Hannah Predicted a Pandemic

0:01Hello and welcome to The Rest is Science. I'm Michael Stevens. And I'm Hannah Fry. And today on Field Notes, we're going to be tackling your questions. And then also, Hannah has brought something. I think it might be a story. I literally don't know. It is a story. You know, I noticed in the introduction that I used my BBC voice. Did you hear it? No, I wasn't even listening. To be honest, I was just looking at my own video going, look at that handsome devil. So do your BBC voice again. it's just much it's a bit more formal and i think i think that might be because because my story is about is about a bbc show that i did where um i accidentally almost perfectly predicted the pandemic two years before it happened whoops whoops um i've got into a lot of trouble for it wait no but do do the bbc voice again hello i'm hannah fry nice yeah i mean it's still definitely you, but it feels like you're not talking to me.

0:57On the spectrum between BBC and Essex, which is, you know, my natural state, I would say that you're closer to the Essex than the BBC. Oh yeah, let me try to do a BBC voice. Go on. Hello and welcome to The Rest is Science. I'm Michael Stevens. Oh, that was good. It's almost like American newscaster, really. That was very good. I was going to say, I think that the only problem with it is that it's the accent, I'm afraid i'm afraid you're sacked hello my name's michael stevens i dig you did that's bbc that's like there you go right there okay notice how it becomes southern and that's because that non-rhotic commonality non-rhotic what's that there's no r right like both both the british and the southern americans will drop the r's out they'll be like yeah i'm working down on the farm but then a a British person will be like, I was dancing at the farm, right?

1:57It's much smoother. That's nice. I like that. Can we do an episode on accents at some point? Because I've got a range in my back catalogue that I can wheel out at will. As do I. I have never been shy to show off the range of accents I can do. That's the best possible hook and tease that we've got for an episode on accents coming up. that doesn't exist yet. But we're going to start with questions.

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4:38I want to start with this one. This is sent in to us by MD Solomon. If your brain constructs your entire reality from electrical signals, including the feeling of this moment right now, if we could perfectly swap your sensory inputs with someone else's for just one minute, would you still feel like you? We're going to start nice and deep here. I think, first of all, is your entire reality constructed from electrical signals? That's a huge assumption to make, but we don't have to belabor that point too much. What we're talking about right now is if I switched my sensory inputs to someone else's, what would it feel like and would it challenge my feeling of myself?

5:20I mean, I think that the closest we've been able to come to doing things like this are like skin grafts where someone's had a tumor removed on their leg and then that flesh is replaced with flesh taken from like their butt cheek. and after surgery, when they touch the leg, they've got skin where the skin was removed, but those nerve cells used to be in the butt. So they'll stroke their leg. And when they touch that new transplant and piece of their own skin, it feels like they're touching their butt. Is that true? It's true. This happens specifically, the leg butt example happened to my friend, Jake Roper, when he had a tumor removed on his leg.

6:04And they've got to replace that tissue. And you've got, I guess, like just so much in your badonkadonk that that's an easy place to grab more to replace it. And the thing is, it's really trippy at first because you're like touching your leg and your brain is going, oh, someone's touching the butt. It's like that signal is moved from your leg by the brain to it's projected onto wherever they removed the nerves from. But it doesn't last forever. Right. I was going to say, surely there's a point where your brain works out and switches. That's right. Your brain works it out. Your brain remains plastic in so many ways your whole life.

6:41It's changeable and it'll eventually fade away and it'll go, ah, these nerves are now next to these other nerves that are in the leg. So I'm going to project those feelings to the leg area from now on. But in that case, you're switching your sensory inputs from yourself to yourself. You're just changing the where on yourself it is. It always still feels like you. But if suddenly I was feeling everything that touched you, Hannah, it would be a trippy experience. But I think there would still be a me there experiencing these signals going, what the heck? This is really trippy. But I would still be there as me, Michael Stevens, wondering what the heck is this about?

7:25I think for almost all of my life, that would have been the assumption that I would also have made. But I had a conversation actually with a retired Cambridge professor about a month ago. And something he said has just really, I've been thinking about it almost nonstop ever since. And I think I might have changed my mind on exactly that point. Tell me why. He was talking about how we have this idea that there is a conscious version of you that is sort of assimilating all of the signals and coming up with a conclusion about where you are, who you are, what you're feeling, etc. But he was saying, actually, we don't have any firm evidence that that is the case.

