Listener Questions #14

00:00:08
Speaker 1: If everything is quantum fields, how do their ripples make banana peels?

00:00:13
Speaker 2: What's the mutation rate for the common cold? Does the virus change moving through my household?

00:00:18
Speaker 1: Is their mass? In pure information? Do I get heavier with more education?

00:00:24
Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's answers will make it right.

00:00:28
Speaker 1: Welcome to another Listener Questions episode on Daniel and Kelly's Extraordinary Universe.

00:00:48
Speaker 2: Hello. I'm Kelly Wienersmith, and I study parasites and space, but not parasites in space.

00:00:53
Speaker 3: Not yet, at least that's all right.

00:00:55
Speaker 4: Hi.

00:00:55
Speaker 3: I'm Daniel.

00:00:55
Speaker 1: I'm a particle physicist, and I want to figure out the problems of the universe before the aliens come and spoil the story by telling.

00:01:02
Speaker 2: Us, oh, interesting, you know. The intro sort of makes it sound like maybe this is going to be an episode about Bigfoot or something. We both have gotten a little bit out there with our intros this morning, but we're going to bring it down to Earth, which reminds me of an interesting talk that I gave on Earth. Well, I don't know if it's interesting. It was my talk, the talk that I gave for Western University Space Day recently and I was giving my usual City on Mars talk and up in the balcony was an entire Girl Scout troop boom.

00:01:33
Speaker 1: Do you think they were looking to plan an expedition to space?

00:01:36
Speaker 2: I don't know. Girl Scouts can do anything. Many maybe they were. Maybe they're planning on taking over the world, but they want to know how to take over space too. They did bring delicious cookies, so that was great.

00:01:45
Speaker 3: Do they ask good questions?

00:01:46
Speaker 2: That's what I was going to say. They asked the greatest questions, so they asked fantastic questions. And I was a little bit nervous because I hadn't planned on there being kids. So I have a whole section about how the process of expanding family size might be indited by the space environment. And the first question that I got was one of the girls from the Scouts raised her hand and said, in your section on reproduction. And I immediately was like, oh God, this is not a good start. I don't want to give the birds and the bees chat. And she said something about the image you used on that slide had two adults in spacesuits holding two babies in spacesuits. Wouldn't it be expensive to make spacesuits.

00:02:27
Speaker 1: For babies, all right, it's an engineering question.

00:02:29
Speaker 3: Yeah, And I think I.

00:02:30
Speaker 2: Said something like I am so relieved that that's what you asked, And then I explained, like, you know, sometimes it's hard using arts to explain concepts, because we didn't actually mean that people will probably be bringing babies in space suits out on the surface because space radiation. You probably wouldn't want to expose your baby to that on the Martian surface.

00:02:48
Speaker 1: And then you need like constantly new spacesuits as they grow. I know, as a parent of children who once grew very rapidly, that's very frustrating how quickly they outgrow all their stuff.

00:02:57
Speaker 2: Oh my gosh. Yes, but I mean eventually we will need different shapes and sizes of space suits for the diversity of body types that will be up there. But my question for you is, have you ever worked with an artist or use some art that didn't at all portray what you had intended and you didn't realize it would be taken seriously because you just meant it to be like a cute, funny image about families in space, for example.

00:03:20
Speaker 1: Well, the stuff that I write about usually is pretty family friendly, but often it's kind of abstract, and I struggle sometimes to describe it accurately with words, and then I wonder, like, hmmm, how is my illustrator friend going to put this into a picture? Like what visual can you use to describe quantum fields and tie this all together? But I've been lucky to work with very talented illustrators who do a great job of making these exceptional visuals, taking the abstract and making a concrete so that the reader can understand the concepts.

00:03:53
Speaker 2: To be clear, I think my artist collaborator, slash husband does a great job. But I think sometimes you just assume that the audience will get that this is just like a fun artistic image, as like a palette cleanser for the difficult stuff we just told you. But you know it doesn't always go over the way that you intended.

00:04:10
Speaker 1: Yeah, well, there's another fine line there, which is sometimes you want to make jokes to lighten the mood, right. I remember in our first book, we talked about what space can do, and I'd written this space can bend, it can expand, it can ripple, and Jorge drew a hilarious little doodle of space bending and expanding and rippling, and then he added a fourth one of like space breakdancing, and you always got to wonder like, okay, is that ridiculous enough that people get Okay, that's obviously a joke to lighten the mood, or somebody out there being like, well, I don't know if space can ripple and expand maybe it could breakdance.

00:04:44
Speaker 3: What does that mean?

00:04:45
Speaker 1: We are the equations of breakdancing.

00:04:47
Speaker 2: Yep.

00:04:47
Speaker 1: So you always gott to walk that fine line.

00:04:49
Speaker 2: Zach and I have had so many of those conversations where he's like, people are going to get it's a joke, and I was like, maybe they won't. There are humorless people out there who will be confused.

00:04:59
Speaker 1: And sometimes the reality is so ridiculous people might think you're making a joke. In our latest book about what science Aliens Might do, we talk about how people tried to communicate with aliens, and there's a guy who wrote letters in the sand and set them on fire hoping that Martians would read them. And that sounds like I'm made up ridiculous example. So I remember adding a footnote being like, I know, we make a ridiculous example sometimes for humor. This is not one of those cases.

