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Are you the kind of person that wonders if black holes have hair on them? Do you ever think about what it's like to be in a fighter jet and roll down the windows? Do you ever wonder if light gets tired on its way across the universe from distant stars? All the way to Earth. If so, then you're the right person to be listening to this podcast, because that's exactly the kind of stuff we're going to be talking about today. Hi. I'm Daniel. I'm a particle physicist, and I'm the co author of the book We Have No Idea, A Guide to the Unknown Universe. My co author, Jorge Chim, is usually the co host of the podcast Daniel and Horagey Explain the Universe, brought to you by iHeartRadio. Today, Hoge has to be away, so I'm going to do the podcast by myself, and today we're doing something which is absolutely my favorite, which is answering listener questions. I love listener questions because they give me feedback and help me understand what people out there are thinking, what they're understanding, and what they're confused about. When Hoge and I do lectures live, we talk about all the amazing mysteries of the universe, and then people ask questions. And those questions are so valuable because they show me exactly what people have misunderstood. If I said something and I thought I was super clear, and then somebody asked the question, it helps me see how to better explain something, so I really value listener questions. Thank you to everybody who has written in, either with a point of confusion about something that we said on the podcast or something totally crazy that they were thinking about and they wanted us to explain. And for all of you who have not written into the podcast, what are you waiting for? We want to hear your questions. When I say I answer every email, I mean it. And when I say I love getting questions from listeners, I am being totally serious. So please send us your questions to questions at Danielandjorge dot com. You might even hear yourself on the podcast. So today we'll be answering listener questions. Questions about lights, questions about black holes, questions about flying at the speed of sound with the windows open, and all these questions have something in common, which is they're sort of like what if questions, like how could you do this? Or how could you make this work? Or what would happen if you did this thing? And all of these reveal people just desire to understand what happens in the universe, to reveal secrets of the universe by cooking up crazy scenarios, scenarios where nature has to reveal the truth. And in the end, that's really what experimental physics is. We want to know the answer to a question, you know, does the universe work this way or that way? And so we come up with some scenario Nature has to reveal to us the answer. We corner nature and say, well, show us, you know, is light a particle or is it a wave? Does the Higgs boson have this much mass or that much mass? Really, all experimental physics is is constructing physical scenarios where Nature has to show us her cards. And so a lot of the questions you'll hear about today are exactly that kind of question. So today we have three questions. Let's dive in.

Are you the kind of person that wonders if black holes have hair on them? Do you ever think about what it's like to be in a fighter jet and roll down the windows? Do you ever wonder if light gets tired on its way across the universe from distant stars? All the way to Earth. If so, then you're the right person to be listening to this podcast, because that's exactly the kind of stuff we're going to be talking about today. Hi. I'm Daniel. I'm a particle physicist, and I'm the co author of the book We Have No Idea, A Guide to the Unknown Universe. My co author, Jorge Chim, is usually the co host of the podcast Daniel and Horagey Explain the Universe, brought to you by iHeartRadio. Today, Hoge has to be away, so I'm going to do the podcast by myself, and today we're doing something which is absolutely my favorite, which is answering listener questions. I love listener questions because they give me feedback and help me understand what people out there are thinking, what they're understanding, and what they're confused about. When Hoge and I do lectures live, we talk about all the amazing mysteries of the universe, and then people ask questions. And those questions are so valuable because they show me exactly what people have misunderstood. If I said something and I thought I was super clear, and then somebody asked the question, it helps me see how to better explain something, so I really value listener questions. Thank you to everybody who has written in, either with a point of confusion about something that we said on the podcast or something totally crazy that they were thinking about and they wanted us to explain. And for all of you who have not written into the podcast, what are you waiting for? We want to hear your questions. When I say I answer every email, I mean it. And when I say I love getting questions from listeners, I am being totally serious. So please send us your questions to questions at Danielandjorge dot com. You might even hear yourself on the podcast. So today we'll be answering listener questions. Questions about lights, questions about black holes, questions about flying at the speed of sound with the windows open, and all these questions have something in common, which is they're sort of like what if questions, like how could you do this? Or how could you make this work? Or what would happen if you did this thing? And all of these reveal people just desire to understand what happens in the universe, to reveal secrets of the universe by cooking up crazy scenarios, scenarios where nature has to reveal the truth. And in the end, that's really what experimental physics is. We want to know the answer to a question, you know, does the universe work this way or that way? And so we come up with some scenario Nature has to reveal to us the answer. We corner nature and say, well, show us, you know, is light a particle or is it a wave? Does the Higgs boson have this much mass or that much mass? Really, all experimental physics is is constructing physical scenarios where Nature has to show us her cards. And so a lot of the questions you'll hear about today are exactly that kind of question. So today we have three questions. Let's dive in.

Hey, guys, my question is what would happen if we quantum entangled two particles and took particle one and shot it into a black hole? Could we learn anything? And what do you think we could learn if we can from particle two? Shout out to South Dakota and LEXI.

Hey, guys, my question is what would happen if we quantum entangled two particles and took particle one and shot it into a black hole? Could we learn anything? And what do you think we could learn if we can from particle two? Shout out to South Dakota and LEXI.

