Speaker 1: Have you ever wanted to travel to a distant star
Speaker 1: or to a planet orbiting another sun all the time? However,
Speaker 1: I've heard that it's impossible. Yeah. The problem is that
Speaker 1: the universe is just so big and it comes with
Speaker 1: it's built in speed limit makes it pretty tough. So
Speaker 1: that means that we'll never build a spaceship that will
Speaker 1: get us to another star within the span of a
Speaker 1: human left time. That's almost true. It's almost a hard
Speaker 1: and fast rule. It turns out there's one or two
Speaker 1: exceptions to that, immortality being frozen like an ice cube. Hello,
Speaker 1: a lot more hand And I'm Daniel and this is
Speaker 1: our podcast Daniel and Jorge explain the universe, where we're
Speaker 1: going to take the whole universe, break it into little
Speaker 1: bits that are bite size, and feed them to you
Speaker 1: one at a time. Today on the program, we are
Speaker 1: going to ask the question, will we ever be able
Speaker 1: to travel faster than the speed of light? Zoom? That's
Speaker 1: the sound it would make if we traveled faster than
Speaker 1: the speed of light. Right there. We're going full throttle
Speaker 1: on this episode. Pedal to the metal, that's right, Pedal
Speaker 1: to the podcast, that's right. And I love this question
Speaker 1: because not only do people like traveling fast, but it
Speaker 1: gives us a sense for like, will we ever be
Speaker 1: able to I feel like the subtext to the question
Speaker 1: is will we ever travel to other stars and get
Speaker 1: to other places in the universe? Because the universe is
Speaker 1: so darn big that it's hard to get places. Right.
Speaker 1: So if we could travel fast in the speed of light,
Speaker 1: we can actually see some cool stuff. Like what's the
Speaker 1: nearest star to us? Oh, man, I should ask Siri,
Speaker 1: but I think it's about four light years away. Okay,
Speaker 1: So even if we're able to go at this peed
Speaker 1: of light, you still have to sit in a spaceship
Speaker 1: for four years to get there. Let's if you could
Speaker 1: travel at the speed of light. Yeah, but there's also
Speaker 1: the question of accelerating to the speed of light, Like
Speaker 1: if you could, if you had a spaceship which could
Speaker 1: get up to the speed of light, it would take
Speaker 1: a long time to get going that fast because, oh,
Speaker 1: just to get to the speed of light, yeah, you
Speaker 1: can't tolerate a huge amount of acceleration, you know, like
Speaker 1: fighter pilots can take like eight or nine g s, right,
Speaker 1: the eight or nine times the acceleration you feel on Earth.
Speaker 1: But squishy people like me, and you get into a jet,
Speaker 1: we can't tolerate, tolerate more than a couple of geese.
Speaker 1: You know, it'd be like being on the craziest roller
Speaker 1: coaster ride for like a year, years just to get
Speaker 1: to the speed of light, just to get to the
Speaker 1: speed of light. Yeah, and if you accelerate faster, you
Speaker 1: would just get smushed against the sea. Yeah, exactly. You'd
Speaker 1: arrived as a puddle of Google. And don't forget you
Speaker 1: have to decelerate also because you don't want to arrive
Speaker 1: someplace going the speed of light. To you'll be traveling
Speaker 1: as a puddle of goo, and you would arrive as
Speaker 1: a splatter of Google on the front. When that's right.
Speaker 1: But hey, if you're public good, it doesn't really matter
Speaker 1: when you arrive, does it. You're not feeling it or
Speaker 1: if you arrive or if you arrive. Yeah, that's why
Speaker 1: in a lot of these awesome science fiction books I've
Speaker 1: been reading, you spend half the trip accelerating and then
Speaker 1: you turn the ship turns around and spends the second
Speaker 1: half the ship decelerating, slowing down because you know, if
Speaker 1: you arrive at your destination going a gazillion miles an hour.
Speaker 1: You just blow right through their solar system. You can't
Speaker 1: even stop or you know, get a smoothie or anything. Okay,
Speaker 1: So the question is is their hope of us ever
Speaker 1: getting to other stars or planets out during the universe?
Speaker 1: Can we ever go faster than the speed of light?
Speaker 1: That's right, So we went around and we asked people
Speaker 1: on the street. Here's what they had to say. I
Speaker 1: do believe that one day we'll be able to travel
Speaker 1: faster than to speak the light. Essentially, yes, I don't
Speaker 1: think so because it's you know, Einstein series, something based
Speaker 1: on nothing, coin Fester p Night someone say no, honestly,
Speaker 1: with like the way technology is going, I do think
Speaker 1: eventually we'll reach the point. Yeah optimistic. Okay, So the
Speaker 1: first thing I find interesting about the responses is that
Speaker 1: everyone has an opinion, you know, like it's like no evidence,
Speaker 1: no theoretical background. They're like I think so, or they're
Speaker 1: like no, I don't think So's everybody feels like technological
Speaker 1: progress is inevitable, Like you can say whatever bar you
Speaker 1: want and eventually we'll get there. Science will figure it out.
