Daniel and Jorge Explain the UniverseDaniel answers Listener Questions about hawking radiation, 5G networks and wireless phone chargers!
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The world around you is like an amazing mirage. That rock you see over there, it's not actually one object, but a collection of ten to the twenty five particles, all shaking and buzzing and wiggling together. That star you see in the sky, those are photons generated from zillions of kilograms of hot plasma that traveled billions of light years before hitting your retina. That chair that's holding you up, that's not solid. It's actually a web of atoms linked together by electromagnetic forces. Physics gives you a way to peel back a layer of reality and figure out what's happening underneath, to see the world in a new way by understanding its nature at the microscopic level and seeing how all the incredible complexity and the insanity in our universe arises from the simple interactions of a all number of pieces. It's bonkers, but it's beautiful.
Hi.
I'm Daniel, I'm a particle physicist, and I'm in love with the insanity of our universe. And welcome to our podcast. Daniel and Jorge Explain the Universe, a production of iHeartRadio in which we take a mental journey through the cosmos. We think about how everything out there works. We try to understand the craziness of neutron stars, of black holes evaporating, the tiny, little buzzing particles that make it all up. We try to take the whole universe and wrap it up so that you can understand it or at least understand a little piece of it, because the universe is not something that is understood, remains an enormous cosmic mystery. Though we have peeled back layers of reality to see that most of what we are looking at is made of elements, and those elements are made of even smaller particles, which are made of even smaller particles. We have dug deep into the nature of reality, but our questions are not yet answered. We need to understand and we have not yet understood. There remain enormous mysteries about the nature of the universe. What is most of the matter out there in the universe? What is driving the acceleration of the cosmic expansion of the universe. We have really basic questions about how things work. But those questions are not failings. They're not a disappointment in science. They are exciting opportunities. They are the threads that we will pull on to help us reveal the nature of the universe. They are the clues that will lead us to incredible, mind blowing discoveries about the nature of the cosmos. Just the way that our journey through physics so far has revealed so many times that the universe is not the way that we thought it was, since our intuition built up from the times that we climbed down from the trees and walked around on two feet and tried to understand this world around us, that that intuition has often led us astray, and that when we follow the science, when we carefully built up knowledge by asking and answering questions, is when we reveal the true nature of the universe. And it's crazy and it's weird, and it violates our intuitions, but it's still beautiful and it's our universe. And that's why on our podcast we love to celebrate questions, not just questions asked by scientists working at the forefront of knowledge, peering out into the depths of the universe, but your questions, our questions, everybody's questions. Because if you wonder about the nature of the universe, if you yearn to understand the truth about reality, then you are a scientist, then you are asking questions. Then you would be surprised to discover how many of your questions are the same questions being asked by scientists. So don't be embarrassed to ask your questions, ask them out loud, talk to people about them, try to find the answers, and if you can't, send them to us, because we love answering your questions. Everybody out there who has thought about a topic and not quite understood it, or heard an explanation about something weird and crazy and it didn't really sync in, please write to us. We will answer your questions. We're available online. We answer emails to questions at Danielanjorge dot com. We respond on Twitter at Daniel Jorge and sometimes we'll take some of these questions and feature them on the podcast. And so on today's program, we'll be answering listener questions about Hawking radiation, five G networks, and wireless charging. As you might have gathered, my cohost friend and collaborse jorhe Hm, is not around today, so I'm taking this opportunity to dig into our backlog of wonderful, wonderful questions asked to us by listeners. So I'll be digging into a few questions from listeners, and you have lots of opportunities to get your questions answered. You can email us, you can tweet us. You can also come to my public office hours. I hang out on Zoom and answer questions from anybody out there who's interested in physics and wants to understand the universe. Check out my website sites dot UCI dot edu slash Daniel for all the details about the next upcoming public office hours. All right, so let's dig into it and start answering listener questions. This first one is an awesome question about hawking radiation, black holes, and dark matter.
Hello, Daniel are My question is about talking radiation and in oporational my quotes.
So if there is there.
