question, Daniel. I mean, how would our son feel?
Speaker 1: Maybe we should have asked it the other way, to say,
Speaker 1: why is our star so special and wonderful? Yeah, there
Speaker 1: you go. That sounds better. Maybe it should be the
Speaker 1: yellow sun bonus situation. There you go straight from our
Speaker 1: pr department. But our son is kind of special. I mean,
Speaker 1: if you look out in the universe, our son is
Speaker 1: not the most common kind of son. Instead, like seventy
Speaker 1: five percent of the stars in the galaxy are red dwarves.
Speaker 1: These things like dominate the galaxy. Most of the stars
Speaker 1: out there are red dwarves, not yellow stars like ours.
Speaker 1: What do you mean dominate? What kind of numbers are
Speaker 1: we talking about? So three quarters of all stars in
Speaker 1: our galaxy are red dwarfs. It's like overwhelming. M Well,
Speaker 1: that's kind of interesting. So three quarters of the stars
Speaker 1: in our galaxy are red dwarves, but they don't look
Speaker 1: red when you look out into the night sky. Yeah,
Speaker 1: this is really fascinating. Most of the stars in the
Speaker 1: galaxy are red dwarves, but none of the stars you
Speaker 1: can see in the sky with the naked eye are
Speaker 1: red dwarfs. And The reason as that these red dwarfs
Speaker 1: are pretty dim. Remember they can be like ten thousand
Speaker 1: times less bright than our sun, and so they're all
Speaker 1: over the place. They're out there. But the stars we
Speaker 1: see in the sky are not red dwarves. We see
Speaker 1: the bright ones, the rare ones. MM. Interesting. So I
Speaker 1: guess if you looked at the sky with maybe like
Speaker 1: an infrared glasses, or if you could see into the
Speaker 1: lower frequency light spectrum, then you might see a whole
Speaker 1: bunch more stars when you look at the nice sky. Yeah.
Speaker 1: In fact, that the closest star to us, Proximus Centauri,
Speaker 1: is a red dwarf. It is like twelve point five
Speaker 1: percent the mass of the Sun. You can't see it
Speaker 1: with the naked eye, even though it's the closest star
Speaker 1: to Earth. Most of the stars so you're looking at
Speaker 1: in the sky are what we call like FK or
Speaker 1: G type stars instead of red dwarfs. Well, it's super interesting.
Speaker 1: So I guess animals I can see that have night vision,
Speaker 1: basically I can see infrared more that would they look
Speaker 1: out into the nice sky and see a totally different
Speaker 1: picture than we would. Wow, that's a super fascinating question.
Speaker 1: I don't know. I guess we'll have to have an
Speaker 1: animal on the podcast as a guest, our first animal astronomer,
Speaker 1: and ask them all about what they see. Yeah, sounds good.
Speaker 1: Which animal would that be? An anteater? Of course for Ucia. Now,
Speaker 1: but we have built infrared eyeballs, right, James Webb. Remember
Speaker 1: is an infrared telescope. It specializes in seeing in the infrared.
Speaker 1: And we have lots of other infrared facilities that can
Speaker 1: see these spectra, and so we have, of course observed
Speaker 1: these stars. We look out into the universe and notice them.
Speaker 1: That's how we know that they are there. But it's
Speaker 1: really interesting to me to think, like, not only is
Speaker 1: our star not a red dwarf, but none of the
Speaker 1: stars we see are red dwarfs, even though they dominate
Speaker 1: the universe. I guess maybe the first question I would have,
Speaker 1: and I imagine anyone would have, is why is the
Speaker 1: universe mostly made out of red dwarves? Why is it
Speaker 1: seventy stars in the galaxy are red dwars? Why isn't
Speaker 1: it more distributed? Yeah, it's a really cool question. There's
Speaker 1: this concept in astronomy called the initial mass function, which
Speaker 1: tries to describe basically how much stuff a star gets.