All right, I got this question and it blew my mind. And it blew my mind because it combines so many different things that I love. You got black holes, you got quantum mechanics, you got inventing new ways to explore the universe. Right, So I love when listeners think up new ideas for how we could solve ancient questions. All right, so first let's talk about why would we want to know what's going on inside a black hole? Like, why does anybody care? Isn't it just basically the garbage disposal of the universe, jammed filled with rejected matter that's got swoshed down the toilet bowl and into the black hole. Well, that's what we don't know. General relativity tells us that black holes might have a singularity in the center of them, right, a tiny dot of matter with infinite density, something which is hard for us to imagine. What does infinite density mean? But according to Einstein's equations, that's exactly the conditions you need to create a black hole. Fine, And we know that Einstein's equations have been validated many, many times, and nobody's ever found a flaw on them. They predicted gravitational waves, We've seen them. They predicted all sorts of other crazy gravitational phenomena, and they've been verified and checked. So, as far as we know, Einstein's equations are correct except to mechanics tells us that you can't have a singularity at the center of a black hole. Remember, quantum mechanics tells us the universe is not smooth and continuous, instead that the universe is discrete. Space itself is probably pixelated into tiny little units, right, Mass is probably pixelated, time is probably pixelated. All these things are probably discrete and not continuous. And that means you can't have an infinitely small dot, certainly not one with an infinite mass inside of it. In addition, is all sorts of issues about the Heisenberg uncertainty principle. Can you have so much matter localized in one spot for such a long time? Quantum mechanics says that you should not find a singularity inside a black hole. The problem, of course, is it's awfully difficult to look inside a black hole. So I think that's probably what motivates this question, the desire to see what's inside a black hole. And I'll be honest, if I could see inside a black hole, I would do it in a second. I would love to know what is going on inside there, all right. So the idea from this question is to quantum entangle two particles and shoot one into a black hole, and I guess use the other one to sort of learn something about what's going on inside the black hole. Right, well, let's talk about quantum entanglement. Quantum entanglement is a very tricky topic, and we discussed it in some depth on our quantum computing episode. The short version is that it links two particles potentially across gray distances or great barriers like the edge of a black hole. The link is a kind of constraint. If one particle spins up, the other one has to spin down. So by knowing something about one of the particles discovering that it's spin up, for example, you can learn something about the other such as knowing that it's spinned down, even if you never see it or can't possibly see it because it's hidden. So you see the attraction for potentially probing a black hole using pairs of entangled particles to sort of extract some information from one particle by looking at the other one. All right, Well, the short answer is we would learn nothing, and the reason is that there are pretty solid theorems about getting information out of the black hole. All right, So the no hair theorem, I'm not joking. It's literally called the no hair theorem, And I don't know if it was invented by a visitist without hair, but the no hair theorem says that the only information you could get about a black hole is its mass, it's total electric charge, and its momentum. That's it, right. You can't get any other information. Nothing that's going on inside the black hole can never leave, right. You certainly can't see things escaping the black hole. Nothing can escape, so no light can come out to reveal to you what's inside the black hole. But more than that, you cannot get any information, no matter how clever you are, other than those three pieces of information. And this raises all sorts of fascinating questions. Like the listener was asking about quantum entangled particles where one is inside and one is outside the black hole. That actually happens already. There's something called called Hawking radiation, where a photon inside the black hole will decay to two quantum entangled particles, and the decay will happen so close to the event horizon that one of the particles slips out of the event horizon and gets to leave. That's Hawking radiation. It requires this quantum fluctuation, right, right, at the edge of the event horizon. And so you might ask, can we learn something about the side of the hawking radiation that got slurped into the black hole by looking at what happens outside the black hole by measuring that hawking radiation. Well, the answer is no, no information can leave the black hole. It's just impossible to extract any information. Even though that electron and that positron are entangled with each other, right, they do not contain any information about what's going on inside the black hole. And the shorter answer is, as soon as you're trying to interact with the electron and positron, you will anyway break that entanglement.

All right, I got this question and it blew my mind. And it blew my mind because it combines so many different things that I love. You got black holes, you got quantum mechanics, you got inventing new ways to explore the universe. Right, So I love when listeners think up new ideas for how we could solve ancient questions. All right, so first let's talk about why would we want to know what's going on inside a black hole? Like, why does anybody care? Isn't it just basically the garbage disposal of the universe, jammed filled with rejected matter that's got swoshed down the toilet bowl and into the black hole. Well, that's what we don't know. General relativity tells us that black holes might have a singularity in the center of them, right, a tiny dot of matter with infinite density, something which is hard for us to imagine. What does infinite density mean? But according to Einstein's equations, that's exactly the conditions you need to create a black hole. Fine, And we know that Einstein's equations have been validated many, many times, and nobody's ever found a flaw on them. They predicted gravitational waves, We've seen them. They predicted all sorts of other crazy gravitational phenomena, and they've been verified and checked. So, as far as we know, Einstein's equations are correct except to mechanics tells us that you can't have a singularity at the center of a black hole. Remember, quantum mechanics tells us the universe is not smooth and continuous, instead that the universe is discrete. Space itself is probably pixelated into tiny little units, right, Mass is probably pixelated, time is probably pixelated. All these things are probably discrete and not continuous. And that means you can't have an infinitely small dot, certainly not one with an infinite mass inside of it. In addition, is all sorts of issues about the Heisenberg uncertainty principle. Can you have so much matter localized in one spot for such a long time? Quantum mechanics says that you should not find a singularity inside a black hole. The problem, of course, is it's awfully difficult to look inside a black hole. So I think that's probably what motivates this question, the desire to see what's inside a black hole. And I'll be honest, if I could see inside a black hole, I would do it in a second. I would love to know what is going on inside there, all right. So the idea from this question is to quantum entangle two particles and shoot one into a black hole, and I guess use the other one to sort of learn something about what's going on inside the black hole. Right, well, let's talk about quantum entanglement. Quantum entanglement is a very tricky topic, and we discussed it in some depth on our quantum computing episode. The short version is that it links two particles potentially across gray distances or great barriers like the edge of a black hole. The link is a kind of constraint. If one particle spins up, the other one has to spin down. So by knowing something about one of the particles discovering that it's spin up, for example, you can learn something about the other such as knowing that it's spinned down, even if you never see it or can't possibly see it because it's hidden. So you see the attraction for potentially probing a black hole using pairs of entangled particles to sort of extract some information from one particle by looking at the other one. All right, Well, the short answer is we would learn nothing, and the reason is that there are pretty solid theorems about getting information out of the black hole. All right, So the no hair theorem, I'm not joking. It's literally called the no hair theorem, And I don't know if it was invented by a visitist without hair, but the no hair theorem says that the only information you could get about a black hole is its mass, it's total electric charge, and its momentum. That's it, right. You can't get any other information. Nothing that's going on inside the black hole can never leave, right. You certainly can't see things escaping the black hole. Nothing can escape, so no light can come out to reveal to you what's inside the black hole. But more than that, you cannot get any information, no matter how clever you are, other than those three pieces of information. And this raises all sorts of fascinating questions. Like the listener was asking about quantum entangled particles where one is inside and one is outside the black hole. That actually happens already. There's something called called Hawking radiation, where a photon inside the black hole will decay to two quantum entangled particles, and the decay will happen so close to the event horizon that one of the particles slips out of the event horizon and gets to leave. That's Hawking radiation. It requires this quantum fluctuation, right, right, at the edge of the event horizon. And so you might ask, can we learn something about the side of the hawking radiation that got slurped into the black hole by looking at what happens outside the black hole by measuring that hawking radiation. Well, the answer is no, no information can leave the black hole. It's just impossible to extract any information. Even though that electron and that positron are entangled with each other, right, they do not contain any information about what's going on inside the black hole. And the shorter answer is, as soon as you're trying to interact with the electron and positron, you will anyway break that entanglement.

