Speaker 1: Hey, Jorney, Maybe you're not aware of you recently coined
Speaker 1: a word that I now use all the time. Oh yeah,
Speaker 1: I've been in his movies. Know. The word that you
Speaker 1: made up that I really like is the word engineeringly.
Speaker 1: That was pretty a pretty good word. But how do
Speaker 1: you use it in a sentence. Let's say you could say,
Speaker 1: for example, a warp drive is physically possible, but engineeringly impossible.
Speaker 1: That just sounds to me like you need better engineers.
Speaker 1: We definitely need better engineers, and I hope that they're
Speaker 1: out there in our audience listening today because we have
Speaker 1: some engineeringly very challenging projects on the docket. Ye hi,
Speaker 1: am orhammy cartoonists and the creator of PhD comments, Hi,
Speaker 1: I'm Daniel. I'm a particle physicist, and I'm happy to
Speaker 1: put off my problems onto engineers, even your personal problems.
Speaker 1: There does seem to be a proliferation of engineers. You know,
Speaker 1: back in the day that was mechanical electric. You make
Speaker 1: it sound like we're a pest or, but you know,
Speaker 1: now you've got the software engineers, you've got social engineers,
Speaker 1: You've got every kind of engineer. It's crazy. So yeah,
Speaker 1: maybe Daniel's personal problem engineers, I supposed to physicists who
Speaker 1: there's only one kind. There are only a few of us. Yeah,
Speaker 1: that's true. There's like solid state matter, wet matter, dark matter.
Speaker 1: It's been a while since we invented a new kind
Speaker 1: of physicist. Yah, maybe it's time. Maybe it's time. Yeah,
Speaker 1: Daniel's personal problem physicists. I don't think any of my
Speaker 1: personal problems can be solved with physics. That there's learnal
Speaker 1: laws there to be found. But welcome to our podcast.
Speaker 1: Daniel and Jorge explained the Universe State production of Hard Radio,
Speaker 1: in which we focus on the questions that can be answered,
Speaker 1: the questions that might one day in the future be answered,
Speaker 1: questions about how the world works, about what the universe
Speaker 1: is like, how it will end, and how it is
Speaker 1: put together on the smallest scale. Yeah, we love questions,
Speaker 1: and we love questions for which we know the answers
Speaker 1: and we know the question. We love the also questions
Speaker 1: for which we don't know the answers, because there are
Speaker 1: still a lot of questions out there in the universe
Speaker 1: that nobody knows the answer to, and often on this
Speaker 1: podcast we take a tour of some of those questions.
Speaker 1: We show you what's in the mind of scientists at
Speaker 1: the forefront of knowledge is they try to peel back
Speaker 1: a layer of reality and expose the universe as it
Speaker 1: really is. And sometimes we take you on a tour
Speaker 1: of the minds of our listeners, thinking about what everybody
Speaker 1: out there is wondering about. Yeah, and we love taking
Speaker 1: lists questions from listeners because they really sort of give
Speaker 1: us an insight into what people are thinking and what
Speaker 1: they're what our podcast is kind of make them think about.
Speaker 1: That's right, and not just because they give us sort
Speaker 1: of like a checkpoint so that we understand what listeners
Speaker 1: are getting and what they're confused about. But sometimes listeners
Speaker 1: questions really put their finger on something amazing about the universe.
Speaker 1: When I teach, you know, freshman physics here you see Irvine,
Speaker 1: it's when they ask a question that it makes me
Speaker 1: think about a topic in a new way, makes me
Speaker 1: explain in a new way, and then it really makes
Speaker 1: me understand it. So listener questions are really a source
Speaker 1: of insight. Yeah, And let's face it, we have I
Speaker 1: think the best listeners in the universe Daniel Podcast on Earth,
Speaker 1: and I would say in anywhere else in the universe,
Speaker 1: I think we have the best listeners. That's right, And
Speaker 1: we're talking specifically about you. You know who you are.
Speaker 1: We're talking about you right there listening to us right now.
Speaker 1: You're the best. You're our favorite listen. You're the best looking,
Speaker 1: you smell great today, and you ask awesome questions and
Speaker 1: tell my kids that all the time. I'm like, you're
Speaker 1: my favorite daughter, and she's like, I'm your only daughter
Speaker 1: that I know of. Daniel and Jorge dig Into or
Speaker 1: his sort of past. Hey, you know, if this is
Speaker 1: going to be Daniel and Jorge starting to tell a novella,
Speaker 1: then you're going to have some sort of you know,
Speaker 1: other family show up at some point in season seven.
Speaker 1: My evil twin twins genetically the same. Does that mean
Speaker 1: their kids are sort of also like your kids? Boy? Interesting,
Speaker 1: he's had a great listener question. Yeah, Or does that
Speaker 1: mean if you can have, if you can be twins
Speaker 1: and one of you is evil, does that mean that
Speaker 1: evil is not genetic? Or maybe you are evil but
Speaker 1: you do you don't know it. There are no good twins,
Speaker 1: is that what you're saying? Well, they should either both
Speaker 1: be good or both be evil. I'm sure that all
Speaker 1: the twins listening right now are both good? Well, anyways,
Speaker 1: we do have the best listeners and they do ask
Speaker 1: the best questions that they send us through Twitter or
Speaker 1: Facebook or Instagram or by email. And if you're out
Speaker 1: there listening to this podcast and you have a question
Speaker 1: about the universe, you can also write it to us
Speaker 1: and we will eventually get to it on the podcast.
Speaker 1: That's right, And we answer all of our listener emails
Speaker 1: pretty promptly. Sometimes people writing asking a good physics questions.