Speaker 1: You know, ask the question like, if you're forming a star,
Speaker 1: how much stuff are you likely to get? What's the
Speaker 1: distribution of the mass of stars, for example, and what
Speaker 1: turns out to be like a power law, You're much
Speaker 1: much less likely to make a big star than a
Speaker 1: small star. And you know, as gas clouds are sort
Speaker 1: of coming together and forming stars, you're just less likely
Speaker 1: to grab a bigger blob of stuff. You're more likely
Speaker 1: to form multiple smaller stars than a single larger star
Speaker 1: because it's just how gravity works out there in space
Speaker 1: in a gas cloud. Yeah, it's actually quite complicated because
Speaker 1: it involves not just gravity but also where metals are
Speaker 1: and how they're distributed. Imagine this big gas cloud where
Speaker 1: gravity pulls things together to make stars depends on where
Speaker 1: you have little bits of density to start with, and
Speaker 1: the universe is mostly hydrogen, but it's also sprinkled with
Speaker 1: a bunch of metals, right, the metals from previous stars
Speaker 1: that burned and fused these heavy things and then sprayed
Speaker 1: them out into the universe. So we think that also
Speaker 1: as time goes on and the universe gets more and
Speaker 1: more metallic, less hydrogen and more heavy stuff, that the
Speaker 1: size of stars decreased, like the first generation of stars
Speaker 1: will be weirdly call type three. We think these were
Speaker 1: all really really big, hugely massive stars, like three or
Speaker 1: four hundred times the mass of our sun, and they
Speaker 1: burned out really really quickly. But while they burned, they
Speaker 1: also made some heavier metals, So the next generation of
Speaker 1: stars got seated with more overdensities because you have this
Speaker 1: like spray of little dots of metal to start more
Speaker 1: stars and sort of collapsed more easily into these cold blobs.
Speaker 1: So it's a complicated interplay with like the temperature of
Speaker 1: these gas clouds and the distribution of where the metal
Speaker 1: seeds are to start these things, and there's a lot
Speaker 1: of uncertainty. People aren't really sure exactly what the shape
Speaker 1: of this initial mass function is, but we are sure
Speaker 1: of the overall trend that bigger stars tend to be
Speaker 1: more rare and smaller stars more common, and that's why
Speaker 1: we have more small stars than big stars. M Interesting.
Speaker 1: I wonder what that was like when we first discovered
Speaker 1: that effect that most of the stars in the universe
Speaker 1: are red dwarfs, Because I imagine we looked that into
Speaker 1: the sky and saw a bunch of starts and thought, oh,
Speaker 1: that's pretty neat. But then we looked at the universe
Speaker 1: at a different kind of line, and so I'm lean, boom,
Speaker 1: there's like a three times more stars than we thought
Speaker 1: there were. Yeah, exactly. It's one of my favorite things
Speaker 1: about a start, me that every time we build a
Speaker 1: new kind of instrument and look out into the universe,
Speaker 1: we discover, Wow, there's a lot more going on than
Speaker 1: we thought. It's like a whole other universe out there
Speaker 1: filled with these red dwarves. We've been looking mostly at
Speaker 1: the rare stuff and not at the common stuff, not
Speaker 1: at the typical stuff, and it turns out that our
Speaker 1: sun is not one of the usual ones. And that's
Speaker 1: sort of the core of the red dwarf paradox. It's like,
Speaker 1: if most of the stars out there are red dwarfs,
Speaker 1: and they live much much longer than our kind of star,
Speaker 1: then why did we happen to evolve around one of
Speaker 1: these rare, shorter lived stars instead of one of the
Speaker 1: more common, longer lived ones. So that's the basic red
Speaker 1: dwarf paradox. It's like, why didn't we get to evolved
Speaker 1: or come up in a star that's the red dwarf
Speaker 1: because there is three times more common than our kind
Speaker 1: of star, They're five times more common, and on average
Speaker 1: they outlast our star by twenty So like, either it's
Speaker 1: a one in one hundred chance, or maybe there's a reason,
Speaker 1: Maybe there's an explanation why life can't happen around red
Speaker 1: dwarves or it's less likely around red dwarves. One thing
Speaker 1: we do know is that red dwarves tend to have
Speaker 1: planets around them, just like our kind of star. And
Speaker 1: so it's a fun question, like is there life around
Speaker 1: red dwarves? Are we an unusual kind of life? Is
Speaker 1: everybody else out there in the universe? Superman? Are all
Speaker 1: their planets called Krypton? That is what does this day
Speaker 1: up at night wondering about. But this is an interesting scenario.
Speaker 1: You're saying that most red dwarfs are kind of just
Speaker 1: like our stars. They can have planets orbiting around them.
Speaker 1: What would their sun look like to someone living at
Speaker 1: a planet like that, Well, if you're at the same
Speaker 1: distance from that red dwarf as we are from our sun,
Speaker 1: then of course there'd be a lot dimmer, right and colder, right, Yeah, exactly,
Speaker 1: dimmer and colder. It'd be dark and chilly. Of course,
Speaker 1: you could be closer up and then you'd be brighter
Speaker 1: and warmer. But the star itself also would look different.