Right.

Right.

The entanglement only exists when those particles are isolated from the rest of the system. So as soon as you try to measure something about that electron, you're probably going to break that entanglement anyway, which is usually usually the problem with entanglement is that you can't really use it to convey information because interacting with the particles breaks that entanglement all right. This brings us to another fascinating and current topic in black hole physics, which is people are wondering where the information goes like, according to black hole theories, no information can leave the black hole. Right, But according to Hawking, radiation particles do escape the black hole, which means the black hole can shrink. In fact, for small black holes, black holes could even evaporate and disappear. So what happens to the information that went into the black hole? What happened to all those quantum states and all that stuff that went into the black hole and then the black hole disappeared, Because there's another law of quantum mechanics that says It says that all the information about past states in the universe is contained in the arrangement of the current universe, right, no information should be lost. For those mathematically inclined, this means essentially that the wave function is unitary, right, The transformations through time do not change the overall normalization of the wave function. So if black holes can evaporate and disappear, but no information can leave the black hole, that suggests that information is destroyed, and that particular puzzle goes by the name of the black hole information paradox, and people have proposed all sorts of crazy solutions to this, including firewalls and all sorts of crazy stuff that we might actually see at the edges of black holes one day. So thank you for this wonderful question about black holes and quantum mechanics and entanglement and information and all sorts of crazy amazing stuff. One of my favorite things about these kinds of questions is that they seem theoretical, they seem crazy abstract, but these are real, like black holes, they're real objects. They are out there, and one day, if we build the right kind of spaceship and the right kind of probes, we could go when we could observe them, and we might learn the answer to some of these questions. So thanks for sending in that question, and keep writing. Well, this is a perfect spot to take a break. We'll be right back. With big wireless providers, what you see is never what you get. Somewhere between the store and your first month's bill, the price, your thoughts you were paying magically skyrockets. With mint Mobile, 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 mean it. 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 dit 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 mint mobile dot com slash universe. That's mintmobile dot com slash universe. Cut your wireless build 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 speeds and restrictions apply. See mint mobile for details.

The entanglement only exists when those particles are isolated from the rest of the system. So as soon as you try to measure something about that electron, you're probably going to break that entanglement anyway, which is usually usually the problem with entanglement is that you can't really use it to convey information because interacting with the particles breaks that entanglement all right. This brings us to another fascinating and current topic in black hole physics, which is people are wondering where the information goes like, according to black hole theories, no information can leave the black hole. Right, But according to Hawking, radiation particles do escape the black hole, which means the black hole can shrink. In fact, for small black holes, black holes could even evaporate and disappear. So what happens to the information that went into the black hole? What happened to all those quantum states and all that stuff that went into the black hole and then the black hole disappeared, Because there's another law of quantum mechanics that says It says that all the information about past states in the universe is contained in the arrangement of the current universe, right, no information should be lost. For those mathematically inclined, this means essentially that the wave function is unitary, right, The transformations through time do not change the overall normalization of the wave function. So if black holes can evaporate and disappear, but no information can leave the black hole, that suggests that information is destroyed, and that particular puzzle goes by the name of the black hole information paradox, and people have proposed all sorts of crazy solutions to this, including firewalls and all sorts of crazy stuff that we might actually see at the edges of black holes one day. So thank you for this wonderful question about black holes and quantum mechanics and entanglement and information and all sorts of crazy amazing stuff. One of my favorite things about these kinds of questions is that they seem theoretical, they seem crazy abstract, but these are real, like black holes, they're real objects. They are out there, and one day, if we build the right kind of spaceship and the right kind of probes, we could go when we could observe them, and we might learn the answer to some of these questions. So thanks for sending in that question, and keep writing. Well, this is a perfect spot to take a break. We'll be right back. With big wireless providers, what you see is never what you get. Somewhere between the store and your first month's bill, the price, your thoughts you were paying magically skyrockets. With mint Mobile, 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 mean it. 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 dit 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 mint mobile dot com slash universe. That's mintmobile dot com slash universe. Cut your wireless build 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 speeds and restrictions apply. See mint mobile for details.

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If you love iPhone, you'll love Applecard. 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 Applecard in the wallet app, subject to credit approval. Savings is available to Applecard 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. This is a wonderful question that we got recently from a listener and from that listener's dad.

Hi, my name is Phineas and I'm in four and I live in Psicho, Alaska. I was wondering if you were in an airplane going faster than the speed of sound and you said something to the person next to you, would they actually be able to hear what you said.

Hi, my name is Phineas and I'm in four and I live in Psicho, Alaska. I was wondering if you were in an airplane going faster than the speed of sound and you said something to the person next to you, would they actually be able to hear what you said.

This is Phineas's dad. Phineas asked me this question a while ago, and it got me wondering if one was traveling at or above the speed of light, would they be able to see the person next to them?

This is Phineas's dad. Phineas asked me this question a while ago, and it got me wondering if one was traveling at or above the speed of light, would they be able to see the person next to them?

