Can we build a wormhole?

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Speaker 1: Hey, orry, did you figure out how to build a wormhole yet? What you're expecting me to do it? I was hoping you draw in your engineering background. Shouldn't it be physicists trying to figure this out? Now we've already done our part. What do you mean, Well, we proved it's theoretically possible. Isn't that enough? That's all you have to do, prove that it's not theoretically prohibited. Yeah, you know, the rest is just engineering, actually, like making it happen, just engineering. It seems like it's most of the work. To be honest, that's probably true. We should, you know, work on flying cars and feeding the world first. All right, well you know, just let me know when I could place an order from my wormhole. All right, you just let me know when you've proven flying cart and feeding the world aren't possible. It's a deal him or hand me. Cartoonists and the creator of PhD comics. Hi, I'm Daniel. I'm a particle physicist and a professor of physics that you see Irvine, and I'm a bunch of particles that likes to think about particles. You're just a bunch of particles. Is that what you're saying that's all there is, man, just soul particles to it's particles all the way down. If you ask me when you saying these particles like to study particles, Yeah, I'm a bunch of particles that likes to think about and talk about and study particles. Well, it's gonna meta meta particles. It's particles really, all the way down down to the philosophy of it. I'm particularly interested in particle philosophy. But welcome to our podcast Daniel and Jorge Explained the Universe, a production of I Heart Radio, in which we take the entire universe and break it into its fundamental particles. We take a part all of the big ideas of physics, the age of the universe, the reason the universe exists, how it got to look the way the it does today, what it's made out of, and we break all of these ideas down into tiny little particles of understanding. We bounced them around, wrap them up in some dad jokes, and send them along the audio waves to you. That's right, because we are not particular about the scale of the questions we have about the universe. We wonder about the little, tiny things that the universe is made out of and we also wonder about the entire universe. How do we get to the far corners of this cosmos and what are we going to find there. We've sort of woken up as an intelligent species and discovered that we are in this one tiny little corner of an incredibly vast universe, and we're now learning the rules of how that universe works, how it's put together, how you can move around it, how you can't move around it, And of course we wonder are their loopoles in those rules? Is it possible to get from here to there without spending millions of years on a slow rocket ship? Make it sounds like we're a little planet in a big universe. It sounds like a premise for a movie or something, you know, the little planet goes to the big city. It reminds me of that great book we talked about once, Long Journey to the Small Angry Planet. But we are a tiny, little planet and it is an incredibly vast universe. And some of the answers to the questions that we struggle with, the ones that keep us up late at night. You know, what's inside a black hole or what's at the center of the galaxy? Or what's it the far reaches of the universe? Or are there aliens? Some of these questions could be rapidly answered if only we could get to other parts of the universe to just look at the answers. Yeah, because we can learn a lot just from here on Earth, looking through our telescopes and our antennas, we can learn a lot about the universe, but it's just not quite the same as actually getting there or seeing it with your own eyes, or being able to touch other planets or shake the hands or tentacles or other aliens. Because if there are, for example, aliens on other planets, then photons leaving those planets are hitting us here on Earth. It's possible that a photon that left some alien tentacle flew through space and then landed on your eyeball. But of course it's difficult to know that because it's mixed in with so many other photons and it's basically impossible to distinguish. So even with our most powerful telescopes, we can't see what's going on on the surfaces of other planets yet. So wouldn't it be great if instead we could just pop on over. Yeah. Unfortunately, it is a pretty big universe, and it takes a long long time just to get to the nearest star. There are millions of light years to other galaxies, tens of light years to other planets, and so even if we were able to go at the speed of light, it would still take a long time and a spaceship to get their Amazon Prime has not yet conquered free same day delivery to Andromeda. You need Amazon Prime Prime. You haven't unlocked that in your account now. I haven't paid the ten billion dollar annual fee yet to get intergalactic deliveries. It's coming, though, only for billionaires, billionaire podcasters faster than light drones. But yeah, it would be great if we could get to other stars and other galaxies to explore the universe, to see what's out there, to get a closer look at things like black holes and other planets and trump stars. But you know, space is what it is. You can't move through it faster than the speed of light. And that's a pretty hard and fast rule. We know that no matter who you are and how hard you push, how big your rocket, you can't get going faster than the speed of light. It's sort of strange to think about, because you can add energy to things like at the Large Hadron Collider, we can pour more and more energy into particles. There's no limit on how energetic a proton can get in an accelerator. But even though they get more energetic, they just don't get going faster. They very slowly approached the speed of light. So it's a hard and a fast rule. And when the physics says just cannot be broken. We've been looking all over the universe and nothing has ever broken that rule. But there are loopholes. There might be other ways to accomplish those goals without breaking that rule. Not a way to move faster than light, but to avoid having to go through as much space in order to get to your destination. That's right. Physicists have read the fine print of the universe, and it seems there's a you know, a loophole, something that you can and used to warm your way to other parts of the universe. Because when physicists and lawyers get together, oh boy, you never know what you're going to invent. It's like matter and antimatter colliding. It's pure invention. Energy is what comes out. Pure energy, no ethics exactly. And it turns out that the rules of space and time do allow for some crazy possibilities. We know that space can do all sorts of things that our ancestors and even genius physicists from the past never imagined. It can bend, and it can twist, and it can be rearranged in all sorts of complicated ways. Yeah, and this special loophole is called a wormhole, a special tunnel through space and time that maybe we can use to get to other spaces or even other times. But the big question is can we make one? Is it possible to make one? Yeah, it's easy. All you do is you call up your favorite cartoonists slash engineer and say, where's my wormhole? I thought you just have to call some worms. My wife is deep into the compost sting, so she's got a big hole in our backyard filled with worms. So I guess you could say she's already invented a wormhole. There you go. Now, we just need a cosmic compost bin. Well, our solar system is a cosmic compost because we are the left over remnants of previous solar systems having been spewed out into the cosmos to fertilize new systems. I guess with the second lost thermodynamics. Everything is you know, increasing in enterprise. So technically