Speaker 1: The star itself is colder, which means it's light is redder.
Speaker 1: So you look in the sky, you wouldn't see like
Speaker 1: a yellow or white sun. You see like a pale
Speaker 1: orange or a red disc in the sky. It would
Speaker 1: be a very different experience. Well, I wonder if it
Speaker 1: would be different, you know, because you would have to
Speaker 1: be closer to the star to get the same warmth
Speaker 1: as us. So it is possible for there to be
Speaker 1: a planet I run, a red dwarf that feels like
Speaker 1: our situation here, and you'd be closer to it, so
Speaker 1: would be just as warm and maybe just as bright
Speaker 1: as our sun is to us, wouldn't it. Yeah, you
Speaker 1: could definitely have a planet in a habitable zone where
Speaker 1: water is liquid at the surface and it's about the
Speaker 1: same temperature as Earth. But it would look different in
Speaker 1: the sky, right, It would still be red instead of yellow.
Speaker 1: Though if you evolve on that planet, then who knows
Speaker 1: what your experience of red is. Yeah, that's what I mean, Like,
Speaker 1: it would only look red if a human went over
Speaker 1: there and landed on that planet. But to some species
Speaker 1: that evolved there, it would just look like white light,
Speaker 1: or it would be what they call white light, because
Speaker 1: they would maybe see a different, totally different spectrum of light.
Speaker 1: The visible spectrum would be you know, shifted it over,
Speaker 1: but they would call that white light, right. I don't
Speaker 1: know what they would call it, but you're totally right
Speaker 1: that it's very likely that their visible spectrum would be
Speaker 1: different from ours because ours evolved in response to the
Speaker 1: light that happens to be here on Earth. What we
Speaker 1: call visible is no coincidence. Peaks around the light that
Speaker 1: the sun puts out our sun, and so it makes
Speaker 1: a lot of sense, as you say, for aliens around
Speaker 1: a red dwarf, for their visible sensitivity to peek around
Speaker 1: the light emitted by their star instead of ours. Whether
Speaker 1: they would call that white or not, I'm not sure
Speaker 1: what they would experience it, what would their art be like?
Speaker 1: You know, I guess what I mean is like what
Speaker 1: we call white light is just light that has all
Speaker 1: the frequencies in our visible spectrum. Like that's our experience
Speaker 1: of white light. And so if you're growing up in
Speaker 1: that red dwarf planet, you know, your eyes would probably
Speaker 1: evolve to also interpret, you know, everything that's in your
Speaker 1: visible spectrum to be you know, the white or what
Speaker 1: we would call white. And so you know, they wouldn't
Speaker 1: know they're in a red planet. That's interesting. And if
Speaker 1: they tend to paint like all their walls white, we
Speaker 1: show up to visit, there would be like, why is
Speaker 1: everything painted red? You guys have like a red sun.
Speaker 1: It's not enough. You'll also have to paint all of
Speaker 1: your walls red, right, That's what I mean. Or if
Speaker 1: they came to our planet, they'd be like, why is
Speaker 1: everything blue? You guys are nuts. That's not blue. That's
Speaker 1: not white. That blue. We say, we just got the
Speaker 1: blues because we didn't get to grow up around a
Speaker 1: red dwarf. We got the yellow dwarf blues. Yeah, and
Speaker 1: so our star is not a red dwarf. It's a
Speaker 1: different kind of star. It's bigger. We have a G dwarf. Wait,
Speaker 1: it's still a dwarf. Well, you might not be surprised,
Speaker 1: but there's a lot of disagreement about what to call them.