Speaker 1: Sometimes people writing asking sort of off the wall questions. Uh,
Speaker 1: nobody so far is asking for marriage advice. But here's
Speaker 1: a question we got last week which sort of made
Speaker 1: me chuckle. It's from Gridget saying and here's what he
Speaker 1: had to say. He wrote, if we assume the world
Speaker 1: is a simulation, do you think there's only one conscious
Speaker 1: being and the rest of the world are just biological zombies?
Speaker 1: Or everyone is conscious? I love this question. It's like
Speaker 1: am I playing a video game? Or are we all
Speaker 1: playing a video game together? It's like are you a
Speaker 1: non player? Yeah? Yeah? Or is there somebody really in there? Interesting? Well,
Speaker 1: it just gets to the bottom of consciousness, right, like
Speaker 1: kind of machine be conscious, kind of machine be conscious. Yeah,
Speaker 1: and maybe this guy spends a lot of time in
Speaker 1: video games wondering if those other players are real or not.
Speaker 1: But a fun question, but not one that I, you know,
Speaker 1: necessarily have any expertise or ability to answer. So I
Speaker 1: could pontificate as a physicist, but I think the physicists
Speaker 1: spend too much time talking about things outside their area
Speaker 1: of expertise. So I'm gonna have to point on that one.
Speaker 1: Maybe you've noticed that what if? What if you're playing
Speaker 1: a bit of games where you have to kill zombies,
Speaker 1: then technically are those zombies? But are those zombies conscious?
Speaker 1: But they can't because there's zombies? Yeah, well you could
Speaker 1: be committing digital moral crimes. But we love answering listener
Speaker 1: questions and sometimes we have episodes where we ask to them,
Speaker 1: and so today is what are those episodes? So today
Speaker 1: on the program, we'll be tackling listener questions about the universe.
Speaker 1: That's right. We'll be touching on exotic matter, will be
Speaker 1: building roads that span the Earth, and we'll take our
Speaker 1: minds to other galaxies and wondering what life is like
Speaker 1: out there aliens. Basically, we're feel I feel like we
Speaker 1: can have a listener questions episode without touching the hitting
Speaker 1: the alien button. Are you saying that's because our listeners
Speaker 1: are fascinated with aliens? Are you suspecting that I'm picking
Speaker 1: the alien questions out of the slush pile. I feel
Speaker 1: like there's a Van diagram there listener questions and things
Speaker 1: Daniel loves to talk about. If you have a question
Speaker 1: about anything, dear listeners, just put the word alien in
Speaker 1: it and it will increase your chances that we'll talk
Speaker 1: about it. That's fair, that's good advice. Yea, I have
Speaker 1: a question about dark matter. Just wonder if dark about
Speaker 1: her could be made by aliens? And well, I'm sure
Speaker 1: we'll consider it. My kids know that already. They're like, hey, Dad,
Speaker 1: can I have ten bucks? It's for aliens? Yeah, sure,
Speaker 1: here we go. All right, So today we have three
Speaker 1: questions from listeners from all around the world, and so
Speaker 1: we'll be tackling each of these questions one by one.
Speaker 1: And so the first question comes from Maria from Canada
Speaker 1: and she has a question about exotic matter. Here's your question. Hi,
Speaker 1: Daniel and Jorgey. My name is Maria and I'm a
Speaker 1: listen from Victoria, Canada and I was wondering what's exotic matter,
Speaker 1: how is it different from dark matter or antimatter? And
Speaker 1: how many different kinds of matter even are there? Anyways,
Speaker 1: thank you so much, awesome questions. I feel like she's
Speaker 1: sort of get throwing little shaded physicists. I felt that,
Speaker 1: I felt that shade, like, hey, get this under control,
Speaker 1: Like people are ridiculous, Yeah, that this matter naming is
Speaker 1: getting out of control. It's we have as many kinds
Speaker 1: of matter as there are like fields of engineering, and
Speaker 1: that's absurd. We we need a new feel for every
Speaker 1: kind of matter you guys come up with. So it's
Speaker 1: not our fault. We need exotic physics and exotic physicists.
Speaker 1: We're just trying to plug the holes of physicist are creedive.
Speaker 1: Thank you, by the way for your tireless work plugging
Speaker 1: our holes. We just need to have a lot of
Speaker 1: kinds of matter in our universe. There's, for example, baryonic matter, antimatter,
Speaker 1: dark matter, exotic matter, supersymmetric matter. Yeah. Yeah, the list
Speaker 1: goes on. And this is a totally great question, and
Speaker 1: it's a fair question also because this term is used
Speaker 1: in lots of different ways. In a very general way,
Speaker 1: people use the phrase exotic matter to me literally, just
Speaker 1: that like matter that seems kind of weird, like exotic,
Speaker 1: something different from the every day you know, the everyday
Speaker 1: matter is made of quarks and electrons, and so from
Speaker 1: that definition, exotic matter could be like dark matter, you know,
Speaker 1: or other weird stuff that's out there. Oh boy, now
Speaker 1: you're just making it worse, Daniel. Now you're like overlapping
Speaker 1: all these matter designations. We're not great at that. In
Speaker 1: particle physics, you know, matter could just be any matter
Speaker 1: that is against something. Yeah, it could be. So it's
Speaker 1: it's a different opinion. It's a very vague tournament. And
Speaker 1: it could even be weird forms of familiar matter. Like
Speaker 1: if you take atoms and you cool them down and
Speaker 1: make weird quantum states like Bose Einstein condensates, some people
Speaker 1: would call that exotic matter. Or if you make super fluids,
Speaker 1: you could call that exotic matter. Well, well, let's take
Speaker 1: it's a step back here. You're saying that the word
Speaker 1: exotic matter is not well defined in physics. Yeah, if
Speaker 1: you just google what is exotic matter? For example, you
Speaker 1: will see articles physicists discover exotic matter, but then it
Speaker 1: turns out it's actually about super fluids, or physicists use
Speaker 1: exotic matter to communicate quantum mechanically and then it turns
Speaker 1: out it's just bosion stain content. States m hmmm. So
Speaker 1: you're saying, just like in our culture, the word exotic
Speaker 1: is sort of outdated and inappropriate. Yeah, it's a little bit.