Speaker 1: I love that optimism and enthusiasm that like, yeah, scientists
Speaker 1: can do anything. Yeah, Well, think about all the crazy
Speaker 1: things we have been doing, right, Yeah, absolutely, you know,
Speaker 1: like um downloading pictures of cats from the internet. Yeah,
Speaker 1: and then you're able to like change your genome using
Speaker 1: your cell phone or something like that. You want to
Speaker 1: be a ginger, there's an app for that. You want
Speaker 1: to be dial it on your phone? That would oh man,
Speaker 1: swipe right for redhead taller. Well, I think we're spinning
Speaker 1: off ideas for science fiction novels here, But I love
Speaker 1: that optimism. And you know, frankly, I was surprised because
Speaker 1: these days a lot of people aren't really believing in science,
Speaker 1: and like people aren't accepting global warming, and people aren't
Speaker 1: accepting this and that the other. But everybody seems to
Speaker 1: believe that technological advancements will just be continue to be
Speaker 1: delivered on pace. And you know, people, you want technological deliverance,
Speaker 1: if you want technological marvels, you've got a fun science.
Speaker 1: So if you want a fancy new iPhone or to
Speaker 1: travel fast in the speed of light, you better call
Speaker 1: your congress person and tell them to fund basic science.
Speaker 1: All right, and Brant, it's such so permeated in science
Speaker 1: fiction and movies and things right, Like, without faster than
Speaker 1: light travel, most science fiction stories that involve other planets
Speaker 1: would be super boring. Right, that's right exactly because it
Speaker 1: tells us something about the scale of the universe, right, Like,
Speaker 1: the universe is really big. No, the speed of light
Speaker 1: is super fast. Like, let's remind people it's three times
Speaker 1: tend to be eight meters per second or a hundred
Speaker 1: and eighty six thousand miles per second. It's like blindingly fast, right,
Speaker 1: It's not like any kind of speed we're used to.
Speaker 1: It's like, in one second, a ray of light can
Speaker 1: go around the Earth six times? Is that about it?
Speaker 1: Six or seven times? Yeah, in a single second. It's
Speaker 1: incredible to like one, that's it. We went around the
Speaker 1: world six times. That's right. It brought us postcards and
Speaker 1: and uh and drink it exactly, and so it's incredibly fast.
Speaker 1: But the amazing thing is that even though the speed
Speaker 1: of light is so fast, the universe is ridiculously big.
Speaker 1: So even going at the speed of light, it takes
Speaker 1: you forever to get anywhere, right, thousands of years to
Speaker 1: get somewhere, even if you're traveling as a light beam. Well,
Speaker 1: so let's just ask the question. Daniel can we go
Speaker 1: faster than the speed of light? No, boat, We're done.
Speaker 1: That's right, We're done. It's a hard no, you're saying
Speaker 1: it's a hard cannot go faster than the speed of light.
Speaker 1: It's a hard note with a couple of asterisks and loopholes,
Speaker 1: which maybe we'll get too later. Okay, Well, let's talk
Speaker 1: about first, like what kind of speed limit is it? Right, Like,
Speaker 1: if you go faster than this beeed of light, does
Speaker 1: the intergalactic police like pull you over and say and
Speaker 1: give you the intergalactic ticket? No, it's actually they're snipers,
Speaker 1: so they don't even bother the ticket, just take you
Speaker 1: out right thereak you out. They don't mess around the
Speaker 1: laws of physics we're talking about here, dude. Okay, so
Speaker 1: it's embedded in the laws of physics. Yeah, And the
Speaker 1: right way to say it is that you can't travel
Speaker 1: through space faster than light can travel through space. So
Speaker 1: that sounds like a loophole for later. Yeah, there's some
Speaker 1: lawyerly caveats I'm setting up for later. Some intergalactic law
Speaker 1: firms salivating, They're like, I found a loophole. That's right.
Speaker 1: I'm I'm on retainer for some Andromeda lawyers exactly. So
Speaker 1: what does happen? Like if I'm in a spaceship and
Speaker 1: I would say I live forever and I have infinite energy,
Speaker 1: and I just hit the accelerator on my spaceship and
Speaker 1: I just wait pedal to the metal for as long
Speaker 1: as it takes. What's going to happen? So in a scenario,
Speaker 1: you're an infinitely rich alien with who lives forever, and
Speaker 1: this is how you're gonna spend your time. Wow, Well,
Speaker 1: first of all, you don't know that I'm an not
Speaker 1: an infinitely rig It's true. Okay, So you're an infinitely
Speaker 1: rich alien and you're doing a podcast with I think
Speaker 1: even more perplexing. I've lived forever, so you know I
Speaker 1: give my kicks this way. Alright. So you're getting down
Speaker 1: to item number three thousand four in two on your
Speaker 1: bucket list and this is it? So what? Yeah, like,
Speaker 1: do you hit us like you hit a wall? Do
Speaker 1: you know what I mean? Like? At some point I
Speaker 1: can't go faster that do I crash? Does my engine
Speaker 1: burn out? At some point? What happens if I try
Speaker 1: to go faster than the speed line? Yeah? Well, people
Speaker 1: have intuition about this kind of stuff because they're used
Speaker 1: to balls and airplanes and cars and stuff, and they
Speaker 1: think that if you put in twice as much energy,
Speaker 1: you should go twice as fast. And that is true
Speaker 1: if you're on the surface of the Earth or you're
Speaker 1: going pretty slowly, meaning like if you burn a certain
Speaker 1: amount of fuel you should get you should accelerate a
Speaker 1: certain amount, you should go faster a little bit, that's right,
Speaker 1: And if you burn the same amount of fuel again,
Speaker 1: you should go twice as fast. Yeah, there's a linear relationship.