00:05:25
Speaker 2: Yes, everyone while humans are just so crazy you need to be like, no, this isn't a joke. I'm not going into fiction here.

00:05:31
Speaker 1: Amazing And if anybody's interested in that book, it's coming out in November. It's called Do Aliens Speak Physics? By it anywhere you get books, and.

00:05:39
Speaker 2: I read an early copy and I can tell you it's amazing.

00:05:42
Speaker 3: And we're gonna be talking about it a lot until it comes out.

00:05:44
Speaker 2: Yep. Yeah, nice to have a platform. You know what else is awesome?

00:05:48
Speaker 3: What's that?

00:05:49
Speaker 2: Our listeners, they are so awesome and they ask such amazing questions. And we've got like a question from kids theme going on today, and so let's start with our first ques question from Ryan and thirteen year old Grace from the best states in these United States.

00:06:07
Speaker 1: I'm confused, they're not from California.

00:06:09
Speaker 3: What are you.

00:06:09
Speaker 2: Talking about, oh, Daniel.

00:06:12
Speaker 1: Despite their coming from Virginia, Let's hear about Grace's question.

00:06:15
Speaker 4: Hey, Daniel and Kelly. My name is Ryan and I have my thirteen year old daughter, Grace here with me. We live in Virginia, and she came up with an interesting question after we discussed your episode on particles and the current understanding that they are ripples in fields?

00:06:28
Speaker 5: Hi, this is Grace, and here's my question. I don't understand how ripples make things. For instance, how do a bunch of ripples in a field somehow all add up to make a person or banana or sloth? Thanks for taking my question. We love the podcast all.

00:06:42
Speaker 2: Right, Daniel, As someone who is a huge fan of sloths, I now desperately want to understand how ripples help make up a sloth.

00:06:50
Speaker 1: I love this question because this is the whole point of physics, to take our everyday experience and explain it in terms of the microscopic stuff that's happening. To like pull back the veil and say what's really going on underneath? And it's cool to say, oh, what's going on underneath? Is this complicated thing with fields and particles and waves and whatever. But Grace is exactly right that the second part of that is to weave it together so that it does explain our everyday experience. You've got to give a path sort of like an intellectual ladder, from the microscopic explanation back to the macroscopic to show how they come together. So thank you Grace for asking this question.

00:07:25
Speaker 2: It's a fantastic question, and I love that both banana's and sloughts got featured exactly because what good is physics if it's not explaining biology.

00:07:36
Speaker 1: And maybe there's a banana sloth out there, oh that we could explain.

00:07:39
Speaker 2: One day, delicious and easy to catch.

00:07:46
Speaker 3: Probably why they went extinct.

00:07:47
Speaker 1: So let's get to particles and ripples and quantum fields and all that. Grace's question is how ripples make things. So let's zoom all the way back down to ripples, and then let's walk our way back up to the macroscopics to the sloth in the banana. So like one hundred years ago, we were trying to understand what stuff is made out of. We started taking stuff apart, and we realized it's made out of elements, and those elements are made out of atoms, and eventually we had little particles protons and neutrons and electrons, and back then, I think people were still thinking that those were little bits of stuff that you could like pack together like legos to make bigger stuff that was the sort of microscopic to macroscopic, Like the legos were super duper tiny, almost incomprehensibly tiny, and there were so many of them. You know, Avogado's number is a big number. But if you click them all together, you made macroscopic stuff. And that was our understanding, right.

00:08:34
Speaker 2: And on the plus side, you can step on them and it doesn't hurt.

00:08:40
Speaker 3: The a particle legos.

00:08:41
Speaker 1: Yes, But then we learned, oh, they're not really little bits of stuff. Actually, they're like waves. And quantum mechanics came around and told us that they don't have specific locations and maybe these particles are actually tiny zero volume points. And then quantum mechanics grew up and said, those waves are actually even more important because the particles themselves are just waves and quantum fields.

00:09:04
Speaker 3: And so that's where.

00:09:05
Speaker 1: We are now that we understand that all the matter that's out there, the electron, the quarks inside the proton and the neutron, all these things are actually just ripples in quantum.

00:09:13
Speaker 3: Fields, all right.

00:09:14
Speaker 2: And there are a bunch of different kinds of fields. We've talked about those before, right, And so are we talking about a very particular kind of field that makes up bananas and slots or are all the fields relevant?

00:09:25
Speaker 1: So you're right, there are lots of different kinds of fields. Every particle has a field. So the electron is a field, the muon has a field, the cow has a field, the top qrk has a field. Every different kind of particle has a field. We don't understand why there are so many. There're dozens of these fields. Every bit of space that's out there has all these fields sitting on top of each other in the same chunk of space. It's kind of hard to wrap your mind around because if you're thinking of like blankets, you know, blankets you stack because they can't be in the same location. But these fields are all in the same place, and they can all oscillate independently. And you asked, which fields are we talking about in this case, we're talking mostly about the fields that make up us, which are electron fields, and two of the cork fields, the upfield in the downfield. So there are dozens of those fields out there, and there's like big fundamental questions about what that means and how do we unify them, and it can be simplified, et cetera. But most of the matter in the universe is made out of particles which are oscillations in three of those fields, the electron field and then the up and down cork fields which make the proton and the neutron. And how do you understand like a particle being an oscillation of a field, what does that really mean?