Speaker 1: Some people call it a yellow dwarf or a G
Speaker 1: type or a G dwarf, but it's part of a
Speaker 1: category of stars F, G, and K, where those letters
Speaker 1: just indicate basically the mass of the star and therefore
Speaker 1: it's temperature. So every star that has a mass of
Speaker 1: our sun within about ten percent we call a G
Speaker 1: type or G dwarf. And then there are F type
Speaker 1: and K type that can be like a little bigger
Speaker 1: or a little hotter or whatever. Lots of famous stars
Speaker 1: like Alpha Centauri, for example, is also a G type star. Interesting, well,
Speaker 1: I like our star. It's pretty nice and sunny for
Speaker 1: us here. Maybe my next question is like, why is
Speaker 1: this a paradox? I feel like maybe you're stretching the
Speaker 1: definition of the work because it doesn't feel like a
Speaker 1: logical inconsistency. It just feels like a philosophical question, like
Speaker 1: why did we happen to live around a star that represents,
Speaker 1: you know, the fifteen percent of all the stars in
Speaker 1: the universe. I think it's called a paradox because it
Speaker 1: asks a basic question. It says, if it's true that
Speaker 1: these stars are just as likely to have life as ours,
Speaker 1: then it's much more likely that we would have evolved
Speaker 1: on a red dwarf instead of a G type star.
Speaker 1: And so you have to either say all right, something
Speaker 1: very unlikely happened, or there's a reason. This an explanation
Speaker 1: is to again just a tool to dig into all
Speaker 1: of those assumptions. In this case, it's not like ridiculously unlikely.
Speaker 1: We're talking about it's like a one in a hundred chance.
Speaker 1: If life is equally like need to evolve around G type,
Speaker 1: F type K type and red dwarfs, then it's like
Speaker 1: a one one hundred chance to not end up evolving
Speaker 1: around a red dwarf. And that's not crazy. You know,
Speaker 1: one and one hundred chances happen, But it's an invitation
Speaker 1: to dig deeper. And for those of us who want
Speaker 1: to understand the universe, these are opportunities. These are clues
Speaker 1: that say maybe there's something else going on. All right, well,
Speaker 1: let's dig into what could be going on there. What
Speaker 1: kinds of assumptions are we making about life here on
Speaker 1: Earth and what life could be like around a red
Speaker 1: dwarf planet. So let's tag into that. But first let's
Speaker 1: take another quick break. All right, we're talking about Superman.
Speaker 1: What's your favorite Superman storyline, Denny? The one where Daniel
Speaker 1: didn't know that Superman required sunlight to work. You didn't
Speaker 1: know Superman was big on solar energy. The one where
Speaker 1: Superman makes a crossover on my favorite TV show, Red Dwarf.
Speaker 1: That might happen. You never know, You know, all these
Speaker 1: companies keep getting bought out by other companies. That's right.
Speaker 1: If DC buys the BBC and we have the DC
Speaker 1: BBC extended Universe, maybe it'll happen. Right the DBC. We're
Speaker 1: talking about red dwarves, and apparently our star, the one
Speaker 1: we see during the day, is not the most common
Speaker 1: type of star in the universe. It's only maybe fifteen
Speaker 1: percent of all it's kind, It's only fifty percent of
Speaker 1: all the stars out there in the galleys in our galaxy.
Speaker 1: Most of the stars seventy stars in the galaxy are
Speaker 1: red dwarves, which are different, smaller, cooler, And so maybe
Speaker 1: a question you can ask is like, why isn't our
Speaker 1: star a red dwarf? I guess I'm wondering what we're
Speaker 1: really asking here. We're asking why our star is not
Speaker 1: a red dwarf? Or are we asking why we're not
Speaker 1: a species that grew up around a red dwarf? Yeah?
Speaker 1: The second one we're asking is it just chance that
Speaker 1: we haven't evolve not in the most likely situation, or
Speaker 1: is there a reason or we misunderstood where life is
Speaker 1: possible and likely. I guess that's a weird question to ask,
Speaker 1: because the answer could be both. Right. It could be
Speaker 1: that there's equal chances of a species growing up around
Speaker 1: any star, but we just happened to be one one
Speaker 1: of the ones that grew up around a yellow star. Yeah. Absolutely,
Speaker 1: it certainly could be both, and it could also just
Speaker 1: be chanced. Those coincidences do happen. But we've made a
Speaker 1: lot of progress in science just by pushing this basic principle.
Speaker 1: The Copernican principle is saying, let's never assume that there's
Speaker 1: something special or weird about our situation. Let's try to
Speaker 1: describe what we see under the assumption that no place
Speaker 1: is special. And that's been very useful. It's not a
Speaker 1: hard and fast rule, but it's guided our thinking and
Speaker 1: helped us make discoveries. All Right, Well, if you apply
Speaker 1: that principle, what would be some of the answers to
Speaker 1: the red poarf paradox. Well, one way you could reduce
Speaker 1: the unlikeliness of the paradox is to think about how
Speaker 1: fast life does evolve into intelligent life. One thing we're
Speaker 1: saying is that these red dwarfs is five times as
Speaker 1: many of them, and they last twenty times is long.
