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Here's a little secret. Most smartphone deals aren't that exciting. To be honest, they're barely worth mentioning. But then there's AT and T and their best deals. Those are quite exciting.

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Traveling to the stars always seems so exciting in the movies. At least, it involves lots of dramatic wooshing noises. There's some streaks of flight, exotic planets to visit, and probably dramatic meetings with aliens. You also noticed in those movies, everybody's always well rested. They walk everywhere with a purpose, and they're wearing a well fitting uniform, and everybody seems to be in great shape. I don't know about you, but that's not like any travel experience that I've ever had. Realistically, a trip to the stars is more likely to involve tired people eating junk food and shopping at duty free stores. It probably resembles the experience of a cruise ship more than a trip on the Star Trek Enterprise. So load up on the buffet because we're going to Alpha Centauri. Hi. I'm Daniel. I'm a particle physicist, and you're listening to the podcast Daniel and Jorge Explain the Universe, brought to you by iHeartRadio. Orge is still away. He's my friend and collaborator and usual co host of this podcast in which we zoom all around the universe and try to find interesting, amazing facts and talk to you about them and explain them to you so that you really understand them. So they're not just words that you hear coming out of your mouth to try to impress your friends, but actual concepts in your mind that you can manipulate and talk about with intelligence, and today we're going to do more than just zoom around the universe. We're going to talk about how we're going to zoom around the universe. And if you're like me, you like looking up at the stars and imagining what it's like to be over there. What would it be like to orbit that other star? Are there planets over there? Could you put your foot on them? And I think there's a natural human desire to explore, to see other parts of the world and other parts of the universe. Well, the problem is that the universe is big, frustratingly big, stubbornly huge. Like the nearest star, the closest one to our Sun, is four point two light years away. It's called proxima centauri. That's a huge distance by any measure. If you use kilometers, which is sort of absurd, you get a number like forty trillion kilometers. It's sort of like we're on a little island in the middle of nowhere. If anybody out there has been to like Tahiti or a tiny little dot in the Pacific Ocean, you know the feeling of standing on an island and being surrounded by water and feeling like maybe there's nothing else out there. That's sort of the way I feel standing on Earth. We're in an ocean of space, and everything else out there is super duper far away. These distances, they're sort of hard to grasp, you know. Let's talk about how long would it take to get there. Well, if you traveled on speeds that are familiar here on Earth, like if you traveled at the speed of a car, then going forty trillion kilometers would take you about forty five million years. Even if you traveled at the speed of an airplane, it would take you five million years. Now, nobody's actually gonna drive to Alpha Centari or even fly an airplane. You can imagine some technology that might take you there in a spaceship at a respectable fraction in the speed of light, maybe five percent or ten percent. Even those kind of ships would take hundreds of years to get to Alpha Centauri. And who wants to board a ship knowing that they're going to die on it? And who wants to have kids on a ship knowing that those kids will probably never set foot on land, any land on any planet. This kind of structure, of course, is called the colony ship, where you have generations upon generations of humanity living on board, and then eventually one day some group of people generations down the road get to actually land on that planet. That could work. That's one way to explore the universe. But I want more. I'm greedy and I want to walk on those other planets myself. But even if you traveled like at the speed of light, it would still take you four years to get to proximates centauri. That's a long time to spend eating junk food and shopping duty free, and so it makes you wonder is there any way to get there faster? So today on the podcast, we're asking the question can we build a warp drive to travel the universe? I want to take a step back and talk about how we travel the universe and sort of the size of our horizons. You know, one hundred years ago or five hundred years ago, things on the other side of the Earth seemed unreachable. To travel to China, for example, would take months or years. It's not the kind of thing you could do in an afternoon or even a week. Now. Of course, because we have better technology for transportation, it's not a big deal to go to the other side of the planet. You can go there and come back a couple of days later. So the scope of the universe that we can explore has expanded, and has expanded because our technology is improved. And so the thing to understand is that it's not actually distances that are important. The number, the actual number of kilometers between you and another location isn't the thing that determines whether or not it's in sort of your sphere of explorability. What determines that is the maximum speed you can travel. Back when the fastest thing you could do is ride a horse, then going across country was a huge endeavor, not something you can do in days and weeks. Going to the other side of the planet in less than months or years was impossible. Now, of course, the top speed we can travel is much much higher. We have airplanes. It can go hundreds of kilometers per hour. And so our sphere of explorability now encompasses essentially the entire Earth. And if you talk to old people who remember the day when those kind of technologies weren't widely available to them, the world seem to have suddenly gotten smaller. So you might wonder, like, can science just continue? Can science deliver an engine that brings the stars into our sphere of explorability, so that you'll be talking one day to your great great grandkids about how amazing it is that you can go to Alpha Centauri and come back in the same afternoon. That's the question we're focusing on today. Is it possible for science to bring those stars into our grasp. So before we dig into the question, I of course walked around campus that you see Airvine, and I asked people if they thought that a warp drive was possible. How much faith did they have in science or do they think that we have them already. Before you hear these answers, think to yourself, do you believe a warp drive is possible now or in the future. Here's what people that you see Airvine had to say.