Matter inside my quotes, wouldn't it been necessary for hawking radiation in.
Direct to the dark matter in order to for this?
Like host completely tey.
This is such a fun question because it gives me a little glimpse into what's going on in somebody's mind. Somebody's thinking about black holes and hawking radiation and wondering how that happens, and all of a sudden, they're running to a wall. They think, whole on a second, this doesn't make sense. How can the products of hawking radiation annihilate with the dark matter inside the black holes? And so they come to that point they don't understand it, and that's when they reach out. And I love seeing people do that taking two ideas and trying to fit them together into one understanding, because that's what we do in physics, right We want a single understanding that explains everything. You can't have one explanation for this thing and a totally different explanation for that. We want a complete holistic view of the universe. So kudos to you for asking this question. But before I dive into the details of dark matter and black holes and hawking radiation, let's back up and make sure we understand the basics of what's going on hawking radiation, because I think there might be a small misunderstanding in the process, which is actually leading to the core of this question. The first thing you should understand about hawking radiation is that we do not have a good microscopic understanding of how it works. We like to look at the world and peel it back and understand how it works at the particle level and sometimes work back up from the particle level to the macroscopic and say, okay, we understand this temperature is just the buzzing of particles whizzing around or and electrical conductivity comes from how electrons are filling their orbitals, et cetera, et cetera. But that's not something we have yet for Hawking radiation because it relies on two things that don't play well together, tiny little quantum particles which obey the rules of quantum mechanics and gravity, and gravity and quantum mechanics don't play very nicely together. We do not understand gravitational effects on individual quantum particles. That would require a theory of quantum gravity, which we don't have. So Hawking radiation actually doesn't come from a microscopic understanding of what happens to quantum particles near the edge of the black holes. No, it comes from statistical and thermal physics. It's comes from thinking about black holes as big objects made of many particles and thinking about them statistically, sort of the same way we think about like temperature and pressure for a gas. Pressure doesn't make any sense. It doesn't have a meaning for an individual particle. It's a property only of a gas. So this is the way that Hawking derived this concept of a temperature an entropy for a black hole. He invented this field of black hole thermodynamics, and from it came this concept of Hawking radiation. But we don't have a microscopic understanding of what's actually happening at the particle level. But we do have some not terrible kind of hand wavy descriptions for how hawking radiation might work. Now, they don't actually work theoretically on the quantum level if you try to do these calculations, but they're a good way to sort of guide your thinking for what might be happening and help you to think about it. Okay, so what is our understanding of hawking radiation at the microscopic level. So the space near a black hole, of course has energy in it. All of space has energy in it because space is filled with quantum fields and those fields can't relax all the way down to zero. And sometimes that energy in the field turns into a particle or a particle and an anti particle. So this happens all the time. Things turn into an electron and apositron, and then they annihilate back and they go back into the field. So this is going on all the times, this frothing at the quantum level, even around black holes. Now, when this happens in the vicinity of a black hole, sometimes these particles get a little extra boost of energy because there is more energy around a black hole. There's the gravitational energy of the black hole. And this is the wonky part because we don't really understand how gravity interacts with particles. We can't do experiments to see the gravitational effect on particles because particles have almost no mass and gravity is supernuber weak, so we haven't been able to do these experiments. But anyway, imagine that somehow this particle antiparticle pair gets extra energy because of the gravitational field of the black hole. Now one of these particles happens to leave the area of the black hole. They were created outside the event horizon, so that's cool. The other one falls back into the black hole. Let's think first about the one that leaves. What happens to it, Well, it flies off into the universe. Maybe it's an electron. Maybe it's a positron. Maybe it's a top quark, maybe it's a gluon. It can be any kind of particle because the quantum field can fluctuate into any kind of particle. There are some different probabilities based on the masses, but that doesn't really matter. But that particle leaves and it takes with it some energy. Where did that energy come from It came just from the quantum field, but part of it also came from the gravitational energy of the black hole. And if you take the gravitational energy, you were decreasing the mass of the black hole. Now you might be thinking, hold on a second, how does the mass leave the black hole? This particle was never in the black hole. Right, that's true, But remember the mass of the black hole is not like the amount of stuff in the black hole. It's like a meter that tells you how much energy is stored in the black hole. It doesn't matter what the form of that energy is. It can be photons, it can be protons, it can be something else super duper weird. It can be a singularity that has no state of matter we can think about or calculate. The mass of the black hole comes from the energy stored within it. So if you remove energy from the black hole, you reduce its mass. You can reduce the mass of a black hole without carrying a particle from inside the event horizon to outside the event horizon. And you might be thinking, hold on a second, that's crazy. I thought black holes could never release information, they could never lose anything. And it's true. That nothing can leave. If it's inside the event horizon, no information can escape. However, the black hole's energy goes beyond the edge of the event horizon, its gravitational influence does not stop at the event horizon. The event horizon is just a place after which all of your paths now point towards the center of the black hole. It's not the edge of the black hole's influence on the universe, and that influence can extend to things created outside the event horizon, and it can lose that energy once it's donated it to those particles, and when it loses that energy, it loses some mass.