So I love this question for so many reasons. I love that that young boy is imagining what it's like to be on a spaceship or what it's like to be on a plane traveling past the speed of sound. And it's a great question. He's wondering about how this information is processed, how this information is transmitted. Essentially, are you leaving that information behind right? Well, first of all, I want to break his bubble and say, if you're on a fighter jet that's traveling faster than the speed of sound. Probably you don't have the windows open, right, which means that you're in a little air bubble. That air bubble is moving with you fast and the speed of sound. If you had the windows open and the air was rushing past you fasten the speed of sound, it would probably tear you to shreds. And that's why fighter jets, for example, have that little bubble right the window that protects them from what's going on outside. All right, so they have a little bubble of air. And that's the key. Because sound is a wave, right, Sound is just vibrations of the air, and so what it does is it moves relative to the air. Right. It's like if you have a bathtub of water and you're slapping it to make to make waves, the waves move relative to the water. If that water, if that bathtub was on a train traveling a super duper fast, it wouldn't make any difference. Right, You could still have a bath and you could still make splashes and they wouldn't be any different. In the same way, if you're on a fighter jet and you're in a little bubble of air inside the fighter jet, you can turn to the person next to you can say hello, would you please pass the peanuts?

So I love this question for so many reasons. I love that that young boy is imagining what it's like to be on a spaceship or what it's like to be on a plane traveling past the speed of sound. And it's a great question. He's wondering about how this information is processed, how this information is transmitted. Essentially, are you leaving that information behind right? Well, first of all, I want to break his bubble and say, if you're on a fighter jet that's traveling faster than the speed of sound. Probably you don't have the windows open, right, which means that you're in a little air bubble. That air bubble is moving with you fast and the speed of sound. If you had the windows open and the air was rushing past you fasten the speed of sound, it would probably tear you to shreds. And that's why fighter jets, for example, have that little bubble right the window that protects them from what's going on outside. All right, so they have a little bubble of air. And that's the key. Because sound is a wave, right, Sound is just vibrations of the air, and so what it does is it moves relative to the air. Right. It's like if you have a bathtub of water and you're slapping it to make to make waves, the waves move relative to the water. If that water, if that bathtub was on a train traveling a super duper fast, it wouldn't make any difference. Right, You could still have a bath and you could still make splashes and they wouldn't be any different. In the same way, if you're on a fighter jet and you're in a little bubble of air inside the fighter jet, you can turn to the person next to you can say hello, would you please pass the peanuts?

Or whatever?

Or whatever?

You say to somebody in a fighter jet and the air between you is not moving relative to you, so you can send waves through it normally, just as you would if you were sitting on your couch in your living room. So the sort of cheap answer to the question is that there's no difference if you're in a little bubble of air that's moving with you, all right, So that's no fun. Let's imagine what happens when you open the windows, right, you're going mock to you're zooming through the atmosphere. You open the windows, all of a sudden, the wind is screaming past you at two thousand miles per hour. Right now, that's an interesting question. What happens if you turn to your friend and you say, pass the bananas? Right? Can they hear you? The key thing to remember is that sound moves at a fixed speed relative to the air. So if you shout into a wind blowing at your back, then your shout gets carried away from you by the wind more quickly than if there had been no wind. Similarly, if the wind is blowing in your face, it can slow down your shout. If the wind blows in your face at this of sound. Ouch. Then when you scream, your scream doesn't actually go anywhere, it stays right there on top of you. So in the fighter jet, if the windshield is down or whatever they call it in a fighter jet, then they can just talk normally. Right they're in a bubble of air, just like if you're in a bathtub and you make waves. It doesn't matter if you're on a train at the time, because the water is moving with you. But if they open the windshield, the wind is whipping by them at faster than the speed of sound, and so they will leave their words behind. There's no way that they can talk, even if they shout straightforwards. This is also why planes make sonic booms. If a plane is traveling faster than the sound it's making, then it's catching up to its own sound, and the sound from two seconds ago gets piled up on top of the sound from one second ago and the sound from right now. It's the same amount of sound total, doesn't generate more sound, but it gets concentrated in certain places because the plane is outracing the sound it's making. It's like with a boat in the water if it travels faster than the waves and water, then those waves pile up and you get a wake. A sonic boom is just a plane's wake. All right, awesome question. And my favorite part I think of this is that his dad couldn't help but jump in and ask an even more physics e question, right, A question about traveling at or faster than the speed of light. Wonderful And I love this because it allows us to draw this contrast between the speed of sound and the speed of light. Now, first of all, of course, you can't travel at the speed of light, right, Nothing that has mass can travel at the speed of light. Only things that are massless travel at the speed of light, and everything that's massless travels at the speed of light. Photons, gravitons, if they exist, anything that does not have mass has to travel at the speed of light, and always at the speed of light. It can't go any slower. The amazing thing about photons is not only that they travel at the speed of light, which is super duper fast, but that they don't travel relative to some medium sound and water. Waves travel at fixed speeds relative to their medium air or water, but the rules are totally different for light. It's a wave, but it always moves at the speed of light relative to the person measuring it, not relative to the medium, because it doesn't have a medium. Now, for a while people thought that there has to be some medium that light traveled through, and they called it ether and searched for it. But now we know that there is no ether, no medium that's doing the waving for light like air does for sound. The Michaelson Morally experiments showed us that because they measured the speed of light in two different directions and found them to be identical, even though the Earth is obviously moving in one direction or the other as it goes around the Sun. The reason is because light doesn't have a medium. It's the waving of quantum fields that are the properties of space itself. So space can be empty and still have light in it. And the way we sh Yoda is that we discovered that light moves at the speed of light relative to everybody, no matter how fast you're going. So if you are standing on Earth and you turn on a flashlight, those photons leave your flashlight at the speed of light. Right. Cool. Now, what happens if you jump into Lamborghini and you turn on a flashlight, the Lamborghini is going to two hundred miles per hour. You're in the Lamborghini, you turn on the flashlight. What happens, Well, the light leaves your flashlight at the speed of light relative to you. No big deal. What about somebody on the ground, right, the person you left behind who you didn't offer a ride in your Lamborghini to. When you turn on the flashlight in your Lamborghini, how fast do they see the light going? Well, you might think, well, it's the speed of light plus the speed of the Lamborghini, right, because the flashlight itself is moving at two hundred miles per hour. But that's where you'd be wrong. Right, That's why light is weird. That's how our whole universe is super bizarre. Frankly, it's bunkers. We know that light always travels at the speed of light, no matter what the speed of the thing making it is, right, And everybody who measures the speed of light always sees it moving at the speed of light relative to them. And that's different from sound.