8:04It may be that actually all of that is just an illusion of a conscious self. You know, in the same way that when you look carefully about sight or smell, I mean, there's all sorts of illusions that are evidenced in the way that our brain works. And he was saying, maybe they're like the idea of you as a single entity sort of sitting on top of all of these electrical signals. Maybe that is in itself an illusion. And then I was thinking about there's a very famous experiment, which you and I have talked about before. There's a very famous experiment where someone presses a button, but at the same time as their brain is being monitored.

8:45And actually the decision to press the button and the physical action that they take to press the button are offset, but not in the way around that you might imagine it. The cause and effect is not, oh, I think I'll press that button over there. And then the message gets sent to your arm, at which point you go to move the button. it's the other way around your arm makes the movement and then your brain retrospectively comes up with that decision afterwards yeah i actually got to meet uh dr moran who does these experiments in a minefield episode and we ran this on some other science youtubers you try to predict the readiness potentials of their neurons so that you know that they're about to push the button and as it turns out that happens before their conscious awareness that i'm going to push it light the buttons up, turn the button red, meaning don't push me before they're aware that they were about to and they become paralyzed.

9:42So, I mean, this throws into question the entire notion of is there a you? We certainly act like there is. We think to ourselves and we explain ourselves to others as though there is a little self that's riding along, manning the controls, but it does seem more like there might not be a you, there's a you-ing that your brain does, where it looks at what it's done and what's happening, and it goes, oh, yes, yes, yes, that's what I meant to do. Thank you very much. And it might only really do that because it helps us explain ourselves to others. And as I've said before, that might be something that happened not even that long ago, that social life amongst homo sapiens became complicated enough and broad enough that we had to start being like, okay, I'm an individual, and you're someone else.

10:33And so, yeah, I think switching our sensory inputs so that I'm tasting what you taste, I think I'd still you-ify it, or I guess me-ify it, and I'd say, whoa, this is happening to me. But to what extent there's actually a me, like a part of my brain that is going, uh-huh, I'm just going to pull the levers and oh, I'm getting a weird signal here from the taste buds. I don't know. I think that it's something you learn. So, I'm still learning about this. I've got some good books about how children are believed to develop their sense of self. And we might actually get our best evidence from the way they dream.

11:14I mean, this could become a three-hour long episode. But when you look at dreams, the earliest reports of dreams we have from humans, they're different than the way we dream today. And this is something we're all pretty aware of. Like dreams from ancient texts are almost always seen as they're not as fanciful. It is someone appeared to me while I was in my bed. There aren't a lot of dreams that are like, whoa, I was on the beach that I'd vacationed on years ago. And like there was this animal that was my dog, but wasn't. No, no, no. It's just like I woke up and I saw an angel and it told me about the future.

11:55So you're still in the same place you really are. And you're talking to people or you're interacting with people right where you really are. And that's also how children dream when they're very, very young. And it's only later that we start to become disembodied observers in dreams that go all over the place. Does that tell us something about the learning of a you, of a thing that can be disembodied and go and control another organism or be something else or experience things from other people's perspectives? Maybe. maybe but i mean there's a reason why they call this the hard problem right which is literally the name of it what is what is it like to experience the world from inside somebody else's body we just it's it's it's a hard problem because we have it's it's not falsifiable right there's no real way you can have ideas and theories but but ultimately we just for now don't know maybe it is i mean i think i think you're probably right that actually if you just if you just swapped over the taste for example just the signal for taste it would be like well this is a trippy experience but actually ultimately i don't think it would disintegrate your sense of self but if you swapped over all of it the whole lot i don't know i think maybe i think there's a chance you'd completely disintegrate there wouldn't be a you left right and we have to ask where do i begin?

13:19Do I begin at my sensory inputs or later on in the processing? Because if I had all of your taste nerves connected to the right places in my brain, it might feel projected weirdly across space. But would I be tasting things as you do or as I do? At what point does it become my experience? Would you suddenly absolutely despise olives and love chili, you know? Right. There's probably a food that you despise that I love. If I was able to tap into your nerve impulses coming from you eating that food you hate that I love, would I love it or hate it? I don't know. It depends where the liking that judgment is happening.

14:01Is it being done by the cells in the tongue or by the cells in the brain? We know, for example, that like colorblindness can happen in lots of places. It can happen in the brain or it can be because of the retina itself, because of the actual cone receptors in the retina. We know that. So if I had my eyeballs replaced with a colorblind person's eyeballs and it was perfectly synced up nerve to nerve by some surgeon, I would not see those colors anymore. At first, I thought, well, I don't know. My body might still like expect to see, you know, red and green divisions. and so it might fix it itself.