00:10:28
Speaker 3: What are we talking about?

00:10:29
Speaker 1: Well, when we say an oscillation of a field, we really mean that it's vibrating, like the value of the field is going up and down, and so because it's moving, it can have kinetic energy. And as it has different values, it can have potential energy. The way they like a book on a shelf has a different potential energy if it's on a high point of the shelf or a low point on the shelf. Right, you like store energy in a book by moving to the top of the shelf, you release energy from the book when it falls off the shelf. The same way these fields oscillate. They go up and they go down, They slosh back and forth between tential and kinetic energy, and so there's energy stored in the field. So you should think of the particles as like not a little dot of stuff, but instead a little vibrating blob of energy in the field.

00:11:11
Speaker 2: Oh way, already, like where this is going, I'm a vibrating field of energy or made up of vibrating fields of energy, and If so, why are the sloths so slow?

00:11:20
Speaker 3: Exactly, they are filled with energy.

00:11:22
Speaker 2: They should be all right.

00:11:24
Speaker 1: So now we have these little vibrating fields of energy. Grace's question is how do you put that together to make a banana.

00:11:29
Speaker 3: Or a sloth?

00:11:30
Speaker 1: Basically, these things are super duper tiny, but they're not like little volume cubes like legos. How do you put them together to make something big?

00:11:38
Speaker 3: Right?

00:11:39
Speaker 1: Well, here's the crucial insight. You need the volume that we experience. The reason things take up space is not from the stuff that they make, but from their interactions with each other. So it's not like you have two particles and they have surfaces and those surfaces click together, or even that they're like two tennis balls that you're packing into a space and their surfaces are particles have interactions with each other. They exchange energy. This energy we were talking about slashing in the electron field or slashing in the quarkfield. That energy can slide from one field to another. That's when an interaction is so. For example, an electron moving through space will also make ripples in the electromagnetic field the photons field because those two fields interact. There's a connection between those two fields and the ripples in the electromagnetic field will then push or pull on other electrons. So how do two electrons interact with each other? Why do they repel? Because they are both making ripples in the electromagnetic field, which has the capacity to affect other electrons.

00:12:38
Speaker 2: So I'm going to try to tie this back to biology. So I'm thinking, you know, Christmas has ended and I'm feeling like my body could do with fewer interactions. Is there is there a way to think about it, like as you go into calorie deficit, can you think about it as like electrons sort of leaving the electric field? Or am I just making this too complicated?

00:12:57
Speaker 1: I think there's a Christmas analogy if we can do use to understand here. Think about what happens at a Christmas party. Right when you put people into a room at a Christmas party, do they stack like sardines against the wall or like physically phase on top of each other and occupy the same space. No, they talk to each other and they get like a comfortable distance from each other. Right, So you're at a party, people are sort of scattered.

00:13:18
Speaker 3: Through a room.

00:13:19
Speaker 1: You're all sipping your Christmas cocktails or whatever, and they're not squeezed and touching each other. Right, there's this comfortable distance because people are talking to each other and they respect each other's personal space. The reason that we can generate volume in a banana from a bunch of tiny little particles, which are actually ripples in the fields, is for the same reason that they have their own little personal space. Their interactions keep them apart, and so like inside your banana, are a bunch of little ripples that are keeping their space between them because of their interactions. So the volume of the material comes from the bonds between these particles, these little ripples, not from like the inherent volume of them, as they're stacked together on top of each other. So let's zoom all the way in and then out again, just to make sure it all makes sense. We zoom as far in as we understand the nature of the universe. We have these little ripples and fields which are just little buzzing blobs of energy. Right, particles are not little scoops of universe stuff. They are little blobs of buzzing energy in the field, and the fields interact with each other. So buzzing energy in the electron field also means buzzing in the electromagnetic field, and also in the Higgs field and all sorts of other fields. Whatever the electron interacts with and interactions between those fields keep these little buzzing blobs in harmony and in balance and allow you to build up bigger things. So they're not little lego bricks that you click together, but they little buzzing blobs sort of in balance with each other, keeping their space. And that's where the volume comes from. So you zoom all the way out and you look at a banana, should think of it as like a matrix of these buzzing blobs that are all somehow in balance with each other because of their interactions.

00:14:51
Speaker 2: It doesn't sound beautiful, but you know, I study dumb trucks full of dead fists, so who are to judge?

00:14:57
Speaker 1: No, but I think that is like peeling back a layer of reality, like seeing the matrix and like, oh, this is what makes up the banana. And you know, what's a banana in your mind is your experience the banana, poking on it, pushing on and tasting it, whatever, chasing that sloth, all these experiences of what build your sort of your mental construct of the banana. But it's nice to know, like mathematically, how that comes from the littlest bits it's made out of. So thank you Grace for asking that question. And we're curious if this answered your question and if you have follow ups, So we'll ship this off to Grace and we'll hear what she.

00:15:30
Speaker 3: Has to say.

00:15:31
Speaker 2: I also don't think answers have to be beautiful, but maybe that's because I'm a biologist. Our answers are rarely.

00:15:36
Speaker 3: Beautiful, but often they're insightful.