You say to somebody in a fighter jet and the air between you is not moving relative to you, so you can send waves through it normally, just as you would if you were sitting on your couch in your living room. So the sort of cheap answer to the question is that there's no difference if you're in a little bubble of air that's moving with you, all right, So that's no fun. Let's imagine what happens when you open the windows, right, you're going mock to you're zooming through the atmosphere. You open the windows, all of a sudden, the wind is screaming past you at two thousand miles per hour. Right now, that's an interesting question. What happens if you turn to your friend and you say, pass the bananas? Right? Can they hear you? The key thing to remember is that sound moves at a fixed speed relative to the air. So if you shout into a wind blowing at your back, then your shout gets carried away from you by the wind more quickly than if there had been no wind. Similarly, if the wind is blowing in your face, it can slow down your shout. If the wind blows in your face at this of sound. Ouch. Then when you scream, your scream doesn't actually go anywhere, it stays right there on top of you. So in the fighter jet, if the windshield is down or whatever they call it in a fighter jet, then they can just talk normally. Right they're in a bubble of air, just like if you're in a bathtub and you make waves. It doesn't matter if you're on a train at the time, because the water is moving with you. But if they open the windshield, the wind is whipping by them at faster than the speed of sound, and so they will leave their words behind. There's no way that they can talk, even if they shout straightforwards. This is also why planes make sonic booms. If a plane is traveling faster than the sound it's making, then it's catching up to its own sound, and the sound from two seconds ago gets piled up on top of the sound from one second ago and the sound from right now. It's the same amount of sound total, doesn't generate more sound, but it gets concentrated in certain places because the plane is outracing the sound it's making. It's like with a boat in the water if it travels faster than the waves and water, then those waves pile up and you get a wake. A sonic boom is just a plane's wake. All right, awesome question. And my favorite part I think of this is that his dad couldn't help but jump in and ask an even more physics e question, right, A question about traveling at or faster than the speed of light. Wonderful And I love this because it allows us to draw this contrast between the speed of sound and the speed of light. Now, first of all, of course, you can't travel at the speed of light, right, Nothing that has mass can travel at the speed of light. Only things that are massless travel at the speed of light, and everything that's massless travels at the speed of light. Photons, gravitons, if they exist, anything that does not have mass has to travel at the speed of light, and always at the speed of light. It can't go any slower. The amazing thing about photons is not only that they travel at the speed of light, which is super duper fast, but that they don't travel relative to some medium sound and water. Waves travel at fixed speeds relative to their medium air or water, but the rules are totally different for light. It's a wave, but it always moves at the speed of light relative to the person measuring it, not relative to the medium, because it doesn't have a medium. Now, for a while people thought that there has to be some medium that light traveled through, and they called it ether and searched for it. But now we know that there is no ether, no medium that's doing the waving for light like air does for sound. The Michaelson Morally experiments showed us that because they measured the speed of light in two different directions and found them to be identical, even though the Earth is obviously moving in one direction or the other as it goes around the Sun. The reason is because light doesn't have a medium. It's the waving of quantum fields that are the properties of space itself. So space can be empty and still have light in it. And the way we sh Yoda is that we discovered that light moves at the speed of light relative to everybody, no matter how fast you're going. So if you are standing on Earth and you turn on a flashlight, those photons leave your flashlight at the speed of light. Right. Cool. Now, what happens if you jump into Lamborghini and you turn on a flashlight, the Lamborghini is going to two hundred miles per hour. You're in the Lamborghini, you turn on the flashlight. What happens, Well, the light leaves your flashlight at the speed of light relative to you. No big deal. What about somebody on the ground, right, the person you left behind who you didn't offer a ride in your Lamborghini to. When you turn on the flashlight in your Lamborghini, how fast do they see the light going? Well, you might think, well, it's the speed of light plus the speed of the Lamborghini, right, because the flashlight itself is moving at two hundred miles per hour. But that's where you'd be wrong. Right, That's why light is weird. That's how our whole universe is super bizarre. Frankly, it's bunkers. We know that light always travels at the speed of light, no matter what the speed of the thing making it is, right, And everybody who measures the speed of light always sees it moving at the speed of light relative to them. And that's different from sound.

Right.

Right.

Sound travels relative to a medium like air, and that's sort of an absolute reference frame, and sound always moves at the same speed relative to the air. And so if you're moving with respect to the air, like you're in a fighter jet and you're moving at the speed of sound, if you scream, then you're moving with that sound. Right, So if you scream in a fighter jet and you're moving at the speed of sound, and you can basically just like stay inside your scream, you can fly along through the air with your scream. That's not true with light, right. Light will always move at the speed of light relative to you. You turn on that flashlight, even if you were traveling very close to the speed of light, you couldn't stay with those photons. They would leave you at the speed of light. And so if you're traveling very close to the speed of light, because you can't travel at the speed of light, and you look next to you, right, and the person next to you has a flashlight, it's going to act totally normally for you, right, It doesn't matter what's happening outside. Light always travels at the speed of light relative to you. So the short answer to your question is, if you're traveling nearly at the speed of light, then everything will feel normal inside your spaceship, clocks will run normally. Everything will seem normal. Now if you look outside your spaceship, but things that are not traveling at that high speed, that's when relativity kicks in. Things seem to run slow and they seem to get shrunk, right, But light always travels at the same speed no matter what. I hope that was an answer to your question. Thank you so much for writing in, thank you for wondering about the universe, and thank you to all the parents out there who are sharing their wonderings about the universe with their kids, and sharing this podcast with their kids and letting their kids ask us crazy, awesome, amazing, super fun questions about the universe that we totally love to answer. Let's get to our last this question, but first let's take a break. When you pop a piece of cheese into your mouth or enjoy a rich spoonful of Greek 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 every products we love with less of an impact. Visit us dairy dot com slash sustainability to learn more.