All right.
So now we have a sort of handwavy understanding of how hawking radiation might work at the microscopic level. Let's get to the question. The question was about the particle that goes into the black hole, not the one that escapes, and it was asking, if the particle goes into the black hole, doesn't it need to find something to annihilate with the sort of contribute back its energy to the black hole. And if black holes are mostly dark matter, then how can they do that because it can't interact with dark matter? All right? So a lot of things to talk about there. First of all, we don't know how much dark matter is in black holes. I've said on the podcast it's almost certain that there is some, and that's true. But remember that dark matter has a harder time falling into black holes because it can't get rid of its angular momentum like other kinds of matter. It can spin around a black hole, but other kinds of matter can lose their angular momentum by radiating off energy, for example, or bumping into each other. These kinds of interactions are crucial for losing your angular momentum and falling into the black hole, falling out of orbit and falling into the black hole. Dark matter can't do that, so it stays fluffy, And so we think that there is dark matter in black holes. We don't really know how much. It may not be that it's dominated by dark matter, but even still, let's imagine that the black hole is filled with dark matter. What happens to this particle that falls into the black hole. Well, it doesn't actually need to annihilate with anything to contribute to the mass of the black hole. Remember, the mass of the black hole is just a measure of how much energy is stored inside it. It's not necessary for that particle to annihilate with something else and return its energy. It already has returned its energy. Everything that's in the vicinity of the black hole contributes to the gravitational system and therefore to the mass of the black hole. If particles inside the black hole change from photons to particle antiparticle pairs, it has no effect on the black hole's mass. So if there is dark matter inside black holes, it doesn't affect this hawking radiation all right. So the things to remember about hawking radiation are number one, that we only have a handwavy description of the microscopic effects. We don't really understand how it works. Our understanding of hawking radiation is that the level of statistical physics talking about many, many particles and averaging over lots of quantum details that we do not yet understand, and that hawking radiation happens outside the black hole, borrowing some of the gravitational energy from the black hole and carrying it off with it because you can interact with the black hole without actually falling into it, and that means that it's possible to steal a little bit of its energy and therefore decrease its mass, and that's sort of our understanding of Hawking radiation and how black holes can evaporate. All right, thank you for that wonderful question, and thank you for thinking deeply about how black holes work and how they evaporate, and what might be inside them and what's going on inside the black holes. They are one of my favorite mysteries because they potentially contain the answers to so many basic questions about how the universe works. What happens to quantum particles when gravity gets really really strong, and the gravitational effects and the quantum effects both become important. We have almost nowhere in the universe we can probe quantum gravity because it's so hard to study. But the center of black holes is that place. Unfortunately, of course, we can't see what's inside them. All right, So thanks for that question. I have more questions I want to get to, 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 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. 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Hello, Daniel and Jorge, this is a Mario from Los Angeles. While I was listening to your show, I heard a commercial about five G and I got curious because there's a lot of conspiracy theories about the pandemic and five G. I was hoping you guys could explain the effects that five G have on our society, give an informed an opinion about the conspiracy theories.