00:15:38
Speaker 2: Yeah, I wasn't implying they weren't, Daniel. I don't know why you felt you needed to say that, well.

00:15:45
Speaker 1: Because that's where the beauty comes from, right the inside. Like, oh, no, I understand this in a way I didn't before. Yeah, it can still be gooey, it's true.

00:15:53
Speaker 5: Hi, Daniel Keilly, thank you so much for answering our question. I'm still not sure I understand all of it, but it was really helpful here you explain it.

00:16:01
Speaker 6: I agree, it's clear I need to change my mental model of ways and particles stecking up like lego bricks to make things like sloths and instead think about blobs of energy. Thank you for all that you both do to help educate us and break down complex topics and have fun while doing it. I rate your answer a solid A plus.

00:16:21
Speaker 5: Thank you so much.

00:16:22
Speaker 7: Bye.

00:16:44
Speaker 2: All right, we're back and the next question is from a listener who, when they emailed us, was working through a very miserable cold. I believe they're feeling better now. But here is their question.

00:16:54
Speaker 8: A common COLDE seems to have a lot of variants, But how quickly does it mutate? Such as for the common I'm suffering with at the moment, Is there a quantifiable percentage of my sneezing and coughing that I accidentally spew onto others noticeably different compared to my original infection? Or are the variants pretty rare? But given the billions of us who get a cold that can create variants, a big number times a small percentage can have a surprisingly noticeable number.

00:17:25
Speaker 1: Help me out, all right, this is a great question, and it's sort of similar in spirit to the previous one, Right, getting a microscopic understanding of a common experience, in this case, the common cold. So let's see if biology can provide the insights to give you that sense of understanding, even if we are talking about mucus.

00:17:43
Speaker 2: Well, let's give it a shot, all right, So it gets complicated right from the beginning. The common cold. According to the Centers for Disease Control, this is defined as a viral infection of the upper respiratory track. Okay, okay, but it turns out it's not caused by just one kind of virus. It's caused by something like over two hundred different kinds of viruses. But depending on the time of year, between fifty to eighty percent of the common colds that people have are caused by a group of viruses called the rhinoviruses. So we're going to answer Tim's question based on data that we've gotten in labs that have looked at rhinoviruses.

00:18:20
Speaker 1: So this is like asking, why is my house infected with insects? Well, it turns out there's lots of different kind of insects that couldn't infest your house.

00:18:27
Speaker 2: That's right, that's right. And so to answer your question without taking too many lifetimes, we need to narrow down on an example. So we're narrowing down on the rhinoviruses.

00:18:37
Speaker 1: And so for those of us who are not biologists, remind us, like, what is a virus and how does it work?

00:18:42
Speaker 3: What is its plan?

00:18:43
Speaker 2: Yeah, So what viruses do is when they get inside of you, they have this way of injecting themselves into your cell. So they've got like some machinery that helps them move around, and then when they get to a cell, they clamp down and then they inject genetic material into the cell.

00:18:58
Speaker 1: This is amazing. It's empazing. It sounds so mechanical.

00:19:02
Speaker 2: It does. Yeah, I know, sometimes biology is just as good as Sci Fi, maybe better. So they hijack the cell's machinery and they get the cell to start replicating the virus. And this is part of where Tim's question comes in. As the virus replicates, sometimes mistakes are made, and cold viruses tend to not correct these genetic mistakes very often, and so we're going to get to that in a little bit more detail layered. So the host cell replicates the virus many times, and then the virus breaks out of the cell and goes and completes that cycle again.

00:19:35
Speaker 1: So the element of the cell that is taking over is the bit where it replicates the genetic material. That's what the virus can't do for itself. Yes, so this is like a hacker breaking into a publishing house. And getting it to print his personal manifesto instead of whatever it was going to print otherwise.

00:19:49
Speaker 2: That's right, yep. Print it's pamphlets over and over and over again. And then through some mechanism that sort of breaks the metaphor, it sneaks into another publishing house and does the same thing over and over and over again until you stop sneezing. So anyway, so it goes through this process, and it is finding cells in particular in like your nasal passage and your lungs, and it's replicating in there. And as it replicates, your immune system sort of amps up and starts attacking it. And this cold process can last for about a week, and so you get a build up of virus particles and then your immune system starts to get it in control, and the density of virus goes down over time.

00:20:29
Speaker 1: And so if I've had the common cold and my immune system has figured out how to combat it, why do I then get the common cold again the next year or three weeks later when my kids come back with a different one.

00:20:39
Speaker 2: Well, that great question brings me to mutation rates. So, as I mentioned, the virus doesn't correct mistakes as often as for example, human cells do. And so the question that we want to ask here to really address Tim's question is how many mutations do you tend to get and how much do they build up? So I found estimates that the mutation rate is you get something like ten to the negative three to ten to the negative five mutations, and ten to the negative three is one in a thousand, one in a thousand. Yeah, per nucleotide, per genome replication event. Don't worry about all of those numbers. The point is that a virus is about seven two hundred pieces long, and each time it replicates, you usually end up with about one mutation on average in that genetic code.

00:21:26
Speaker 1: So it's getting the cell to replicate it, but it's not a perfect copy.

00:21:30
Speaker 2: That's right, and then it doesn't get corrected, and so that error goes on to the next cell and that gets replicated over and over again.