Speaker 1: It's been a bit abused. But there is also sort
Speaker 1: of a narrower version of exotic matter that has a
Speaker 1: very specific, fascinating meeting in particle physics that I think
Speaker 1: we could dig into. Oh I see, all right, So
Speaker 1: in general, it can just mean any kind of non
Speaker 1: normal matter, weird, spooky Halloween matter in the loose sort
Speaker 1: of definition of yes, spooky Halloween matter, or you know
Speaker 1: matter from the Orient, which is that racist. Yeah yeah, yeah,
Speaker 1: extern centric and but um no, you're saying, and in
Speaker 1: general sense it just means weird matter. But there's also
Speaker 1: sort of maybe a hardcore group of physicists who are like, hey,
Speaker 1: this means something very specific. Yeah, they rock out the
Speaker 1: heavy metal and they talk about this kind of matter.
Speaker 1: They are hardcore, and that's matter with negative mass. So
Speaker 1: in particle physics we talk about exotic particles or exotic
Speaker 1: matter and what we mean are particles that have negative mass,
Speaker 1: Like you know that mass is something we attached to particles,
Speaker 1: and I have mass and you have mass, And a
Speaker 1: fascinating thing about mass is that it seems to always
Speaker 1: be positive. So we've invented this idea. Maybe there are
Speaker 1: particles out there with the other kind of mass and
Speaker 1: negative kind of mass. Mm hmmm, because right, because mass
Speaker 1: is just kind of a label, right, it's not actually
Speaker 1: like stuff. It's just kind of a like an electric
Speaker 1: charge can be positive or negative. Yeah, we don't really
Speaker 1: understand it. And if you zoom down to an individual particle,
Speaker 1: particles have no volume. They're just points and base with labels, right,
Speaker 1: like electric charges, you said, And mass is another property,
Speaker 1: and mass is a property that these particles get from
Speaker 1: interaction with the Higgs field. But the fascinating thing about
Speaker 1: mass is that it always seems to be positive. Right.
Speaker 1: We measure the mass of all of these particles and
Speaker 1: we see that they have positive mass, and that has
Speaker 1: fascinating consequences because the Higgs field always gives these particles
Speaker 1: positive mass, or like the interaction is always positive, like
Speaker 1: I has anyone had a bad experience with the Higgs field?
Speaker 1: I guess it only has five star reviews on Yelp.
Speaker 1: So yeah, in the Higgs field widely loved, would recommend yes,
Speaker 1: Higgs field good. Um, But did you know what I mean? Like,
Speaker 1: if something has negative masses, that mean that when it
Speaker 1: interacts with the Higgs field it gets the negative mass
Speaker 1: or what does that mean? Well, if a particle had
Speaker 1: negative mass, we don't know how it would get that mass.
Speaker 1: One way to get mass is to interact with the
Speaker 1: Higgs field. We think there might be other ways for
Speaker 1: particles to get mass too, but we've never seen one
Speaker 1: like that, So there could be various ways for articles
Speaker 1: to get mass. It doesn't just have to be the
Speaker 1: Higgs field. The Higgs field just kind of determs how
Speaker 1: it moves in the universe. Right, But you can still
Speaker 1: have mass independent of the Higgs field. Yes, you can
Speaker 1: get mass without getting it from the Higgs field. We
Speaker 1: haven't ever done that, but like, we don't know neutrinos,
Speaker 1: do they get mass from the Higgs field or not?
Speaker 1: Do they get mass in this other weird way And
Speaker 1: we can dive into that and a whole other podcast,
Speaker 1: But I think the important concept to remember is what
Speaker 1: you just said is that it changes how you move
Speaker 1: through the universe. Often, when we talk about mass, we
Speaker 1: really mean two different things. One is inertia, like you
Speaker 1: give something a push. It takes a push to move something,
Speaker 1: to change something's momentum, to get it started, takes a push.
Speaker 1: We call that inertia. Really, that's mass, right, and that
Speaker 1: comes from the formula F equals M. A force is
Speaker 1: mass times acceleration. To accelerate something, you have to apply
Speaker 1: a force, and the mass is the relationship between those two.
Speaker 1: So that's mass. Concept Number one is inertial methods. How
Speaker 1: hard it is to push? Yeah, how hard is it
Speaker 1: to push to get it going? And also how hard
Speaker 1: is it to slow it down? Like a semi truck
Speaker 1: has a huge amount of mass, takes a huge force
Speaker 1: to slow it down. Can something have negative inertial mass?
Speaker 1: Is that possible where you like, you push it and
Speaker 1: it goes faster, or you know, like it pushed you
Speaker 1: push it and it actually pulls you or something, and
Speaker 1: you know what, that's what would happen if you gave
Speaker 1: it a push to the left and it had negative
Speaker 1: inertial mass, it would move to the right, it would
Speaker 1: push you, push you back. Yeah, so the force would
Speaker 1: be the opposite direction of the acceleration. So the weird
Speaker 1: thing about negative mass is like, it seems weird. It's
Speaker 1: totally counterintuitive, but mathematically it kind of hangs together, like
Speaker 1: we don't have a reason to believe it doesn't exist.