Traveling to the stars always seems so exciting in the movies. At least, it involves lots of dramatic wooshing noises. There's some streaks of flight, exotic planets to visit, and probably dramatic meetings with aliens. You also noticed in those movies, everybody's always well rested. They walk everywhere with a purpose, and they're wearing a well fitting uniform, and everybody seems to be in great shape. I don't know about you, but that's not like any travel experience that I've ever had. Realistically, a trip to the stars is more likely to involve tired people eating junk food and shopping at duty free stores. It probably resembles the experience of a cruise ship more than a trip on the Star Trek Enterprise. So load up on the buffet because we're going to Alpha Centauri. Hi. I'm Daniel. I'm a particle physicist, and you're listening to the podcast Daniel and Jorge Explain the Universe, brought to you by iHeartRadio. Orge is still away. He's my friend and collaborator and usual co host of this podcast in which we zoom all around the universe and try to find interesting, amazing facts and talk to you about them and explain them to you so that you really understand them. So they're not just words that you hear coming out of your mouth to try to impress your friends, but actual concepts in your mind that you can manipulate and talk about with intelligence, and today we're going to do more than just zoom around the universe. We're going to talk about how we're going to zoom around the universe. And if you're like me, you like looking up at the stars and imagining what it's like to be over there. What would it be like to orbit that other star? Are there planets over there? Could you put your foot on them? And I think there's a natural human desire to explore, to see other parts of the world and other parts of the universe. Well, the problem is that the universe is big, frustratingly big, stubbornly huge. Like the nearest star, the closest one to our Sun, is four point two light years away. It's called proxima centauri. That's a huge distance by any measure. If you use kilometers, which is sort of absurd, you get a number like forty trillion kilometers. It's sort of like we're on a little island in the middle of nowhere. If anybody out there has been to like Tahiti or a tiny little dot in the Pacific Ocean, you know the feeling of standing on an island and being surrounded by water and feeling like maybe there's nothing else out there. That's sort of the way I feel standing on Earth. We're in an ocean of space, and everything else out there is super duper far away. These distances, they're sort of hard to grasp, you know. Let's talk about how long would it take to get there. Well, if you traveled on speeds that are familiar here on Earth, like if you traveled at the speed of a car, then going forty trillion kilometers would take you about forty five million years. Even if you traveled at the speed of an airplane, it would take you five million years. Now, nobody's actually gonna drive to Alpha Centari or even fly an airplane. You can imagine some technology that might take you there in a spaceship at a respectable fraction in the speed of light, maybe five percent or ten percent. Even those kind of ships would take hundreds of years to get to Alpha Centauri. And who wants to board a ship knowing that they're going to die on it? And who wants to have kids on a ship knowing that those kids will probably never set foot on land, any land on any planet. This kind of structure, of course, is called the colony ship, where you have generations upon generations of humanity living on board, and then eventually one day some group of people generations down the road get to actually land on that planet. That could work. That's one way to explore the universe. But I want more. I'm greedy and I want to walk on those other planets myself. But even if you traveled like at the speed of light, it would still take you four years to get to proximates centauri. That's a long time to spend eating junk food and shopping duty free, and so it makes you wonder is there any way to get there faster? So today on the podcast, we're asking the question can we build a warp drive to travel the universe? I want to take a step back and talk about how we travel the universe and sort of the size of our horizons. You know, one hundred years ago or five hundred years ago, things on the other side of the Earth seemed unreachable. To travel to China, for example, would take months or years. It's not the kind of thing you could do in an afternoon or even a week. Now. Of course, because we have better technology for transportation, it's not a big deal to go to the other side of the planet. You can go there and come back a couple of days later. So the scope of the universe that we can explore has expanded, and has expanded because our technology is improved. And so the thing to understand is that it's not actually distances that are important. The number, the actual number of kilometers between you and another location isn't the thing that determines whether or not it's in sort of your sphere of explorability. What determines that is the maximum speed you can travel. Back when the fastest thing you could do is ride a horse, then going across country was a huge endeavor, not something you can do in days and weeks. Going to the other side of the planet in less than months or years was impossible. Now, of course, the top speed we can travel is much much higher. We have airplanes. It can go hundreds of kilometers per hour. And so our sphere of explorability now encompasses essentially the entire Earth. And if you talk to old people who remember the day when those kind of technologies weren't widely available to them, the world seem to have suddenly gotten smaller. So you might wonder, like, can science just continue? Can science deliver an engine that brings the stars into our sphere of explorability, so that you'll be talking one day to your great great grandkids about how amazing it is that you can go to Alpha Centauri and come back in the same afternoon. That's the question we're focusing on today. Is it possible for science to bring those stars into our grasp. So before we dig into the question, I of course walked around campus that you see Airvine, and I asked people if they thought that a warp drive was possible. How much faith did they have in science or do they think that we have them already. Before you hear these answers, think to yourself, do you believe a warp drive is possible now or in the future. Here's what people that you see Airvine had to say.

I honestly don't know enough about that to even answer it.

I honestly don't know enough about that to even answer it.

I don't know what a warp drive is, Yes, I say it. You think like possible in the future, are possible today?

I don't know what a warp drive is, Yes, I say it. You think like possible in the future, are possible today?

You know?

You know?

I think so.

I think so.

I remember seeing a guide that proved that.

I remember seeing a guide that proved that.

It was possible, but you would have to use a lot of energy, and it was changing the space time ahead and afterwards.

It was possible, but you would have to use a lot of energy, and it was changing the space time ahead and afterwards.

Maybe like today or in the future.

Maybe like today or in the future.

Or in the future today. Probably not at this point.

Or in the future today. Probably not at this point.

I think it can well, certainly not now.

I think it can well, certainly not now.

So of all the questions I've ever asked people on the street, this is the one that maybe got the broadest set of responses. You have people saying I don't know what a warp drive is. You have people saying very confidently, yeah, I'm pretty sure we'll figure it out. To people saying I think people could build them today. It's crazy. And let me clarify again what I mean by a warp drive. I mean an engine that could take a spaceship from here to somewhere else faster than light could get there. That's the goal. We don't want to travel just close to the speed of light, because even that would take us years and years to get anywhere. Year of stars four light years away, but other stars, many more stars that we'd love to visit in our galaxy are hundreds or thousands of light years away. Remember that our galaxy is one hundred thousand light years across, and the next galaxy is millions of light years away. So if we want to explore the universe, if we want to find alien life, if we want to see crazy things that would never happen in our neighborhood of the universe. After all, that's what's so amazing about traveling. Then we need to develop some sort of technology that lets us get to places faster than light would get there. And that's the question we're going to dig into today. But first let's take a quick break. With big wireless providers, what you see is never what you get. Somewhere between the store and your first month's bill, the price you thought you were paying magically skyrockets. With Mintmobile, You'll never have to worry about gotcha's ever again. When Mint Mobile says fifteen dollars a month for a three month plan, they really I've used mint Mobile and the call quality is always so crisp and so clear I can recommend it to you. So say bye bye to your overpriced wireless plans, jaw dropping monthly bills and unexpected overages. You can use your own phone with any Mint Mobile plan and bring your phone number along with your existing contacts. So ditch your overpriced wireless with mint Mobiles deal and get three months a premium wireless service for fifteen bucks a month. To get this new customer offer and your new three month premium wireless plan for just fifteen bucks a month. Go to mintmobile dot com slash universe. That's mintmobile dot com slash universe. Cut your wireless bill to fifteen bucks a month. At mintmobile dot com slash universe, forty five dollars upfront payment required equivalent to fifteen dollars per month new customers on first three month plan only speeds slower about forty gigabytes on unlimited plan. Additional taxi spees and restrictions apply. See mint mobile for details.