the whole universe is like a compost bin. There you go. The universe was so green and smelt so weird. Yeah, and so to the on the podcast, we'll be tackling the question can we build a wormhole? Interesting? I guess first of all, did you build a wormhole? Or do you have to dig a wormhole in space? Let's figure out the verb first, then we'll deal with the other. Let's get the question right, like, how do you build a whole? Maybe you spin a wormhole. Maybe it's or like knitting or sewing. You know, it's still I feel like the hole is an emptiness, right, how do you build one? Or even a mid one? Yeah, put one together? Yeah. Well, you know, we make light of it, but it is a fascinating leap to say something is allowed in the universe to figuring out how to actually make it happen. You know, you might, for example, know that su flas can be made. Maybe you had one at a restaurant. That doesn't mean you know how to go home and actually make that soufle in your kitchen. Knowing it could exist in the universe and figuring out how to make one happen from the current situation are two very different things. Yep. So then we can put this in the recipe book for the universe. Warmhole who flays? Don't accidentally add too much chocolate and make it a black hole, soufle, it's very dangerous. Or dark chocolate matter dark chocolate matter? Wow? Is that a phrase anybody's ever said before? Dark matter chocolate? I mean, technically you might be able to make dark matter chocolate. Wow. You know, I wonder if there's a chocolate brand out there called dark matter. You might need a whole different recipe book for that. I'd like to toss that one in my mouth. Hole. Well, it is an interesting question because we know that wormholes are technically theoretically possible, and this has been worked out in the math of the laws of physics. But the bigger question is how do you make one? And how do you make one big enough for people to go through it? Exactly. It's the next frontier in understanding wormholes, and it's a crucial step in getting us to the place where we can step through a portal and walk on an alien planet. So, as usual, we were wondering how many people add there have thought about this question of how to build or dig or excavate a warmhole out there in space, And so Daniel went out there into the internet to ask people could we actually make a wormhole? So thank you to everybody who answered these crazy questions without any chance to prepare. If you'd like to participate for a future episode of the podcast, I can't encourage you enough and we'd love to hear some new fresh boy is, so please write to us two questions at Daniel and Jorge dot com. Think about it for a second. How would you make a wormhole? Here's what people had to say. We can make a wormhole. We can do anything if we started flying too. Honestly, I don't have anything else to add. I think this is theoretically possible, and I give us a thousand years until we achieve it. Sure, why not? If we can understand it, we can conceive the technology to do it. I doubt we have the technology right now, and I don't even know what that technology would be, no idea at all. Concentrate a bunch of matter into one place and instead of becoming a black hole, it becomes a wormhole. Maybe you spin a bunch of things in a spinnyway to make a vortex that everybody gets sucked down and through to another place. I would like to think we could, and maybe not yet, but soon. And Daniel, I know that you love Interstellar. I remember that you were talking about it earlier one of the podcasts, and I could imagine it's a thing like that, like bending space somewhere, maybe even in our own solar system. And we really don't know a lot about like Dark Meadow or what's inside the black hole, or there's really still lots of secrets around and in the universe, so I'm pretty sure that we can find some surprises there as well, and maybe with that information we get closer and closer to actually be able to make a wormhole. I don't think we have enough energy right now, but eventually we could. I'm not even sure wormholes are real, nor we's ever observed one or measured one or study one. I know they're a mathematical thing, but I'm not even sure that real. But if they were real, there's no way we could deal with those types of energies. Because what's the most proful thing humans have ever made, The large hard drunk collider, nuclear weapons. I mean, if you take all the hard drink collider, all the nuclear weapons ever exploded wherever there ever are on Earth, there's energies don't compare anything to the Sun. And when you're dealing with a wormhole, you're dealing with black holes and and things that are a thousands millions of times of more massive sun. So I think it's impossible for humans to ever create or make or benifest or manage or anything with the worm hole. Stupid. Theoretically it's possible, but we don't have the technology. So my answer is yes, but not at the moment. All right, pretty good answers here. I feel like I'm not sure they quite answered your question because I think you asked the question, could we actually make a warm hole? But and so people just said yes, why not sure, instead of actually giving us ideas before how to make a warm hoole. Oh. They didn't take it as a homework project, like go and give me the recipe figured out right now, I want the answer today. That's right. They read the fine print in the question, and the question only asked could we make a wormhole? Which is a the other or no answer? Well, but again, knowing that something can exist in the universe doesn't mean we know how to make it right. It's not always easy to assemble something even if you know that it can exist right. Right, So I guess, let's dig into this topic and no pun intended, And so let's start with the basics. I guess what is a wormhole exactly? And what do we know about it? So wormhole is a fascinating idea, and it comes out of the basic realization from general relativity, which tells us that space itself is not nothingness. It's not like the background in which the universe actions happen, which is sort of the way that Newton saw space. He saw spaces like absolute and fundamental and sort of like the stage of the universe on which things move and shift. So he thought space and time where it's just these sort of eternal basics to the universe. And then Einstein showed is that that's not true at all, that space and time are actually dynamic, that they change in response to what's in them. So you put a blob of mass in space, for example, a curve space, and then that curvature tells those masses how to move. So it's not like space is the background. It's instead one of the players on the stage, and mass and space interact with each other to create all the crazy dynamics, the orbits, the black holes, everything that we see. And Einstein gave us these equations to tell us what space can do. As long as space follows those equations, everything that the equations predicts should be possible to exist in the universe, and that includes really simple stuff like you have an empty universe, okay, so space is just totally flat, there's nothing interesting there. Or you have a singularity, a point of infinite density mass with zero volume, in which case you get crazy things like an event horizon. And so general relativity tells us that space can do all sorts of crazy things, and wormholes are just one of those predictions. Yeah. People often make the analogy that we're like fish swimming in water, and you know, we thought we were like swimming and emptiness, but actually we're swimming in something, and that something can sort of like banned and pushes and compressed and make swirls and everything. I guess maybe a difficult thing to think about though, is like you can imagine space bending and distorting, but it's it's kind of hard to imagine poking a hole in it, Like it's