Speaker 1: You could fit it into all of our equations. We've
Speaker 1: just never seen an example of it. That kind of
Speaker 1: weird example could happen where you like push it one
Speaker 1: way with the with the force field or something, but
Speaker 1: it goes the other way. Yeah, you could do that
Speaker 1: in theory. It's possible. We've never seen it, but you
Speaker 1: can work out all the equations of motion and it works.
Speaker 1: So you push into the left and it moves to
Speaker 1: the right. But that's only one way of thinking about mass.
Speaker 1: Is a whole second concept of mass, which is mass
Speaker 1: in gravity. Like two objects that have mass feel gravity
Speaker 1: and attract each other. So so if something has negative mass,
Speaker 1: it could maybe repel another thing, would mass. Yeah, the
Speaker 1: fascinating thing about positive mass and gravity is that gravity
Speaker 1: is one of the only forces that so far seems
Speaker 1: to be just attractive. Right, you get pulled in by
Speaker 1: the sun, you get pulled in by the moon. There's
Speaker 1: no way, you get pushed by gravity, whereas like electromagnetism,
Speaker 1: there's a positive and negativity, and if you have the
Speaker 1: same charges you get repelled and gravity it is only
Speaker 1: positive and it seems to only be attractive. So if
Speaker 1: you add negative mass, then yeah, you could get repulsive gravity.
Speaker 1: Or I guess maybe in like the Einstein space bending picture,
Speaker 1: it would be sort of bend space the other way. Yeah,
Speaker 1: instead of having like a dent down into space, it
Speaker 1: would be like a like an explosion of space a
Speaker 1: little bit. So things like slide away from you like
Speaker 1: a z in space, like a like a bump a space.
Speaker 1: Don't pop at ZiT. That's like a gravity bomb. Yeah,
Speaker 1: you have a negative experience. Don't do it. It's weird though,
Speaker 1: because this is a little counterintuitive. You know that positive
Speaker 1: mass of course attracts other positive mass. It would also
Speaker 1: attract negative mass, and negative mass would repel negative mass
Speaker 1: and also positive masses. Wait what, it wouldn't be like
Speaker 1: electrical charges. It's not like electrical charges because you just
Speaker 1: said that. We don't think of gravity as a force.
Speaker 1: We think as a bending of space. So positive mass
Speaker 1: makes like a dent in space like a whole in
Speaker 1: space for things to fall into regardless of their mass,
Speaker 1: and negative masses make space zits. That was actually Einstein's term,
Speaker 1: and is it z it's their spation and now that's
Speaker 1: a joke. But a negative mass make these would make
Speaker 1: these like you know, or I'm gonna say zits in
Speaker 1: space because regardless of the mass of the other thing. Right, So,
Speaker 1: positive masses attract other positive or negative masses, and negative
Speaker 1: masses repel negative or positive masses. It's like the opposite
Speaker 1: of a black hole. Yeah, and it's weirdly sort of asymmetric, right.
Speaker 1: You like to think about the forces as being symmetric,
Speaker 1: so like it depends on the product of the charges
Speaker 1: or something, but it wouldn't be. And that means if
Speaker 1: you have like a positive mass and a negative mass
Speaker 1: next to each other, then the positive masses pulling on
Speaker 1: the negative mass, but the negative mass is pushing on
Speaker 1: the positive mass. Um what would happen? They would actually
Speaker 1: just like lead to this runaway motion because the positive
Speaker 1: masses pulling on the negative the negative is trying to
Speaker 1: repel the positive. Attraction of the negative actually pushes the
Speaker 1: other direction, right because of negative and inertial mass, And
Speaker 1: it would just skip out of town. Let's skip out
Speaker 1: of town for real. Well, we don't know, Like this
Speaker 1: is the idea, so we've never seen this stuff. It's
Speaker 1: just sort of an idea, and and it would be
Speaker 1: pretty helpful because if we did have exotic mass, we
Speaker 1: could use it to, for example, stabilize wormholes and travel
Speaker 1: through the galaxy and this kind of stuff. But we've
Speaker 1: never seen any of it. It's just sort of like, yeah,
Speaker 1: I guess that's in the lad. The next question, which
Speaker 1: is is this even real or is it just theoretical.
Speaker 1: It's just theoretical, but it's important to recognize these sort
Speaker 1: of theoretical opportunities. Some of these other kinds of matter
Speaker 1: we talked about, like antimatter. They started out it's theoretical,
Speaker 1: and somebody noticed, hey, the equations also work if you
Speaker 1: flip all these signs and make this other weird kind
Speaker 1: of matter. So maybe that's real, and it turns out
Speaker 1: it's true. So seeing these mathematical symmetries are often guides
Speaker 1: actually binding stuff in reality, and that will tell us
Speaker 1: more about the universe. Yeah, but the universe is asymmetric sometimes,
Speaker 1: like there's a lot of matter out there, very very
Speaker 1: little antimatter, if any. We don't know why that is.
Speaker 1: So there's a lot of positive matter out there, none
Speaker 1: or maybe very little negative matter. Why is that right?
Speaker 1: Fascinating questions? Yeah, maybe not all the matter matters. All
Speaker 1: matter matters, man, but all right, so, um, it seems
Speaker 1: like to answer Maria's question, exotic matter. Um can mean
Speaker 1: a lot of things, but it generally it's terribly used
Speaker 1: just to me, like not normal matter, meaning the matter
Speaker 1: you and I are made out of. It's kind of
Speaker 1: weird or unusual. Some physicists call that exotic matter. But
Speaker 1: there's also sort of the hardcore definition, which is that
Speaker 1: it means matter with negative mass, which is theoretically fascinating,
Speaker 1: totally possible, but never been seen. But you know, she
Speaker 1: also asked another question, which is how many different kinds
Speaker 1: of matter are there? Anyway? And that's such a good question.