Sound travels relative to a medium like air, and that's sort of an absolute reference frame, and sound always moves at the same speed relative to the air. And so if you're moving with respect to the air, like you're in a fighter jet and you're moving at the speed of sound, if you scream, then you're moving with that sound. Right, So if you scream in a fighter jet and you're moving at the speed of sound, and you can basically just like stay inside your scream, you can fly along through the air with your scream. That's not true with light, right. Light will always move at the speed of light relative to you. You turn on that flashlight, even if you were traveling very close to the speed of light, you couldn't stay with those photons. They would leave you at the speed of light. And so if you're traveling very close to the speed of light, because you can't travel at the speed of light, and you look next to you, right, and the person next to you has a flashlight, it's going to act totally normally for you, right, It doesn't matter what's happening outside. Light always travels at the speed of light relative to you. So the short answer to your question is, if you're traveling nearly at the speed of light, then everything will feel normal inside your spaceship, clocks will run normally. Everything will seem normal. Now if you look outside your spaceship, but things that are not traveling at that high speed, that's when relativity kicks in. Things seem to run slow and they seem to get shrunk, right, But light always travels at the same speed no matter what. I hope that was an answer to your question. Thank you so much for writing in, thank you for wondering about the universe, and thank you to all the parents out there who are sharing their wonderings about the universe with their kids, and sharing this podcast with their kids and letting their kids ask us crazy, awesome, amazing, super fun questions about the universe that we totally love to answer. Let's get to our last this question, but first let's take a break. When you pop a piece of cheese into your mouth or enjoy a rich spoonful of Greek 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 every 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 paths and roads every day. Remember they're 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 paths and roads every day. Remember they're 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.

In the rhythm of our daily lives, it's the little things that make the greatest impact. At the Monterey Bay Aquarium. Those moments blossom into memories where every side and sound connects us with the natural world. Embark on a journey of discovery today, from the captivating canopy of the Kelpforest to the enigmatic depths of the deep sea. Monterey Bay Aquarium inspiring conservation of the ocean. Visit Monterey Bay Aquarium dot org, slash together.

In the rhythm of our daily lives, it's the little things that make the greatest impact. At the Monterey Bay Aquarium. Those moments blossom into memories where every side and sound connects us with the natural world. Embark on a journey of discovery today, from the captivating canopy of the Kelpforest to the enigmatic depths of the deep sea. Monterey Bay Aquarium inspiring conservation of the ocean. Visit Monterey Bay Aquarium dot org, slash together.

Okay, and we're answering listener questions. Today. We talked about zooming around at the speed of sound or the speed of light, and we talked about quantum entanglement and black holes. And our last question is also related to light and zooming across the universe. Here it is.

Okay, and we're answering listener questions. Today. We talked about zooming around at the speed of sound or the speed of light, and we talked about quantum entanglement and black holes. And our last question is also related to light and zooming across the universe. Here it is.

Hello, Daniel and Jorge. My name is Marcella and I'm Fromrio Janeto, Brazil. I'm a big fan of your podcasts and your book. So my question is about how does light carry information or how exactly does a photon transmit or carry within itself a pixel so that we are able to see the images we see on our telescopes. How does it not disintegrate after traveling so far? Thank you so much.

Hello, Daniel and Jorge. My name is Marcella and I'm Fromrio Janeto, Brazil. I'm a big fan of your podcasts and your book. So my question is about how does light carry information or how exactly does a photon transmit or carry within itself a pixel so that we are able to see the images we see on our telescopes. How does it not disintegrate after traveling so far? Thank you so much.

All right, that's not really one question, that's like a bunch of questions all stuck together, but totally fair. We'll answer all of them. The first part of the question was essentially what information does light carry? And I think the question is trying to ask, like, when you see a picture of like a distant star, what is it that the photon is carrying? How does that picture come from the star and end up in my eyeballs or in my telescope. First, let's be really microscopic about it, right, what happens when you see a star is that you're seeing photons from that star. So somewhere really far away, at billions of miles away, that big ball of fusion is shooting out photons. And once the photons leave the star, they have nothing to do with the star anymore. Right, they are flying through space and the fact that they came from the star is irrelevant. But they do carry information. They're pointing in a specific direction.

All right, that's not really one question, that's like a bunch of questions all stuck together, but totally fair. We'll answer all of them. The first part of the question was essentially what information does light carry? And I think the question is trying to ask, like, when you see a picture of like a distant star, what is it that the photon is carrying? How does that picture come from the star and end up in my eyeballs or in my telescope. First, let's be really microscopic about it, right, what happens when you see a star is that you're seeing photons from that star. So somewhere really far away, at billions of miles away, that big ball of fusion is shooting out photons. And once the photons leave the star, they have nothing to do with the star anymore. Right, they are flying through space and the fact that they came from the star is irrelevant. But they do carry information. They're pointing in a specific direction.

Right.

Right.