Speaker 1: Doesn't matter what your speed is. If you add energy,
Speaker 1: add speed. That's the people's intuition, But that's not true.
Speaker 1: That's not the way the universe actually works. So what
Speaker 1: happens in your scenario is you keep pouring on energy,
Speaker 1: but your speed, the increase in your speed, starts to
Speaker 1: slow down. So at first you speed up a lot
Speaker 1: when you when you're burning rocket fuel, but then you
Speaker 1: just can't get faster very quickly, and you start to
Speaker 1: approach the speed of light slower and slower and slower,
Speaker 1: so that every pile of energy or bottle of fuel
Speaker 1: you burn gives you a smaller increase in your speed.
Speaker 1: So somebody watching you do this like from the outside
Speaker 1: of your spaceship, they're gonna see you take off really fast,
Speaker 1: and but at some point you're not. They're not going
Speaker 1: to see you go faster and faster. They're just gonna
Speaker 1: see you peek in velocity. Yeah, your legions of screaming
Speaker 1: fans are just gonna watch. It's gonna get kind of
Speaker 1: boring because you're gonna get faster and faster and approach
Speaker 1: to the speed of light, but never actually get there. Right,
Speaker 1: But what's happening to me inside the spaceship though? Do
Speaker 1: I think I'm going faster than the speed of light?
Speaker 1: Or no? No, you don't. You are aware of your speed,
Speaker 1: and you are aware of the fact that you're not
Speaker 1: going fast in the speed of light, and you're are
Speaker 1: you frustrated? And you're screaming at your agent to get
Speaker 1: your bettership or whatever whatever infinitely rich horhe alien Jorge does,
Speaker 1: and but you just never get there. So, but it
Speaker 1: doesn't time slow down for me too. I've heard the
Speaker 1: time slows down for me so that I think I'm
Speaker 1: going faster, but I'm actually times slowing down for me.
Speaker 1: This isn't that how it works? Am I just infinitely wrong? Here. Well,
Speaker 1: you on the spaceship, time always moves for you at
Speaker 1: one second per second, but um, other people looking at
Speaker 1: you will think the time is slowing down for you.
Speaker 1: So people watching you will will see if they're like
Speaker 1: watching a clock that's in your ship, they'll see it's
Speaker 1: slowing down. And that's one of the really bizarre things
Speaker 1: about relativity is that not only does it tell us
Speaker 1: that there's a speed limit, which is hard to understand,
Speaker 1: but it also tells us that time is not the
Speaker 1: same for everybody. Time is a local thing. Like how
Speaker 1: I feel time depends on where I am and how
Speaker 1: fast I'm going, So it's kind of an incremental uh
Speaker 1: slowing down of you. Like I was thinking, like that's
Speaker 1: really cool because we think of the speed limit as
Speaker 1: like a hard stop, but it really kind of affects
Speaker 1: us all the way to the speed of light. Right,
Speaker 1: that's right, Like even now, if I burn hot twice
Speaker 1: the amount of fuel, I'm not going to go twice
Speaker 1: as fast with my car. I'm actually gonna go a
Speaker 1: little bit less than twice as fast, right, Yeah, But
Speaker 1: it's a really tiny effect until you get anywhere close
Speaker 1: to the speed of light. You can get up to
Speaker 1: like half the speed of light without really noticing the
Speaker 1: limits of relativity. It's not because and and then it
Speaker 1: starts to get very very strong the closer you get
Speaker 1: to the speed of light. So unless you have a
Speaker 1: really sleepy car, you won't notice. Yeah, but I think
Speaker 1: people are used to thinking of it as like this
Speaker 1: thing that happens in spaceships or like physics experiments, but
Speaker 1: really it's happening all around. Is like if I move
Speaker 1: my arm back and forth here and in my studio, Um,
Speaker 1: I'm being affected by relativity, like it's slowing me down somehow.
Speaker 1: That's right. Yeah, And the fact that you're looking at
Speaker 1: your arm means you're using light to see it. And uh,
Speaker 1: and so relativity is everywhere. It's it's deeply woven into
Speaker 1: the very fabric of our understanding of physics. Now, it's
Speaker 1: amazing that we went so long without understanding this really
Speaker 1: basic concept that space and time are different from what
Speaker 1: we thought they were. So I guess the question then,
Speaker 1: is why should there be a speed limit? Like why
Speaker 1: does relativity have this weird limit baked into it? Yeah,
Speaker 1: it's a really bizarre feature, and it comes from the
Speaker 1: observation that light always travels at the speed of light.
