Speaker 1: The world around you is like an amazing mirage. That
Speaker 1: rock you see over there, it's not actually one object,
Speaker 1: but a collection of ten to the twenty five particles,
Speaker 1: all shaking and buzzing and wiggling together. That star you
Speaker 1: see in the sky, those are photons generated from zillions
Speaker 1: of kilograms of hot plasma that traveled billions of light
Speaker 1: years before hitting your retina. That chair that's holding you up,
Speaker 1: that's not solid. It's actually a web of atoms linked
Speaker 1: together by electromagnetic forces. Physics gives you a way to
Speaker 1: peel back a layer of reality and figure out what's
Speaker 1: happening underneath, to see the world in a new way
Speaker 1: by understanding its nature at the microscopic level and seeing
Speaker 1: how all the incredible complexity in the insanity in our
Speaker 1: universe arises from the simple interactions of a small number
Speaker 1: of pieces. It's bonkers, but it's beautiful. Hi. I'm Daniel,
Speaker 1: I'm a particle physicist, and I'm in love with the
Speaker 1: insanity of our universe. And welcome to our podcast Daniel
Speaker 1: and Jorge Explain the Universe, a production of My Heart
Speaker 1: Radio in which we take a mental journey through the cosmos.
Speaker 1: We think about how everything out there works. We try
Speaker 1: to understand the craziness of neutron stars, of black holes evaporating,
Speaker 1: the tiny, little, buzzing particles that make it all up.
Speaker 1: We try to take the whole universe and wrap it
Speaker 1: up so that you can understand it, or at least
Speaker 1: understand a little piece of it. Because the universe is
Speaker 1: not something that is understood. It remains an enormous cosmic mystery.
Speaker 1: Though we have peeled back layers of reality to see
Speaker 1: that most of what we are looking at is made
Speaker 1: of elements, and those elements are made of even smaller particles,
Speaker 1: which are made of even smaller particles. We have dug
Speaker 1: deep into the nature of reality, but our questions are
Speaker 1: not yet answered. We need to understand, and we have
Speaker 1: not yet understood, the remain enormous mysteries about the nature
Speaker 1: of the universe. What is most of the matter out
Speaker 1: there in the universe? What is driving the acceleration of
Speaker 1: the cosmic expansion of the universe. We have really basic
Speaker 1: questions about how things work. But those questions are not failings.
Speaker 1: They're not a disappointment in science. They are exciting opportunities.
Speaker 1: They are the threads that we will pull on to
Speaker 1: help us reveal the nature of the universe. They are
Speaker 1: the clues that will lead us to incredible, mind blowing
Speaker 1: discoveries about the nature of the cosmos, just the way
Speaker 1: that our journey through physics so far has revealed so
Speaker 1: many times that the universe is not the way that
Speaker 1: we thought it was, since our intuition built up from
Speaker 1: the times that we climbed down from the trees and
Speaker 1: walked around on two feet and tried to understand this
Speaker 1: world around us, that that intuition has often led us astray,
Speaker 1: and that when we follow the science, when we carefully
Speaker 1: build up knowledge by asking and answering questions, is when
Speaker 1: we reveal the true nature of the universe. And it's
Speaker 1: crazy and it's weird, and it violates our intuitions, but
Speaker 1: it's still beautiful and it's our universe. And that's why
Speaker 1: on our podcast we love to celebrate questions, not just
Speaker 1: questions asked by scientists working at the forefront of knowledge
Speaker 1: peering out into the depths of the universe, but your questions,
Speaker 1: our questions, everybody's questions, Because if you wonder about the
Speaker 1: nature of the universe, if you yearn to understand the
Speaker 1: truth about reality. Then you are a scientist, then you
Speaker 1: are asking questions. Then you would be surprised to discover
Speaker 1: how many of your questions are the same questions being
Speaker 1: asked by scientists. So don't be embarrassed to ask your questions,
Speaker 1: ask them out loud, talk to people about them, try
Speaker 1: to find the answers, and if you can't, send them
Speaker 1: to us, because we love answering your questions. Everybody out
Speaker 1: there who has thought about a topic and not quite
Speaker 1: understood it, or heard an explanation about something weird and
Speaker 1: crazy and it didn't really sink in, please write to us.
Speaker 1: We will answer your questions. We're available online. We answer
Speaker 1: emails to questions at Daniel and Jorge dot com. We
Speaker 1: respond on Twitter at Daniel and Jorge, and sometimes we'll
Speaker 1: take some of these questions and feature them on the
Speaker 1: podcast and so on. Today's program will be answering listener
Speaker 1: questions about Hawking, radiation, five G networks, and wireless charging.
Speaker 1: As you might have gathered, my co host friend and
Speaker 1: collaborator Jorge him is not around today, so I'm taking
Speaker 1: this opportunity to dig into our backlog of wonderful, wonderful
Speaker 1: questions asked to us by listeners. So I'll be digging
Speaker 1: into a few questions from listeners, and you have lots
Speaker 1: of opportunities to get your questions answers. You can email us,
Speaker 1: you can tweet us. You can also come to my
Speaker 1: public office hours. I hang out on zoom and answer
Speaker 1: questions from anybody out there who's interested in physics and
Speaker 1: wants to understand the universe. Check out my website sites
Speaker 1: dot U, c I, dot E, d U slash Daniel
Speaker 1: for all the details about the next upcoming public office hours.