00:21:37
Speaker 1: So already the initial virus that infected Tim, all of its little babies likely are different than it was by one nucleotide.

00:21:45
Speaker 2: That's right. And so then the question you want to ask yourself is does that matter? And I think a lot of the time it's not going to matter. So a lot of mutations don't change the kind of protein that ends up getting made, or they don't have any meaningful change based on this one little that flips to a different value.

00:22:01
Speaker 3: Right.

00:22:02
Speaker 1: It's not like the common cold suddenly becomes a completely different disease measles all of a sudden with one slip or something.

00:22:07
Speaker 2: Right. But you know, as Tim noted in his question, if this is happening many many times in your body, and then it's happening to many many people, these changes can add up over time. Amazingly. This all seems to also be temperature dependent. And I have a lot of friends who will say things like, oh, don't go outside without a coat on. It's cold out, and then you're gonna get sick. And that's not quite how it works. But there is some evidence that at colder temperatures, cold viruses do replicate more quickly in mice. I don't think this has been done in humans. It's always in mice. But it's not because that's better for the virus in some way, which I think is implied when they're like, oh, don't go outside without your coat on. It's because the immune systems in mice seem to react less strongly at low temperatures. So these replication rates that we're talking about here, they're all a little bit handwavy, and they depend on what temperature you're at, and so Tim, I hope you're staying nice and warm. Yeah, So what do we know about how much the cell replicates inside of a host? And the answer is well as complicated. So at a lot of our data come from what I think of as the wrong kinds of cells in the lab. And so the cells that are often used in these experiments are HeLa cells. So these are I think ovarian cells collected from a woman named Henriette Lex a long time ago. They were collected without her permission.

00:23:24
Speaker 1: Bad bad biologists.

00:23:26
Speaker 3: Bad.

00:23:27
Speaker 2: Yeah, yeah, no, bad biologists. You're right, I'll take that one.

00:23:31
Speaker 1: I mean, we've never gotten consent from any of the protons we've destroyed, but I don't think they are the same rights.

00:23:35
Speaker 2: Yeah, no, it's you're right. This was not a bright spot in the history of biology. So we stole those cells. There's a whole very interesting book on that which I recommend people check out. But anyway, so these cells are really great at surviving in the lab, and so we will infect them with cold viruses and see how they replicate. But the problem is they're ovarian cells. They're not like nasal passage cells, and the body is complicated. So just because something happens in a petri dish, does it I mean it would happen the same in a body. So when a cell explodes, how many baby viruses are made? And the answer is probably something like one hundred thousand, maybe even more than that. And then how long is the cycle of infection before you get an explosion? And you know, we don't really know. It's probably longer than minutes, but less than weeks, which is a pretty big timeframe. And thank you so much to Katrina Whitson for giving us this information, because I was having trouble sort of narrowing down the numbers to use for this question, and I.

00:24:31
Speaker 1: Think Coatinia would probably want me to emphasize that these are very fuzzy numbers because it's a research question. Nobody knows the answer to these things, which is sort of shocking and amazing, but it's hard to measure. And she was also telling me that sometimes a virus wants to slow down how long the process takes because it wants the cell to get like stronger and fatter before it explodes. So sometimes they like beef up the cell, sort of like fattening a calf before you kill it.

00:24:54
Speaker 2: That's right, And so as a group effort, I would say the Whitesn Research Institute plus adjunct faculty member or Kelly Wiener Smith decided that the virus that you sneeze out sort of towards the end of your cold probably has something like twenty mutations and is about one percent different than the virus that you were infected by GO team. But Tim wanted to know if it was noticeably variable, and we've mentioned that it really depends where those mutations are happening. But over time this is adding up. The cold virus does end up being noticeably variable enough that it's really hard to make a vaccine for the cold. And this is for a couple reasons. So one, we've already mentioned that there's like something like two hundred different kinds of viruses that can cause colds. Additionally, each strain of the cold virus is replicating pretty rapidly, so from one season to another it might be different enough that the vaccine wouldn't work. And additionally, colds don't tend to be as serious as something like the flu, So there's not a lot of impetus to try to create a vaccine, even though I sure would love to have not spent oh my gosh, when my kids started elementary school, I think I spent like sixty percent of my time at home with a cold. I would have loved to have had that time back. But what are you gonna do?

00:26:06
Speaker 1: And that's interesting because colds are varying constantly and it's hard to maintain immunity against them. Yet they mostly feel the same, right, Yeah, yeah, you got a head cold or a chest cold or whatever. But it's not like, oh wow, this one makes my head green, or now my thumb is swollen or something. It's basically the same disease, it feels like to me.

00:26:24
Speaker 2: Yeah, no, it feels that way to me as well. And just to be clear, the flu viruses are also doing quite a bit of mutating, but I think they mutate a little bit less. But every year, the reason you get a new flu vaccine is because that vaccine is meant to replicate the strains of the flu that we think are going to be most common in a given year, Given like mutations that we've seen in those flu virus strains in the past.

00:26:45
Speaker 1: Yeah, And I think there's a lot of detective work and guesswork that goes into the flu. Right, they're like thinking about what it might be because they obviously don't have the examples for the flu that's gonna come.

00:26:54
Speaker 3: In the future.