So of all the questions I've ever asked people on the street, this is the one that maybe got the broadest set of responses. You have people saying I don't know what a warp drive is. You have people saying very confidently, yeah, I'm pretty sure we'll figure it out. To people saying I think people could build them today. It's crazy. And let me clarify again what I mean by a warp drive. I mean an engine that could take a spaceship from here to somewhere else faster than light could get there. That's the goal. We don't want to travel just close to the speed of light, because even that would take us years and years to get anywhere. Year of stars four light years away, but other stars, many more stars that we'd love to visit in our galaxy are hundreds or thousands of light years away. Remember that our galaxy is one hundred thousand light years across, and the next galaxy is millions of light years away. So if we want to explore the universe, if we want to find alien life, if we want to see crazy things that would never happen in our neighborhood of the universe. After all, that's what's so amazing about traveling. Then we need to develop some sort of technology that lets us get to places faster than light would get there. And that's the question we're going to dig into today. But first let's take a quick break. With big wireless providers, what you see is never what you get. Somewhere between the store and your first month's bill, the price you thought you were paying magically skyrockets. With Mintmobile, You'll never have to worry about gotcha's ever again. When Mint Mobile says fifteen dollars a month for a three month plan, they really I've used mint Mobile and the call quality is always so crisp and so clear I can recommend it to you. So say bye bye to your overpriced wireless plans, jaw dropping monthly bills and unexpected overages. You can use your own phone with any Mint Mobile plan and bring your phone number along with your existing contacts. So ditch your overpriced wireless with mint Mobiles deal and get three months a premium wireless service for fifteen bucks a month. To get this new customer offer and your new three month premium wireless plan for just fifteen bucks a month. Go to mintmobile dot com slash universe. That's mintmobile dot com slash universe. Cut your wireless bill to fifteen bucks a month. At mintmobile dot com slash universe, forty five dollars upfront payment required equivalent to fifteen dollars per month new customers on first three month plan only speeds slower about forty gigabytes on unlimited plan. Additional taxi spees and restrictions apply. See mint mobile for details.

AI might be the most important new computer technology ever. It's storming every industry and literally billions of dollars are being invested, so buckle up. The problem is that AI needs a lot of speed and processing power. How do you compete without cost spiraling out of control. It's time to upgrade to the next generation of the cloud. Oracle Cloud Infrastructure or OCI. OCI is a single platform for your infrastructure, database, application development, and AI needs. OCI has four to eight times the bandwidth of other clouds, offers one consistent price instead of variable regional pricing, and of course nobody does data better than Oracle. So now you can train your AI models at twice the speed and less than half the cost. Of other clouds if you want to do more and spend less, like Uber eight by eight and Data Bricks Mosaic. Take a free test drive of Oci at Oracle dot com slash Strategic. That's Oracle dot com slash Strategic Oracle dot com slash Strategic.

AI might be the most important new computer technology ever. It's storming every industry and literally billions of dollars are being invested, so buckle up. The problem is that AI needs a lot of speed and processing power. How do you compete without cost spiraling out of control. It's time to upgrade to the next generation of the cloud. Oracle Cloud Infrastructure or OCI. OCI is a single platform for your infrastructure, database, application development, and AI needs. OCI has four to eight times the bandwidth of other clouds, offers one consistent price instead of variable regional pricing, and of course nobody does data better than Oracle. So now you can train your AI models at twice the speed and less than half the cost. Of other clouds if you want to do more and spend less, like Uber eight by eight and Data Bricks Mosaic. Take a free test drive of Oci at Oracle dot com slash Strategic. That's Oracle dot com slash Strategic Oracle dot com slash Strategic.