Speaker 1: No matter what you're doing or how fast you're going
Speaker 1: relative to the thing that's shooting out the light. Light
Speaker 1: is always traveling at the speed of light. That's like
Speaker 1: saying Jorge is always traveling at the speed of Joge,
Speaker 1: that's right, orhe is always at maximal humor right? Or
Speaker 1: are always the same funny? Um? Well, I mean it's
Speaker 1: kind of a weird statement. It's like saying I'm always
Speaker 1: going as fast as I'm going, that's right. So think
Speaker 1: about it like this. You're you know, if you have
Speaker 1: a ball you can throw at ten miles an hour. Cool. Now,
Speaker 1: what if you're sitting in a car that's moving at
Speaker 1: ten miles an hour, then you throw the ball. Somebody
Speaker 1: on the ground is going to see the balls going.
Speaker 1: It's twenty miles an hour. Right, that's cool. It's like
Speaker 1: the velocities add. Yeah, velocities add. They're supposed to add.
Speaker 1: You feel like they should add. It makes sense. It's
Speaker 1: it's an intuitive thing for us. Right. What if the
Speaker 1: person in the car, instead of having a ball, has
Speaker 1: a flashlight. Well, they shine their flashlight. How fast is
Speaker 1: the light going from their flashlight at the speed of light, duh, right,
Speaker 1: speed of light. Okay, But if they're in the car
Speaker 1: and they're moving at ten miles an hour and I'm
Speaker 1: on the ground, how fast do I measure the speed
Speaker 1: of light? Well, your intuition would say speed of light
Speaker 1: plus ten miles an hour, right, because they add and
Speaker 1: that's where it breaks. You measure those photons is leaving
Speaker 1: your flashlight the speed of light, and I'm outside the
Speaker 1: car on the ground, I still measure those photons as
Speaker 1: moving at the same speed. So like if I put
Speaker 1: a rocket on a flashlight and the flashlight is going
Speaker 1: super fast, Let's say the flashlights going at the speed
Speaker 1: of light or close to the speed of light, and
Speaker 1: then it shoots the Pope boton or a beam of light.
Speaker 1: The light coming out of the flashlight is not going
Speaker 1: to go faster than the speed of light either. That's right.
Speaker 1: Two people always measure light traveling at the same speed,
Speaker 1: no matter how fast they're going relative to each other,
Speaker 1: which is really weird. That's the core nugget of the
Speaker 1: counterintuitive bits of relativity, and everything follows from that. So
Speaker 1: you can ask why does light always travel at the
Speaker 1: speed of light? And let's get to that in a minute.
Speaker 1: But first, let's connected back to what we were saying earlier.
Speaker 1: So if light always travels at the speed of light,
Speaker 1: that's the thing that makes it impossible to go faster
Speaker 1: than light. Okay, because it's this observation that light can
Speaker 1: go faster than the speed of light or never does
Speaker 1: that then limits our ability to go faster than the
Speaker 1: speed of light. Is that what you're saying. Yeah, because
Speaker 1: velocity and time are connected in relativity. If you're moving
Speaker 1: really fast past the Earth, you see time on the
Speaker 1: Earth passing more slowly. If you were moving the speed
Speaker 1: of light, you would see Tom and Earth as frozen.
Speaker 1: If you were moving faster than the speed of light,
Speaker 1: you would see Tom and Earth moving backwards, which is
Speaker 1: totally impossible and breaks causality. I mean, trains would arrive
Speaker 1: at the station before they left. It would be crazy.
Speaker 1: I have so many questions for you, But before we
Speaker 1: dive in, let's take a short break so we can
Speaker 1: go fast in the speed of light. Because light can't
Speaker 1: go faster than the speed of light. And if we
Speaker 1: were to go fast in the speed of light, things
Speaker 1: just like don't don't make any time would be reversed
Speaker 1: and crazy stuff like that, and to understand that in
Speaker 1: great detail you have to have a few moving bits
Speaker 1: in some sort of thought experiments. We actually go into
Speaker 1: that in some fun detail in our book We have
Speaker 1: no idea. There's a whole chapter outlining that and and
Speaker 1: dotting all the logic lines from the statement that lights
Speaker 1: always traveling at the same speed to nothing can go
Speaker 1: faster than the speed of light. So that's pretty solid. Yeah,
Speaker 1: And so that all comes from this one observation that
Speaker 1: light travels at the same speed no matter what. And
Speaker 1: people discovered that about a hundred years ago, and that
Speaker 1: blew people's minds. It didn't make any sense at all.
Speaker 1: I mean, people did this experiment, it's called the Michaelson
Speaker 1: Morley experiment, and they shot beams of light in two
Speaker 1: different directions and then measured how fast they went and
Speaker 1: came back. And the idea as well, the Earth is moving,
Speaker 1: and so if the Earth is moving through space, it
Speaker 1: has some speed, right, and so we should be able
Speaker 1: to measure that speed by seeing how fast light is
Speaker 1: moving in one direction versus another direction. But no matter
Speaker 1: when they did it or how they did it, they
Speaker 1: always got the answer that light is traveling at the
Speaker 1: same speed, which shocked everybody was like, it's the kind
Speaker 1: of result I always fantasize about, you know, the kind
Speaker 1: of physics experiment where you get the result and people say, no,
Speaker 1: that doesn't make any sense. You must have done something wrong.
Speaker 1: But instead it requires unraveling like the whole foundation of physics. Well,
Speaker 1: I think it's weird for people because you can't imagine
Speaker 1: light going faster than light that you can imagine a
Speaker 1: little photon, little wave moving faster and faster and faster,
Speaker 1: Like why should this little photon be limited in speed?