00:26:54
Speaker 2: Yep, exactly. I mean they're making their guests based on years of data, looking at trends and how this stuff plays out. But you're right, at the end of the day, you just need to guess which flu strains are going to be the most important ones to make vaccines against. And I hope you got it.

00:27:07
Speaker 1: Right thanks to folks working on the front lines of public health.

00:27:11
Speaker 2: Yes, oh my gosh, they're the best. All right, Tim, We hope you're feeling better, and let's find out if we were able to answer your question.

00:27:18
Speaker 9: Yes, that answer my question. And wow, that is rather terrifying that two hundred variants out there make up the cold virus. I don't know if I'm going to sleep well at night knowing that fact on top of all the other mutation rates. But luckily we feel a little bit on the safe side.

00:27:54
Speaker 3: All right.

00:27:55
Speaker 1: And our last question comes from Mark in Newcastle, who asks a very heavy question about something very ephemeral.

00:28:02
Speaker 10: Hi guys, it's Markia from Newcastle upon Tyne in the UK, and I've got a question for you about data. I was recently working on a project with my orduino writing to some SD cards and of course when you switch off the power and switch it back on, the data is retained. So these cards do store something. This storing charge and charge is electrons. Electrons have mass, So does data have mass? Would an SD card full of data way more than an SD card that didn't I guess this is an extra opulation of this question, how much does the Internet Way? Book pops for another day.

00:28:39
Speaker 2: This is such a great question because, well, for a variety of reasons. But I love this question because in the past on this show you have said that when a Tesla battery is charged, it weighs more than when it's not charged, And that makes sense now, but at the moment it totally surprised me and I didn't expect that. And so, yeah, how much does the Internet Way.

00:28:59
Speaker 3: Daniel seven at weighs seven?

00:29:02
Speaker 2: Oh good, I was going to guess forty two.

00:29:04
Speaker 1: Yeah, remember that mass as a measure of internal stored energy, So if you increase the internal stored energy of an object, then you are increasing its mass.

00:29:13
Speaker 3: Like if you have a.

00:29:14
Speaker 1: Rock and use zapp it with a photon and it gets hotter, it also has more mass. Now, so when you charge your Tesla battery, you're giving it more energy, not because you're adding more electrons, you know, like physically adding more scoops of universe stuff. Just giving more energy to that configuration does increase the mass of the battery. Since equals mc squared and C squared is a really big number, you need an enormous amount of energy to make a tiny increase in mass. So nobody really notices this, and that's why. But Mark's question is sort of related. He's asking about whether the arrangements to configuration of information on his SD card or on your hard drive or in your brain also has mass, which is a really fascinating question and touches on deep concepts about information and entropy.

00:30:00
Speaker 2: And we luckily have someone who is part computer scientist, part physicists who is absolutely prepared to answer this question for us.

00:30:09
Speaker 1: Yeah, so information is really fascinating. It's hard to think about like whether information has mass because information seems sort of subjective, right, like, if you have a hard drive and it has just random ones and zeros on it, does it have more or less information than if you put a picture of your dog on the hard drive? Well, it depends, like do you consider the picture of your dog to be useful or information in some way?

00:30:33
Speaker 3: Right?

00:30:34
Speaker 1: Or like did you encrypt the picture of your dog? Because the best encryption algorithms make data that's valuable it has some information look like random noise. So you can imagine a scenario where you, like, you take a picture of your dog, you put it on the hard drive, looks like your dog, then you encrypt it. Somebody else coming along is like, no, that's just random noise. There's no information. And what if you, like, lose the password, has the information decreased? And so information turns out to be a fascinatingly subjective concept, which makes it very hard to link to masks because mass is something physical and invariant that everybody agrees on that you can like measure without knowing about dogs or passwords?

00:31:10
Speaker 2: Should I be thinking about information differently than I think about like you know, before I put my PowerPoint presentation on my SD card, it has fifty megabytes of data and after the PowerPoint presentation is on there, it has one thy fifty. So how is information different than megabytes?

00:31:29
Speaker 1: Yeah, if you have an empty disc and then you put files on there, it's counting, like how much of the drive has information you've put on there. There could also be information on the other bits that it's not counting, maybe somebody else put it on there, but then you format it the drive, so you consider it to be empty. So it's a different question of like when you're filling up the drive, right, because it's just like using some of the bits for this rather than considering them unused. But the question of information is subtle, and we're going to have to dip into our understanding of entropy in order to understand it, because it's turns out these two concepts are closely related.

00:32:02
Speaker 2: So okay, So just to clarify, then, information is not how much stuff is on a card, it's how informative is the thing?

00:32:12
Speaker 1: Yeah, Because you could take a card and just fill it with random ones and zeros, right, there's no information there for you. So just because you put a big file in your hard drive doesn't mean you add a lot of information. It's about the contents and this seems really subjective, and physics is all about equations and crisp definitions. So how do we think about information from the point of view of science and physics. So Claude Shannon defined this in the middle of the last century. He was thinking about this and he came up with something of an arbitrary but very useful definition of information, and he defines it as how much you have learned, how much surprising information you have gained. So he was imagining like, I'm communicating to you by sending you symbols across some channel ones and zero's on a hard drive or you know, text on a phone or whatever, and you want to measure how much information is in these messages from Daniel and to his definition, if when you learn something surprising, that's high information. If you learn something you already know, that's low information. So for example, let's say every day I text you and I say, hey, Kelly, the earth didn't explode last nightew every day you look at it and you're like, Okay, that's not a surprise, right, this has happened every day so far in my life.