If you love iPhone, you'll love Apple Card. It's the credit card designed for iPhone. It gives you unlimited daily cash back that can earn four point four zero percent annual percentage yield. When you open a high Yield savings account through Applecard, apply for Apple Card in the wallet app, subject to credit approval. Savings is available to Apple Card owners subject to eligibility. Apple Card and Savings by Goldman Sachs Bank USA, Salt Lake City Branch Member, FDIC, terms and more at applecard dot com. We're back and we're talking about whether we can build an engine. We could put in a starship that would take us somewhere faster than light would get there. So the naturally, the first question you might ask is can we travel faster than light? And here physics is pretty specific. Physics says no, nothing can move through space faster than light moves through space. And there's already a little clue there. There's a little wrinkle, a little loophole you might want to try to take advantage of. Nothing moves through space faster than light moves through that space. Those of you out there who know something about physics and particle physics might have heard of Cherenkov light. For example, when a muon moves really fast through ice, it can emit this special kind of radiation, a blue glow called charankof light, and it does that because it's moving faster than the light moves through the ice. Right, So muons can go through ice faster than light goes through ice, and they produce this charankoff radiation sort of for the same reason that a plane produces a sonic boom. The muons are traveling faster than the light they make, and so the light they catch up to the light they make and they're adding to it creates this wake, right, So it's sort of like an aluminal bloom, not a sonic boom. But that doesn't mean that you could travel through space faster than light can travel through space. It just means that in some materials, some particles can travel through that material faster than light travels through that material. But the speed of light in a vacuum is still the absolute top speed anything can move through space. It just so happens that ice slows light down more than it slows down on Muance, for example. So you get this special little loophole. But loopholes are a key. We want to pay very careful attention to exactly what the laws of physics say so we can try to exploit them later. But back to traveling faster than the speed of light. You've probably heard me say it and learned it in lots of other places. It's impossible to travel faster than the speed of light, and not just because it would require you to have infinite mass or anything else, but just because the universe does not allow it. According to special relativity, there is no way to get faster than the speed of light. In fact, you can't even travel at the speed of light if you have any mass at all. Only massless things like photons and gravitons can travel at the speed of light. So unless you have a way to transform your spaceship into light and beam it over there, you can't even travel at the speed of light. And you might ask, okay, but that's the way we think today, that's today's physics idea of the way the universe works. Isn't it possible that we're wrong. That's a good point. And I'm always saying on this podcast and in other places that we have so much to learn about the universe, that we've learned approximately zero percent of the physics of the universe. And that might give you hope. It might give you the idea that, well, there could be a crack in that armor, or maybe later we'll learn that that was wrong. And you know, there's always a possibility, there's always a chance that future physics will discover that that was not correct. But I'd be very surprised if that were true. This is the kind of thing that we have tested extensively. We've come up with all sorts of scenarios to try this. We've tested it out the wazoo. We've even tested it into the wazoo. And it's the cornerstone of modern quantum field theory. The special relativity and the Lorentz groups that we used to build quantum field theory would be totally broken if special relativity was wrong. And this is the basic assumption of special relativity. So it's one of the most well tested axioms in all of modern physics that nothing can travel faster than the speed of light. So I'd be really shocked if that was cracked. If we found a way to move through space faster than the speed of light. Now, I can't rule it out definitively, because who knows what amazing things the future physics will discover. Maybe we all live in a simulation and there's a way to rewrite the program so that things change, or who knows what. I can't rule it out forever. But I don't think that that's a fruitful path to developing a warp drive. And even if you were to find a crack in that armor, you'd still have all sorts of practical problems, like accelerating to really high speeds. Say you want to go a million light years somewhere, Traveling through space at those high speeds is difficult because you have to accelerate to those high speeds, which can take a long long time and a huge amount of energy. So theoretically I think it's very unlikely, and practically I don't think it's a good approach. But I think the lesson to learn from that thought experiment is that we should look for loopholes. After all, what is our goal is our goal to travel faster than light. I don't have an inherent desire to move through space faster than the speed of light. What I want to do is I want to get to some distance star faster than that light would get there. I want to get to have Proximus centauri, for example, in less than four years. I'd love to do it in an afternoon. So my goal is not actually to travel through space faster than the speed of light. What I want to do is to get there faster than light would get there. And that sounds like it's basically saying the same thing, but there's an important difference because the rule, the actual limitation according to special relativity, is not about arriving somewhere faster than the speed of light. Wouldn't move through that space. It's about moving through space faster than the speed of light. There's an opportunity there. Instead of just moving through space and accepting that the space between here and Proximus centauri is four million light years, what if we could somehow manipulate that space. What if we could squeeze that space or twist it or bend it or do something to it so that we didn't have to move through as much space, so we could keep under that and that speed limit but still get there in a shorter amount of time. That's the key, and I think some credit we owe here to science fiction authors because a lot of these ideas, the possibility of getting somewhere faster than life could get there, come originally from science fiction. Those people are thinking about the impact of new technologies and what the future might look like, and so their job is to think most creatively, to think how could we change human society or how had human society changed if we had this new technology. So they're unbound by the rules of physics and certainly by the practicalities of the engineering. It's free to think inventively about how to change our lives and explore the universe. So kudos to them for coming up with the whole concept of a warp drive, and of course I love it in all of those movies. But the next step, once the science fiction authors have come up with the idea is for physicists to figure out how to make it possible. To take an idea from WHOA that would be super awesome, wish we could do that to you know, there might be a way that we could do it, and then figuring out how to sort of avoid the physics blockades, to work away around the rules of the universe that seem to be preventing that from being possible. And once the physicists have figured out how to make it sort of theoretically possible, then to hand it off to the next people in the chain, which are of course the engineers, because they have to actually build it, you know, design it and build it and make it practical, build something which costs less than ten quadrillion dollars or use less than the mass of the universe. So that's the sort of progression of how you go from I really want this thing to you know, boarding the next flight to Alpha Centauri at four o'clock. Start with the science fiction, move through the physicists, and get to the engineers. So where are we on that step of the process. Clearly, science fiction authors have thought of the idea of warp drive, and now we're in the step where physicists are thinking what could we do, what loopholes could we exploit? And so, as I mentioned a few moments ago, the idea here is not to move through space faster than light could move through space, because that's just forbidden. But instead to try to manipulate space. And if manipulate space sounds weird to you, then get ready for some weirdness because we're going to do a lot of this on the podcast, where we use normal sounding words together in a way that might make no sense initially, and that's because we're pushing the boundaries of what we can do and what we can understand, and doing that requires challenging our assumptions. And so what does it mean to manipulate space? Well, first you have to let go of maybe your initial concept of space, space being emptiness, space being nothing. If I say the words space and you close your eyes, do you imagine twinkling stars out there?