Speaker 1: All right, so let's dig into it and start answering
Speaker 1: listener questions. This first one is an awesome question about
Speaker 1: hawking radiation, black holes, and dark matter. Hello Dan, My
Speaker 1: question is about talking radiation and the operation of BLAT. So,
Speaker 1: if there is there's matter inside my cote, what had
Speaker 1: it been necessary for hawking radiation to interact with the
Speaker 1: dark matter in order to produce like holes completely. This
Speaker 1: is such a fun question because it gives me a
Speaker 1: little glimpse into what's going on in somebody's mind. Somebody's
Speaker 1: thinking about black holes and hawking radiation and wondering how
Speaker 1: that happens, and all of a sudden they run into
Speaker 1: a wall. They think a whole lot of a second,
Speaker 1: this doesn't make sense. How can the products of hawking
Speaker 1: radiation annihilate with the dark matter inside the black holes?
Speaker 1: And so they come to that point they don't understand it,
Speaker 1: and that's when they reach out. And I love seeing
Speaker 1: people do that, taking two ideas and trying to fit
Speaker 1: them together into one understanding, because that's what we do
Speaker 1: in physics, right We want a single understanding that explains everything.
Speaker 1: You can't have one explanation for this thing and a
Speaker 1: totally different explanation for that. We want a complete, holistic
Speaker 1: view of the universe. So kudos to you for asking
Speaker 1: this question. But before I dive into the details of
Speaker 1: dark matter and black holes and hawking radiation, let's back
Speaker 1: up and make sure we understand the basics of what's
Speaker 1: going on in hawking radiation, because I think there might
Speaker 1: be a small misunderstanding in the process, which is actually
Speaker 1: leading to the core of this question. The first thing
Speaker 1: you should understand about hawking radiation is that we do
Speaker 1: not have a good microscopic understanding of how it works.
Speaker 1: You know, we like to look at the world and
Speaker 1: peel it back and understand how it works. At the
Speaker 1: particle level and sometimes work back up from the particle
Speaker 1: level to the macroscopic and say, okay, we understand this
Speaker 1: temperature is just the buzzing of particles whizzing around, or
Speaker 1: an electrical conductivity comes from how electrons are filling their orbitals, etcetera, etcetera.
Speaker 1: But that's not something we have yet for Hawking radiation
Speaker 1: because it relies on two things that don't play well together,
Speaker 1: tiny little quantum particles which obey the rules of quantum
Speaker 1: mechanics and gravity, and gravity and quantum mechanics don't play
Speaker 1: very nicely together. We do not understand gravitational effects on
Speaker 1: individual quantum part nicles. That would require a theory of
Speaker 1: quantum gravity, which we don't have. So Hawking radiation actually
Speaker 1: doesn't come from a microscopic understanding of what happens to
Speaker 1: quantum particles near the edge of the black holes. No,
Speaker 1: it comes from statistical and thermal physics. It's come from
Speaker 1: thinking about black holes as big objects made of many particles,
Speaker 1: and thinking about them statistically, sort of the same way
Speaker 1: we think about like temperature and pressure. For a gas
Speaker 1: pressure doesn't make any sense, It doesn't have a meaning
Speaker 1: for an individual particle. It's a property only of a gas.
Speaker 1: So this is the way that Hawking derived this concept
Speaker 1: of a temperature and entropy for a black hole. He
Speaker 1: invented this field of black hole thermodynamics, and from it
Speaker 1: came this concept of Hawking radiation. But we don't have
Speaker 1: a microscopic understanding of what's actually happening at the particle level.
Speaker 1: But we do have some not terrible kind of hand
Speaker 1: wavy descriptions for how Hawking radiation might work. Now, they
Speaker 1: don't actually work theoretically on the quantum level if you
Speaker 1: try to do these calculations, but they're a good way
Speaker 1: to sort of guide your thinking for what might be
Speaker 1: happening and help you to think about it. Okay, so
Speaker 1: what is our understanding of Hawking radiation at the microscopic level.
Speaker 1: So the space near a black hole, of course has
Speaker 1: energy in it. All of space has energy in it
Speaker 1: because space is filled with quantum fields and those fields
Speaker 1: can't relax all the way down to zero, and sometimes
Speaker 1: that energy in the field turns into a particle or
Speaker 1: a particle and an antiparticle. So this happens all the time.
Speaker 1: Things turn into an electron and apositron, and then they
Speaker 1: annihilate back and they go back into the field. So
Speaker 1: this is going on all the times, this frothing at
Speaker 1: the quantum level, even around black holes. Now, when this
Speaker 1: happens in the vicinity of a black hole, sometimes these
Speaker 1: particles get a little extra boost of energy because there
Speaker 1: is more energy around the black hole. There's the gravitational
Speaker 1: energy of the black hole. And this is the wonky
Speaker 1: part because we don't really understand how gravity interacts with particles.