Speaker 1: It seems to suggest that you're like a hundred times
Speaker 1: more likely to revolve around a red dwarf than our
Speaker 1: kind of star. But that is actually making some assumptions.
Speaker 1: That's assuming, for example, that life might take a long
Speaker 1: time to evolve. You know, that's very unlikely, and so
Speaker 1: these Red Dwarfs, because they last longer and they're more
Speaker 1: of them, they're basically like buying more lottery tickets, and
Speaker 1: so they're more likely to win. But instead, if intelligent
Speaker 1: life evolves pretty rapidly, it doesn't take very long to evolve,
Speaker 1: then the fact that Red Dwarves happen to live longer,
Speaker 1: have longer lifespan doesn't necessarily help them. And so in
Speaker 1: that scenario, instead of being like one hundred to one,
Speaker 1: it's more like five to one odds. It's just basically
Speaker 1: the relative rates of occurrence that determines your likelihood of
Speaker 1: being around a Red dwarf or a yellow star. I
Speaker 1: guess maybe I'm not quite sure I understand that argument.
Speaker 1: If you are around longer, if a red Dwarf is
Speaker 1: around longer, which it is, As you say, can we
Speaker 1: get even less longer than the eight of the universe
Speaker 1: doesn't make it more likely that it has or at
Speaker 1: some point in its history will have life. Then let's
Speaker 1: say our star. If life is really unusual or it
Speaker 1: takes a long time to evolve, then yes, But say
Speaker 1: life happens really quickly when it does. Right, then the
Speaker 1: fact that the red Dwarf is going to last for
Speaker 1: trillions of years means that civilization gets to live longer
Speaker 1: around its star. But it doesn't mean that it's twenty
Speaker 1: times as likely to evolve around one of those Why not?
Speaker 1: I guess you know you're assuming that life is sort
Speaker 1: of a certainty if you have a certain set of conditions.
Speaker 1: But maybe it's a probability thing for life to occur,
Speaker 1: right like if you need to roll the die and
Speaker 1: get a certain number to get any kind of seed
Speaker 1: of life when you're around your star, then the longer
Speaker 1: you are, the more times you get to throw the die.
Speaker 1: You're assuming it's a certainty, but it's not right. It's
Speaker 1: maybe chance base it maybe is right. But what we're
Speaker 1: doing here is we're examining which assumptions could possibly explain.
Speaker 1: It's what assumptions will we have to change in order
Speaker 1: to explain what we're seeing. You're totally right that if
Speaker 1: it's like rolling the dice and it's very unlikely, then
Speaker 1: the more times you roll the dice, the more odds
Speaker 1: you have, and so then you would be much more
Speaker 1: likely to evolve around a red star. But if it's not,
Speaker 1: if it's basically certain it happens pretty quickly, then you
Speaker 1: would expect life to happen around red dwarfs only five
Speaker 1: times as often as around yellow stars, because that's the
Speaker 1: relative rate of their occurrence, and the time wouldn't be
Speaker 1: a factor. And that could be the case, right, it
Speaker 1: could be five times more Kryptonians and Earthlings out during
Speaker 1: the universe. There certainly could be. And we also don't
Speaker 1: really know, you know, how common is life? How long
Speaker 1: does it take to evolve? We think that on Earth,
Speaker 1: life itself evolved pretty quickly. There's like fossil records going
Speaker 1: billions of years back, so we think it didn't take
Speaker 1: very long for life itself to evolve, although intelligent life
Speaker 1: is much more recent development, and so it might be
Speaker 1: that life is very common in the universe and all
Speaker 1: those red dwarfs are teeming with little bacteria. But intelligent life,
Speaker 1: you know, people making podcasts and writing comic books and
Speaker 1: all that kind of stuff, is more rare. We just
Speaker 1: don't know the answer to those questions. Well, if it
Speaker 1: is more rreer, then having five times more stars and
Speaker 1: being around longer would make that so much more likely
Speaker 1: that they have intelligent life, right exactly. Yeah, so this
Speaker 1: isn't a great answer to the question, but it changes
Speaker 1: the probabilities, right, the likelihood and the time it takes
Speaker 1: for intelligent life to evolve does change how likely you
Speaker 1: are to evolve around a red star or a yellow dwarf.