If you love iPhone, you'll love Apple Card. It's the credit card designed for iPhone. It gives you unlimited daily cash back that can earn four point four zero percent annual percentage yield. When you open a high Yield savings account through Applecard, apply for Apple Card in the wallet app, subject to credit approval. Savings is available to Apple Card owners subject to eligibility. Apple Card and Savings by Goldman Sachs Bank USA, Salt Lake City Branch Member, FDIC, terms and more at applecard dot com. We're back and we're talking about whether we can build an engine. We could put in a starship that would take us somewhere faster than light would get there. So the naturally, the first question you might ask is can we travel faster than light? And here physics is pretty specific. Physics says no, nothing can move through space faster than light moves through space. And there's already a little clue there. There's a little wrinkle, a little loophole you might want to try to take advantage of. Nothing moves through space faster than light moves through that space. Those of you out there who know something about physics and particle physics might have heard of Cherenkov light. For example, when a muon moves really fast through ice, it can emit this special kind of radiation, a blue glow called charankof light, and it does that because it's moving faster than the light moves through the ice. Right, So muons can go through ice faster than light goes through ice, and they produce this charankoff radiation sort of for the same reason that a plane produces a sonic boom. The muons are traveling faster than the light they make, and so the light they catch up to the light they make and they're adding to it creates this wake, right, So it's sort of like an aluminal bloom, not a sonic boom. But that doesn't mean that you could travel through space faster than light can travel through space. It just means that in some materials, some particles can travel through that material faster than light travels through that material. But the speed of light in a vacuum is still the absolute top speed anything can move through space. It just so happens that ice slows light down more than it slows down on Muance, for example. So you get this special little loophole. But loopholes are a key. We want to pay very careful attention to exactly what the laws of physics say so we can try to exploit them later. But back to traveling faster than the speed of light. You've probably heard me say it and learned it in lots of other places. It's impossible to travel faster than the speed of light, and not just because it would require you to have infinite mass or anything else, but just because the universe does not allow it. According to special relativity, there is no way to get faster than the speed of light. In fact, you can't even travel at the speed of light if you have any mass at all. Only massless things like photons and gravitons can travel at the speed of light. So unless you have a way to transform your spaceship into light and beam it over there, you can't even travel at the speed of light. And you might ask, okay, but that's the way we think today, that's today's physics idea of the way the universe works. Isn't it possible that we're wrong. That's a good point. And I'm always saying on this podcast and in other places that we have so much to learn about the universe, that we've learned approximately zero percent of the physics of the universe. And that might give you hope. It might give you the idea that, well, there could be a crack in that armor, or maybe later we'll learn that that was wrong. And you know, there's always a possibility, there's always a chance that future physics will discover that that was not correct. But I'd be very surprised if that were true. This is the kind of thing that we have tested extensively. We've come up with all sorts of scenarios to try this. We've tested it out the wazoo. We've even tested it into the wazoo. And it's the cornerstone of modern quantum field theory. The special relativity and the Lorentz groups that we used to build quantum field theory would be totally broken if special relativity was wrong. And this is the basic assumption of special relativity. So it's one of the most well tested axioms in all of modern physics that nothing can travel faster than the speed of light. So I'd be really shocked if that was cracked. If we found a way to move through space faster than the speed of light. Now, I can't rule it out definitively, because who knows what amazing things the future physics will discover. Maybe we all live in a simulation and there's a way to rewrite the program so that things change, or who knows what. I can't rule it out forever. But I don't think that that's a fruitful path to developing a warp drive. And even if you were to find a crack in that armor, you'd still have all sorts of practical problems, like accelerating to really high speeds. Say you want to go a million light years somewhere, Traveling through space at those high speeds is difficult because you have to accelerate to those high speeds, which can take a long long time and a huge amount of energy. So theoretically I think it's very unlikely, and practically I don't think it's a good approach. But I think the lesson to learn from that thought experiment is that we should look for loopholes. After all, what is our goal is our goal to travel faster than light. I don't have an inherent desire to move through space faster than the speed of light. What I want to do is I want to get to some distance star faster than that light would get there. I want to get to have Proximus centauri, for example, in less than four years. I'd love to do it in an afternoon. So my goal is not actually to travel through space faster than the speed of light. What I want to do is to get there faster than light would get there. And that sounds like it's basically saying the same thing, but there's an important difference because the rule, the actual limitation according to special relativity, is not about arriving somewhere faster than the speed of light. Wouldn't move through that space. It's about moving through space faster than the speed of light. There's an opportunity there. Instead of just moving through space and accepting that the space between here and Proximus centauri is four million light years, what if we could somehow manipulate that space. What if we could squeeze that space or twist it or bend it or do something to it so that we didn't have to move through as much space, so we could keep under that and that speed limit but still get there in a shorter amount of time. That's the key, and I think some credit we owe here to science fiction authors because a lot of these ideas, the possibility of getting somewhere faster than life could get there, come originally from science fiction. Those people are thinking about the impact of new technologies and what the future might look like, and so their job is to think most creatively, to think how could we change human society or how had human society changed if we had this new technology. So they're unbound by the rules of physics and certainly by the practicalities of the engineering. It's free to think inventively about how to change our lives and explore the universe. So kudos to them for coming up with the whole concept of a warp drive, and of course I love it in all of those movies. But the next step, once the science fiction authors have come up with the idea is for physicists to figure out how to make it possible. To take an idea from WHOA that would be super awesome, wish we could do that to you know, there might be a way that we could do it, and then figuring out how to sort of avoid the physics blockades, to work away around the rules of the universe that seem to be preventing that from being possible. And once the physicists have figured out how to make it sort of theoretically possible, then to hand it off to the next people in the chain, which are of course the engineers, because they have to actually build it, you know, design it and build it and make it practical, build something which costs less than ten quadrillion dollars or use less than the mass of the universe. So that's the sort of progression of how you go from I really want this thing to you know, boarding the next flight to Alpha Centauri at four o'clock. Start with the science fiction, move through the physicists, and get to the engineers. So where are we on that step of the process. Clearly, science fiction authors have thought of the idea of warp drive, and now we're in the step where physicists are thinking what could we do, what loopholes could we exploit? And so, as I mentioned a few moments ago, the idea here is not to move through space faster than light could move through space, because that's just forbidden. But instead to try to manipulate space. And if manipulate space sounds weird to you, then get ready for some weirdness because we're going to do a lot of this on the podcast, where we use normal sounding words together in a way that might make no sense initially, and that's because we're pushing the boundaries of what we can do and what we can understand, and doing that requires challenging our assumptions. And so what does it mean to manipulate space? Well, first you have to let go of maybe your initial concept of space, space being emptiness, space being nothing. If I say the words space and you close your eyes, do you imagine twinkling stars out there?

Sure?

Sure?