14:35But colorblindness can also be induced and it can be non-genetic. It can happen to someone who used to be able to see the colors. I didn't know this until this morning. I thought it was purely a genetic thing. I know you could hypnotize people into being colorblind. That is one thing I... I did not even know that. But you could also damage someone's brain if they have swelling in the occipital lobe, in the back where vision is first processed, can lead to colorblindness and so can medications. As it turns out, one of the chemicals in Viagra can lead to blue-yellow colorblindness. No. Permanently or as a temporary?

15:12I mean, you gain one thing, you lose another. Yeah, it's a trade-off. You know, it's a good life lesson. I don't know if it's permanent or not, but I'll do some experiments later and I'll let you know what I find. There's also a medication used for treating tuberculosis called ethambutol, and that can lead to red-green colorblindness. Vitamin A deficiency can cause colorblindness. Certain UV exposure to your retinas can lead to it. So even if your brain has always been aware of red and green, blue and yellow and the differences, you can lose that ability later in life. I have a question about that.

15:51Does it happen in a way that people notice it? or because because the thing is this is the the thing that i find it gives a real insight into the hard problem is that a lot of people who are colorblind do not know that they are colorblind it's sometimes ever but but often until later in life um and that i think is very interesting that i think really demonstrates because because this is something that is testable this is something that you can recreate so that we can understand how it looks for different people who suffer from, you know, red-green colorblindness, for example. And it's so fundamentally different to the experience of the rest of us.

16:36And yet you can go through your life having conversations with people the entire time and never know that you were viewing the world in a fundamentally different way. That's right. And yet you have access to yourself and your history. So people are aware that something's changed for them. I remember there's a YouTube video you can look up where a guy who has colorblindness talks about how peanuts and peanut butter are extremely different colors to him. Whereas to us, it might change its hue of brown a little bit. But for him, they were able to show him peanuts and he's like, oh yeah, they're green or whatever.

17:09I forget exactly, but it was quite different than a regular vision experience. And then they put the peanuts in a blender and they tell him, tell us when it changes color and they start spinning them up. And to me, it just looks like the same color, but like fast. And at a certain point he goes, okay, now it's different. Now it's, you know, now it's become a whole different color. And I'm like, what in the world? Wow. I was plugged into his eyeballs or, or I don't actually know what, what was causing it. Let's, let's assume it was the retina. Cause this was a lifelong thing for him. For me, I would experience the same thing.

17:47I would notice the color change as well because different signals were being sent to my brain. But I might, I might like fix it myself as my brain went, nah, nah, nah. It's supposed to be the same. I don't know if the illusion would persist. It might be like transplanting parts of my skin. It might go, uh, yeah, yeah, yeah. This is not helpful. This is not what we expected. Let's fix that. But I don't know. We'll have to, will have to do these experiments but it's very hard to do things like this my brother-in-law is colorblind and um and so for christmas one year i i made him a t-shirt um where i i did one of the you know the colorblind tests where you have all the dots and it's one one color against the other so i made him one of those and in it it says in a pattern that he couldn't read f the colorblind no kidding okay so first of all did when did he find out i think he knew straight away i was messing with him we have a um we have a sort of christmas tradition in my family of where we get each other gifts um that sort of play on the other people's absolute weaknesses it's kind of it's quite an Irish thing I love this yeah yeah he got me what he got me a t-shirt once um where I'd been I'd done a um I'd done a tv program where I had I'd hosted have I got news for you in the UK and uh during at one point I'd done air quotes and he got uh as someone had made a joke about whether my whether I really was a professor while I was hosting this program and so he got me a t-shirt of just a screenshot of me going air quotes and just saying professor in inverted commas as though and to really call my credibility into question.

19:31So, you know, it's sort of a, it's a running thing. It's a very great tradition. I'd love to start one of those, but this colorblind shirt, the F the colorblind shirt, that is very similar to the shirt that's coming in the summer curiosity box. Oh, is it? Go on. Instead of making fun of the colorblind, which I do not support, It makes fun of dogs. And so the shirt is red. It's a red t-shirt. And in white, it says no bones in here. Because of course, dogs really like bones. And if you if a dog knew that I was full of bones, they might want to play with them. So it says in white letters, no bones in here.