Thank you.
Okay, so this is a really interesting question and one that actually a few people have written to us about. So I thought it'd be interesting to sort of take the physics point of view. What do we know about five G networks? What are they, how do they work, what's the physics of five G and how it interacts with the human body, And then you'll have everything you need to make up your own mind about whether or not five G is a good idea. All right, So, first of all, what is five G? Five gen means fifth generation cell phone networks. People have been upgrading and improving our cell phone networks to make them faster and more reliable, et cetera. And now they have the fifth generation which is now being installed. Five G is a thing. It exists. It's out there in patches in our world. It's not complete, it's not everywhere. They're still putting it together, so it's sort of in its embryonic phase. And it's an exciting technology because potentially it could deliver data to your devices one hundred or more times faster than the four gene networks, and so that would allow a lot of things to happen. You can have a screen on the door to your refrigerator to let's use stream movies while you're deciding what to eat. You can have everything connected. You could just send a lot more data everywhere. So if you're excited about data, then you should be excited about five gene networks. So what's different between five G and four G? Right, the fourth generation of network and what makes people so interested and excited and concerned about it. While there are a couple of differences about five G, there're some sort of smaller ones, like the way they organize the data to make it faster and the way they route it from tower to tower, But the major differences are one that the antennas are directional. So an antenna is just a bunch of electrons wiggling in a conducting rod that generates electromagnetic fields, and often these antennas broadcast in every direction simultaneously, so then the power of the radiation the intensity of the signal decreases as you get further away from the antenna. But sort of the same way every direction. These five G antennas are directional. They can be focused in certain directions to provide like longer range connections in certain directions and to black out other directions, And this way you can sort of like more intelligently decide where you want your coverage. So that's number one. They have these directional antennas. Number two, and this is probably the big one, is that they're using a different frequency to communicate. The wavelength of these signals is something like ten millimeters. The frequency is like in the range of twenty to fifty gigahertz. And this is interesting and this is new because it's ten times higher frequency, shorter wavelength than have existed in cell phones before. It's not the first time we've seen technology that emits radiation in this wavelength or frequency spectrum. It's the same sort of wavelength this is used in those airport scanners when you go to the airport and they try to figure out if you have something in your pocket. But these are much lower power than those airport scanners. On the other hand, they're kind of on all the time, and so they're sort of blanketing the world with this radiation. And the question is about the long term exposure to this wavelength of radiation, and that's where I think the concern arises. And you may have heard some conspiracy theories about how this is created the pandemic or responded to the pandemic, and that, of course, is all just bonkers. There is no connection between five G and the pandemic. There are no microchips inside the vaccines. All that stuff is just fear mongering nonsense. There are some interesting physics questions about five G, and some interesting medical questions about the impact of five G on the human body, and some interesting policy questions about how to roll out a technology, how many tests you really need to have done before you take a risk and roll out something new. That's all fascinating, but let's push aside for now the crazy conspiracy theories connected the pandemic. We're insane lizard people using five G to control your minds, and let's just talk about the physics. So I said radiation, and I talked about the intensity of it. Does that mean that these things are like radioactive, that you're basically living next to a nuclear power plant? No? No, no, Remember that radiation is a very very broad term. It includes any sort of wave or particle which transmit energy, including yes, radioactivity from nuclear power plants. But that's not what we're talking about today. We're talking about the kind of radiation that's just photons, right, Just a kind of light an electromagnetic radiation, which is a very very broad term, but all of it is just a different kind of photon, and those photons are different based on their frequency, based on the wavelength of the photon, and different wavelength photons we give different names, from very long wavelength photons, which are like radio waves or infrared waves, up to visible light, of course, which is just photons of a certain frequency that hits your eyes and your brain knows how to interpret. Up to ultraviolet light, which has a frequency higher than you can see, all the way up to X rays and gamma rays. It's all part of one continuous spectrum. The difference between a gamma ray and a photon that makes up a radio wave is just the wavelength of that photon, and all these photons can we use to encode information. So we use electromagnetic radiation as a way to pass information around. And you can think of it as waves, right. We think about radio waves as waves washing over the Earth's surface. TV antennas and all that kind of stuff send electromagnetic waves, and you can think about it as waves. That makes perfect sense, but it's also important to remember that it's actually made of photons. It's made of individual particles, and that's important because the energy of the individual photons depends on the wavelength of the radiation. So when we say higher frequency, we mean this more energy per photon. So UV photons have more energy in them than radio wave photons. Gamma ray photons have even more energy in them. X ray photons have a lot