hard to imagine poking a hole in water. It is hard to imagine poking a hole in water. But that's because if or a fish, all you can think about are the basic things that you've seen water do. But if you are a sort of water scientist, you know that under different configurations, under different circumstances, water can do other things. It can be crazy. You can form solids, right, it can form drops and fall from the sky. You can even form a gas and expand. And so we're stretching the analogy a little bit, but the idea is that under different circumstances, space can do other things. And I think this is a real demonstration of the power of theoretical physics, because this is a case where theoretical physics really is leading the charge. You know, we take these like abstract principles, these mathematical equations that Einstein came up with to describe the things we had already seen in the universe, and then we explored the predictions of them. We said, well, if these are true, if these really are the rules of the universe, what else can they do? And for example, we discovered black holes. In this way, we discover them theoretically as like a consequence of these laws, and then went out in the universe and found them to be real. So it's a really powerful way to do science. One is go out in the universe and find crazy stuff and try to explain it. The other is look at the crazy consequences of the rules you have already gathered from your experiments and see if you can predict interesting, fascinating things. So wormholes are that kind of example where people have tried to find weird corners of Einstein's equations to tell us that it's possible, right right, Although to be fair and not everything theorists come up with turns out to be true almost nothing in fact that they think, Like, of all the theories out there about what new particles might be, I bet none of them are true. I don't think that the real theory of nature in particles is in any human mind right now. But that doesn't stop them from being creative and coming up with lots of ideas. But wormholes are fascinating because it's not just like one idea, it's more like a category of ideas. The basic concept of wormhole is say you have a patch of space from one spot, you have a patch of space in another spot. Is it possible to connect them? Is it possible to make it so that this one patch of space A is like next two hatch of space B, even though they're otherwise separated, maybe by light years of distance or even by time. Is it possible to build a tunnel so that one patch of flat space is now connected to another? And this is sort of like the overarching theme of a wormhole. And people have explored this for decades now, and they've come up with a few possible ways to connect patch of space A and patch of space B. And there's sort of very different ideas. You may have heard several different ones which sound contradictory, And the reason is that there are different ideas for what a wormhole might be. Like. There are different flavors of this wormhole moves, you know, this earthworms holes, and then this ring wormholes and all sorts of different kind of worms. Oh boy, this is getting a little uncomfortable. Yeah, so there's different flavors of wormholes, and but I guess you know, it's sort of strange, how it Like, what is it about the theory that allows wormholes, like, you know, doesn't the theory sort of treat spaces like the thing where other particles move around, And how does it actually allow, you know, you to make discontinuities in this space? Well, singularities are in aparently like a discontinuity. There are a very weird point in the theory. And so the very first idea for a wormhole was imagined two black holes which share a singularity, you know, which have the same singularity. So you have like a black hole with two exteriors and a common interior, like it just overlaps because I guess if you have space, you know, people usually imagine it as like a giant rubber sheet, and you can have maybe a black hole, something so heavy and intense that it kind of makes this dip in the rubber sheet and it ends in a singularity maybe. And so that's kind of where the idea came from, Like what if this singularity down at the bottom of the rubber sheet somehow connected to another singularity from another black hole somewhere else in space and the rubber sheet analogy is useful for getting you thinking about how space bends, but it's a little bit misleading sometimes because it suggests that space bends like into some other direction, like in the rubber sheet analogy, the universe is a two dimensional rubber sheet and it's bending in a third dimension. In our universe it is three dimensions of space, but doesn't bend in some like other weird fourth dimension. The bending is intrinsic, meaning it's all about the changing of the relative distances of points in space. And we don't know what it is that ties space together, like why is this bit of space next to that bit of space next to that bit of space. And so what we're doing when we're making wormholes is we're just like fundamentally reorganizing the arrangement of space. We're saying, this bit of space is now next to that bit of space. It's like you're sowing the universe together. You know, you're knitting, and you just sort of like make a stitch from the frontier sweater to the back of your sweater and you say, these two things are now next to each other on my sweater. Right. It's like you're taking this singularity from one black hole, and then you're taking another singularity from another black hole, and then you're joining them together. But doesn't that seem sort of implausible, Like, isn't the point of a singularity is that it's single, you know what I mean, Like it's supposed to be like unique and and and you know, a singular point, Like how do you make two points? Need? Oh man, I love that idea. You know, you're right, it's a funny name because there's not just one singularity in the universe, right, there's a singularity at the heart of every black hole, and so we shouldn't be called them singularities. They should be called like what multiple ularities or many ularities? Singularities apparently is apparently they're not exclusive. But the idea of a singularity just implies that something is becoming infinite. In that case, the idea is the density. The density is becoming infinite, So it's a singularity in that sense, right, That's what I mean. It's like, how do you take an infinite dense point and connected to another infinite dense point, Like, what are the chances they're going to meet up together? Yeah, well we don't know, but it's possible. Like if you plug that into Einstein's equation, that comes out with a check mark. Like if you shape space in that way, and you say, can space have this shape? Einstein's equation says, yes, you absolutely can. It's like can you mold a block of clay into a donut? The answer is yes, and so therefore donuts are possible. Just because that configuration satisfies Enstein's equations doesn't tell you how to actually make it real, because in order to make something, every step along the way also have to satisfy the laws of physics. Right. It's sort of like if you want to build an arch, like a Roman arch, where you have those bricks that suspend each other. Yeah, you know that works if you can get it up there. But you can't just like put one brick up there and have it levitate while you assemble the other bricks below it. Every step in between also has to satisfy the laws of physics. And that's the tricky part finding a recipe to go from you don't have a wormhole. Two, now you do have a wormhole. Even if you know the last step is allowed, every step in between also has to be allowed. Interesting. All right, let's get into the different flavors of wormholes, and it's getting through the problems of making one. But first, let's take