Speaker 1: We can't do experiments to see the gravitational effect on
Speaker 1: particles because particles have almost no mass and gravity is
Speaker 1: super nuber weak, so we haven't been able to do
Speaker 1: these experiments. But anyway, imagine that somehow this particle antiparticle
Speaker 1: pair gets extra energy because of the gravitational field of
Speaker 1: the black hole. Now, one of these particles happens to
Speaker 1: leave the area of the black hole. They were created
Speaker 1: outside the event horizon, so that's cool. The other one
Speaker 1: falls back into the black hole. Let's think first about
Speaker 1: the one that leaves. What happens to it, Well, it
Speaker 1: flies off into the universe. Maybe it's an electron, Maybe
Speaker 1: it's a positron. Maybe it's a top cork, maybe it's
Speaker 1: a gluon. It can be any kind of particle because
Speaker 1: the quantum field can fluctuate into any kind of particle.
Speaker 1: There are some different probabilities based on the masses, but
Speaker 1: that doesn't really matter. But that particle leaves and it
Speaker 1: takes with it some energy. Where did that energy come from?
Speaker 1: Part of it came just from the quantum field, but
Speaker 1: part of it also came from the gravitational energy of
Speaker 1: the black hole. And if you take the gravitational energy,
Speaker 1: you are decreasing the mass of the black hole. Now
Speaker 1: you might be thinking, hold on a second, how does
Speaker 1: the mass leave the black hole? This particle was never
Speaker 1: in the black hole, right, that's true, But remember the
Speaker 1: mass of the black hole is not like the amount
Speaker 1: of stuff in the black hole. It's like a meter
Speaker 1: that tells you how much energy is stored in the
Speaker 1: black hole. Doesn't matter what the form of that energy is.
Speaker 1: It can be photons, it can be protons, it can
Speaker 1: be something else super duper weird. It can be a
Speaker 1: singularity that has no like state of matter we can
Speaker 1: think about or calculate. The mass of the black hole
Speaker 1: comes from the energy stored within it. So if you
Speaker 1: remove energy from the black hole, you reduce its mass.
Speaker 1: You can reduce the mass of a black hole without
Speaker 1: carrying a particle from inside the event horizon to outside
Speaker 1: the event horizon. And you might be thinking, hold on
Speaker 1: a second, that's crazy. I thought black holes can never
Speaker 1: release information, they could never lose anything. And it's true
Speaker 1: that nothing can leave if it's inside the event horizon.
Speaker 1: No information can escape. However, the black hole's energy goes
Speaker 1: beyond the edge of the event horizon. It's gravitational influence
Speaker 1: does not stop at the event horizon. The event horizon
Speaker 1: is just a place after which all of your paths
Speaker 1: now point towards the center of the black hole. It's
Speaker 1: not the edge of the black hole's influence on the universe,
Speaker 1: and that influence can extend to things created outside the
Speaker 1: event horizon, and it can lose that energy once it's
Speaker 1: donated it to those particles, and when it loses that energy,
Speaker 1: it loses some mass. All right. So now we have
Speaker 1: a sort of hand wavy understanding of how hawking radiation
Speaker 1: might work at the microscopic level. Let's get to the question.
Speaker 1: The question was about the particle that goes into the
Speaker 1: black hole, not the one that escapes, and it was asking,
Speaker 1: if the particle goes into the black hole, doesn't it
Speaker 1: need to find something to annihilate with the sort of
Speaker 1: contribute back its energy to the black hole. And if
Speaker 1: black holes are mostly dark matter, then how can they
Speaker 1: do that because it can't interact with dark matter. All right,
Speaker 1: So a lot of things to talk about there. First
Speaker 1: of all, we don't know how much dark matter is
Speaker 1: in black holes. I've said on the podcast, it's almost
Speaker 1: certain that there is some, and that's true. But remember
Speaker 1: that dark matter has a harder time falling into black
Speaker 1: holes because it can't get rid of its angular momentum
Speaker 1: like other kinds of matter. It can spin around a
Speaker 1: black hole, but other kinds of matter can lose their
Speaker 1: angular momentum by radiating off energy, for example, or bumping
Speaker 1: into each other. These kinds of interactions are crucial for
Speaker 1: losing your angular momentum and falling into the black hole,
Speaker 1: falling out of orbit and falling into the black hole.
Speaker 1: Dark matter can't do that, so it stays fluffy. And
Speaker 1: so we think that there is dark matter in black holes,
Speaker 1: we don't really know how much. It may not be
Speaker 1: that it's dominated by dark matter, but even still, let's
Speaker 1: imagine that the black hole is filled with dark matter.
Speaker 1: What happens to this particle that falls into the black hole, Well,
Speaker 1: it doesn't actually need to annihilate with anything to contribute
Speaker 1: to the mass of the black hole. Remember, the mass
Speaker 1: of the black holes just a measure of how much
Speaker 1: energy is stored inside it. It's not necessary for that
Speaker 1: particle to annihilate with something else and return its energy.
Speaker 1: It already has returned its energy. Everything that's in the
Speaker 1: vicinity of the black hole contributes to the gravitational system
Speaker 1: and therefore to the mass of the black hole. If
Speaker 1: particles inside the black hole change from photons to particle
Speaker 1: antiparticle pairs, it has no effect on the black hole's mass.