Speaker 1: Like why can't it just keep going faster? Yeah? Why
Speaker 1: should there be a maximum speed limit at all? Right? Yeah,
Speaker 1: even for light? Right, Yeah, it's totally but saying like
Speaker 1: that's not how then, like the universe doesn't like things
Speaker 1: to go faster than that, Like I know it was
Speaker 1: an idea of them either at some point in physics history,
Speaker 1: like maybe we're swimming in some kind of goo that
Speaker 1: just doesn't let things travel very fast through it, right, Well,
Speaker 1: the idea of ether was trying to explain what light
Speaker 1: is wiggling through, right, I mean, light is a wave,
Speaker 1: and most waves like sound waves or pressure waves are
Speaker 1: waves through something like sound waves are pressure waves in air, right,
Speaker 1: So people were wondering what is light moving through because
Speaker 1: if lights a wave, it has to be the wiggling
Speaker 1: of something. And that's why they invented the ether. They thought, well,
Speaker 1: light must be wiggles in this invisible thing we've never
Speaker 1: seen before, called the ether. And it was not a
Speaker 1: terrible It just turned out to be wrong, you know,
Speaker 1: and so um, that's what that was the origin of
Speaker 1: this experiment. People thought, let's measure the velocity of the
Speaker 1: Earth through the ether, and then we'll be able to
Speaker 1: tell how fast light is going relative to the ether.
Speaker 1: But it turns out it wasn't. Light is not wiggling
Speaker 1: through ether. Light is an electromagnetic radiation that moves through
Speaker 1: vacuum on its own. It's a really bizarre thing. It
Speaker 1: doesn't have to wiggle something else, right, but it's it
Speaker 1: is limited in like speed, like there's only so fast
Speaker 1: and this stuff we call space around this there's only
Speaker 1: there's a kind of a maximum propagation speed. Yeah, so
Speaker 1: light is this really bizarre thing that can only move
Speaker 1: at a certain maximum speed and nothing can move faster
Speaker 1: than that. And no matter how how fast you're going,
Speaker 1: you always measure light moving at the same speed, And
Speaker 1: that always boggled my mind because it makes me feel
Speaker 1: like two people can observe the same things and get
Speaker 1: different answers and both be right. You know, Like if
Speaker 1: you shoot a flashlight and I'm traveling at half the
Speaker 1: speed of light to try to catch up with it,
Speaker 1: It's strange to me that you'll measure those photons going
Speaker 1: at the speed of light, and I'll also measure those
Speaker 1: photons are going at the speed of light. It feels
Speaker 1: like our observations disagree, but we're both correct, you know,
Speaker 1: we can have different views of the same events and
Speaker 1: both be right. That's the craziest thing about relativity. I
Speaker 1: feel like a really great um way to kind of
Speaker 1: visualize how things break down that you once told me
Speaker 1: about was this idea that like, if there's a ray
Speaker 1: of light going through the universe, and like you, you
Speaker 1: were able to catch up to it, Like you could
Speaker 1: go as fast as that beam of light, and you
Speaker 1: were standing next to it, going at the speed of light,
Speaker 1: it wouldn't make any sense for you to see a
Speaker 1: beam of light just standing there, you know what I mean.
Speaker 1: Like if I'm going down the highway and I catch
Speaker 1: up to a truck and I match it speed to me,
Speaker 1: the truck will seem like it's just standing there. But
Speaker 1: for a ray of light like that just doesn't make
Speaker 1: any sense to see a light ray just standing there
Speaker 1: like that's where things would sort of break down, right, Yeah,
Speaker 1: because not only did I no, No, that's totally right.
Speaker 1: Not only can you never go the speed of light
Speaker 1: because you have mass, and things that have mass can
Speaker 1: approach to the speed of light and never get there,
Speaker 1: But things that are mass less always go the speed
Speaker 1: of light. So not only photons, but also gravitons and
Speaker 1: and other things that have no mass always go the
Speaker 1: speed of light. And the reason is that exactly what
Speaker 1: you said, that if they weren't going the speed of light,
Speaker 1: then you could eventually catch up to them and be
Speaker 1: next to them. But what is a photon, right, It
Speaker 1: has no mass, there's no stuff to it, there's nothing there.
Speaker 1: It's just it's velocity. So if you catch up to
Speaker 1: it and it's not moving relative to you, then it
Speaker 1: doesn't really exist. So it actually makes more sense for
Speaker 1: light to always be zooming along at the speed of
Speaker 1: light relative to everybody who's measuring it at the maximum
Speaker 1: speed at the maximum speed. Yeah, and I think something
Speaker 1: you said earlier is interesting. Why should there be a
Speaker 1: maximum speed? Right? And um, I think that's really cool,
Speaker 1: But it tells you something about our universe. Right. We
Speaker 1: we need there to be a maximum speed so that
Speaker 1: there's causality, so the things make sense, that things don't
Speaker 1: happen out of order, so that cause happens before effect. Right,
Speaker 1: if you go faster than the speed of light, then
Speaker 1: cause and effect breaks. Well, let's let's break it down.