20:10so any dog sees me they know this guy doesn't have any bones in him i'm not going to mess with them but then in green letters underneath it says jk i'm actually full of bones now dogs have a red green color blindness meaning that they won't see that part but humans will so i'll be telling the truth to humans who i want to know that i have a skeleton but to the dogs i'll be safe yours yours is a much more pc version of or much more human-centric version it's a human-centric one yes to be clear i'm not anti-colorblind people just you know sometimes anti my brother-in-law yeah exactly yeah yeah all right so that so answering that question um md uh i think uh went many directions you may not have expected but i appreciate it it did but it's a really interesting question and we spent 20 minutes on the first question that's how it should be It should be, shouldn't it?

21:04Okay. All right. Here's another question. This one's from Matthew. Matthew asks, hey, what's the deal with quantum spin? By the way, Matthew, absolutely love that you started your question with hey. I'm here for it. What the hell is it? Why are people talking about it? And if it is just a metaphor, what is it a metaphor for? Thank you. That's one of my favorite messages ever. okay um i have done i'll be honest with you until before this morning i was quite rusty on quantum quantum spin it's been a while i'll be honest um because you do people people use this phrase it gets thrown around and in your head i think it conjures up a mental image of a of a ball that's literally spinning yeah it is absolutely not like that at all um i sort of think in a way it shouldn't be called spin because because the analogy only works really on one level we're not talking about physical spin here um it's more like a uh a property of the particle that's like mass or electric charge right just in the same way as you can't take away the mass of a of an electron you can't take away its spin either it's it's it's like a characteristic of it um but the reason why they've used the word spin is because it's all around how the particle behaves and it's got these similarities to angular momentum right it's a it's a quantity that gets conserved essentially i just interrupt and say my favorite quote about this i don't know who it came from but it shows up all the time it's this definition of quantum spin so here's the quote the spin of an electron is like a spinning ball, except that it's not spinning and there is no ball.

22:49So, it is metaphoric. It's important to remember that when people talk about spin. It is a property of particles, but you got to just realize there's no actual spinning ball there. There's no spinning ball there. No. Unless there is a way, there is a way to get them to spin, to physically spin the thing is is that you have to remember that like electrons in particular for example it's like a teeny tiny little bar magnet right and it has this magnetic field that exists around it and it can align with other magnetic fields that you that you that you impose upon it so um for example let's you know let's say that i've got an electric field and i have a really heavy magnet right really like meaty magnet uh and i put the the the electric the electric field do you know what i get so scared because the exact words that you use in this situation right field for example you have to be so careful to get the exact one right because otherwise i mean i'm literally looking at the department for theoretical physics of cambridge university out of my window i can feel the judgment the war yeah of all of those guys so i'm going to be really careful and if i make mistakes you can tell me in the comments okay so all right if you put an electron into a magnetic field then that electron can align itself with that field it can either spin up or it can spin down essentially that direction is a physical genuine direction okay but it only has two states it doesn't it doesn't like float around it doesn't rotate like a bar magnet does, or like a compass would, it's sort of, it's two states only, right?

24:39It kind of switches between, it can flip between them, jump between them. And so this is one way that you can actually make an electron spin. Because if you are careful, and you slowly rotate, slowly, your magnetic field, so that you have your electrons aligning with it, you can effectively rotate an electron, right? But that's the only way that you can do it. And that's different than the property of spin that we assign to particles yeah exactly but this is one of the ways that they get um that the the quantum computers work basically is by altering the magnetic field in order to um to to impose certain characteristics on the quantum particles um but the numbers that are associated with spin they sort of do make sense uh when it comes to rotation yeah the thing is is that spin really does indicate how weird quantum particles are because if you have a spin one particle then if you if you rotate it 360 degrees it returns to the same state you michael are a spin one particle thank you for noticing just a slightly larger version right then then one might expect in the quantum realm um a spin half particle right like an electron uh see if you can spot this a little bit weirder if you rotate it 360 degrees it doesn't go back to the same point you have to rotate it twice you have to rotate it 720 degrees for it to return to where it started weird which is i mean that yes weird it is this is one of the reasons why uh fineman says um anyone who says they understand quantum mechanics doesn't understand quantum mechanics yeah it's very non-intuitive it's very non-intuitive so we've got all these metaphors We use words like spin.

26:24And yet it's just kind of a thing that we may never truly understand. That said, do we really know what gravity is? Like we experience it so often, it's easy for us to go, oh yeah, I get it, gravity. But really, like what's happening? This is absolutely one of the reasons why people say that the fundamental language of the universe is mathematics because it becomes so difficult to translate these concepts into words and analogies and you lose something in the telling. It's all of this stuff that we're describing here essentially comes out from the structure of an equation and the way that different things relate to one another.