But what's between us and those stars? Maybe you imagine some sort of wireframe grid of emptiness, right, just like the rulers. They're just like the notches on a ruler between here and there. And you might think, well, that's just sort of human interpretations to an overlay we put onto the nothingness that's between here and space. But space is not nothingness, and I'm not talking about the quantum fields that are inside it or the particles that are zooming around, or the little bits of radiation. I'm not making an argument that space is never actually empty. I'm saying that space is more than just the backdrop. It's not just the stage on which the universe plays out. Space itself is dynamical. It can do things that nothingness can't, like what well space can bend. We've talked on this podcast about what gravity is. Newton thought about gravity as a force between two objects, pulling them together, but Einstein showed us that it's actually more natural to talk about gravity as the bending of space when the presence of mass and energy. So, for example, you can imagine the Earth moving around the Sun, not as the Sun pulling on the Earth using some force, but the Sun distorting space so that it's most natural for the Earth to move in this orbit, to blend its velocity with the bending of space to come up with a stable motion. So it's actually quite an old idea that you could manipulate space. That space is not nothing, that it can bend. This is an idea from Einstein's theory of relativity that space can bend. So already that breaks the idea that space is nothing, and it opens the door to space doing other things right, space can bend. It can also ripple. We've seen gravitational waves when huge objects like binary black holes accelerate around each other and collapse into a single black hole. Then you get ripples in space. What does that mean. It doesn't mean anything if space is emptiness. But it means something if space is a thing, if it has properties, if it can do stuff, if it can be distorted and twisted. So we're familiar with space bending due to gravity. We're recently aware the space can do things like ripple, and space can also expand we know from the Big Bang. We know from dark energy that space is expanding. Right now, sixty percent of all the energy in the universe is devoted to something we call dark energy, which we don't understand. But whatever it is is expanding space all the time. It's creating new space between us and other galaxies. Right now, it's doing it. It's making a new space between you and the person sitting next to you. It's everywhere. So space can do all of these things. And the amazing thing is that there's no limit to it. As far as we know, there's no speed limit to how fast you can shrink or expand space. Take for example, the Big Bang. What happened in the very first moments of the universe. The universe expanded very, very rapidly, much faster than the speed of light, much faster than light could have moved through that space. That's why, for example, the universe now is larger than the speed of light times the age of the universe. How is that possible? If nothing can travel faster than the speed of light, how could stuff get further away from each other then light could have traveled through that space. The answer, of course is space expanded inflation. And the Big Bang is more than just stuff moving through space, it's space itself expanding. So this is an idea we're familiar with that space can expand you might almost say the universe warped. You might even think of the Big Bang as a huge warping of space and dark energy now is the continued warping of space, all right? So that gives us an opportunity. We're talking about how to get somewhere faster than light would get us there. And the idea we're working towards is not to try to move through space using some specially fast, zippy engine but to change the nature of the problem by shrinking the space. And that's the idea for a warp drive. That's how we might actually make it work. The idea is like this, you want to get from here to Alpha Centauri. How do you do it? Well, you don't just move through that space. You somehow shrink the space between you and that star. You squeeze it, just the way the Sun changes the shape the whole nature space in the Solar System. Use some mass and energy. In a moment, we'll talk about the details of what we know about how engineers might actually make that happen. Use mass and energy in some way to squeeze the space so that instead of having four point two light years between you and the star, you have four point two meters. And similarly, you turn around behind you, and instead of having four point two meters between you and where you've left, you can expand the space behind you. So the idea for a warp drive is something which shrinks the space in front of you and expands the space behind you. In that way, you're sort of inside the little bubble, and inside that bubble you don't even need to move with respect to space. It's sort of like, instead of running through the airport, you stand on a moving walkway and the walkway moves for you. That's not a perfect analogy because in that analogy the walkway is still moving, and I'd be talking about like pulling the terminal closer to you instead of running there and stretching the distance behind you. But that's the idea. So you'd build the sort of warp drive that shrinks the space in front of you, expands the space behind you, and then you're in this sort of warp bubble, and then you pop out of the bubble right and then you're there. And because there's no limit on how fast you can expand space or how much you can shrink space in theory, there's no limit to how far a warp drive could take you, as long as you have the ability to do this and the energy budget to get it done. So let's talk about how you might actually build a warp drive and how much progress science and engineers and science fiction authors have made towards making it to reality. But first, let's take another break. When you pop a piece of cheese into your mouth or enjoy a rich spoonful of greeky yogurt, you're probably not thinking about the environmental impact of each and every bite, But the people in the dairy industry are. US Dairy has set themselves some ambitious sustainability goals, including being greenhouse gas neutral by twenty to fifty. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. Take water, for example, most dairy farms reuse water up to four times the same water cools the milk, cleans equipment, washes the barn, and irrigates the crops. How is US Dairy tackling greenhouse gases. Many farms use anaerobic digestors that turn the methane from maneuver into renewable energy that can power farms, towns, and electric cars. So the next time you grab a slice of pizza or lick an ice cream cone, know that dairy farmers and processors around the country are using the latest practices and innovations to provide the nutrient dense dairy products we love with less of an impact. Visit US dairy dot com slash sustainability to learn more.

But what's between us and those stars? Maybe you imagine some sort of wireframe grid of emptiness, right, just like the rulers. They're just like the notches on a ruler between here and there. And you might think, well, that's just sort of human interpretations to an overlay we put onto the nothingness that's between here and space. But space is not nothingness, and I'm not talking about the quantum fields that are inside it or the particles that are zooming around, or the little bits of radiation. I'm not making an argument that space is never actually empty. I'm saying that space is more than just the backdrop. It's not just the stage on which the universe plays out. Space itself is dynamical. It can do things that nothingness can't, like what well space can bend. We've talked on this podcast about what gravity is. Newton thought about gravity as a force between two objects, pulling them together, but Einstein showed us that it's actually more natural to talk about gravity as the bending of space when the presence of mass and energy. So, for example, you can imagine the Earth moving around the Sun, not as the Sun pulling on the Earth using some force, but the Sun distorting space so that it's most natural for the Earth to move in this orbit, to blend its velocity with the bending of space to come up with a stable motion. So it's actually quite an old idea that you could manipulate space. That space is not nothing, that it can bend. This is an idea from Einstein's theory of relativity that space can bend. So already that breaks the idea that space is nothing, and it opens the door to space doing other things right, space can bend. It can also ripple. We've seen gravitational waves when huge objects like binary black holes accelerate around each other and collapse into a single black hole. Then you get ripples in space. What does that mean. It doesn't mean anything if space is emptiness. But it means something if space is a thing, if it has properties, if it can do stuff, if it can be distorted and twisted. So we're familiar with space bending due to gravity. We're recently aware the space can do things like ripple, and space can also expand we know from the Big Bang. We know from dark energy that space is expanding. Right now, sixty percent of all the energy in the universe is devoted to something we call dark energy, which we don't understand. But whatever it is is expanding space all the time. It's creating new space between us and other galaxies. Right now, it's doing it. It's making a new space between you and the person sitting next to you. It's everywhere. So space can do all of these things. And the amazing thing is that there's no limit to it. As far as we know, there's no speed limit to how fast you can shrink or expand space. Take for example, the Big Bang. What happened in the very first moments of the universe. The universe expanded very, very rapidly, much faster than the speed of light, much faster than light could have moved through that space. That's why, for example, the universe now is larger than the speed of light times the age of the universe. How is that possible? If nothing can travel faster than the speed of light, how could stuff get further away from each other then light could have traveled through that space. The answer, of course is space expanded inflation. And the Big Bang is more than just stuff moving through space, it's space itself expanding. So this is an idea we're familiar with that space can expand you might almost say the universe warped. You might even think of the Big Bang as a huge warping of space and dark energy now is the continued warping of space, all right? So that gives us an opportunity. We're talking about how to get somewhere faster than light would get us there. And the idea we're working towards is not to try to move through space using some specially fast, zippy engine but to change the nature of the problem by shrinking the space. And that's the idea for a warp drive. That's how we might actually make it work. The idea is like this, you want to get from here to Alpha Centauri. How do you do it? Well, you don't just move through that space. You somehow shrink the space between you and that star. You squeeze it, just the way the Sun changes the shape the whole nature space in the Solar System. Use some mass and energy. In a moment, we'll talk about the details of what we know about how engineers might actually make that happen. Use mass and energy in some way to squeeze the space so that instead of having four point two light years between you and the star, you have four point two meters. And similarly, you turn around behind you, and instead of having four point two meters between you and where you've left, you can expand the space behind you. So the idea for a warp drive is something which shrinks the space in front of you and expands the space behind you. In that way, you're sort of inside the little bubble, and inside that bubble you don't even need to move with respect to space. It's sort of like, instead of running through the airport, you stand on a moving walkway and the walkway moves for you. That's not a perfect analogy because in that analogy the walkway is still moving, and I'd be talking about like pulling the terminal closer to you instead of running there and stretching the distance behind you. But that's the idea. So you'd build the sort of warp drive that shrinks the space in front of you, expands the space behind you, and then you're in this sort of warp bubble, and then you pop out of the bubble right and then you're there. And because there's no limit on how fast you can expand space or how much you can shrink space in theory, there's no limit to how far a warp drive could take you, as long as you have the ability to do this and the energy budget to get it done. So let's talk about how you might actually build a warp drive and how much progress science and engineers and science fiction authors have made towards making it to reality. But first, let's take another break. When you pop a piece of cheese into your mouth or enjoy a rich spoonful of greeky yogurt, you're probably not thinking about the environmental impact of each and every bite, But the people in the dairy industry are. US Dairy has set themselves some ambitious sustainability goals, including being greenhouse gas neutral by twenty to fifty. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. Take water, for example, most dairy farms reuse water up to four times the same water cools the milk, cleans equipment, washes the barn, and irrigates the crops. How is US Dairy tackling greenhouse gases. Many farms use anaerobic digestors that turn the methane from maneuver into renewable energy that can power farms, towns, and electric cars. So the next time you grab a slice of pizza or lick an ice cream cone, know that dairy farmers and processors around the country are using the latest practices and innovations to provide the nutrient dense dairy products we love with less of an impact. Visit US dairy dot com slash sustainability to learn more.