Speaker 1: Like I think, maybe it breaks down to the question
Speaker 1: what would happen if we had no speed limit in
Speaker 1: the universe? Like, what if things could go faster than
Speaker 1: the speed of light? What would happen? Well, you'd have
Speaker 1: to have a totally different universe because the way our
Speaker 1: universe is set up, that's pretty much baked in at
Speaker 1: the at the ground level, and so the universe would
Speaker 1: be totally different if there was no maximum speed. I
Speaker 1: think one thing that's fun to think about is what
Speaker 1: if the maximum speed was different? Right, what if it
Speaker 1: was like twice as much or ten times as much
Speaker 1: or a tenth as much. Because one deep question we
Speaker 1: have is why is the speed of light this speed?
Speaker 1: And not some other speed, Right, that's a thing idea,
Speaker 1: the idea that that's just how our universe is put together,
Speaker 1: Like that's just baked into the rules. And maybe there's
Speaker 1: another universe where the speed of light is different or
Speaker 1: there's no speed of light. Is that kind of what
Speaker 1: you're saying, Like, it's possible maybe to construct the universe
Speaker 1: without a speed limit. I'm not sure if it's possible
Speaker 1: to construct the universe with no speed limit, but it's
Speaker 1: definitely possible to construct the universe with a different speed limit,
Speaker 1: one that's much higher or one that's much lower. I mean,
Speaker 1: as far as we know. You know, if you're like
Speaker 1: at the control panel of the universe, this is just
Speaker 1: a parameter that you can set, and if you change
Speaker 1: the speed of light to something else, physics still works.
Speaker 1: So we don't know why the speed limit is what
Speaker 1: it is, um it. We can't construct the universes that
Speaker 1: don't have speed limits, where things travel instantaneously um across
Speaker 1: time and space. Those things don't work because they break causality.
Speaker 1: Things can arrive before they leave and stuff like that.
Speaker 1: But we can make universes where the speed of light
Speaker 1: is different, and that's fun to think about because it
Speaker 1: changes your relationship, like we were talking about earlier, with
Speaker 1: far away things. You know, the fact that stars are
Speaker 1: really far away really tells you about how far the
Speaker 1: way they are relative to the speed of light. Yeah,
Speaker 1: let's talk about that, but first let's take a quick break.
Speaker 1: How would breaking the speed of light break the fundamental
Speaker 1: like logic of the universe. It's it would break the
Speaker 1: universe because it would break causality. And by that I
Speaker 1: mean that things could happen out of order. Relativity tells
Speaker 1: us that things happen differently depending on your velocity, right,
Speaker 1: and so, and time works differently depending on your velocity.
Speaker 1: As you go faster, you can see the order of events,
Speaker 1: the time of events change, and if you go fast
Speaker 1: in the speed of light, some things flip so that
Speaker 1: the effect happens before the cause. Like the equations just
Speaker 1: no longer make any sense. It just no longer makes sense,
Speaker 1: like it it just breaks. And it comes from this
Speaker 1: this fact that how you see time changes based on
Speaker 1: how fast you're going, which again is totally connected to
Speaker 1: the fact that everybody sees the speed of light always
Speaker 1: moving at the same speed no matter what. Wow. But
Speaker 1: the basic idea is just that it's just baked into
Speaker 1: the equations that nothing can go faster than the speed
Speaker 1: of light. That's right, Like it's just big. If you
Speaker 1: try to go faster, it will just break the equations
Speaker 1: by which the universe is put together. And we have
Speaker 1: tested it a zillion ways from here to Sunday, and
Speaker 1: relativity is very solid. This part of relativity, it's called
Speaker 1: special relativity, that describes how light moves and time is affected,
Speaker 1: is totally well tested and we really believe it, and
Speaker 1: and it's the underpinnings of everything we've built. So if
Speaker 1: it's wrong, then we're going to throw everything away. Now
Speaker 1: I'm not saying that doesn't mean it's wrong, right, It
Speaker 1: could be wrong. And it could be that we discover
Speaker 1: that it's replaced by a different theory and and everything
Speaker 1: is wrong. That would be frankly kind of awesome. I
Speaker 1: love these revolutions in physics. But so far it seems
Speaker 1: to be pretty solid. Like maybe like your kids or
Speaker 1: some kid out there right now, future physicists might figure
Speaker 1: it out that it's a that real special realtibilities is wrong. Yeah,
Speaker 1: And in fact, there was a result a few years
Speaker 1: ago where people thought they had figured that out there
Speaker 1: was this result from the opera experiment at CERN that
Speaker 1: sent new trinos zooming through Italy, and they thought they
Speaker 1: measured some new trinos going faster than the speed of light,
Speaker 1: and they put out this big paper and then it
Speaker 1: turned out to be wrong and turned out to be
Speaker 1: an operatic track. That's right. Um, it was actually quite embarrassing.
Speaker 1: One of the cables they were using to measure the
Speaker 1: timing had come loose and there was a little bit
Speaker 1: of jiggle and and that was the source of the
Speaker 1: whole mistake and they had to pull it back and
Speaker 1: the spokespeople resigned, and it was embarrassing. So if you're
Speaker 1: gonna try to disprove all of modern physics, check your cables.