That's information. If you see light coming from one direction or another left versus right, it tells you where that object is. Right, So where in the sky the light is coming from is very important information to know where that star might be. So first piece of information light carries is its direction. Second very important piece of information is its energy. Every photon has a certain amount of energy, and this is the critical thing about photons. This is the reason we know photons exist is that light comes in these little packets of energy. That's basically what a photon is. And the specific energy that a photon has also determines its frequency. Remember, photons their particles, their waves, but when you think about them as waves, you have to think about them as sort of electromagnetic fluctuations, like vibrations in the electromagnetic field. Those vibrations have a certain frequency, and you've probably heard of visible light having frequencies in the range of hundreds of nanometers. So every photon has a certain amount of energy. That energy determines a few things about the photon. It determines the frequency of the wiggles, because remember photons are just electromagnetic waves and they're wiggling along through space their vibrations in the electromagnetic field or the quantum photon field, if you want to think about it in terms of quantum field theory. So it determines its frequency and also its wavelength, and in addition, those things determine the photon's color. But color, of course, is something even more complicated. We're gonna have a whole episode about that soon, what it means to see different colors. But essentially the energy carries all this information. So so far we have a photon zooming through space, and it's carrying information about its direction, and it's carrying information about the energy, and that's most of the information you need from a photon. If you think about all the photons coming off the sun, for example, then there's a big mix of frequencies. There's green, there's red, there's blue, there's all those together and together they make white. So the image you see of the sun, if you look at the sun please don't or if you take a picture of the sun, is you see all those photons coming together into your telescope or your camera or your eye, and it's making that image. It's summed up all those little bits of photons together make that image. It's really similar to the way you look at a screen. A screen is a bunch of pixels. It's an image broken down into little pieces, and the same thing happens in nature even without a screen, even without a device, right just your eye essentially just gathers all those photons and builds an image in your mind. So the second part of the question was how does a photon care carry within itself a pixel so that we're able to see the images we see on our telescopes. We'll remember the photons don't carry the pixels. Pixels themselves are a way to see photons or way to detect photons. So if you think about what happens inside a telescope, these days, telescopes are all digital, meaning you have a bunch of lenses to gather the light and focus the light, but the light in the end is focused onto a digital device, a digital camera basically that gathers and measures the amount of light. And the way those work is essentially they have a bunch of little buckets, and if a photon lands in that bucket, then it gets counted, and then you just count the number of photons you see, and the picture is formed by having the places where more photons landed be more intense and the places where fewer photons landed be less intense. So you divide up the whole space into these buckets, and in each one you count how many photons you saw, and that forms your image. So that's how you might form like a black and white image. If you're just counting the number of photons. You don't care what the energy was for any individual photon. That's how black and white camera works. We of course, are very interested in color photography or color images of things that come from space. We want to know not just what's there, but how bright is it in red, or in green or in blue. So the way that works is instead of just having a bunch of individual buckets that capture photons regardless of their energy, we have different kinds of buckets, just like in your eye, how you have different kinds of things in the back of your eye, the rods and the cones, some of which can capture light and some of which can capture light of only specific wavelengths. In the same way, a digital camera has different kinds of buckets, buckets with filters over them, so they capture light in different wavelengths, different frequencies, different energies. All those things are equivalent, and so you'll have like a red bucket that only captures reddish photons, or a blue bucket that captures things around the blue part of the spectrum, and a green one that captures things around the green part of the spectrum. In an ideal world, For every pixel in your image, you would have a red, green, and a blue bucket, so that you could figure out afterwards exactly what the color was by combining them back from red, green and blue and figuring out exactly what the mixture was and telling you what color it is. But you can't really have these buckets on top of each other. So practically what happens in most digital cameras is that for one pixel, you'll only have one kind of bucket. So for a certain pixel you might have a blue bucket, the next pixel will be only a red bucket, and the next one will be only a green bucket. And then later when you want to understand how much green light is there in a place where there was only a red pixel, you don't know because you didn't measure it because you didn't have a green bucket there. So what they do is they interpolate. They say how much green was there over there on the right, and how much green was there over there on the left, and it figures it out. It guesses how much green there might have been. So color photography is much more complicated, and even color photography using digital cameras attached to telescopes is much more complicated than you might imagine. So that's the way that photons carry information that creates the pixels we see in our images. Right, they don't carry the pixel. They don't show up and say, Hi, you should make this pixel a certain amount. The pixels instead add up, they integrate over all the photons that they detect. All right, wonderful question. And my favorite part is this last bit that how do photons not disintegrade after traveling so far?

That's information. If you see light coming from one direction or another left versus right, it tells you where that object is. Right, So where in the sky the light is coming from is very important information to know where that star might be. So first piece of information light carries is its direction. Second very important piece of information is its energy. Every photon has a certain amount of energy, and this is the critical thing about photons. This is the reason we know photons exist is that light comes in these little packets of energy. That's basically what a photon is. And the specific energy that a photon has also determines its frequency. Remember, photons their particles, their waves, but when you think about them as waves, you have to think about them as sort of electromagnetic fluctuations, like vibrations in the electromagnetic field. Those vibrations have a certain frequency, and you've probably heard of visible light having frequencies in the range of hundreds of nanometers. So every photon has a certain amount of energy. That energy determines a few things about the photon. It determines the frequency of the wiggles, because remember photons are just electromagnetic waves and they're wiggling along through space their vibrations in the electromagnetic field or the quantum photon field, if you want to think about it in terms of quantum field theory. So it determines its frequency and also its wavelength, and in addition, those things determine the photon's color. But color, of course, is something even more complicated. We're gonna have a whole episode about that soon, what it means to see different colors. But essentially the energy carries all this information. So so far we have a photon zooming through space, and it's carrying information about its direction, and it's carrying information about the energy, and that's most of the information you need from a photon. If you think about all the photons coming off the sun, for example, then there's a big mix of frequencies. There's green, there's red, there's blue, there's all those together and together they make white. So the image you see of the sun, if you look at the sun please don't or if you take a picture of the sun, is you see all those photons coming together into your telescope or your camera or your eye, and it's making that image. It's summed up all those little bits of photons together make that image. It's really similar to the way you look at a screen. A screen is a bunch of pixels. It's an image broken down into little pieces, and the same thing happens in nature even without a screen, even without a device, right just your eye essentially just gathers all those photons and builds an image in your mind. So the second part of the question was how does a photon care carry within itself a pixel so that we're able to see the images we see on our telescopes. We'll remember the photons don't carry the pixels. Pixels themselves are a way to see photons or way to detect photons. So if you think about what happens inside a telescope, these days, telescopes are all digital, meaning you have a bunch of lenses to gather the light and focus the light, but the light in the end is focused onto a digital device, a digital camera basically that gathers and measures the amount of light. And the way those work is essentially they have a bunch of little buckets, and if a photon lands in that bucket, then it gets counted, and then you just count the number of photons you see, and the picture is formed by having the places where more photons landed be more intense and the places where fewer photons landed be less intense. So you divide up the whole space into these buckets, and in each one you count how many photons you saw, and that forms your image. So that's how you might form like a black and white image. If you're just counting the number of photons. You don't care what the energy was for any individual photon. That's how black and white camera works. We of course, are very interested in color photography or color images of things that come from space. We want to know not just what's there, but how bright is it in red, or in green or in blue. So the way that works is instead of just having a bunch of individual buckets that capture photons regardless of their energy, we have different kinds of buckets, just like in your eye, how you have different kinds of things in the back of your eye, the rods and the cones, some of which can capture light and some of which can capture light of only specific wavelengths. In the same way, a digital camera has different kinds of buckets, buckets with filters over them, so they capture light in different wavelengths, different frequencies, different energies. All those things are equivalent, and so you'll have like a red bucket that only captures reddish photons, or a blue bucket that captures things around the blue part of the spectrum, and a green one that captures things around the green part of the spectrum. In an ideal world, For every pixel in your image, you would have a red, green, and a blue bucket, so that you could figure out afterwards exactly what the color was by combining them back from red, green and blue and figuring out exactly what the mixture was and telling you what color it is. But you can't really have these buckets on top of each other. So practically what happens in most digital cameras is that for one pixel, you'll only have one kind of bucket. So for a certain pixel you might have a blue bucket, the next pixel will be only a red bucket, and the next one will be only a green bucket. And then later when you want to understand how much green light is there in a place where there was only a red pixel, you don't know because you didn't measure it because you didn't have a green bucket there. So what they do is they interpolate. They say how much green was there over there on the right, and how much green was there over there on the left, and it figures it out. It guesses how much green there might have been. So color photography is much more complicated, and even color photography using digital cameras attached to telescopes is much more complicated than you might imagine. So that's the way that photons carry information that creates the pixels we see in our images. Right, they don't carry the pixel. They don't show up and say, Hi, you should make this pixel a certain amount. The pixels instead add up, they integrate over all the photons that they detect. All right, wonderful question. And my favorite part is this last bit that how do photons not disintegrade after traveling so far?