a quick break right, Daniel. We are worming our way into the hearts and minds of audiences everywhere. And we're talking about at wormholes maybe a possible way for us to get to other galaxies or other parts of the universe through a loophole in the spacetime fabric of the universe. And so you mentioned there are different flavors of wormholes, like you can order a vanilla wormhole and a chocolate wormhole. I recommend mint chip. Really it's the taste, not mint well exactly. And because people might be wondering, hey, if I want to get from here to Alpha Centauri, are you telling me I have to use a wormhole which has two black holes on it, Because if you fall into a black hole, you're not coming out the other side, right, And so that's why this wormhole is more like a category of ideas. And the kind we're looking for is a traversable wormhole, one that you can go into and actually come out the other side. Not every wormhole. You can imagine if physics satisfies that requirement. For example, when we have two black holes with a common singularity, definitely not a trip I would recommend. But there are other flavors of wormholes, when we've talked about in the podcast before, is a black hole with a singularity, and on the other side, instead of being another black hole, is now a white hole something which is like the inverse of a black hole. Instead of something that's impossible to escape, it's something that's impossible to fall into. So you fall into the black hole side of it, passed through somehow, and then come out the white hole side some other place in the universe. I see. So this is like the chocolate vanilla swirl flavor worm hole. Yeah, but they don't swirl, right, there's a singularity of the heart there that keeps them apart, which is the best time because if you order chocolate in vanilla swirl, you don't want them mixed together because then it's just like sort of you know, light chocolate. You want the contrast a right, maybe it's more like cookies and cream. Then, well, so you're saying that another type of worm hole is one that connects the black hole to a white hole. Now, our white holes are sort of like the inverse of a black hole, where it doesn't suck things in, it actually spews things out. And these are also theoretically possible, but unlike black holes. We've never observed any white holes. Right. That's right, black holes theoretically possible and observed. We're pretty sure they exist, So check out some of our episodes about like quantity stars and dark He knows about whether they actually are out there in the universe. But wormholes and white holes still purely theoretical. Nobody's ever seen one. We don't actually know if they can exist in the universe, although the math suggests that they are possible. I see, so you could maybe take the singularity from a white hole and connected to a singularity from a black hole. But wouldn't they be sort of different kinds of singularities or it's still allowed by the theory. No, it's a single singularity. In fact, if you look at like the Penrose diagram for a black hole, this is something that's pretty cool that lets you think about the shape of space in the vicinity of a black hole. This sort of a gap on the other side of the Penrose diagram. If the black hole in our universe, which is centered around the singularity and then the diagram has this gap, you like what's on the other side, And that's sort of the genesis of the idea of a white hole. It's like the other side of the singularity. And so it would be very natural for a black hole in a white hole to be connected by a singularity. And again, this wouldn't necessarily be a traversable wormhole, right because like you've got to pass through a singularity. That sounds like a pretty tight squeak. Yeah. Yeah, you'd have to really lose a lot of weight to be that single. And so that's also not a traversible wormhole one that you'd like to pass through. But there are other kinds of ideas about wormholes, and these are a little bit more exotic, but they're also maybe more promising because it turns out to have a connection between two points in space, you don't necessarily even need any mass. You might not even need a singularity at all. What do you mean, like, how can you have a wormhole without a singularity or without a hole. Well, it's just a question of having space be curved in the right way that this patch of space and that patch of space can connect to each other. And so people talk about whether that's possible. Obviously, singularities are incredibly dense sources of mass can curve space, but that's not the only way to get space to be curved. And it's possible to have curved space without necessarily having any mass. So, for example, in the vicinity of a black hole, where you don't actually have any mass, space is still curved. Right, there's like complex interest in geometry near a black hole, even though you're not actually in the massive part of it. And so it's a bit of a stretch. But if you might be able to come up with some solutions to the Einstein equations that connect two portions of space without actually having any huge amounts of mass, without any singularities at all, and so this is the kind of wormhole which might actually be traversable. I see you're saying, like, we know that space is kind of bendable and squishy, so why not, Like it's theoretically possible you could just squish it all the way into a tunnel without needing a black hole. But you have no idea how to do that. There, I have no idea how to do that. I mean I have some ideas how to do that, I have no plausible ideas for how to do that. I don't have a recipe that one can follow. And before you even get there. There are theoretical problems with these kinds of wormholes. One is that these kind of wormholes, when people play with them in the equations, they tend to try to like snap shut immediately. They're not stable. It's not like a black hole which you can sit there forever essentially sucking stuff up. These kind of wormholes when you set them up, they collapse that like pinch closed. These tubes don't like to just sort of like hang out connecting two parts of space. They pinch off almost immediately. I mean, like if I just take space and I dig a hole or connect to far away points together, your equations actually tell you that it's not stable, Like why wouldn't it be stable and in space just sit there and stay bent. It's a great question. And just to clarify, like we don't know how to dig this hole, but say you started with universe where that whole existed, we don't know how to go from. There's no hole too, there is a hole. But say you had the universe with this one of these wormholes in space already came built that way, then we can't play with it and say what would happen in this scenario? Just like I don't know how to make two black holes collide, but you know, if it's already happening in the universe, our calculations can tell you what to expect. I say, it's like you bought a house and you discovered has a secret tunnel in the middle of your house. Yes, yeah, And then we can ask, well, what would happen, And the calculations suggest that it would pinch closed immediately because like the pressure from the curving of space would immediately collapse. This interesting mean that space doesn't like to be bent. It's not stable, right, I mean, I don't want to say what space likes. If it likes mint chip or if it likes vanilla, you know, but it doesn't stay that way. It's not stable unless you add something to your wormhole. Like, it's not stable. Like the equations tell you that in the next instant in time, curvature would snap back into flat space. Just like if you put a particle near a black hole, that's not a stable configuration. The particle will roll into the black hole eventually, right, You can't just have it hanging out there. The dynamics predict that things will