Speaker 1: So if there is dark matter inside black holes, it
Speaker 1: doesn't affect this Hawking radiation alright. So the things to
Speaker 1: remember about hawking radiation are number one, that we only
Speaker 1: have a hand wavy description of the microscopic effects. We
Speaker 1: don't really understand how it works. Our understanding of hawking
Speaker 1: radiation is at the level of statistical physics, talking about many,
Speaker 1: many particles and averaging over lots of quantum details that
Speaker 1: we do not yet understand. And that hawking radiation happens
Speaker 1: outside the black hole, borrowing some of the gravitational energy
Speaker 1: from the black hole and carrying it off with it,
Speaker 1: because you can interact with the black hole without actually
Speaker 1: falling into it, and that means that it's possible to
Speaker 1: steal a little bit of its energy and therefore decrease
Speaker 1: its mass. And that's sort of our understanding of Hawking
Speaker 1: radiation and how black holes can't evaporate. All right. Thank
Speaker 1: you for that oh wonderful question, and thank you for
Speaker 1: thinking deeply about how black holes work and how they evaporate,
Speaker 1: and what might be inside them and what's going on
Speaker 1: inside the black holes. They are one of my favorite
Speaker 1: mysteries because they potentially contain the answers just so many
Speaker 1: basic questions about how the universe works, what happens to
Speaker 1: quantum particles when gravity gets really really strong, and the
Speaker 1: gravitational effects and quantum effects both become important. We have
Speaker 1: almost nowhere in the universe we can probe quantum gravity
Speaker 1: because it's so hard to study. But the center of
Speaker 1: black holes is that place. Unfortunately, of course, we can't
Speaker 1: see what's inside them, all right, So thanks to that question,
Speaker 1: I have more questions. I want to get to but
Speaker 1: first let's take a quick break. All right, we're back
Speaker 1: in today. It's just me, Daniel. I'm a particle of
Speaker 1: physicists by day and by night I like to answer
Speaker 1: physics questions from the public, and today we are answering
Speaker 1: questions sent in by listeners. We thought about something or
Speaker 1: read something and wanted to hear it explained. And today's
Speaker 1: episode is focused on the topic of radiation. We talked
Speaker 1: about radiation from black holes, and here's a question from
Speaker 1: listeners about another kind of potential radiation. Low Daniel Horrey,
Speaker 1: this is a Mario from Los Angeles. While I was
Speaker 1: listening to your show, I heard a commercial about five
Speaker 1: G and I got curious because there's a lot of
Speaker 1: conspiracy theories about the pandemic and five G. I was
Speaker 1: hoping you guys could explain the effects of five G
Speaker 1: have on our society given informed an opinion about the
Speaker 1: conspiracy theories. Thank you. Okay, So this is a really
Speaker 1: interesting question and one that actually a few people have
Speaker 1: written to us about. So I thought it'd be interesting
Speaker 1: to sort of take the physics point of view. What
Speaker 1: do we know about five G networks? What are they,
Speaker 1: how do they work, what's the physics of five G
Speaker 1: and how it interacts with a human body, and then
Speaker 1: you'll have everything you need to make up your own
Speaker 1: mind about whether or not five G is a good idea. Alright,
Speaker 1: so first of all, what is five G. Five G
Speaker 1: means fifth generation cell phone networks. People have been upgrading
Speaker 1: and improving our cell phone network to make them faster
Speaker 1: and more reliable, etcetera. And now they have the fifth
Speaker 1: generation which is now being installed. Five G is a thing.
Speaker 1: It exists, it's out there in patches in our world.
Speaker 1: It's not complete, it's not everywhere. They're still putting it together,
Speaker 1: so it's sort of in its embryonic phase. And it's
Speaker 1: an exciting technology because potentially it could deliver data to
Speaker 1: your devices a hundred or more times faster than the
Speaker 1: four gene networks, and so that would allow a lot
Speaker 1: of things to happen. You can have a screen on
Speaker 1: the door to your refrigerator to let's use stream movies
Speaker 1: while you're deciding what to eat. You can have everything connecting.
Speaker 1: You can just send a lot more data everywhere. So
Speaker 1: if you're excited about data, then you should be excited
Speaker 1: about five gene networks. So what's different between five G
Speaker 1: and four G? Right, the fourth generation of network and
Speaker 1: what makes people so interested and excited and concerned about it.
Speaker 1: While there are a couple of differences about five G,
Speaker 1: there's some sort of smaller ones, like the way they
Speaker 1: organize the data to make it faster, in the way
Speaker 1: they route it from tower to tower, But the major
Speaker 1: differences are one that the antennas are directional. So an
Speaker 1: antenna is just a bunch of electrons with going in
Speaker 1: a conducting rod that generates electromagnetic fields, and often these
Speaker 1: antennas broadcast in every direction simultaneously, so then the power
Speaker 1: of the radiation, the intensity of the signal decreases as
Speaker 1: you get further away from the antenna, but sort of
Speaker 1: the same way every direction. These five G antennas are directional.
Speaker 1: They can be focused in certain directions to provide like
Speaker 1: longer range connections in certain directions and to black out
Speaker 1: other directions. And this way you can sort of like
Speaker 1: more intelligently decide where you want your coverage. So that's
Speaker 1: number one, they have these directional antennas. Number two, and
Speaker 1: this is probably the big one, is that they're using
Speaker 1: a different frequency to communicate the wavelength of these signals
Speaker 1: is something like ten millimeters. The frequency is like in
Speaker 1: the range of twenty to fifty giga hurts. And this
Speaker 1: is interesting, and this is new because it's ten times
Speaker 1: higher frequency shorter wavelength than have existed in cell phones before.