Speaker 1: It's a question that I have also because we see
Speaker 1: these symmetries in nature. We see like, oh, there's matter
Speaker 1: and antimatter, there's maybe positive matter and negative mass matter,
Speaker 1: and there's other symmetries like we talked about supersymmetry on
Speaker 1: this program, like maybe every spin half particle has a
Speaker 1: spin one particle that that balances it, and vice versa,
Speaker 1: and all these symmetries tell us something deep about the universe,
Speaker 1: about the way it's put together, about what it reflects
Speaker 1: that its deepest level, And we don't know what the
Speaker 1: answers are. But every time we find a symmetry, I
Speaker 1: feel like it's revealed something about the universe that we've
Speaker 1: been desperate to find out. Every time you find a
Speaker 1: new kind of matter or think up but you kind
Speaker 1: of matter, it kind of pushes your definition of what
Speaker 1: can exist. Yeah, and these symmetries are really important. You know.
Speaker 1: We talked also on this program about how the universe
Speaker 1: is left handed. It prefers particles that spin in a
Speaker 1: certain way relative to their motion. We don't know why
Speaker 1: that is, and so people suggested and maybe there's another
Speaker 1: kind of matter called mirror matter, where it's the opposite.
Speaker 1: And every time you have these symmetries, you have to ask,
Speaker 1: why is it this way and not the other way?
Speaker 1: Why is the universe sort of by furcated into two options.
Speaker 1: What does that mean about the nature of the universe
Speaker 1: At some higher temperature earlier in the universe, was this
Speaker 1: all unified into something beautiful? And crystalline, and then it's
Speaker 1: just sort of cracked and fell apart. We don't know.
Speaker 1: I think my favorite kind of matter are the matters
Speaker 1: of the heart. Daniel. All right, well, we hope that
Speaker 1: answered your question, Maria, thanks so much for asking the question.
Speaker 1: And so let's get into our two other questions for
Speaker 1: the episode, and these are about the biggest road ever
Speaker 1: built and also about intergalactic aliens. But first let's take
Speaker 1: a quick break. Alright, we're answering listener questions today. Answer
Speaker 1: Our next question comes from Rahul from India, and so
Speaker 1: he has a question about an interesting idea for an
Speaker 1: infinite road. Here is so, imagine you start building a
Speaker 1: bridge or a highway above the surface, and it goes
Speaker 1: all the way around the earth and meets each other.
Speaker 1: Now you have this one long, continuous bridge. So obviously
Speaker 1: those bridges have pillars, and now you decide to bomb
Speaker 1: all the pillars that supposed the bridge at the same
Speaker 1: exact time. So what would happen to the bridge? Will
Speaker 1: it stay floating above the surface or will it fall down?
Speaker 1: And at which direction? Or will it hoholla hoop the earth?
Speaker 1: And the second condition is what would happen if the
Speaker 1: Earth was perfect sphere. So I think this one might
Speaker 1: be more in your alley because it's kind of a
Speaker 1: question about, you know, whether something is engineeringly possible. You're like,
Speaker 1: this is not interesting to me, or hey, you can
Speaker 1: take this one. It's just about building a road. Now,
Speaker 1: if aliens built a road, that's just positive that. Let's
Speaker 1: just let's imagine we're in an alien planet. But the
Speaker 1: question is kind of interesting, and I have to say
Speaker 1: it took me a second to sort of get it.
Speaker 1: So he's he's asking, what if you build a road
Speaker 1: all around the Earth, like a suspended road, right, and
Speaker 1: it goes you know, from it starts here in California,
Speaker 1: goes through the US, crosses the Atlantic, goes over Europe Asia,
Speaker 1: and then it comes back around and connects in a
Speaker 1: perfect circle to where we started the road. And then
Speaker 1: so you build this road, it rings the earth and
Speaker 1: then you take out all the columns, the pillars that
Speaker 1: supported simultaneously with bombs. Right. I like that detail. Yeah,
Speaker 1: that would probably the funnest part actually, But you remove
Speaker 1: the pillars, all of a sudden, does the bridge stay
Speaker 1: up floating or does it all fall down? Yeah, And
Speaker 1: it's a fun question because you imagine you build a road,
Speaker 1: you support it with pillars, you knock the pillars down,
Speaker 1: the road falls down. But in this scenario, you've made
Speaker 1: it go all the way around the earth. And so
Speaker 1: then he's wondering, like, is it possible for a road
Speaker 1: to float in the air? Would it be in orbit, Daniel?
Speaker 1: Would it just be sort of like a pula who
Speaker 1: held around your waist. Let's answer this from a physics
Speaker 1: point of view, which means we have to like simplify
Speaker 1: things a little bit, and then we'll make it a
Speaker 1: bit more practical. So first let's start with the let's
Speaker 1: hear answer A from Daniel. First, is a perfectly spherical earth,
Speaker 1: like very smooth, no deformities, etcetera. And so the road
Speaker 1: is like a hundred meters or a hundred feet or
Speaker 1: whatever above the surface all the way around the Earth.
Speaker 1: Now that scenario you knock out all the pillars. Think
Speaker 1: about the gravitational force on this thing. It's going to
Speaker 1: be balanced, Like the Earth is pulling on one part
Speaker 1: over California, but it's also pulling on another part over China,
Speaker 1: and those two things are going to balance. And if
Speaker 1: the road really goes all the way around the Earth.
Speaker 1: Then for every part of the road there's a counterpart
Speaker 1: that's balancing its force, and so it should just hover there.
Speaker 1: So that's your answer that it would stay up floating.