change. You know. Some things are stable, like a particle can be an orbit around a black hole. That is a stable configuration. So there are some stable solutions to the Eis equations, but there are also some that are unstable. They won't just like hang out with the same solution forever. But Kip Thorne and some friends came up with the idea of how to keep that throat from collapsing. Interesting. Just get a bigger worm, they said, actually get a negative worm. What they discovered is that you need some sort of like repulsion. Right, gravity tends to be attractive. I'm a try acted by the Earth, and the Earth is attracted by the Sun, and the Sun is attracted by the rest of the Milky Way. We tend to see gravity as an attractive force in the universe. Here, what we need is like repulsion. We need something like pressing on the edges of the throat of the wormhole to keep it open. And to do that you need gravity to do the opposite of what it usually does. And so they thought, well, perhaps if you had like negative energy density, something with like negative mass instead of positive mass, you would apply some sort of like pressure on the edges of this wormhole and it would keep it open. It would keep it from collapsing gravitationally, wouldn't that be the same as sort of like a white hole, right, like something that's the opposite of super heavy. It's the opposite, but in another direction, right, a white hole is the opposite of a black hole. And then it's like the inverted shape of space time, but here it's the opposite of mass. I think it's pretty cool though. In particle physics, we have lots of like opposites. You have matter and antimatter, you have positive mass and negative mass. You have you know, electrons and different flavors of electrons, mus and towns. There's so many different f actions physicists and engineers, engineers and mint chip engineers, you know, that's right, and lawyers exactly. And so the idea is if you have some kind of matter with negative energy density to it, you know, like a particle with negative mass, which is something we've never seen, and you threaded that through your wormhole, then that configuration is actually stable. They will keep the wormholes open. Interesting, so are we still talking about like a big tunnel in space or are we talking about a wormhole that only like a single particle can go through. That's the other problem is that in their calculations. This is like particle level wormholes. We're talking microscopic wormholes. And so you know, if we're gonna send Jorge to Alpha Centauri, we would have to combine this with some machine that like disintegrated you into your particles or your information and then like beamed photons through it and reassembled you. On the other end. This is not something you could like pass a living object or a macroscopic object through. I see, well, I mean, I guess paint paint a picture to me, Like, how do we keep it open? Then do you You have to keep feeding it this negative mass, this inverse negative energy matter through it, Like there has to be a stream of it or it's like it's like the scaffolding that holds it open, and it's there and then we passed kind of in the middle of it. Yeah, it's more like the scaffolding. As long as it hangs out inside the wormhole, it should keep it open. But again, we don't know that negative mass exists. So this was sort of the forefront of current thinking until a few years ago. People thought, well, wormholes, maybe they exist, but they need us to use this kind of exotic matter, which is theoretical which might not exist in the universe, but which is theoretically possible. It's theoretically possible. Yeah that we've never seen it and it would be really weird. And we actually have a whole podcast episode about exotic matter and how strange it might be to check that out if you like. But now people are thinking about other ways to maybe keep wormholes open and maybe to make them larger, to make the macroscopic so you can put like real people and objects and you know, your suitcase through it interesting. So we have some new ideas, and so this is something physicist actually work on. Like you know, it's not just science fiction authors and TV writers that think about these things like a field. There are warm, whole physicists. There are This is not like the lunatic fringe, like people at the very end of their careers noodling around with crazy ideas they daren't mention otherwise. These are prominent folks, you know. Kip Thorne is like mainstream physicist you want a Nobel Prize. There's guys like Juan Malda Senna, who was one of the smartest guys in the universe at the Institute for Advanced science. Cunning edge string theorist works on this kind of stuff. It's a really interesting area because it's not just like, hey, can we get to other places in the universe. It touches really deep questions about the nature of space and time itself and connects to questions in string theory and quantum information and black hole information paradoxes, and so wormholes have become like really core to a lot of these questions. You remember that episode we had recently about the potential solution to the black hole information paradox. One of those solutions implies that there's like a wormhole that connects the inside of the black hole to your simulation of a black hole on your computer, like informational wormhole. And so these wormholes are like popping up everywhere these days on the forefront of theoretical physics. Interesting, all right, So what are some of these new ideas about wormholes. So one of the new ideas about how to keep a wormhole open says, well, let's not try to use something that doesn't exist in the universe, like negative mass matter, because maybe that doesn't exist and so it's not practical. Instead, let's try to use some of the cool features of quantum mechanics to maybe keep this wormhole open. So quantum mechanics has really fascinating properties, and one of the most interesting is something called entanglement. When you connect two particles which can be really far apart, but you have their fates intertwined. So, for example, maybe you have a photon which decays to two electrons, and those two electrons have to like satisfy one of the rules of the original photon. You know, if the photon had no spin, for example, then the two electrons together have to have no spin when you add them up, which means if one electron to spin up, the other one has to be spinned down. So you have these two elect stron's and maybe they're now like really far apart, they're a light year apart in the universe. As soon as you know one of them is spin up, the other one has to be spin down. Quantum mechanics tells you that both of them can be in either state, and until you measure electron A, you don't actually know what's going on with electron B. So these two particles are entangled. There's some like weird spooky connection between them because as soon as you ask about electron A and discover oh it's spin up or oh it's spin down. Now you know something about electron B. So this is like a way to connect two places in space somehow across vast distances, and this collapse, this coordination of their results seems to be instantaneous. So this is a starting place to think about, like how to maybe make connections between two points in space using quantum mechanics rather than general relativity. I see, all right, So these two electrons are tied together by some rule of quantum mechanics, and now how to use them to keep it a wormhole open? So this is gonna sound bonkers, right, even on top of all the bonker stuff we've been talking about today. The idea is if you can entangle the two edges of the wormhole. So take your wormhole, which otherwise would have collapsed, and somehow entangled the two boundaries, Like you have a boundary of the wormhole in this part of space and the edge of the