Speaker 1: It's not the first time we've seen technology that emits
Speaker 1: radiation in this wavelength or frequency spectrum. It's the same
Speaker 1: sort of wavelength this is used in those airport scanners
Speaker 1: when you go to the airport and they try to
Speaker 1: figure out if you have something in your pocket. But
Speaker 1: these are much lower power than those airport scanners. On
Speaker 1: the other hand, they're kind of on all the time,
Speaker 1: so they're sort of blanketing the world with this radiation.
Speaker 1: And the question is about the long term exposure to
Speaker 1: this wavelength of radiation, and that's where I think the
Speaker 1: concern arises. And you may have heard some conspiracy theories
Speaker 1: about how this has created the pandemic or responded to
Speaker 1: the pandemic, and that, of course, is all just bonkers.
Speaker 1: There's no connection between five G and the pandemic. There
Speaker 1: are no microchips inside the vaccines. All that stuff is
Speaker 1: just fearmongering nonsense. There are some interesting physics questions about
Speaker 1: five G, and some interesting medical questions about the impact
Speaker 1: of five G on the human body, and some interesting
Speaker 1: policy questions about how to roll out of technology. How
Speaker 1: many st you really need to have done before you
Speaker 1: take a risk and roll out something new. That's all fascinating,
Speaker 1: but let's push aside for now the crazy conspiracy theories
Speaker 1: connect to the pandemic. We're in seeing lizard people using
Speaker 1: five G to control your minds, And let's just talk
Speaker 1: about the physics. So I said radiation, and I talked
Speaker 1: about the intensity of it. Does that mean that these
Speaker 1: things are like radioactive, that you're basically living next to
Speaker 1: a nuclear power plant? No, no, no, Remember that radiation
Speaker 1: is a very very broad term. It includes any sort
Speaker 1: of wave or particle which transmits energy, including yes, radioactivity
Speaker 1: from nuclear power plants. But that's not what we're talking
Speaker 1: about today. We're talking about the kind of radiation that's
Speaker 1: just photons, right, just a kind of light electro magnetic radiation,
Speaker 1: which is a very very broad term. But all of
Speaker 1: it is just a different kind of photon, and those
Speaker 1: photons are different based on their frequency, based on the
Speaker 1: wavelength of the photon, and different wavelength photons we give
Speaker 1: different names, from very long wavelength photons, which are like
Speaker 1: radio waves or infrared waves, up to visible light, of course,
Speaker 1: which is just photons of a certain frequency that hits
Speaker 1: your eyes and your brain knows how to interpret. Up
Speaker 1: to ultra violet light, which has a frequency higher than
Speaker 1: you can see, all the way up to X rays
Speaker 1: and gamma rays. It's all part of one continuous spectrum.
Speaker 1: The difference between a gamma ray and a photon that
Speaker 1: makes up a radio wave is just the wavelength of
Speaker 1: that photon, and all these photons can be used to
Speaker 1: encode information. So we use electromagnetic radiation as a way
Speaker 1: to pass information around, and you can think of it
Speaker 1: as waves, right. We think about radio waves as waves
Speaker 1: washing over the earth surface. TV antennas and all that
Speaker 1: kind of stuff send electromagnetic waves, and you can think
Speaker 1: about it as waves. That makes perfect sense. But it's
Speaker 1: also important to remember that it's actually made of photons.
Speaker 1: It's made of individual particles, and that's important because the
Speaker 1: energy of the individual photons depends on the wavelength of
Speaker 1: the radiation. So when we say higher frequency, we mean
Speaker 1: there's more energy per photon, so you v photons have
Speaker 1: more energy in them than radio wave photons. Gamma ray
Speaker 1: photons have even more energy in them. X ray photons
Speaker 1: have a lot of energy in them, more than visible
Speaker 1: light photons. And it's broken up into these pieces, right.
Speaker 1: You can't have half a photon or one and a
Speaker 1: half photons. If you have a beam of light in
Speaker 1: the X ray part of the spectrum, then each of
Speaker 1: those photons has a lot of energy. If you have
Speaker 1: a beam of light in the infrared, than each of
Speaker 1: those photons has less energy. And that turns out to
Speaker 1: be really important because when the photon hits your body,
Speaker 1: it's the energy of that individual photon that determines whether
Speaker 1: or not it can ionize something, whether or not it
Speaker 1: can kick an electron, for example, out of an atom,
Speaker 1: or it can break one of those bonds. And the
Speaker 1: most damaging thing radiation can do is ionized parts of
Speaker 1: your body. When it does this, it does things like
Speaker 1: break up DNA molecules. It acts like a tiny little
Speaker 1: bullet that shoots through your body and breaks things. So
Speaker 1: ionizing radiation is very, very dangerous, and that's why it's
Speaker 1: important to reduce your exposure to ionizing radiation. Now, things
Speaker 1: like uranium and plutonium give off ionizing radiation, which is
Speaker 1: very dangerous, and some forms of electromagnetic radiation can have
Speaker 1: enough energy to ionize. The threshold for ionizing radiation is
Speaker 1: a little bit fuzzy, depends on the material, etcetera. But
Speaker 1: it's on the order of magnitude of about ten e
Speaker 1: v per photon. This is like the binding energy of molecules.