of energy in them, more than visible light photons. And it's broken up into these pieces, right. You can't have half a photon or one and a half photons. If you have a beam of light light in the X ray part of the spectrum, then each of those photons has a lot of energy. You have a beam of light in the infrared, then each of those photons has less energy. And that turns out to be really important because when the photon hits your body, it's the energy of that individual photon that determines whether or not it can ionize something, whether or not it can kick an electron, for example, out of an atom, or it can break one of those bonds. And the most damaging thing radiation can do is ionize parts of your body. When it does this, it does things like break up DNA molecules. It acts like a tiny little bullet that shoots through your body and breaks things. So ionizing radiation is very, very dangerous, and that's why it's important to reduce your exposure to ionizing radiation. Now, things like uranium and plutonium give off ionizing radiation, which is very dangerous, and some forms of electromagnetic radiation can have enough energy to ionize. The threshold for ionizing radiation is a little bit fun depends on the material, etc. But it's on the order of magnitutive, about ten ev per photon. This is like the binding energy of molecules. And in order to have that much energy of photon has to be in the ultraviolet. That's why ultraviolet radiation UV rays are bad for you. UV does cause cancer, and that's what you're blocking when you're putting on sunscreen, and that UV light can pass through clouds, which is how you can get a sunburn on a cloudy day. So visible light and everything with a wavelength lower than that, it's not ionizing. It can't cause ionization in your body and so is much much safer. Now, five G is well below the wavelength of even visible light. It's below the infrared. So from the point of view of ionization, the most dangerous thing that radiation can do. Five G is not a concern. Yes, it does have a higher wavelength than previous generations of cell phones, but it's well below the energy needed to do any damage from an ionizing point of view. But that's not the only way that radiation can damage you. Ionization is not the only thing that it can do. For example, it can deposit energy in your body even without actually ionizing. I mean, this is what an oven does. Right when you cook a turkey in your oven, you're using infrared photons. You're using the heat of the oven to cook that turkey, and yeah, it certainly does damage the turkey. And so you can hurt people with a high intensity of low energy radiation. Right here, we're talking about the intensity and microwave oven uses microwave radiation, which is much much longer in wavelength than ultraviolet photons. But it's a very high intensity, and so it can deposit a lot of energy and eventually it can hurt you. So this is the area to focus on from a sort of physics and medical point of view. Can being exposed to a large amount of five G signals do some damage to the human body. Well, it turns out that humans have a sort of built in shield to a lot of this stuff. Most of these photons will actually scatter off of your skin. Your skin is like a shield that will reflect a lot of this energy. The upper layers of your skin are opaque to this kind of photon, so most of it won't even enter your body. There were some very early studies that showed the amount of damage done to tissue based on the frequency and show the five G was in a range it did more damage, but it neglected to take into account the fact that most of that five G radiation won't even get into your body. But the fact remains that this is a kind of electromagnetic radiation where its long term exposure has not been studied on the public. We haven't bathed people and the kinds of radiation that five G will generate for long periods and seeing what would happen. So we just don't know. That doesn't mean we don't have a good guess. We understand the physics of it. We think that it's too low energy to do any ionization damage. We think that the skin is opaque to it will reflect most of it, and so we think we can do the calculations and it seems totally safe, but we don't have direct evidence. And the folks that are citing studies that show that there's no connection between for example, cell phone towers and cancer are missing the point a little bit because those cell phone towers are using a different frequency than five G. So we don't actually have direct data that shows that five G is safe because it was just invented, right, And so what can we do here? Science can say we don't see a reason why it would be dangerous. We think it will be safe. We do not have direct proof, so we can't conclusively say it's safe. We can't point to studies that prove that it's safe. We can argue and we can make reasonable points that suggest that it will be safe. But in the end, it's a question for policy makers when do you make a decision for how to roll out of new technology which could have lots of benefits for the public, but also every new technology does have some inherent dangers, and in the end, sometimes policymakers do have to make these very difficult decisions knowing they could help people, but they could also potentially hurt people. So that's not something I'm going to comment on because I'm not a policy maker, but I think that the policymaker should at least be informed by the science. And I hope that you guys out there understand the science of five G. It is a new technology with higher frequency photons, not high enough frequency to do ionizing damage, but the impact of this frequency radiation of very low intensities has not been studied on the general public. That doesn't mean that it's caused the pandemic or that it's something that you should worry about. Read more about it, think about it, Write to your congress people or representatives, or your president or whoever if you have a deep and passionate opinion about how to balance this question of technology versus safety. All Right, I want to answer another question, 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 maneure 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 usdairy dot com slash sustainability to learn more.