wormhole in the other part of space. Somehow quantum entangled those two boundaries. So they're like linked by quantum mechanics, and there's going to be a connection between them that entanglement between them creates like a special field, which creates negative energy density inside the wormhole, which is equivalent to having negative mass in there. So it does the same job as negative mass matter, but without actually having to have any negative mass. Wait what all right, So you're saying that if I entangled two electrons, right like, I have two electrons entangle, and I have one here and I have one there where you are, you know, fifty miles away, you're saying, there's some kind of like energy linked to them, some energy, some negative energy linking them together, or there's some negative energy in between us. Yeah, there's a negative energy fee old in between these two objects, like a real tangible field or like a theoretical field. It's like a theoretical field. I mean, nobody really understands quantum entanglement. Frankly, it's a mystery. It's not something that we really understand what's going on. And in the various interpretations of quantum mechanics, there are different explanations for it, and there are even viable theories of quantum mechanics that suggest that entanglement can be explained by like hidden variables, that there is no randomness anyway, a lot of this is still theoretical, but it doesn't involve invoking negative mass particles, just negative energy we don't know exists, but which in these calculations does come out of this special entanglement. If you entangle two sides of wormhole, the idea is that now they are connected in this special way and that keeps them from collapsing. Interesting, like there's actual like energy between them that is somehow keeping this warmhole open. Yeah, there's some way that these two are connected now, right, Because if you have two electrons that have their fates entangled, they are part of the same wave function, and that wave function and is a ripple in some quantum field, and so there's a field that it now goes through the wormhole, connecting these two electrons and basically keeps them from snapping shut. The way I think about it in my mind is like you have this wormhole which wants to close down, but there's a thread that's through it, and that threat is the entanglement of these two particles, and it keeps it from closing. Why why wouldn't it just close, cut the court and break the rules of quantum mechanics, sir? Why not? What are you talking about that's crazy, very inventing things left and right. Here, I'm gonna invent the quantum scissors that the universe has to do what it wants. Well, nobody knows that this is real. And you know, this is a calculation in a paper by one Maldacena, again one of the real smarty pants in the universe. And I took this paper to some theoretical physicists I know, and frankly a lot of them said, you know, I don't understand this paper. But one Mondasna is a really smart guy, so I believe it's true. I see he's like, he's like negative energy. He's gonna assume he exists in his right. He's never made a mistake before, so people trust his calculations. I didn't understand the details of the paper theoretical this is I talked to also admitted not understanding how the calculations work. But this is a prediction of those calculations. Okay, So that's one way to keep a warm hole open, and so there are other ways, including using dark matter. So let's get into those other ways to make warmholes. But for us, let's take another quick break. Al Right, we are struggling to keep wormholes open because the universe wants to shut them down. If there is a path between two distant points in space, some kind of tunnel, the universe actually wants to close them. It wants to zip up that hole. And so the big problem with making warmholes is how to keep them open. So we talked about maybe using quantum entanglement, which is very theoretical, but there might be a way to do it with dark matter. Daniel, right, Well, we talked about how to maybe keep them open using quantum entanglement, which is super fun. And before we move on to how to make them large and macroscopic using ar matter, I just want to talk about one more advantage of that solution, which is that it might solve this time travel paradox we've talked about sometimes how wormholes might be a way to travel through time because one edge of the wormhole might be in the present and the other edge might be in the past. Somehow, if you like boost the edge of the wormhole so it's going at relativistic speeds, you can take advantage of special relativity and the two sides of the wormhole could be at different times. The cool thing about quantum entanglement as a way to keep the wormhole open is that it prevents any of those paradoxes from happening, because now you've made like a direct link, a connection between the two boundaries of the wormhole and actually prevents any time travel paradoxes from happening. So it's sort of cool in that way, sort of neat when you see a solution to a problem also prevent other problems from cropping up. It's sometimes a hint that maybe you're going in the right direction. M I didn't know that paradoxes were possible with wormholes. I thought that, you know, they might connect spacetime, which means you can travel back in time, but since you're all part of the same universe, you can sort of change the past. Well, that's true in some other configurations of general relativity, like closed timelike curves, which put you in like a forever loop where you're repeating yourself. Wormholes, however, do potentially open the door to paradoxes, because if you can travel into the past and you're not in that past limited to repeating what you did last time. So it's not something people understand how to reconcile wormholes with paradoxes and constality. But this solution to keeping wormholes open does actually rectify that because by directly connecting the two edges of the wormhole using quantum entanglement, you prevent any of these paradoxes from happening. M that's good news, I guess. We don't want to crash the universe. It's good news for your grandfather because you can no longer go back in time and kill him or your grandkids. Exactly for you, because your grangkids might come back to that's right, exactly. You ate all the mid chip, you jerk to capital offense. The other problem we're trying to solve with wormholes is not just to keep them open, but to make them big enough for us to go inside. We talked about how they are just like particle sized. These kind of wormholes we're talking about are like big enough just in one particle through. So other thing people are working on is like, how do you make a wormhole whose throat is macroscopic, is like you know, two meters wide, so that like a person or a spaceship or a rocket could go through them. And that's the solution we tried to address by adding dark matter to the equation, right, because all of the ones that we've talked about before, you can only send like literally one particle at a time. You can't send two particles next to each other, only one behind the other. And so how do you make one big enough to like fit a spaceship through, Well, nobody knows. But in the same paper one Mile de Center worked on this problem and he thought, well, let's try to come up with a way to make them larger. And let's again not use like a crazy invented exotic matter that we don't know exists. Let's think about the things that do exist in the universe. So he explored what would happen if you use dark matter, but again not just like normal, everyday dark matter. He was considering dark matter in combination with another idea of additional spatial dimensions. We've talked on this podcast about how the universe seems to have three directions you can go in space, but there's some parts