Right?

Right?

Because the photons have gone really far away. They might have left their star a bis million miles away and flown through space for oodles of years before finally landing on your telescope or on your eyeball or on that rock. Right, think about how many amazing things have happened in the universe and the light from them has just been ignored. It's just like you know, hit a dog, or hit a street light, or just you know, hit the Earth when it was daytime so we couldn't even see it anyway. The question is how does it not disintegrate? How does it last for so long? Well, a photon can go forever it has the energy it needs, and it can fly through space. If it doesn't hit something. If it doesn't bunce into an electron or hit some atmosphere, it could literally fly forever. A photon is self sustaining. It's this amazing combination of electric fields and magnetic fields that slosh back and forth to be completely self sustaining. So in an empty universe, if you shot a photon, it would fly forever, nothing nothing, but there's nothing there to stop it, in the same way that if you pushed a ball through space, through empty space, it would fly forever. So photons don't get tired. They're happy to fly through the whole universe to bring to you pictures from amazing and crazy things that are happening super far away. And we're glad that they are. We're glad that they get here, that they deliver this information into our eyeballs because we get to see this beautiful spectacle that is the universe. All right. So that was a wonderful listener Questions episode. Thank you very much to everybody who wrote in and sent us their questions, and to those of you who have sent us your recording of your questions but not heard yourself yet on the air. Be patient. We will get to you. Thanks everybody, for tuning in. I hope you enjoyed hearing about traveling at the speed of sound and hairy black holes and photons limping their way through the universe after billions of miles of journeys, and I hope that your journeys take you to a place where you can appreciate this incredible, beautiful, but perplexing universe that we find ourselves in. Send your questions to Questions at Danielandjorge dot com. 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 at 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. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact, but the people in the dairy industry are. 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. House US dairy tackling greenhouse gases. Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last sustainability to learn more.

Because the photons have gone really far away. They might have left their star a bis million miles away and flown through space for oodles of years before finally landing on your telescope or on your eyeball or on that rock. Right, think about how many amazing things have happened in the universe and the light from them has just been ignored. It's just like you know, hit a dog, or hit a street light, or just you know, hit the Earth when it was daytime so we couldn't even see it anyway. The question is how does it not disintegrate? How does it last for so long? Well, a photon can go forever it has the energy it needs, and it can fly through space. If it doesn't hit something. If it doesn't bunce into an electron or hit some atmosphere, it could literally fly forever. A photon is self sustaining. It's this amazing combination of electric fields and magnetic fields that slosh back and forth to be completely self sustaining. So in an empty universe, if you shot a photon, it would fly forever, nothing nothing, but there's nothing there to stop it, in the same way that if you pushed a ball through space, through empty space, it would fly forever. So photons don't get tired. They're happy to fly through the whole universe to bring to you pictures from amazing and crazy things that are happening super far away. And we're glad that they are. We're glad that they get here, that they deliver this information into our eyeballs because we get to see this beautiful spectacle that is the universe. All right. So that was a wonderful listener Questions episode. Thank you very much to everybody who wrote in and sent us their questions, and to those of you who have sent us your recording of your questions but not heard yourself yet on the air. Be patient. We will get to you. Thanks everybody, for tuning in. I hope you enjoyed hearing about traveling at the speed of sound and hairy black holes and photons limping their way through the universe after billions of miles of journeys, and I hope that your journeys take you to a place where you can appreciate this incredible, beautiful, but perplexing universe that we find ourselves in. Send your questions to Questions at Danielandjorge dot com. 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 at 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. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact, but the people in the dairy industry are. 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. House US dairy tackling greenhouse gases. Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last sustainability to learn more.

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

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

Go safely.

Go safely.

California from the California Office of Traffic Safety and Caltrans.

California from the California Office of Traffic Safety and Caltrans.

We're paint Care and we're all about keeping it simple. We make recycling leftover paint easy with convenient locations like your local paint store. We have three simple rules for painting smarter and reducing waste. One buy only what you need, Two use up what you already have, and three recycle the rest. Visit paintcare dot org slash three simple rules to learn more or find a paint drop off site near you.

We're paint Care and we're all about keeping it simple. We make recycling leftover paint easy with convenient locations like your local paint store. We have three simple rules for painting smarter and reducing waste. One buy only what you need, Two use up what you already have, and three recycle the rest. Visit paintcare dot org slash three simple rules to learn more or find a paint drop off site near you.