Speaker 1: Make sure they're right. That's right. If you're going up
Speaker 1: against Einstein, doubill check the box that's right. If you're
Speaker 1: gonna shoot for the king, you better kill him, so
Speaker 1: I guess. And the last question is like, does that
Speaker 1: mean that we can never reach these like far away
Speaker 1: planets in a decent amount of time without turning into
Speaker 1: puddles of ooze? Like does that mean, like you know,
Speaker 1: like you and me will never get to step on
Speaker 1: another solar system and things like that, or uh, you know,
Speaker 1: if we can't go fast through the speed of light,
Speaker 1: does that mean that interstellar travel is impossible? Right, So
Speaker 1: it's time to return to those caveats we talked about.
Speaker 1: Traveling through space faster than the speed of light is
Speaker 1: impossible and as far as we can tell, will never
Speaker 1: be possible. It's not like there's some technological breakthrough or
Speaker 1: waiting for. It's like just difficult or expensive or something
Speaker 1: or complicated. Right, it seems totally impossible to move through
Speaker 1: space fasten the speed of light. Now, I say through
Speaker 1: space because that's the caveat we've recently learned the last
Speaker 1: couple of decades that space is not this fixed thing
Speaker 1: that you move through. It's not like this empty backdrop.
Speaker 1: It's squishy, it's dynamical. It can do things, and we
Speaker 1: can squeeze it and expand it and ripple in it.
Speaker 1: So instead, so the caveat is, instead of trying to
Speaker 1: move through space faster than the speed of light, change
Speaker 1: the space we're moving through. So you want to go
Speaker 1: from here to Alpha Centauri, can we squeeze that space
Speaker 1: to make the distance shorter? Right? Then breaking the rules
Speaker 1: of physics to go through it. So it's kind of
Speaker 1: like we're we're not Space is not an empty and
Speaker 1: empty noess right, It's like maybe we are in some
Speaker 1: kind of like a sponge or some kind of liquid
Speaker 1: as if you know, just in as an analogy, and
Speaker 1: you can't move through this sponge faster than the speed
Speaker 1: of light, but you could maybe like bend the sponge
Speaker 1: or squish the sponge to get from one side of
Speaker 1: the sponge to the other side. You could do tricks
Speaker 1: like that. Is that what? That's exactly what I mean,
Speaker 1: And that is theoretically totally possible, though experimentally very very difficult.
Speaker 1: It's not like we've achieved this or we're like on
Speaker 1: the on the edge of being able to do this
Speaker 1: or whatever. But you know, the first step in a
Speaker 1: project like this is go from impossible to possible, and
Speaker 1: then the rest is engineering to go from possible to practical. Right, So, um,
Speaker 1: I leave that for the engineers. The physicist job is
Speaker 1: to go from impossible to possible. Next week will be
Speaker 1: it will be a feature on your test LA Autopilot
Speaker 1: to Alpha Centauri. Anyways. Um, yeah, so you might be wondering, well,
Speaker 1: how is it possible? Well, you know that space can
Speaker 1: bend right, I mean where the Earth goes around the
Speaker 1: Sun because Sun has bent space, so the Earth moves
Speaker 1: around it because the space is bent right, And gravitational
Speaker 1: waves shows that, like colliding black holes can make ripples
Speaker 1: in space. So how did you actually get from here
Speaker 1: to there? You'd have to squeeze the space, which takes
Speaker 1: a huge amount of energy. So just like a gravitational
Speaker 1: wave cannot propagate, you can maybe like create a giant
Speaker 1: wave that somehow compresses space from here to Alpha Centauri
Speaker 1: so that it's just really close. Yeah, or some sort
Speaker 1: of standing wave that's always compressing the space right in
Speaker 1: front of you so that you can move through it rapidly. Yeah,
Speaker 1: like you're surfing a gravitational wave exactly. Surfing a gravitational
Speaker 1: wave exactly. But remember the gravitational wave caused by like
Speaker 1: colliding black holes squeezes space by one part in ten
Speaker 1: to the twenty. So you need an even bigger source
Speaker 1: of gravitational energy than colliding black holes. So that's a
Speaker 1: tall order. Well, in the movies like Star Wars and
Speaker 1: Star Trek, whenever they go into warp speed, you see
Speaker 1: kind of they always show it as this kind of
Speaker 1: like distortion of space, right, like the stars stretch out
Speaker 1: or like the spaceships stretches out before it disappears. But
Speaker 1: maybe there's something I mean, they got something right about that, right,
Speaker 1: Like maybe that's why we're thinking. They were thinking, like
Speaker 1: you're actually like stretching space or you're like compressing space,
Speaker 1: and that's how you're moving faster than like, Yeah, I'm
Speaker 1: pretty sure the guys who wrote Star Trek did these
Speaker 1: calculations before they wrote those episodes, and it's been motivated
Speaker 1: by actual physics. Yeah. Yeah, everyone in Hollywood has a PhD. Right,
Speaker 1: that's right. That's why they never called me to ask
Speaker 1: for physics help, right, they just understand it themselves. And
Speaker 1: that's why there are no physics mistakes in any Hollywood movies.
Speaker 1: I think you've totally figured it out. So that's one loophole,
Speaker 1: is that you can squeeze space so that you and
Speaker 1: travel faster through And are there are the other loopholes
Speaker 1: or is that the main like possibility for getting top Yeah,
Speaker 1: So if you're out there about to write a check
Speaker 1: for our warp drive company, hold on a moment, because
Speaker 1: there are other options, right, And another option is wormholes right.