00:33:19
Speaker 2: I'm changing my phone number. Leave me alone, Daniel.

00:33:23
Speaker 1: Why a physicists text me about the planet's exploding.

00:33:26
Speaker 3: What did I do wrong?

00:33:27
Speaker 2: Low information?

00:33:28
Speaker 1: Low information exactly because it's something you expected to happen. So the fact that it happened you didn't really learn much. If one day I texted you I was like, by the way, at two am, the Earth exploded, you'd be like, wow, that's news to me, right, this is big information.

00:33:41
Speaker 2: But wouldn't that also be low information because I would have been exploded and I would have also been like, thanks for being late to the party, Daniel.

00:33:48
Speaker 1: Don't use the practical details of my analogy to confuse you, audience.

00:33:53
Speaker 2: Okay, whoa, Oh no, I didn't know that, Daniel.

00:33:56
Speaker 1: You're living in a city on Mars in this example. All right, So let's put Kelly on Mars. She and her cute babies in their baby spacesuits, and her and the girl Scout troop are camping up there on Mars awesome. And every day I wake up and my job is to text you about whether the Earth exploded. So the day that you get a text that the Earth exploded, that's big news. Why because it was unlikely and so the fact that it happened is a lot of information.

00:34:20
Speaker 2: Major bummer.

00:34:22
Speaker 1: So This is fascinating because it means a bits of information like did the Earth explode?

00:34:26
Speaker 3: Yes and no.

00:34:27
Speaker 1: It feels like one bit like either value should be equal amounts of information, but they're not because information depends on context, so bits of information are not created equally. And so Shannon said, let's define the amount of information to be the inverse of the probability for that to happen. Right, so if a high probability of it happens, one over that number is a small number, so it's a small amount of information. And if a very unlikely thing happened, then one over that number is a very big number, so that's a lot of information. And he called this surprisal.

00:34:59
Speaker 2: That's cute.

00:34:59
Speaker 1: And to make it well, behave we have the logarithm of it. So he defines information as log of one over the probability for something to happen, which just means that like more probable, lower information, less probable, more information. So now we have like a definition of information. And again this is just something Claude Shannon made up, but we're gonna see in a moment that actually connects with other concepts in physics.

00:35:23
Speaker 2: Would you be like taking the expected value of surprisal after accounting for the fact that people might differ in how surprised they are about some like would you have to average different people's surprisal to really get a good sense of the information.

00:35:38
Speaker 3: That's really cool.

00:35:39
Speaker 1: Yeah, so something might be information to me but not to you, right Like, what if I'm the one who destroyed the earth and then somebody texts me like the earth blew up today, I'm like, yeah, dude, I know. Then that's not information to me because I already knew happened, but it is information to you. And that kind of makes sense, right, Like, the same bit is not the same amount of information for everybody, depending on what they already knew. God, But there is a concept of expected a surprisal. So if you take the kind of surprise you might get from all the different messages you might get from Daniel, and you average them over how likely you are to get those messages, you get this other formula. And this formula is fascinating because it looks just like the formula we have in physics for calculating entropy.

00:36:20
Speaker 3: Remember a few.

00:36:21
Speaker 1: Episodes ago, we talked about what does entropy mean? And we said that entropy was a ratio between basically how much you know and how much you don't know. How many ways can you configure the micro states of a system to be consistent with the macro state you see, So you see that there's particles in a box at a certain temperature. How many ways can you arrange the particles inside? How many different configurations can there be that are consistent with the measurement that you made. And the relationship between the micro states and the macro states is also related by the formula with exactly the same structure as Shannon's formula for average surprisal. So Shannon showed this formula to John von Neumann, famous physicist and mathematics, and he said, oh, you should call this information entropy for two reasons. One because the formula looks the same. It looks like the formula for entropy, and it's conceptually sort of similar. And two because nobody really knows what entropy means, and so they can't argue with you.

00:37:15
Speaker 2: I like that anything that makes it impossible for people to argue with me, I'm down for exactly.

00:37:22
Speaker 1: And so in Shannon's information entropy, low information means low entropy. So if you're getting a bunch of signals from Earth, and you're always getting the same high probability message, like the Earth didn't explode today, The Earth didn't explode today. That's low information entropy. You're always getting the same one. But if you're always getting a different message, like maybe instead of getting texts from Daniel about whether the Earth exploded, you're getting pictures from probes that landed on exoplanets, And every time you open one of those, you're like, I have no idea what to expect. Anything I see is going to be new to me, right, and like this one has rocks, and that one has like lava, and that one has aliens on it, and like what is this over here? Oh my gosh, the way like every time we turn on a new telescope we see something weird and surprising in the universe. Right, that's very high information content because there's lots of different possible outcomes, each of which are equally likely, instead of there being like one very likely outcome. So that's high information entropy.

00:38:19
Speaker 2: Okay, so now let's try to connect to mass. So I'm wondering if an internet made of cat memes, which would be low information, would weigh less than an Internet that reconciles relativity with quantum mechanics, which would be a high information internet. How do you compare those?