Speaker 1: And in order to have that much energy of photon
Speaker 1: has to be in the ultra violet. That's why ultra
Speaker 1: violet radiation u V rays are bad for you. U
Speaker 1: V does cause cancer, and that's what you're blocking when
Speaker 1: you're putting on sunscreen, and that u V light can
Speaker 1: pass through clouds, which is how you can get a
Speaker 1: sunburn on a cloudy day. So visible light and everything
Speaker 1: with a wavelength lower than that, it's not ionizing. It
Speaker 1: can't cause ionization in your body, and so it's much
Speaker 1: much safer. Now. Five G is well below the wavelength
Speaker 1: of even visible light. It's below the infrared. So from
Speaker 1: the point of view of ionization, the most dangerous thing
Speaker 1: that radiation can do. Five G is not a concern. Yes,
Speaker 1: it does have a higher wavelength, and previous generations of
Speaker 1: cell phones, but it's well below the energy needed to
Speaker 1: do any damage from an ionizing point of view. But
Speaker 1: that's not the only way that radiation can damage you.
Speaker 1: Ionization is not the only thing that it can do.
Speaker 1: For example, it can deposit energy in your body even
Speaker 1: without actually ionizing. I mean, this is what an oven does.
Speaker 1: Right when you cook a turkey in your oven, you're
Speaker 1: using infrared photons. You're using the heat of the oven
Speaker 1: to cook that turkey, And yeah, it certainly does damage
Speaker 1: the turkey. And so you can hurt people with a
Speaker 1: high intensity of low energy radiation. Right here, we're talking
Speaker 1: about the intensity and microwave oven uses microwave radiation, which
Speaker 1: is much much longer in wavelength than ultra violet photons.
Speaker 1: But it's a very high intensity, and so it can
Speaker 1: deposit a lot of energy and eventually it can hurt you.
Speaker 1: So this is the area to focus on from a
Speaker 1: sort of physics and medical point of view. Can being
Speaker 1: exposed to a large amount of five G signals do
Speaker 1: some damage to the human body. Well, it turns out
Speaker 1: that humans have a sort of built in shield to
Speaker 1: a lot of this stuff. Most of these photons will
Speaker 1: actually scatter off of your skin. Your skin is like
Speaker 1: a shield that will reflect a lot of this energy.
Speaker 1: The upper layers of your skin are opaque to this
Speaker 1: kind of photon, so most of it won't even enter
Speaker 1: your body. There were some very early studies that showed
Speaker 1: the amount of damage done to tissue based on the
Speaker 1: frequency and showed the five G was in a range
Speaker 1: that did more damage, but it neglected to take new
Speaker 1: count the fact that most of that five G radiation
Speaker 1: won't even get into your body. But the fact remains
Speaker 1: that this is a kind of electromagnetic radiation where it's
Speaker 1: long term exposure has not been studied on the public.
Speaker 1: We haven't based people and the kinds of radiation that
Speaker 1: five G will generate for long periods and seeing what
Speaker 1: would happen. Right, So we just don't know. That doesn't
Speaker 1: mean we don't have a good guess. We understand the
Speaker 1: physics of it. We think that it's too low energy
Speaker 1: to do any ionization damage. We think that the skin
Speaker 1: is opaque to it and will reflect most of it,
Speaker 1: and so we think we can do the calculations and
Speaker 1: it seems totally safe, but we don't have direct evidence.
Speaker 1: And the folks that are citing studies that show that
Speaker 1: there's no connection between for example, cell phone towers and
Speaker 1: cancer are missing the point a little bit because those
Speaker 1: cell phone towers are using a different frequency than five G.
Speaker 1: So we don't actually have direct data that shows that
Speaker 1: five G is safe because it was just invented, right,
Speaker 1: And so what can we do here? Science can say
Speaker 1: we don't see a reason why it would be dangerous.
Speaker 1: We think it will be safe. We do not have
Speaker 1: direct proof, so we can't conclusively say it's safe. We
Speaker 1: can't point to studies that prove that it's safe. We
Speaker 1: can argue and we can make reasonable points that suggest
Speaker 1: that it will be safe. But in the end, it's
Speaker 1: a question for policy makers when do you make a
Speaker 1: decision for how to roll out a new technology which
Speaker 1: could have lots of benefits for the public, but also
Speaker 1: every new technology does have some inherent dangers, and in
Speaker 1: the end, sometimes policy makers do have to make these
Speaker 1: very difficult decisions knowing they could help people, but they
Speaker 1: could also potentially hurt people. So that's not something I'm
Speaker 1: going to comment on because I'm not a policy maker,
Speaker 1: but I think that the policymakers should at least be
Speaker 1: informed by the science, and I hope that you guys
Speaker 1: out there understand the signs of five G. It is
Speaker 1: a new technology with higher frequency photons, not high enough
Speaker 1: frequency to do ionizing damage, but the impact of this
Speaker 1: frequency radiation and very low intensities, how has not been
Speaker 1: studied on the general public. That doesn't mean that it's
Speaker 1: caused the pandemic or that it's something that you should
Speaker 1: worry about. Read more about it, think about it right
Speaker 1: to your congress people or representatives, or your president or whoever,
Speaker 1: if you have a deep and passionate opinion about how
Speaker 1: to balance this question of technology versus safety. All Right,
Speaker 1: I want to answer another question, but first let's take
Speaker 1: another break. All right, we're back and I'm answering questions
Speaker 1: from listeners. We had a question about black holes and
Speaker 1: hawking radiation. We had a question about wireless cell phone
Speaker 1: towers and the radiation they emit. And now we have
Speaker 1: a question about wireless charging. Hi, Daniel, and I was
Speaker 1: wondering how wireless charging devices work. I don't understand how
Speaker 1: the battery is charged without a visible input into the device.