Speaker 1: This is the idea that space might not be simply connected.
Speaker 1: It might not be that every piece of space is
Speaker 1: connected to the piece of space next to it. The
Speaker 1: connection could be a little bit more complicated. It could
Speaker 1: be that, like some piece of space is connected to
Speaker 1: a piece of space that's far far away. Right, That's
Speaker 1: what a wormhole is, this connection between pieces of space
Speaker 1: that are far away, and that requires space. Maybe it's
Speaker 1: not this like just homogeneous thing. It could have like
Speaker 1: little loops in it. It could be like tangled up. Yeah, exactly.
Speaker 1: It requires you to think about space in a really
Speaker 1: different way. It's not just this emptiness you move through.
Speaker 1: It's more like nodes on a subway station, right, and
Speaker 1: you can they can be connected in any way. You
Speaker 1: can travel from one to the other. And so why right, yeah,
Speaker 1: why not? Exactly? In fact, we think that space probably
Speaker 1: is that way. That the tiny quantum level space might
Speaker 1: even be quantized um and discreet, and and that you
Speaker 1: can move around like you move around a subway map um.
Speaker 1: And it could be that on the macroscopic level these
Speaker 1: things exist too. And general relativity, the theory that tells
Speaker 1: us about how space time's bent and all that stuff
Speaker 1: does allow for wormholes, it's totally possible. Now, there's a
Speaker 1: huge number of caveats there, like, we've never seen a wormhole. Um,
Speaker 1: so we're not sure. So they're theoretical only they're theoretical. Okay, yeah,
Speaker 1: but you know what black holes used to be theoretical.
Speaker 1: It used to be like, well, here's a funny property
Speaker 1: of general relativity, but nobody's ever seen one. Gravitational ways
Speaker 1: worth theoretical to write, and we just exactly exactly. So
Speaker 1: maybe you know, wormholes are last year's black holes, right,
Speaker 1: wormholes are the new forty and the trending wormhole. Yeah,
Speaker 1: hashtag put Kanye in a wormhole? Um, And so we
Speaker 1: think they might exist, but we've never seen one. We
Speaker 1: have no idea how to make one, We have no
Speaker 1: idea how to keep them open, and man, maybe most importantly,
Speaker 1: we don't know what we like to go through them.
Speaker 1: Probably if you went through it, it would stretch and
Speaker 1: squish you and you'd be that pile of goo anyway.
Speaker 1: But you can maybe send like a signal or a
Speaker 1: probe or maybe something answer. Are you gonna say, hamster,
Speaker 1: don't send the hamster. I'm gonna call the SPC on
Speaker 1: you not my hamster. My answer, yes, you probably could
Speaker 1: send information through the work, so you can talk to
Speaker 1: the aliens interesting you know, or whoever is on the
Speaker 1: other side of the word, or the future you or whatever. Yeah. So,
Speaker 1: even though you can't travel through space fasten the speed
Speaker 1: of light and that's pretty solid, there are some ways
Speaker 1: you might be able to traverse huge distances without waiting
Speaker 1: at zillion years. So there is some hope. You're saying,
Speaker 1: theoretically it's possible, and so maybe, like our people on
Speaker 1: the street that we talked to, maybe there's some future
Speaker 1: engineer or physicist to figure out how to make it happen.
Speaker 1: That's right, And if you do, please send us a
Speaker 1: note because we want to be involved. Yeah, we want
Speaker 1: to be able to spend my infinite riches out there.
Speaker 1: That's right. And I think probably that's what the folks
Speaker 1: we interviewed, that's probably what they were expressing. They probably
Speaker 1: weren't thinking, well and starting special world too, so it's
Speaker 1: just impossible. So no, they were thinking, well, humans figure
Speaker 1: it out, and whenever we're faced with the problems, somebody
Speaker 1: comes up with a solution. There's so many smart people
Speaker 1: out there with their brains cooking on this. That me
Speaker 1: other that somebody will figure out a way to get
Speaker 1: there faster than lightspeed travel, even if you're not actually
Speaker 1: going faster than lights to feed through space. So that's
Speaker 1: why I like to think that people were thinking that
Speaker 1: they were this optimistic view of science solving every problem
Speaker 1: that we have, and maybe the person who figures it
Speaker 1: out is like out there right now, you know, could
Speaker 1: be some kid or some person out there whom it
Speaker 1: could be somebody listening to this podcast getting inspired right now.
Speaker 1: Scribble those ideas down, don't forget them. Include us in
Speaker 1: the patent please, or we will sue you. I have
Speaker 1: some good lawyers from Office Centar. We will see you
Speaker 1: at the speed of light. Well, thank you very much.
Speaker 1: Hope you enjoyed that. We'll see you guys next time
Speaker 1: as we explain the whole universe. If you still have
Speaker 1: a question after listening to all these explanations, please drop
Speaker 1: us a line. We'd love to hear from you. You
Speaker 1: can find us at Facebook, Twitter, and Instagram at Daniel
Speaker 1: and Jorge that's one word, or email us at Feedback
Speaker 1: at Daniel and Jorge dot com.