27:05So yeah, there we go. I think at some point, I know this is now the second of these questions that we've said this about, we've got sort of a nested system here where every question we ask every question we answer reveals itself into a whole new episode which includes more questions and therefore more episodes um it's sort of exponential growth the rest of science that's um that's kind of what we're going for here but i think at some point we will do something on the very weird nature of quantum and the strangeness that happens when it comes to rotating objects because actually i mean there is quite a quite a nice little puzzle i guess that we could set people between now and when we do a full episode on this, Michael, right?

27:48Yeah, yeah. Go on, you do it. That's right. Here's the puzzle. I want you to put out your hand with your palm facing down. And I want you to then rotate your hand such that your palm is up without rotating your arm or wrist. So no rotations allowed, but you can move your hand and you can bend your elbow. You start off with your palm facing down and your hand flat and you need to get your thumb pointing in the air without rotating your wrist. And you can get your thumb to point the other way. So your palm is facing up. So you're turning your hand all the way over, but you're not going to do it with a rotation.

28:27You're going to do it just by moving through space. Here's a clue. The kind of space you want it to move around might be spherical. Certainly might be. Okay, should we do one more question? Let's do one more question. Okay, here's one from Sebastian. Hello, you mentioned that there's a fair amount of empty space inside atoms. If we could remove all that space, how small would we all end up being? Yes, this is a classic, the empty spaceness of things. I think it's wrong to think about the universe as being made of like tiny, tiny, hard billiard balls called particles and atoms that you could scrunch together.

29:06I mean, when you get into things that small, there are particle type behaviors and there's wave type behaviors. There are, you know, aberrations in fields. And that's really what an electron is. However, we do know that there are ways to make things much more dense. Obviously, a black hole has a density that's so, so large. Its physical size is zero. It's a singularity. But let's avoid that because then everything's boring. I could smash the whole universe into a singularity and now it has no size. Wow, that's small. Look at a neutron star. A neutron star is super, super dense. It's not dense enough to collapse into a singularity, but it's very dense.

29:48It's so dense that a cubic meter of neutron star weighs 10 to the 18 kilograms. What is that? That's like 10 trillion trillion kilograms. The one that I always remember is that a teaspoon of a neutron star weighs more than the Titanic. A teaspoon of neutron star would weigh about 10 million tons. Okay. It's a law. Let's just take that as our goal here. Neutron stars are dense, meaning there's just a lot less empty space in between the matter. It is so close together. So if we could take all the matter in the entire observable universe and squish it all together as densely as a neutron star is packed, how large would this thing be?

30:35Well, I'll tell you the math was done by Reddit user Tomer Lutong. And as it turns out, and I checked this math, by the way, the entire universe, all of its matter, squeezed tightly together as tight as a neutron star is packed, would take up a sphere about 2.9 times 10 to the 11 meters across, which is a little bigger than the orbit of Mars. That's big, but it's also way small. For the entire universe, you could fit all the matter that everything we can see is made of into a ball that's just as wide across as Mars's orbit. Everything. That's insane. Now, if you look up these kind of facts, one that you'll find all the time, especially on Facebook, is the classic, if you did that to a human, or rather, if you got rid of the empty space in a human, the whole human body would fit into a sugar cube.

31:31But using the neutron star math, I get something very different. I get that an 80 kilogram human would only be a cube two micrometers on a side, right? Much, much smaller to two millionths of a centimeter. I mean, less than a grain of grain of sugar than as opposed to a whole sugar cube. Yeah, like a little tiny crystal of sugar. And that seems more correct to me. So basically, that's how small you'd have to be to be a neutron star. To be a black hole, you'd have to be even smaller, much, much smaller still. Amazing. Basically, not only do you have spin of one, Michael, you're also a whole lot of nothing.

32:10I'm a whole lot of nothing. I'm mainly nothing. I'm very diffuse. The matter in my body could be a lot tighter, could all get closer, but they don't want to. And I'm glad for that because it allows me to, you know, be like this. I'm glad for that too It does make you think though You know Sort of Seems a bit of a shame That things are kind of fixed To the size they were Because if you just had like A tiny bit more Empty space Or a tiny bit less empty space You could You could at will Change the size of your body From like a three foot tall human You know And sometimes I think It would be quite useful To be like Poly pocket sized But you would still Weigh the same amount Yeah And you wouldn't be anywhere Near the density of a neutron star For your poly pocket size Oh no But it means you could go on a long haul flight, get the cheapest possible seat, and it would be like living in a luxury villa.