of physics that suggests there should be other directions you should move. In string theory, for example, you know like eleven or twenty six dimensions, which would mean that they're like you know, not just up and down, left and right and forward and backwards, but other weird little dimensions that some particles can move through. We wouldn't be able to notice them or see them or move in them, but there would be features of space. So he explored the idea that if there are these other features of space, it would change sort of how particles move through that space, and it would change how gravity works, which means it would change how spaces bent. So if you combine dark matter with these weird extra dimensions, then you can use them to build a wormhole which is really really wide, big enough that you could actually pass a person through. Well, how does it work? Well, what's the theory prescribed? What are the instructions in this paper to make it warmhole wide? So you need a lot of dark matter, and they go through the calculation in order to have a wormhole whose mouth is wide enough for a human to fit, but not just that for a human to pass through without being torn apart by the tidal forces. You know, these incredible forces of gravity that tug on you more strongly at your feet than on your head, and would tear you apart if you got close to a black hole. If you want a wormhole that's big enough for a human to go through and wouldn't tear you apart, then the mouth of it needs to be three thousand light years wide, which means constructing something out of dark matter. It's three thousand light years in diameter. That's like much bigger than our galaxy, right, you mean, like, you know, take up like a corner of the known universe. Well, our galaxy is something like a hundred thousand light years across, but it's definitely much bigger than our solar system. So we're talking about a massive engineering project, you know. But hey, this is like the first paper on it. The next one it will only be a thousand light years wide, and eventually somebody figure out how to make it one light year wide, and then you know, the engineers will take over and they'll figure out how to actually build this thing. It will be as wide as your phone. Well, but I guess what's the actual recipe? Like you have to take dark matter and shape it somehow, or just put it on in one place, or be lucky that it's somehow Just this with this wormhole with dark matter in it, Like, what do you have to do to make this warmhole work. So again, he doesn't sketch out a recipe for building this thing, just that if you have a wormhole and space has these extra dimensions, and you have dark matter inside this wormhole, and you have the two edges of the wormholes quantum mechanically entangled, then that solution is stable and would allow for people to pass through it. So there's no recipe for like, here's how you put this thing together, or here's the configuration of dark matter you need in order to make this happen. It's just like this configuration would satisfy the equations and meet all of these constraints of being large enough and being stable. I see, But what's the dark matter doing? Like, is it just sitting in the middle of it? Is it shaped like a tube? Is it just hanging out at the ends of it? Is there any sort of specifications about this or it's just a very abstract idea. It's just sort of an abstract idea. The dark matter is there in order to explain why you have these extra dimensions of space and time, and to reconcile all that together with all the other astronomical observations we have about the nature of the universe, and so the game I think Juan Milison was playing was like, can I use things that we already know exists in the universe and features of those theories to try to construct a wormhole which works. There's no description in this paper of like what shape the dark Man has to be in, or where the dark matter needs to go, or what this wormhole would look like. I think. In fact, here's a quote from the paper. He says, quote, another problem seems to be producing the wormhole in the first place. This seems difficult. When one of the smartest guys in the universe says this seems difficult, you know, it's not an easy problem. I see. I feel like he's giving us a recipe for a suffle. But he's just saying, hey, maybe maybe if he's throwing some flour, maybe in some cream and maybe some you know, some sugar, maybe you can make a sufle. But good luck with that. You know. The cutting edge soufle a theorists, that's how they get started. They're like, you know, what are the ingredients of a soufla? We don't even know is it possible theoretically? And you know, eventually a hundred years later, we have a recipe for a su FLA interesting all right, So another way to make a wormhole and maybe keep it open and make it big enough for us to fit through. So where are some of the problems with that? Well, one problem is we don't know how to build that thing, right. We're talking again about a solution that we know might satisfy the equations, but we don't know how to go from here to there. Another issue is if you have these kind of entrances to the wormhole. We're talking about space being really really curved, and when space is curved, it doesn't just affect where you go, it also affects how time passes. We talked on the podcast once about gravitational time dilation. Anytime you're in a place where space is curved, your clock moves more slowly, and so, for example, if you go through this wormhole, it might be that your clock slows down. And so even though you can pass through the wormhole in what feels to you like an instant, to someone on the outside, you would slow down and almost freeze as you pass through the wormhole, and then when you come at the other side, you'd be moving super slow in time. Also, according to their calculations. You can't actually get from one place to another faster than light would have gone because of these time dilation effects I see. So, like, if I have the opening of a wormhole in front of me, and you go through it, and I should have flashlight to the other end, which is like maybe a couple of miles away, you're saying, my light, my flashlight would actually get there, like I could have gone there faster without going through the wormhole exactly. So in that sense, they're theoretically awesome, but totally useless. The time dilation effect, which is really a pretty big deal. You know, that's like a very important piece of fine print. Right, Like, so I would I would flash my flashlight and I would see you go in, but then I would see you sort of freeze at the mouth of it, kind of right, sort of like you freeze when you fall into a black hole. At least to the people outside of the black hole, I would see you just get stuck in the hole. Yeah. Wow, that is the least useful wormhole ever. Yeah, exactly. It's like a Star Trek teleporter, but they just freeze you into a block of ice and then put you on a carrier ship. And like you know, ship you over there and thaw you out. So it's not very useful at all. No, No, I mean I would never see you go through, right, is that what you're saying that? Or would just be super slow, but time we actually freeze, it would just be super slow. The time doesn't actually freeze actually stop, but it would take you longer to go through the wormhole than if you went around the wormhole. What if I just make it bigger. Well, the time dialation effect gets stronger as the wormhole gets more powerful because the curvature increases. I see, all right, So that's another problem, is that it's not useful at all. But I guess the point is that, you know, time doesn't slow down for the person going through the tunnel, So like the person going through the tunnel to another galaxy, it would just be like a breeze, except you wouldn't have to be asleep or cryogenic sleep for