00:38:38
Speaker 1: Yeah, so now we have a definition of information, right, we know how to measure information into something that's low information or high information.

00:38:45
Speaker 3: And you're right.

00:38:46
Speaker 1: If you get on the Internet and you see the same cat memes you're always seeing, then that's low information. If somebody says something really new and clever and surprise and you're like, whoa, my gosh, that's high information. That's more entropy. And we're talking about in terms of entropy because we're trying to get a graph on the physical nature of this and the consequences for it.

00:39:03
Speaker 3: Like does it have mass?

00:39:04
Speaker 1: Because we know entropy is connected to energy, right, and energy is connected to mass. So can we somehow draw a dotted line between information, cat memes and the weight of the Internet. No, unfortunately not, because increasing the information doesn't increase the mass or the energy of the system. The information content is relative to what you already know, depends on the context. You can arrange a set of sticks or bits on the hard drive to mean one thing or another. It doesn't change the mass or the energy. So it has to do with how you interpret the arrangement of the system and what you already know. It does require some mass and some energy to store that information. You want to put bits on a hard drive, you want to write numbers in the sahara and filled them with kerosene. That definitely costs energy, right, And all stored energy does have some mass, But increasing the information on something doesn't increase its mass. So connecting back to Mark's question, he's asking does data have mass? And data does not have mass? Right, And remember that when you're putting a picture of your dog onto the SD card, you're not like downloading electrons and not flowing onto there. You're just moving electrons up or down. You're just flipping switches on that card, so you're not adding matter to it in any way. You're not changing the energy of the card. You're just flipping a switch, which doesn't require any more or less energy. It requires energy to build a card, and it requires energy to change things on the card. But the card is not heavier because you put a picture of a dog rather than a picture of the Earth or a picture of an exoplanet, or like the equations of quantum gravity, which wuld be very surprising that anybody to find have a lot of information but wouldn't have any more mass than any other arrangement of those electrons or bits or sticks or flaming letters in.

00:40:45
Speaker 3: The Sahara course lots.

00:40:46
Speaker 1: But there is one other fascinating connection between information and mass which people may have heard about. It's called the beckensteam bound, which talks about the amount of information you can have in a space, because it turns out there is a limit to how much information you can put in a volume of space, and it turns out that's a black hole. Right, The most information dense arrangement of matter or energy is a black hole. So black holes have the maximum amount of information. It's called the Beckenstein bound. Beckenstein is a student who work with Stephen Hawking. Doesn't get enough credit for hawking radiation and all the black hole work that he did with Hawking, but super genius guy. Now, this doesn't mean, as you often hear in popular science, that if you have too much information something will collapse into a black hole. Like if you download enough amazing pictures of dogs under your computer, it's going to turn into a black hole. That's not the problem. It means that if you need to store a huge amount of information, the only way to do it is a black hole. A black hole is like the most information dense system you can have.

00:41:49
Speaker 3: So if you need to.

00:41:50
Speaker 1: Increase the amount of information you're storing, you might need to increase the mass of your system so much so that you get a black hole.

00:41:57
Speaker 2: Well, you know, DNA is also supposed to be very information dents, and there are people who are arguing that when we can easily print DNA sequences, we might want to start storing data in DNA and sticking it in freezers. That sounds complicated to me, but we'll see what the future holds.

00:42:12
Speaker 1: Yeah, but DNA is an amazing storage system because it lasts for a long long time compared to hard drives. You put something on a hard drive, you think, oh, it's there, but five years later you come back, it could be totally degraded. So if you have like really valuable information the secrets to quantum gravity are on a hard drive in your closet, make sure you're upgrading those every couple of years because that stuff fades.

00:42:32
Speaker 2: You are making me very nervous about the videos from my PhD that are still sitting in the closet a decade on that need to be analystt We.

00:42:40
Speaker 1: Have a real problem with digital storage. People think it's forever because it's ones and zeros, but it's not, and actually a lot of the old analog systems we have last longer. Like my favorite story is computer punch cards. My dad did his graduate thesis on the computer using punch cards. I remember being in the computer room as he would like insert them and pick them up.

00:42:58
Speaker 3: And the cool thing about punch cards is totally resilient.

00:43:00
Speaker 1: They'll last a long long time, right, yea, So he still has like stacks of punch cards that you could still run if the computer was around. But nobody has a hard drive from like nineteen eighty four that still works. So back up all your stuff, folks, and don't create black holes. The Mark, you can keep adding pictures of your dog to your SD card without making it heavier. So let's check in with Mark see if that answered his question.

00:43:24
Speaker 10: Thanks for answering my question, guys. I think I'm fundamentally more enlightened now. I found it interesting how the view on data and mass extended into information value and information entropy and also information density. Pops Bekenstein can have a side hustle selling high density branded SD codes. Anyway, Thanks again and keep up with the good work.

00:43:48
Speaker 2: All right, everyone, thanks for listening today. If you have a question you want to ask us right to us at Questions at Daniel and Kelly dot org. We answer every question we get, some of them end up on the show, and we'd love to know what you're thinking about.

00:44:00
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00:44:20
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00:44:26
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00:44:31
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00:44:38
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00:44:43
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00:44:54
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