There are children, friends and families walking, riding on passing the roads every day. Remember their real people with loved ones who need them to get home safely. Protect our cyclists and pedestrians because they're people too, Go safely California from the California Office of Traffic Safety and Caltrans.

There are children, friends and families walking, riding on passing the roads every day. Remember their real people with loved ones who need them to get home safely. Protect our cyclists and pedestrians because they're people too, Go safely California from the California Office of Traffic Safety and Caltrans.

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All right, So we're talking about warping through the universe, and the basic idea is to avoid the limit of the speed of light by saying we're not going to move through space faster than the speed of light. Instead, we're going to somehow change the shape of space.

All right, So we're talking about warping through the universe, and the basic idea is to avoid the limit of the speed of light by saying we're not going to move through space faster than the speed of light. Instead, we're going to somehow change the shape of space.

We're going to.

We're going to.

Build an engine a warp engine, which changes the nature of the problem. It doesn't solve the problem directly, it changes it to another problem. And you know, that's a standard and very classic approach, Like it's basically what mathematics is. Somebody asks a mathematician, can you solve this problem? They go, no, that seems hard, But I can solve this other problem, and I can prove that the answer is the same. So instead of solving a hard problem, transform it to an easy problem and then solve that. So in this case, we're taking an impossible problem travel through space faster than the speed of light, and transforming it to an easier problem. Still really hard, maybe not feasible, but not theoretically impossible to get there faster than light would have moved through unaltered space. There and the idea again is to change the space, is to squeeze the space in front of you and expand the space behind you. It's the basic operating principle of warp drive. So let's talk about how that happens. Because, like I said earlier, squeezing space. Those are two words you understand, squeezing and space. But what does it mean to squeeze space? How could you possibly do that? What kind of thing when you building your lab to make that happen. What would a warp drive actually look like? All right, so there's two components there, right, there's squeezing the space in front of you and expanding the space behind you. Let's do the easy one first. That's squeezing the space in front of you. How can you squeeze space? How can you make it so the shape of space is smaller, so it's sort of constrained and shrunk a little bit. Well, it turns out that's actually not that hard. You're doing it right now. Everything with mass is changing the shape of space in exactly that way. It's squeezing it, it's constricting, it's constraining it. I don't want to get into the mathematical details of the metric solutions to Einstein's equations, but that's the basic idea. In order to shrink space, all you need is a huge amount of mass or energy density, because space bends in that exact way that you need in the presence of mass and energy. So it basically just becomes an engineering problem. You have positive mass and energy, you can shrink space. How much mass and energy do you need to shrink space enough to get somewhere interesting in the universe. Well, now it's a problem for the engineers, and a bunch of folks have thought about this, and I've even heard there are people in Nassa working on it, and they've done some calculations. And as usual, when you first start out, you make basic assumptions. You try the simplest idea first, and it seems impossible. So the first calculation anybody ever did of how much energy it would take, how much mass it would take in order to bend space to get somewhere like Proxima Centauri, took more mass than all the stuff available in the observable universe. That's one hundred billion solar systems per galaxy in two trillion galaxies. That's an enormous amount of mass. And there's no way you could ever gather that much energy and use it for a warp drive. And anyway, if you did, you would have already destroyed the universe just trying to get somewhere. So it's a bit of a chicken and egg problem. But this is the progression of engineering, right. First you start out with a simple solution that seems impossible and practical, and then somebody figures out a way to do it with one percent of the energy or costing one hundred times less money. That's the way engineering works, and so people have already figured out, oh wait, if you do do it this way and that way, and you focus in this other direction, then you can build a warp drive to get you to the next star using only the amount of mass in the planet Jupiter. Now, whether that seems like a big number to you or not depends on your reference frame if you start out comparing it to all the stars and Solar system and stuff and the observable universe. Yeah, it's a tiny amount of that, but compared to the energy that any human has ever harnessed for any purpose, it's huge. Remember we're talking about the energy stored in some object that has mass. We're talking about releasing all of its energy. An enormous amount of energy stored in every object that has mass because of E equals mc squared. And the reason that's a huge amount of energy and every piece of mass is because of the C squared bit C being the speed of light. Speed of light is a really big number, and C squared is a really big number squared. So you take a small amount of mass like a raisin, which weighs maybe one gram. It has an incredible amount of energy in it. It has as much energy as a nuclear explosion. For example, you wanted to build an intimatter weapon, if you had a raisin and an anti raisin, that's all you would need to have a device with as much explosive power as the bombs that were dropped on Hiroshima. So now imagine Jupiter. Jupiter is a lot of raisins. There's a huge amount of energy. It's an incredible amount of energy in Jupiter. So if somebody tells you, I have a warp drive, but we got to refuel, and we got to stop by Jupiter and suck it all up. We have to transform all of Jupiter the energy to build my warp drive, you'd probably say, we don't have the budget for that. It's a huge reduction. But even requiring all the mass of Jupiter to fuel your warp drive is not good enough. All right, But recently I read an article that somebody came up with a clever reduction in the amount of energy required, so that you'd only need something like the energy stored in a school bus or a large car. And again that's another big step down from all the stuff in the universe down to Jupiter down to the stuff in a car. Requires some real cleverness to focus that energy in a way