like thousands or millions of years. Yeah. Just like if you somehow got up to the speed of light traveling across the galaxy would seem to you like it didn't take very much time because for you the galaxy would be low Renz contracted it would be like shortened, so it doesn't seem like you're going as far. So for you you could survive travel to really really distant parts of the galaxy. It's just that if you walk through the wormhole and then you came back, you know, millions of years might have passed. So you know, say goodbye to your family before you step in. Yeah, or say hello to your great great great great great great great great grandchildren when you come out the other end. Yeah, if you're so lucky. So what are some of the other problems. Well, another problem is the temperature. You know, as you fall into this wormhole, you're accelerated by the curvature of space. So they did this calculation in this paper, and you get like an energy boost of a factor of two trillion, So a particle gets like really sped up as it enters. So one has this other quote newspaper, which I found hilarious. He says, so one would have to put the huge black hole inside a refrigerator in order to prevent this. So not only is he speculating about a three thousand light year wide wormhole, but a refrigerator that you could put that entire wormhole into. I feel like, my freezer is a black hole in my kitchen right now. But you're saying like that it does sort of act like a black hole, and that like if you're near the mouth of the wormhole, it would suck you in kind of that's what you're saying, and accelerate you to fast speeds, and you'll be fast in your frame of reference. Right from the outside, you would still be time slowed down, so you wouldn't be moving that fast from some but else's point of view, But from your point of view, you would be moving quickly towards the mouth of the wormhole, which would be very exciting. Like that would make it fun, right, you'd be like, wow, makes for a better ride. But you're saying the problem is that that danger is somehow to be moving that fast or are you saying like we would heat up somehow. You're basically giving a high temperature to these objects, and you might not worry about that because you know, like energy is frame dependent. I'm not moving at any speed in my reference frame. Somebody flying by me near the speed of light sees me moving at almost a speed of light, So you could argue that I have like a very high temperature in that frame of reference. Doesn't bother me at all in my frame because I see myself as moving at zero velocity, So temperature and energy are sort of frame dependent and so not necessarily something I think you should worry about. I just enjoy thinking about a three thousand light year wide refrigerator. He's not just the smartest man on Earth. He's also pretty funny, I guess. But wouldn't you slow down when you come out the other end, like as you come out with this blinding speed, would in the other mouth of the wormhole slow you down, like try to suck you back in. Yeah, sort of like rolling down a hill on a roller coaster, and then you roll up the other side, so you gain speed as you fall in, and then you lose the speed as you come out. And so in theory, you know, sort of like jumping through a hole in the earth, you should come out the other side with no velocity, right right, And so then they would have to make the black hole big enough not just to fit you, but also for you to raise your hands right like in a roller coaster for the thrill exactly, And they have to put a camera somewhere to capture and as you go in and then sell it to you for fifty dollars on the other side. All right, well, so warmos are possible, and it might be possible to make one and keep one open and make one big enough for us to fit in, but it requires some of these sort of extreme theories and some of these sort of extreme theoretical concepts to be true. So, Daniel, what does it all mean? What does it mean about our understanding about how space works? It's a really exciting feel to try to keep up with because people are really like playing with what space can do, and every time they develop one of these theories, they get like more insight into like what space is and how it works, and sort of sort of like space engineering, you know, or spacetime engineering. I think it's pretty fun stuff. And there's an idea like around the edges of this which has been bubbling around in theoretical physics for a long time, which I think is really deep and it's connected to this, and that's the idea that space itself might be built using wormholes, like we talked earlier about how space is connected and this piece is connected to that piece, and you know you are in a part of space you can go to the part of space that's next to you. You can't just jump from here to Alpha Centauri. There's this connectedness in space. People don't really understand what that is or how it works. One idea of what space is is that maybe it's these like little space pixels that are somehow woven together to make this fabric of space. And the thing that does that weaving, perhaps is quantum entanglement. Like maybe this bit of space is entangled with that bit of space, And it might just be that at the fundamental level that entanglement is accomplished by wormholes. Like maybe the idea is keep a wormhole open by quantum entangling its edges. Maybe that's the way wormholes are. Maybe all of the universe, every bit of space, is just like a bunch of wormholes connected together. Every pixel wormhold together with all of its neighboring pixels. Well, it's crazy you're saying, Like, instead of space being this giant blob or something, maybe it's just a whole bunch of little blobs that are pixel size, which is the smallest unit of space, and they're all sort of a threat together by wormholes. Yeah, otherwise they would all just be disconnected, and maybe the whole idea of space as this like a thing you can move through, comes out of weaving space together into this fabric. And it might be the wormholes are the things that weave it together, that connect various pieces of space, and so that if we try to build a wormhole between like our space and some space somewhere in Alpha Centauri, it could be a very natural thing to do, because what we're doing is like just sort of like engineering the fundamental structure of space time itself interesting. You just need like a special quantum needle exactly, and and entangled threats exactly, weaving singularities so it space might be all wormholes basically, right like when I move from here to my house or here to the bathroom, actually sort of like weaving through tiny little wormholes all the time. It certainly could be all right. Well, I guess these are all pretty exciting ideas and and makes me think that maybe it is possible to get to other parts of the universe using wormholes. It sounds like it's theoretically possible, and there are some pretty smart people thinking about how to make one and keep one open exactly. It's a really fun area and I'm pretty sure that in a hundred years people look back at these ideas and think, oh, those were foolish, naive ideas. But these are the ideas along the path to figuring it out. You can't just go from here to a deep understanding of the universe. You've got to somehow assemble that understanding. You gotta go step by step. And so we're on step one of an unknown number of steps. Yeah, and all we need is three thousand light year y hole using dark matter, which we we don't understand yet. Inside refrigerator. All right, Well, thanks for joining us. We hope you enjoyed that. See you next time. Yeah, thanks for listening, and remember that. Daniel and Jorge Explain the Universe is a production of I Heart Radio. For more podcast for my Heart Radio, visit the I heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.