Speaker 1: So then how does this resolve the paradox? I don't
Speaker 1: think it totally resolves the paradox, But if we did
Speaker 1: live in a universe where intelligent life emerged very, very rapidly,
Speaker 1: then our situation wouldn't be as unlikely. It'd be like
Speaker 1: a one in five chance instead of a one in
Speaker 1: one hundred chance. So it reduces the tension a little bit.
Speaker 1: I see, all right, it makes us less of a miracle,
Speaker 1: yeah exactly, We're less a little less weird. All right, Well,
Speaker 1: what are other possible resolutions to this paradox. Well, it
Speaker 1: might be that it's not as easy for life to
Speaker 1: evolve around red dwarfs, Like maybe red dwarfs are not
Speaker 1: as habitable as yellow stars. There are more differences between
Speaker 1: red dwarfs and yellow stars than just their brightness. Because
Speaker 1: they're so much smaller, they tend to have different sort
Speaker 1: of behaviors, which might make it harder for life to
Speaker 1: evolve around them. Like what kinds of behaviors? Well, for example,
Speaker 1: we talked earlier about how to be in the habitable zone,
Speaker 1: you would have to be much much closer to the star, right,
Speaker 1: because the star is much dimmer. In that scenario, you're
Speaker 1: more likely to be tidally locked to the star, which
Speaker 1: means that like one surface of the planet is always
Speaker 1: facing the star. Tidal forces are really just gravitational forces.
Speaker 1: Gravity hinds to tug on the closer bit harder than
Speaker 1: on the further bit. If you can elongate the planet
Speaker 1: a little bit, then it prevents the planet from spinning
Speaker 1: the way. For example, the same side of the Moon
Speaker 1: is always facing the Earth, and so if you're on
Speaker 1: a planet really close to your star, you might be
Speaker 1: tidally locked and That means that one half of the
Speaker 1: planet would be super duper hot and the other half
Speaker 1: would be super duper cold, and biologists disagree about whether
Speaker 1: that's more or likely or less likely to evolve life.
Speaker 1: Does that assume a planet the same size as Earth.
Speaker 1: What if you're a smaller planet or what if you
Speaker 1: have some spin to begin with? Yeah, smaller planet would
Speaker 1: be less likely to be tightly locked. That's true, And
Speaker 1: it's not guaranteed that all these planets would be tightly locked.
Speaker 1: You right, If you have a lot of spin, you
Speaker 1: might be able to avoid it. But more of these
Speaker 1: planets would be tightly locked than, for example, earthlike planets
Speaker 1: around a yellow dwarf, so it might complicate the evolution
Speaker 1: of life. Another issue with these stars is that a
Speaker 1: lot of red dwarfs tend to be what we call
Speaker 1: flare stars. Unlike the Sun, which burns pretty steadily and
Speaker 1: you know it has some flare ups and some deviations
Speaker 1: in its brightness, red dwarfs can sometimes vary dramatically in
Speaker 1: their brightness. A flare star is something that can be
Speaker 1: like two or five or one hundred times as bright
Speaker 1: as it normally is all of a sudden for a
Speaker 1: little while and then sort of calm back down. They
Speaker 1: don't tend to burn as steadily. Well, you're saying red
Speaker 1: dwarves tend to flare up more than our kind of start. Yeah,
Speaker 1: red dwarfs tend to be more variable than yellow stars.
Speaker 1: I thought they were more like moderate and steady. It's
Speaker 1: a subject of intense debate, and we're not sure we understand.
Speaker 1: But remember that a lot of stars out there are
Speaker 1: also binary stars, and so these red dwarves might be
Speaker 1: in binary systems, and interactions between the magnetic fields of
Speaker 1: the two stars can interfere with what's going on inside
Speaker 1: the star and like heat it up briefly and cause
Speaker 1: it to burn hotter for a short period. So it's
Speaker 1: not something we understand very well. But the stars that
Speaker 1: we have studied, most of the flare stars, tend to
Speaker 1: be these red dwarves, and that would be pretty unpleasant
Speaker 1: for life. If all of a sudden the Sun is
Speaker 1: like a hundred times hotter than it usually is. M
Speaker 1: you might have to leave that planet right or at
Speaker 1: least like put your son in a spaceship and send
Speaker 1: it to another planet. It's like a yellow sun. Perhaps
Speaker 1: that sounds like a great idea for a comic book.
Speaker 1: You should copyright that, like fifty years ago. Let's go
Speaker 1: back in time to your grandfather and tell him that idea.