Speaker 1: If it's a perfectly spherical Earth and a perfectly circular road,
Speaker 1: it would stay up there floating. You don't believe it, well, Um,
Speaker 1: so I have an engineering answer, but I'll just keep
Speaker 1: going with your physics answer here for a bid. The
Speaker 1: other way to think about it, it's just by symmetry,
Speaker 1: like if it goes in one direction, which direction could
Speaker 1: it go? You have to choose a direction, And if
Speaker 1: the Earth is a perfect sphere, then there's no preferred direction,
Speaker 1: so it can't go in anywhere any direction. So it
Speaker 1: would keep rotating with the Earth. It would keep rotating
Speaker 1: with the Earth, Yes, but it wouldn't have to rotate either.
Speaker 1: What if something knocks it off of alignment a little bit,
Speaker 1: Like what if the wind blows an in on one
Speaker 1: side of the Earth and not the other, and now
Speaker 1: it's a little bit closer to one side than it
Speaker 1: is to the other side of the Earth. Yeah, so
Speaker 1: we're leaving the world of perfect physics scenario and we're
Speaker 1: adding things like wind and disturbances, And you're right that
Speaker 1: it would be very unstable because if it moves like
Speaker 1: one foot closer to the Earth here, then so I'll
Speaker 1: foot further from the Earth on the other side. So
Speaker 1: now the force is stronger on this side and weaker
Speaker 1: on the other side. So it's unstable. It's when does
Speaker 1: it deviates from this sort of like perfect spot it's in,
Speaker 1: it's going to come crashing down. Oh, I see it
Speaker 1: moves a little bit, and so now let's say it
Speaker 1: moves down here in California, so it's closer to the Earth,
Speaker 1: and now the center of the mass of the whole
Speaker 1: thing is a line with the center of the Earth.
Speaker 1: Wouldn't that just make it come back to the center
Speaker 1: of the earth realign I'm pretty sure it's unstable. And
Speaker 1: the reason is that the mass of the Earth is
Speaker 1: distributed as a function of the radius. So you can't
Speaker 1: just think of the motion of the center of massive
Speaker 1: two objects. These are two large distributed objects, and as
Speaker 1: one side of it gets closer to the Earth and
Speaker 1: the other side gets further that you're gonna get a
Speaker 1: relative force difference on the whole thing that's going to
Speaker 1: push it further from stability instead of closer to stability.
Speaker 1: But I haven't done the simulations. So maybe we should
Speaker 1: actually build this thing and find out to answer the
Speaker 1: Rahul's question. Let's spend a trillion dollars. Why not? You
Speaker 1: got something better to spend it on. So it sounds
Speaker 1: like a plan. Let's crowdsource it. Everybody's send in ten
Speaker 1: bucks to build Rahul's road. Okay, So you're saying that
Speaker 1: from a physics point of view, it is possible for
Speaker 1: this thing to exist if nothing touches it or knocks
Speaker 1: it out of bound, or moves it at all a
Speaker 1: little bit, it would just float above the earth, certainly
Speaker 1: the Earth, like a like a ring, like a hula. Yeah,
Speaker 1: And I think the key there is that as soon
Speaker 1: as you build something that's the size of the Earth,
Speaker 1: you can no longer apply the rules of your intuition
Speaker 1: that you apply to things that are the size of you,
Speaker 1: or your house or even your city. Right, Like, things
Speaker 1: can float up in space in orbit. That seems weird.
Speaker 1: Why don't they fall? Right? That's because they're largely moving
Speaker 1: at cosmological astronomical speeds. And so here's an object really
Speaker 1: of astronomical scale, and so it wouldn't necessarily fall into
Speaker 1: the earth. It's like an object that spans both sides
Speaker 1: of the Earth, of the center of mass of something big. Yeah,
Speaker 1: and this actually appears in a novel. I mean, not
Speaker 1: as a road, but in Neil Stevenson's recent novel seventives.
Speaker 1: Earth becomes uninhabitable because of X y Z plot devices
Speaker 1: that won't spoil, and humanity builds a huge ring around
Speaker 1: the Earth, like a mechanical ring, and actually live on it. Well,
Speaker 1: that that, I think that's the physic times for I guess,
Speaker 1: you know, as an engineer, when I saw this question,
Speaker 1: I didn't, you know, sit down and make the calculations,
Speaker 1: but I think right away my thought was that no,
Speaker 1: it would it would fall apart right away. You mean,
Speaker 1: because you couldn't build something that big, that was rigid.
Speaker 1: I think I was thinking, you know, the limitations of
Speaker 1: whatever you build it out of, you know, would collapse
Speaker 1: like nothing. I don't think anything that we know of
Speaker 1: can withstand those kinds of forces, and so we just
Speaker 1: crack and fall apart. You mean, forces from like an
Speaker 1: entire four thousand mile road segment pulling on individual piece. Yeah,
Speaker 1: you know, like there's a reason you can't just make
Speaker 1: a suspended bridge without any columns. Like if this was possible,
Speaker 1: then you could just build a bridge, and if you
Speaker 1: make it the curvature of the Earth, then it would
Speaker 1: just stay up, wouldn't it if we just hold both ends. Yeah? Well, uh,
Speaker 1: not an expert on mechanical engineering, So I'll take your
Speaker 1: word for it that I think you're right, And I
Speaker 1: think there are also other practical issues also, you know,
Speaker 1: like you have to have it at the same height
Speaker 1: above the earth all the way around, but of course
Speaker 1: there isn't a constant height above the earth. You know,
Speaker 1: you have to clear mountains and all sorts of stuff,
Speaker 1: and so that would throw the whole thing off balance.