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All right, we're back and I'm answering questions from listeners. We had a question about black holes and hawking radiation. We had a question about wireless cell phone towers in the radiation they emit. And now we have a question about wireless charging.
Hi, Daniel and Jorge. I was wondering how wireless charging devices work. I don't understand how the battery is charged without a visible input into the device. It's baffling to me. It's like magic.
Thanks all right, thank you for this super fun question. Sometimes physics is baffling. It defies our intuition. But you know, the universe works, The universe follows rules. There is always a way to understand what we see and then sometimes to use that understanding to build awesome new technology like wireless charging. And your intuition is that things need a wire because the stuff around you uses wires. Right, either you plug it into the wall or you connect it with a battery, because you're used to a certain kind of way of transmitting energy. You have energy inside a battery or energy coming in the wires, and that's in the form of electrical energy, and those electrons zip along and they deposit that energy into your device, your phone or your camera, or your laptop or your blender or whatever. And that certainly is one way to send electromagnetic energy from one device to another. And by using a wire, which is essentially just a conductor where the electrons can bump into each other and pass that energy along. However, there are lots of ways to transmit energy, and you can transmit energy wirelessly, right. What is a flashlight? A flashlight is a beam of photons. Those photons have energy. What is a laser? A laser can certainly transmit energy, you can use it to heat something up from a distance, right, and those photons can fly through space, even through a vacuum. So conceptually, from a sort of physics point of view, we understand how it's possible for energy to start in one place and get to another place without having a physical connection a wire, right even across the vacuum of quote unquote empty space. But that doesn't tell us how wireless chargers actually work. How do they get the energy from one device to the other without the two actually being connected. There's not some tiny series of lasers in there zapping energy from one to the other. You certainly don't want your blender to be zapped with lasers. So how does it actually work. The first thing to understand is the whole system is not wireless. It's just like one step there that's wireless. Usually you have like a base which is plugged into the wall, and then you can put your phone on top of that base. It sits on the base and it draws power from the base. And so it's that step that we're going to try to understand. How can you get energy from the base which is plugged into the wall and getting energy eventually from your power plant, how does it get from that base and into your phone. So this comes from the magic and the beauty of electromagnetism. And to understand how this works, we need to remember that electricity and magnetism feel like two different things, right. Electricity is lightning bolts and electrons, and magnetism is like fridge magnets and livity trains. But they are actually two parts of the same thing. Maxwell, the Scottish clerk one hundred and fifty years ago, realized that there's a deep symmetry between electricity and magnetism. And he noticed this because he noticed that electricity can cause magnetic field to magnetic fields can cause currents, and so that's exactly how it happens. We have two parts of Maxwell's equations working together. So the first part is that when you have an electric current that creates a magnetic field. If you've ever seen an electromagnet you know this is true. You turn on the current, it goes through coils and those coils create a magnetic field. And every electric engine, for example, has this property inside it. When you turn on the engine, what you're doing is turning on electromagnets inside the engine. Which are using the magnet to sort of tug on another part of the engine and get it to move. So the first step is to use currents inside the base station to create a powerful magnetic field. That magnetic field, in turn can cause electrical currents because another part of Maxwell's equations tells us that varying magnetic fields caused electrical currents. Right, So what happens to the base station is you have this current which is going on and off, creating magnetic fields which are on and off, and those magnetic fields then induce a current inside your phone. So inside the phone there has to be some loop, or inside whatever device you're trying to charge, there has to be some loop, and the magnetic fields then induce a current