Speaker 1: That's right, it's called the Superman I had the idea
Speaker 1: for Superman Paradox. So why are you wasting your time
Speaker 1: on this podcast? You just be counting your money because
Speaker 1: I'm stuck in this multiverse, Daniel. I could be a
Speaker 1: billionaire cartoonist instead, I'm just a cartoonist. Just a cartoonist. Yeah,
Speaker 1: so flare stars would make it harder for life to
Speaker 1: evolve for at least lifelike hours. You know, maybe that
Speaker 1: kind of environment would lead to totally different kinds of
Speaker 1: life that are less sensitive to radiation. Or maybe they'd
Speaker 1: have to burrow underground where it might be safer and
Speaker 1: they could still somehow tap into the heat of the sun.
Speaker 1: M right, because we don't like we assume that you
Speaker 1: need day and nighttime cycles to thrive like we do, right,
Speaker 1: Like you need a good night's sleep. Of course you
Speaker 1: need nighttime for that. But maybe not right, Like, maybe
Speaker 1: it could be even the opposite, Like maybe life flourishes
Speaker 1: better if there's no nighttime. Yeah maybe, and maybe it's
Speaker 1: great to have like super duper hot summers every few
Speaker 1: hundred years. You know, things get fried to a crisp,
Speaker 1: but the strong survive. Who knows. There's one more issue
Speaker 1: with life developing around these red dwarfs is that in
Speaker 1: the systems we have studied so far, we see fewer
Speaker 1: large gas giants, basically fewer Jupiters. So, you know, we
Speaker 1: are very happy to have Jupiter or solar system because
Speaker 1: it's big, and it's gravitational, and it tends to protect
Speaker 1: us from comments and asteroids. Sometimes it sweeps these things
Speaker 1: out of the inner Solar system, But in systems with
Speaker 1: red dwarf stars, we tend to see fewer of these jupiters,
Speaker 1: which might mean that they're not as protected from asteroids,
Speaker 1: so it might mean more big impacts like the ones
Speaker 1: that wiped out the dinosaurs. I see. We don't see
Speaker 1: Jupiter size planets around those other solar systems, But I
Speaker 1: wonder if they have their own version of Jupiter. Right,
Speaker 1: I feel like a red dwarf system would be very
Speaker 1: similar to ours, just kind of scaled down. So maybe
Speaker 1: you have to scale down your expectations for what a
Speaker 1: Jupiter would be like. Yeah, as long as they're being
Speaker 1: hit by mini asteroids and maybe it's cool. And remember, also,
Speaker 1: being hit by an asteroid isn't all bad. I mean, sure,
Speaker 1: lots of things die, but it also can make room
Speaker 1: for all sorts of new evolution like mammals and humans.
Speaker 1: Doesn't necessarily have to be a planet wide extinction event.
Speaker 1: But I guess you're saying that life around a red
Speaker 1: dwarf isn't necessarily rosier than or it might be less
Speaker 1: rosy than technically, both metaphorically and physically speaking than life
Speaker 1: around a yellow start. Yeah, you might be wearing rose
Speaker 1: colored glasses, but there might actually be fewer roses, or
Speaker 1: at least the situation would be different. And if we're
Speaker 1: making a simple argument about the likelihood for life to evolve,
Speaker 1: this sort of undermines sense as well. The conditions we
Speaker 1: know are quite different, and so life might be less
Speaker 1: likely to evolve in those scenarios. On the other hand,
Speaker 1: it could also be more likely. Right, maybe life in
Speaker 1: the universe prefers that situation to ours. We just don't know.