that's going to squeeze space using only you know, hundreds and hundreds of kilograms and stuff. Remember that's still a huge amount of energy compared to the explosions of nuclear weapons. It's an enormous budget, but it's not totally infeasible. So the engineers have already come up with some sort of calculations to make this possible. No, nobody's actually built a prototype. This is still just in the planning stages, the could this ever work stages, But you know, the physicists have showed that to get there you need to squeeze space, and they've pointed to the engineers what we know about squeezing space, which is using mass and energy to do things like gravity does. And the engineers are working on it, they're chugging through it, and there's all the reasons to believe that in a few years, five years, ten years, fifty years, somebody might be able to build something which begins this process. But but to actually have warp drive, you need both sides. You need the thing in front of you that squeezes space, you also need the thing behind you that expands space. Right, you can't have a moving walkway if the whole walkway isn't moving, So let's talk about that. How do you expand the space behind you? Well, this is much harder. You are not expanding space, right, You have positive mass, and so you are shrinking space. You're doing that thing that to space that gravity does. But if shrinking space requires having positive mass, you might be tempted to suggest, sort of as a first dumb idea for how to expand space, that maybe you could expand space with negative mass. The argument is not very sophisticated. It's really just that it says, we don't know how to expand space, but we know how to sort of shrink it using positive mass. What if we use negative mass to expand it. It's not a terrible argument. The problem is, of course, what does negative mass mean. It's another of these examples. You take two words that make sense, negative and mass, and you put them together and you go, huh, what is that? Everything you've ever experienced has positive mass. I have positive mass more than i'd like. Raisins of positive mass, hamsters, bananas, everything has positive mass. If we've never seen anything with negative mass. We talked about on this podcast for wormholes. You might need negative mass exotic matter particles to stabilize wormholes, but that doesn't mean that they exist. It just means that if you write down the equations, that's the kind of thing which could accomplish it. The things that are in equations aren't necessarily also part of the universe. So we've never seen negative mass, and we don't know how to make negative mass. And also, even if you could make negative mass, could you make a school bus size of it, a Jupiter, the planet Jupiter sized negative mass? That seems pretty difficult. It might even be a problem engineers couldn't solve. But there is hope. Right, we know that this thing can happen. We know that space can expand. Decades ago, we might have imagined differently. We might have argued, Look, gravity is just an attractive force. All they can do is attract stuff. There's no repulsive side of gravity. Gravity never pushes things apart the way magnetism can, or the strong force can, or even the weak force. All these things can attract and repel because all of those things have both positive and negative charges for their force. Gravity has only positive charges. This is only positive mass, so it can only attract That's what we think. However, we also know that we don't really understand gravity, and we do know that expansion of space does happen. We don't know how to create negative mass. We don't know if negative mass is the way to expand space, but we do know that space can be expanded because we have seen it happen. We believe that the Big Bang is a huge expansion of space, though we don't know what caused it. We know that dark energy is expanding space, but we don't understand the mechanism. So we know it's possible, but we don't know how to make it happen. We're very far from being able to control it, and we're super far from being able to put it in a warp drive and take you to Alpha Centauri while you stuff your face with junk food. So let's recap. It's impossible to travel to Proximus Centauri or Alpha Centauri or any of the Centauris by moving through space faster than light could do it. You can't build a warp drive that just moves through space. I think the kind of warp drive they have, for example, in Star Trek, does that they traveled some factor of the speed of light and they can get there more rapidly than light would get there. That I'm going to say it's flat out impossible. There's always a possibility that sometimes the future physicists will reveal that it wasn't actually impossible all along, and in some condition we assumed dot dot dot. I think that's very unlikely. The more promising way to build a warp drive is to change the problem from I'm going to move through space faster than the speed of light to I'm going to try to squeeze the space. I'm going to build an engine which changes the nature of the problem. It squeezes the space in front of me and expands the space behind me. Space is not just the ruler you're flying by. It's something we're in. It's like we're fish and we're swimming in water, and to get to the other side of the pond, you want to shrink the amount of water that's between you and the other side of the pond. So theoretically we think that could work. Practically, there's some big issues shrinking space in front of you is very difficult, maybe impractical, though theoretically we think we know what's going on. But expanding the space behind you, that's much harder. We have no idea how to accomplish the expanding of space, but we think it's pro probably possible, because we see it happening in the universe. We just have no handle on what's doing it or how to make it happen in a controlled way where you'd want to invite your grandmother on a trip to the neighboring star. All right, So that's the explanation of where we stand in terms of building warp drives. There's lots of other really fascinating issues connected to space propulsion, and people have written in asking us to talk about em drives and all sorts of other stuff. We'll get to that, but until then, thanks very much for all the folks who requested this topic, and thank you in advance to anybody who sends in a request for a future episode. We love hearing what you'd like to hear about. So until Jorge gets back, this is Daniel signing off for Daniel and Jorge explain the universe. Thanks for tuning in if you still have a question. After listening to all these explanations, please drop us a line. We'd love to hear from you. You can find us on Facebook, Twitter, and Instagram at Daniel and Jorge That's one word, or email us at Feedback at Danielandhorge dot com. Thanks for listening and remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. 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