Speaker 1: All right, Well, I think that's maybe whose question answer,
Speaker 1: which is that it's sort of would be possible, and
Speaker 1: it would hang there floating above the earth if nothing
Speaker 1: touched it or nothing perturbed it at all, no weather,
Speaker 1: and if it was made from like this incredible material
Speaker 1: that that would would stand these incredible forces, which um,
Speaker 1: I'm not sure we have. That we definitely don't, because
Speaker 1: if we did, we could build a space elevator, which
Speaker 1: is sort of weird. And similar ways, something hanging out
Speaker 1: there in space you can actually climb up. And one
Speaker 1: of the limitations there is just building a rope. They
Speaker 1: could even hang That's that that is that long? Right? Yeah,
Speaker 1: something I can that wouldn't just crack under under all
Speaker 1: those forces. It's under but definitely cool and fun to
Speaker 1: think about. Thanks for Hull for sending in your crazy question. Alright,
Speaker 1: are we ready to talk about aliens? Because I'm ready,
Speaker 1: You're always ready, Daniel. All right, let's talk about aliens,
Speaker 1: but first let's take a quick break. Al Right. Our
Speaker 1: last question comes from Nanu from Argentina, and she has
Speaker 1: a question about life from other galaxies. So here's Nanu.
Speaker 1: Why wouldn't we talk about life in other planets? Do
Speaker 1: we always talk about it in terms of our own galaxy?
Speaker 1: Do we not consider life in other galaxies because they're
Speaker 1: so far away it would be inconsequential for us. I
Speaker 1: still have hard time figuring out distances, So I am
Speaker 1: wondering could it be possible for millions of years old
Speaker 1: alien race to take up into galactic trouble and arrive
Speaker 1: to our own galaxy? All right, Daniel, did you just
Speaker 1: get really excited when you opened up your in Boston
Speaker 1: saw this question. Your hearts start racing a little bit.
Speaker 1: You get excited. I got excited, and then I got
Speaker 1: a little offended. You know. She said, what do you mean? Well,
Speaker 1: she said, how can we never think about intergalactic aliens?
Speaker 1: And I was like, what are you talking about? I
Speaker 1: think about intergalactic aliens all the time, and it's one
Speaker 1: of my favorite things to think about. I think maybe
Speaker 1: she thinks she's talking culturally, the culture and in general
Speaker 1: or responsible scientists rarely talk about intergalactic aliens. Yeah, I guess,
Speaker 1: and it's that true. Do I guess? Do most people
Speaker 1: think of aliens is coming from this galaxy? I think so.
Speaker 1: Even in science fiction, often the drama takes place across
Speaker 1: the galaxy or in one galaxy. And there's a reason
Speaker 1: for that. The reason is that galaxies are huge, right there,
Speaker 1: big enough to span enormous space operas and lots of
Speaker 1: different empires and thousands and billions of stars. Plus they're
Speaker 1: super far apart, so it's like each galaxy is an
Speaker 1: island and all the other galaxies they're so far away
Speaker 1: they're almost irrelevant. It's almost impossible to think about communications
Speaker 1: between galaxies, or to travel between galaxies, or travel between galaxies.
Speaker 1: You know, not to mention like intergalactic marriages. You know
Speaker 1: all the problems that would raise a long distance I know,
Speaker 1: you've got the kids over there for one weekend. I
Speaker 1: got the kids over here for another weekend. It's a nightmare.
Speaker 1: But let's give them a sense of scale, right, Like
Speaker 1: the Milky Way is like a hundred thousand light years across.
Speaker 1: That's already like, it's incredibly big. Even if you were
Speaker 1: going at the speed of light, it would take you
Speaker 1: a hundred thousand years, Yeah, to go from one end
Speaker 1: to the other. Yeah, exactly. So it's hard to even
Speaker 1: imagine having like an empire that spans the galaxy because
Speaker 1: you send people a message like all right, let's raise
Speaker 1: taxes one percent, and it doesn't get there for a
Speaker 1: hundred thousand years. It's impossible to coordinate. That's why people invent,
Speaker 1: you know, faster and light travel and faster than light
Speaker 1: communication just to get stuff done within one galaxy in
Speaker 1: novels and movies and hopefully one day in reality, but yes,
Speaker 1: mostly novels and movies. Yes, you seem to mention it
Speaker 1: like because we had, we already have that. People are
Speaker 1: working on it. People are working on it. Hey, we
Speaker 1: were talking about wormholes a minute ago, right, So yeah,
Speaker 1: but you were saying, so the galaxy at typeople of
Speaker 1: galaxy is a hundred thousand light years wide, and but
Speaker 1: the distance between galaxies is you know, many times that
Speaker 1: over by several orders of magnitude. Yeah, like the nearest
Speaker 1: galaxies Andromeda, and that's two and a half million light
Speaker 1: years away, right, it's and a half million years light
Speaker 1: years years. It's twenty five times as why is the
Speaker 1: whole galaxy? It's like if you have a house and
Speaker 1: the neighbor's house is like, you know, blocks and blocks
Speaker 1: away from you. So we're basically living in the middle
Speaker 1: of the woods. So maybe that would explain why we
Speaker 1: don't see it much in movies and novels because you know,
Speaker 1: the plot logistics, which is be too much but um,
Speaker 1: and also I think maybe it's also kind of recent.
Speaker 1: You know, this idea that there are other galaxies. It's
Speaker 1: kind of new, isn't it In the last fifty to
Speaker 1: sixty years or something like that. Before that we thought
Speaker 1: like our galaxy was it. Yeah, it's about a hundred
Speaker 1: years old. It originates with Hubble. He's the guy who
Speaker 1: measured how far away these little smudges in the sky
Speaker 1: where he thought maybe they were nebula, they were gas clouds.
Speaker 1: He measured their distance and found that they were crazy
Speaker 1: far away. They were further away than all the other stars.
Speaker 1: And that's what made him realize, oh, these are other galaxies,
Speaker 1: and the whole universe just became much bigger in his mind.