Speaker 1: All right, Well, then what's another or maybe the last
Speaker 1: possible resolution to this paradox? The last sort of idea
Speaker 1: people have to explain this is that maybe there aren't
Speaker 1: as many earthlike worlds around these red dwarfs as we think. Remember,
Speaker 1: the red dwarfs, they're hard to study because they're small
Speaker 1: and they're dim. Most of the ones that we study
Speaker 1: are like the really big versions of them, sort of
Speaker 1: on the upper edge of red dwarfs. A lot of
Speaker 1: the red dwarfs that are out there, most of them
Speaker 1: that are out there, are smaller. It's not just true
Speaker 1: that there are more red dwarfs than yellow stars. There
Speaker 1: are more small red dwarfs than bigger red dwarfs. So
Speaker 1: most of the red dwarfs out there are the ones
Speaker 1: that we have trouble seeing. So our calculations are estimates
Speaker 1: about like how often there's an earthlike planet inhabitable zone
Speaker 1: around these things. Those could just be wrong, and it
Speaker 1: might be that most of the red dwarves out there
Speaker 1: don't have planets the way our stars do. They're just
Speaker 1: sort of too hard to study. Right now, we're like
Speaker 1: extrapolating into the unknown, well beyond what we really have
Speaker 1: confidence in, I see, because we haven't. We don't actually
Speaker 1: know what the planets around those smaller red dwarves are,
Speaker 1: like yeah, or how many there even are right. So
Speaker 1: we're making these assumptions. We're extrapolating from our situation and
Speaker 1: from the few examples we have been able to study
Speaker 1: about red dwarfs. But that's an extrapolation, and that could
Speaker 1: be where we're going wrong. Maybe only the red dwarves
Speaker 1: have these kind of planets, and most of the ones
Speaker 1: out there, which are most of the stars in the galaxy,
Speaker 1: don't have them. M that would make it less weird
Speaker 1: that we exist around a yellow star. And fortunately we're
Speaker 1: going to learn more about this soon. In twenty thirty five,
Speaker 1: we hope to be launching a new space telescope called
Speaker 1: have X, which is going to specialize in studying planets
Speaker 1: around stars, even dimmer stars. It's going to be super
Speaker 1: awesome with this like four meter sized mirror enough star
Speaker 1: shade to block out the light from the stars, and
Speaker 1: it's going to help us understand where are the planets
Speaker 1: in the galaxy? Are they mostly around yellow stars? Are
Speaker 1: they also around red stars? Are they also around the smaller,
Speaker 1: more variable red stars. What's life like over there? That's
Speaker 1: pretty cool. So a big telescope just to look at
Speaker 1: planets might even looking at star. It's just totally dedicated
Speaker 1: to looking four aliens. Basically, it's really amazing technology. This
Speaker 1: thing it has a star shade. This thing that fits
Speaker 1: in front of it floats in space. It's bread from it.
Speaker 1: It's like a two component thing. The second piece is
Speaker 1: just there to block out light from stars. Right, Mostly
Speaker 1: telescopes are focused on stars. This one specifically has a
Speaker 1: blind spot for stars because it wants to see the planets. Cool. Well,
Speaker 1: that will go up in twenty thirty five, and I'm
Speaker 1: sure we'll do an episode when we get to that point.
Speaker 1: If we're still alive, if neither of us are billionaires
Speaker 1: by the end, if an asteroid hasn't hit us, or
Speaker 1: Superma's income, or other aliens wearing their rose colored glasses
Speaker 1: having come to tell us all the secrets of the universe. Well,
Speaker 1: wouldn't they need blue colored glasses. It's a blue flower,
Speaker 1: a violet violet. There you go, violet colored glasses. Let's
Speaker 1: just hope they bring violets and not violence. All right, Well,
Speaker 1: I think this is an interesting question to think about,
Speaker 1: you know. It against kind of makes you wonder how
Speaker 1: rare it is for us to be here, or maybe
Speaker 1: how common it is. Either way, it's kind of a
Speaker 1: fun question to think about. It's all part of this
Speaker 1: journey looking out into the universe and wondering why it
Speaker 1: is the way that it is, and is our corner
Speaker 1: of it weird or not? Yeah? Are we superman or
Speaker 1: are we just regular earth Links? They're never talking about
Speaker 1: what what happens if you go from the yellow sun
Speaker 1: to a red sun? Do you get weaker? Maybe they
Speaker 1: have a comic book where earth Links go to their
Speaker 1: planet and they're called Underman underwear Man. Maybe, well, I
Speaker 1: think no one's already taken Captain Underpants. Every idea is
Speaker 1: out there. Yeah, there you go. Maybe you can go
Speaker 1: back in time. All right, Well, we hope that made
Speaker 1: you think about your life and how likely it is
Speaker 1: for you to be here, and how appreciative we should
Speaker 1: be every time you go outside and feel the warm
Speaker 1: rays of our sun and wonder about those aliens out there.
Speaker 1: Are they also enjoying a yellow star? Or is everything
Speaker 1: on their planet red? Or is what they call red
Speaker 1: actually yellow? Thanks for joining us, See you next time.
Speaker 1: Thanks for listening, and remember that. Daniel and Jorge Explain
Speaker 1: the Universe is a production of iHeartRadio. For more podcasts
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