Speaker 1: It's baffling to me. It's like magic. Thanks all right,
Speaker 1: thank you for this super fun question. Sometimes physics is baffling.
Speaker 1: It defies our intuition, but you know, the universe works,
Speaker 1: The universe follows rules. There's always a way to understand
Speaker 1: what we see and then sometimes to use that understanding
Speaker 1: to build awesome new technology like wireless charging. And your
Speaker 1: intuition is that things need a wire because the stuff
Speaker 1: around you uses wires. Right, either you plug it into
Speaker 1: the wall or you connect it with a battery, because
Speaker 1: you're used to a certain kind of way of transmitting energy.
Speaker 1: You have energy inside a battery or energy coming in
Speaker 1: the wires, and that's in the form of electrical energy,
Speaker 1: and those electrons zip along and they deposit that energy
Speaker 1: into your device, your phone or your camera, or your
Speaker 1: laptop or your blender or whatever. And that certainly is
Speaker 1: one way to send electromagnetic energy from one device to
Speaker 1: another by using the wire, which is essentially just a
Speaker 1: conductor where the electrons can bump into each other and
Speaker 1: pass that energy along. However, there are lots of ways
Speaker 1: to transmit energy, and you can transmit energy wirelessly, right.
Speaker 1: What is a flashlight. A flashlight is a beam of photons.
Speaker 1: Those photons have energy. What is a laser A laser
Speaker 1: concertainly transmit energy, you can use it to heat something
Speaker 1: up from a distance, right, and those photons can fly
Speaker 1: through space, even through a vacuum. So conceptually, from a
Speaker 1: sort of physics point of view, we understand how it's
Speaker 1: possible for energy to start in one place and get
Speaker 1: to another place without having a physical connection a wire, right,
Speaker 1: even across the vacuum of quote unquote empty space. But
Speaker 1: that doesn't tell us how wireless chargers actually work. How
Speaker 1: do they get the energy from one device to the
Speaker 1: other without the two actually being connected. There's not some
Speaker 1: tiny series of lasers in their zapping energy from one
Speaker 1: to the other. You certainly don't want your blender to
Speaker 1: be zapped with lasers. So how does it actually work.
Speaker 1: The first thing to understand is the whole system is
Speaker 1: not wireless. It's just like one step there that's wireless.
Speaker 1: Usually you have like a base which is plugged into
Speaker 1: the wall, and then you can put your phone on
Speaker 1: top of that base. It sits on the base and
Speaker 1: it draws power from the base. And so it's that
Speaker 1: step that we're gonna try to understand. How can you
Speaker 1: get energy from the base which is plugged into the
Speaker 1: wall and getting energy eventually from your power plant, how
Speaker 1: does it get from that base and into your phone.
Speaker 1: So this comes from the magic and the beauty of
Speaker 1: electro magnetism. And to understand how this works, we need
Speaker 1: to remember that electricity and magnetism feel like two different things, right.
Speaker 1: Electricity is lightning bolts and electrons, and magnetism is like
Speaker 1: fridge magnets and levitating trains. But they are actually two
Speaker 1: parts of the same thing. Maxwell, the Scottish clerk a
Speaker 1: hundred and fifty years ago, realized that there's a deep
Speaker 1: symmetry between electricity and magnetism. And you note us this
Speaker 1: because he noticed that electricity can cause magnetic field to
Speaker 1: magnetic fields can cause currents, and so that's exactly how
Speaker 1: it happens. We have two parts of Maxwell's equations working together.
Speaker 1: So the first part is that when you have an
Speaker 1: electric current that creates a magnetic field. If you've ever
Speaker 1: seen an electro magnet, you know this is true. You
Speaker 1: turn on the current, it goes through coils and those
Speaker 1: coils create a magnetic field. And every electric engine, for example,
Speaker 1: has this property inside it. When you turn on the engine,
Speaker 1: what you're doing is turning on electro magnets inside the engine,
Speaker 1: which are using the magnet to sort of tug on
Speaker 1: another part of the engine and get it to move.
Speaker 1: So the first step is to use currents inside the
Speaker 1: base station to create a powerful magnetic field. That magnetic field,
Speaker 1: in turn can cause electrical currents because another part of
Speaker 1: Maxwell's equations tells us that varying magnetic fields caused electrical currents. Right,
Speaker 1: So what happens to the base station is you have
Speaker 1: this current which is going on and off, creating magnetic
Speaker 1: fields which are on and off, and those magnetic fields
Speaker 1: then induce a current inside your phone. So inside the
Speaker 1: phone there has to be some loop, or inside whatever
Speaker 1: device you're trying to charge, there has to be some loop,
Speaker 1: and the magnetic fields then induce a current inside that loop.