Speaker 1: So you're right. It's but we've had about a hundred
Speaker 1: years to get used to this idea that the universe
Speaker 1: is incredibly vast, but we haven't sort of mentally populated
Speaker 1: it with aliens. And I think you're right. And one
Speaker 1: reason is that they're just so far away it seems
Speaker 1: almost irrelevant. We may never hear from them, or see
Speaker 1: them or visit them. We may never that's true, but
Speaker 1: we can still think about them. And I think a
Speaker 1: really fun angle on this question is wondering, like is
Speaker 1: life more likely to occur in those galaxies or in hours?
Speaker 1: Is our galaxy unus usual? The same way we think
Speaker 1: about is our solar system unusual in our galaxy? We
Speaker 1: can ask is our galaxy unusual in the universe for
Speaker 1: us to have developed here or evolved here? Like maybe
Speaker 1: um most like maybe all other galaxies are too dangerous
Speaker 1: for life to evolved in. Yeah, maybe we're in a
Speaker 1: special place, right, or maybe we're in a totally vanilla galaxy,
Speaker 1: and so we do know something about that, right. We
Speaker 1: know that the Milky Way is a spiral galaxy, and
Speaker 1: spiral galaxies are one of the most common kinds of galaxies.
Speaker 1: We look out in the sky, we see lots and
Speaker 1: lots of spiral galaxies. So there doesn't seem to be
Speaker 1: anything particularly weird about our galaxy. It's not the smallest,
Speaker 1: it's not the biggest, it's not the brightest or the darkest.
Speaker 1: It has dark matter like other galaxies. So it's sort
Speaker 1: of a generic galaxy. I mean, I love it. It's beautiful. Um,
Speaker 1: I don't mean generic in a bad way. I mean
Speaker 1: the generic in a totally vanilla way, by which I
Speaker 1: mean that there's possibilities for life in other galaxies the
Speaker 1: same way there is here. I wish you may And
Speaker 1: it's the example by which all other galaxies are sparring too.
Speaker 1: I mean, it's the role model galaxy. It's the exemplary
Speaker 1: galaxy excisely, and it means that if there's life here,
Speaker 1: there's no reason to believe there couldn't also be life
Speaker 1: in those other galaxies? But could we able to find it?
Speaker 1: Could we ever communicate with them? Could we ever shake
Speaker 1: hands and spend time at a chalkboard, you know, revealing
Speaker 1: secrets of the universe together. Oh boy, that's hard to imagine.
Speaker 1: But but maybe not that hard to imagine. I mean,
Speaker 1: if we can imagine us contacting aliens within this galaxy,
Speaker 1: you know, them crossing the large amount of space between
Speaker 1: us and them. You know, it's not that hard to
Speaker 1: imagine doing that twenty times over to do it between galaxies. Right,
Speaker 1: you won't drive an hour down here to Irvine to
Speaker 1: hang out with me, but you'll drive twenty hours somewhere.
Speaker 1: Is that you're saying. I'm saying if I really wanted
Speaker 1: to see you, the difference between one hour and twenty
Speaker 1: five hours wouldn't be because if I was an alien,
Speaker 1: then you would drive twenty five hours to come back
Speaker 1: to me. If it took twenty five seconds to go
Speaker 1: see Daniel, I don't know if I still would. Oh no,
Speaker 1: it's a good point. Um. You're right that if we're
Speaker 1: going to explore our galaxy, we either need to do
Speaker 1: it very very slowly, over sillions of years, or figure
Speaker 1: out a way to overcome these distances which are already
Speaker 1: an obstacle in our galaxy. And once we do that,
Speaker 1: then maybe we could also hop to nearby galaxies. Yeah, right,
Speaker 1: Like if you invent or you figure out how to
Speaker 1: do wormholes or warp draws or suspended animation, what's the
Speaker 1: difference between a year and twenty five years to go
Speaker 1: to another galaxy? That's true. And you know, while we're
Speaker 1: tossing our ridiculous ideas, remember our recent episode about stellar engines.
Speaker 1: We could drive the Sun out of the Milky Way
Speaker 1: and go visit another galaxy. We could like move galaxies
Speaker 1: and go hang out in Andromeda. All right, Well, to
Speaker 1: answer no question, I guess the answer is, we don't know.
Speaker 1: We don't know why we don't think about any for
Speaker 1: another galaxy, but maybe we should because it's not that
Speaker 1: far off from aliens in our own galaxy. Yeah, and
Speaker 1: it's true, none new that in millions of years, alien
Speaker 1: racist could use intergalactic travel to to come here and
Speaker 1: tell us all about what it's like to live in
Speaker 1: another galaxy. And they'd be like, whoa, this is a
Speaker 1: better galaxy. You're right, it has better reviews. I'm yelled.
Speaker 1: So thank you to everybody for writing in those amazing questions,
Speaker 1: and thank you to everybody else who's writing in questions
Speaker 1: on a daily basis. We'll get to your questions as well,
Speaker 1: and if you have a question, feel free to send
Speaker 1: to us. Daniel likes to sit around and answer questions.
Speaker 1: I like to be distracted from my real job by
Speaker 1: thinking about your crazy ideas about physics. So thanks for listening.
Speaker 1: We hope you enjoyed that. See you next time. If
Speaker 1: you still have a question after listening to all these explanations,
Speaker 1: please drop us a line. We'd love to hear from you.
Speaker 1: You can find us on Facebook, Twitter, and Instagram at
Speaker 1: Daniel and Jorge That's one word, or email us at
Speaker 1: feed act at Daniel and Jorge dot com. Thanks for listening,
Speaker 1: and remember that Daniel and Jorge Explain the Universe is
Speaker 1: a production of I Heart Radio. For more podcast from
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