inside that loop. So you have a loop inside the base station where you create a current using power from the wall. That current inside the loop creates a magnetic field, and that magnetic field then creates a current inside a loop of wire in the thing that you want to charge. And so this is a way to transmit the energy from the bay station to the phone or whatever it is that you're trying to charge without actually having to have a wire between them. It's essentially like using a magnetic wire. And this only works because there is this symmetry between electricity and magnetism, because currents cause magnetic fields, which cause currents. And the other awesome thing about this symmetry is that it's the reason that we can see anything. What is light? What is a photon? It's a ripple in the electromagnetic field, not the electrical field, not the magnetic field, but the electromagnetic field. And that exists because varying electric fields cause magnetic fields, which cause varying electric fields. So what a photon actually is is a field that's slashing back and forth between the electric and the magnetic fields. That's what allows it to pass through the vacuum of space. It supports itself, it propagates itself by going back and forth from electro to magnetic fields. And this was the beautiful inside of Maxwell. He saw these equations and they put them together. He thought, oh, my gosh, well, light looks just like a wave that's slashing back and forth and moving at some speed. And you did the calculation is like, oh, look, it moves at the speed of light. So that was a beautiful moment. Sort of in theoretical physics, putting these two pieces together, understanding the symmetry between electric and magnetic fields. And it's that same insight that allows us to do inductive powering, to use magnetic induction to take a coil of current and transfer that energy into another coil. Now, this is fascinating if people have done a lot of studies to see, like how far can it work. You're probably most familiar with charging stations at Starbucks where you'll get charge from this wireless charging station. Now, the larger the coil inside the base station, the longer the wavelengths of this radiation essentially, and the larger the distance that that power can charge. There was a record set in two thousand and seven where somebody was able to charge something two meters away. That's pretty awesome. Right, two meters away is a good distance. It's not enough that you can like drive around town and keep your phone charged from your but it's pretty cool, and it's the kind of thing where people are making strides and eventually there'll be a breakthrough and we'll be able to send power at even greater distances. And you know, your phone is not the only example of this technology. If anybody out there has an inductive range. It's the kind with coils in it, but those coils don't feel hot because they're not transmitting the energy by making themselves glow really really hot, like the elements inside your oven, which would be giving off infrared radiation. Instead, they are creating magnetic fields which then cause currents inside a pan that you put on top of the stove, So the pan gets hot, but the surface of the stove itself is not hot because there's no infrared heat passing directly from inside the range to the pan. Instead, you have this coil inside the range, and that coil has a lot of electricity in it, which is creating a magnetic field, which is creating a current inside your pot, which then turns into heat of the pot. So it's able to transmiss this energy and heat up the pot without actually heating up the stuff in between, which is pretty awesome and it means that it's harder to burn yourself. So thanks very much for asking that super fun question about this cool technology. It does seem like magic, but it's actually something that we can understand, and that's the beauty of the universe that amazingly, it seems like no matter what happens out there if you think about it carefully, if we put our collective heads together, we can figure it out. And so even though there are so many mysteries remaining about the nature of the universe and what's going on inside black holes, and how the universe started and what is everything made out of, at the smallest, tiniest level, all these questions are just the possibilities for new discoveries, the possibility to reveal something new about the universe that we didn't know that would blow the minds of our grandparents. It means that one day our grandchildren will make these discoveries and will blow our minds. So until then, keep thinking about it, keep asking questions, and send us all of your questions. Love to hear your thoughts. Thanks very much, tune in next time. 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