Speaker 1: So you have a loop inside the base station where
Speaker 1: you create a current using power from the wall. That
Speaker 1: current inside the loop creates a magnetic field, and that
Speaker 1: magnetic field then creates a current inside a loop of
Speaker 1: wire in the thing that you want to charge. And
Speaker 1: so this is a way to transmit the energy from
Speaker 1: the base station to the phone or whatever it is
Speaker 1: that you're trying to charge without actually having to have
Speaker 1: a wire between them. Is essension, like using a magnetic wire.
Speaker 1: And this only works because there is this symmetry between
Speaker 1: electricity and magnetism, because currents cause magnetic fields, which cause currents.
Speaker 1: And the other awesome thing about a symmetry is that
Speaker 1: it's the reason that we can see anything. What is light?
Speaker 1: What is a photon? It's a ripple in the electro
Speaker 1: magnetic field, not the electrical field, not the magnetic field,
Speaker 1: but the electro magnetic field. And that exists because varying
Speaker 1: electric fields caused magnetic fields, which caused varying electric fields.
Speaker 1: So what a photon actually is is a field that
Speaker 1: slashing back and forth between the electric and the magnetic field.
Speaker 1: That's what allows it to like pass through the vacuum
Speaker 1: of space. It supports itself, it propagates itself by going
Speaker 1: back and forth from electro to magnetic fields. And this
Speaker 1: was the beautiful inside of Maxwell. He saw these equations
Speaker 1: and they put them together. He thought, oh, my gosh,
Speaker 1: light looks just like a wave that's slashing back and
Speaker 1: forth and moving at some speed. And he did the calculation.
Speaker 1: He's like, oh, look, it moves at the speed of light.
Speaker 1: So that was a beautiful moment, sort of in theoretical physics,
Speaker 1: putting these two pieces together, understanding the symmetry between electric
Speaker 1: and magnetic field. And it's that same insight that allows
Speaker 1: us to do inductive powering, to use magnetic induction to
Speaker 1: take a coil of current and transfer that energy into
Speaker 1: another coil. Now, this is fascinating if people have done
Speaker 1: a lot of studies to see, like how far can
Speaker 1: it work. You're probably most familiar with charging stations at
Speaker 1: Starbucks where you will get charged from this wireless charging station. Now,
Speaker 1: the larger the coil inside the base station, the longer
Speaker 1: the wavelength of this radiation essentially, and the larger the
Speaker 1: distance that that power can charge. There was a record
Speaker 1: set in two thousand and seven where somebody was able
Speaker 1: to charge something two meters away. That's pretty awesome, Right,
Speaker 1: two meters away is a good distance, not enough that
Speaker 1: you can like drive around town and keep your phone
Speaker 1: charge from your house, but it's pretty cool, and it's
Speaker 1: the kind of thing where people are making strides and
Speaker 1: eventually there'll be a breakthrough and we'll be able to
Speaker 1: send power at even greater distances. And you know, your
Speaker 1: phone is not the only example of this technology. G
Speaker 1: if anybody out there has an inductive range. It's the
Speaker 1: kind with coils in it. But those coils don't feel
Speaker 1: hot because they're not transmitting the energy by making themselves
Speaker 1: glow really really hot, like the elements inside your oven,
Speaker 1: which would be giving off infrared radiation. Instead, they're creating
Speaker 1: magnetic fields, which then cause currents inside a pan that
Speaker 1: you put on top of the stove, so the pan
Speaker 1: gets hot, but the surface of the stove itself is
Speaker 1: not hot because there's no infrared heat passing directly from
Speaker 1: inside the range to the pan. And then you have
Speaker 1: this coil inside the range, and that coil has a
Speaker 1: lot of electricity in it, which is creating a magnetic field,
Speaker 1: which is creating a current inside your pot, which then
Speaker 1: turns into heat of the pot. So it's able to
Speaker 1: transmit this energy and heat of the pot without actually
Speaker 1: heating up the stuff in between, which is pretty awesome
Speaker 1: and it means that it's harder to burn yourself. So
Speaker 1: thanks very much for asking that super fun question about
Speaker 1: this cool technology. It does seem like magic, but it's
Speaker 1: actually something that we can understand, and that's the beauty
Speaker 1: of the universe that amazingly it seems like no matter
Speaker 1: what happens out there, if you think about it carefully,
Speaker 1: if we put our collective heads together, we can figure
Speaker 1: it out. And so, even though there are so many
Speaker 1: mysteries remaining about the nature of the universe and what's
Speaker 1: going on inside black holes, and how the universe started
Speaker 1: and what is everything made out of, at the smallest,
Speaker 1: tiniest level, all these questions are just the possibilities for
Speaker 1: new discoveries, the possibility to reveal something new about the
Speaker 1: universe that we didn't know that would blow the minds
Speaker 1: of our grandparents. It means that one day our grandchildren
Speaker 1: will make these discoveries and will blow our minds. So
Speaker 1: until then, keep thinking about it, keep asking questions, and
Speaker 1: send us all of your questions. We love to hear
Speaker 1: your thoughts. Thanks very much. Tune in next time. Thanks
Speaker 1: for listening. Remember that Daniel and Jorge Explain the Universe
Speaker 1: is a production of I Heart Radio. For more podcast
Speaker 1: from my Heart Radio, visit the I Heart Radio Apple
Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.
Speaker 1: H