The Limits Of Human Knowledge

Welcome to the rest of science. I'm Hannah Fryer. And I'm Michael Stevens. And this is Field Notes, which is the um the part of the week where Michael and I are supposed to take a bit easier to turn up and just answer your questions and show each other an object and have a lovely old time. Um and uh frankly, uh you guys don't notice the amount of effort that we put in in the other one because you like this one just as much. Well, you know what? It's it's the magic that we have, Hannah. We should try to do something really boring. Like how few views can we get on a podcast episode? Make that the challenge, yeah. See what we can optimize for. We could do just like a clip sho w. Like not not a best of clip show, but a worst of clip show. The moments where jokes fell flat, where we we we said something kind of wrong. Unfortunately, it's not gonna be today because it's absolutely amaz it's jam-packed full of amazing stuff. I know, today's is actually good. Today uh I want to show off a tool I invented that helps solve a problem that will never happen. We've done something a bit different today. We've done we've done something a bit upside down. We've uh we've gone through the mailbag and we have found questions that are all to do with time travel or sort of unexpectedly popping out of existence in one place and popping up somewhere el So I'm gonna begin with a question for you, Hannah, and this is also for all the listeners out there. Okay. If I were to time travel you right now, at this instant with what you have on your person, to today, okay, this exact same day, but in 2007. Right. How would you prove that you were from the future? This episode is brought to you by Cancer Research UK. More ancient viral fragments than genes. The genes that build our cells make up only 2% of our DNA. And for years, that is what scientists focused on. They treated the rest, the ancient viruses and stuff, as junk. But now we know that that hidden majority, sometimes called the dark genome, influences how our biology works and how diseases like cancer behave. It's a reminder that progress rarely comes as a single breakthrough. It builds gradually. Cancer Research UK plays a central role in that progress, supporting decades of research into over 200 types of cancer , work that's helped double survival in the UK over the past fifty years. For more information about Cancer Research UK, their research breakthroughs, and how you can support them, visit cancerresearch UK. org forward slash the rest is science. I sold my car in Carvana last night. Well, that's cool. No, you don't understand. It went perfectly. Real offer, down to the penny. They're picking it up tomorrow. Nothing went wrong. So what what's the problem? That is the problem. Nothing in my life goes as smoothly. I'm waiting for the catch. Maybe there's no catch. That's exactly what a catch would want me to think. Wow, you need to relax. I need to knock on wood. Do we have wood? Is this tablewood? I think it's laminate. Okay, yeah, that's good. That's close enough. Car selling without a catch. Sell your car today on Carvana. Pick up these may apply. Hey, business owners. The NFL season is a big revenue driver. Now there's a smarter way to get ready. Everpass is the only authorized commercial platform for NFL Sunday ticket, delivering every live out-of-market regular season Sunday afternoon game. Lock in the best offer now with up to 40% off saving up to $2,000 . For the first time, you can pay over nine months. Get up to six free devices and a free bar kit. Sign up by April 27th. Visit Everpass.com. Limited time offer. Terms apply Yeah, so you're in the same room that you're in right now. If you're listening and you're in the car or you're at home, boom, it's just suddenly 2007. What do you do? How do you get anyone to believe that you actually came from 2026? This whole challenge of a time travel er being able to prove that they're from some win else in time, I call it the time traveler's credibility problem. Nice. There's just too many easier explanations for their behavior and knowledge than the truth, which is that they actually traveled through time. How do we crack it? Do I get advanced notice that I'm gonna go? Like can I prep? Can I bring stuff with me? No. No advanced notice. Just straight away there. Instantly. Or you could imagine that you accidentally time traveled, you had no preparation. You can't bring anything with you except what you have on your person. Okay, so I'm trying to think 2007. Because the thing is is that there's you could say, oh, in the year 2020, there's gonna be a big pandemic, but then people have got to wait thirteen years for that to happen. Exactly. So that's not gonna work. I don't have any lottery results memorized. Nope. Um I don't have like a you know, a catalogue of uh like number one hits in my head that would be like, oh I know that this person's gonna be a big deal. I mean every bet that you could lay would take some time to prove. How quickly do I have to prove that I am that I am from the future? Well, as fast as possible, right? That's the goal here. And the more you think about it, the more you realize how difficult it is. Because even if I gave you some prep time and you brought an almanac with you or a list of lottery numbers, you run the butterfly effect risk where just by you being there and having this book and speaking the numbers, you cause, you know, a little bit of a wind current change which changes how the balls are collected and the number doesn't even match what it should have been if you hadn't been there. Therefore nullifying your attempt to prove you're from the future. Like Biff's dad in um Biff Biff and his dad in Back to the Future, where they swap roles. Exactly. And similarly, if someone were able to predict the lotto numbers like I don't know three days in a row, I still wouldn't think they were from the future. I would think that they were in cahoots with the lottery. That's a much simpler explanation. So what do you do? What do you do, Michael? Well, I'm not entirely sure, but I think I've gotten as close as I can with my own brain. I created last year some slap bracelets that look like this. And I've got them on wooden hands because you know, you gotta you gotta have 'em modeled. They were pretty fancy in seven in two thousand seven, to be fair. Yeah, exactly, right? Um and this is good for any time travel from twenty let's see, from 2022 all the way back to the year 600. Okay. So if you're gonna go before 600, you'll need a different slap bracelet. If you're gonna go back just like a year, you'll need a different slap bracelet. But this thing will stay on you at all times, and it is an emergency tool to prove that you've traveled through time to the people in the past. The way it works, and I want to hear what your thoughts are, because I I'm not saying this is perfect, but what this gives you is a timeline with some bars on it showing famous widely known things that were lost and then later found . Oh . So So hold on. We know where they are now because we live in the future, but if you go back in time, people don't know where they're hidden. Exactly. Because you can't just go back with like a diagram of an iPhone to say the fifties and show people see this is a future technology. They'll just think that you're really smart and came up with it. You know? But could you go back with the exact coordinates of the Titanic? Yes, you could. And so this slap bracelet gives you the timeline and the GPS coordinates. So if you go back to say, let's say you you pull a Marty McFly, you go back to the 1950s, you can You can say, okay guys, well the Titanic has been lost, but it hasn't been found yet. Um but it can be found at 41 degrees north, 49 west, and some change. And they'll go, Wow, how did you know that? You must you must be a C expert. And you're like, no, no, no. I can also tell you where uh let's see, what's another good one for the for the 80s? You can also t I can also tell you where the HMS endurance earnest shackleton ship is. Oh, nice. So they're stuck going either this guy independently discovered these two sunken ships or traveled through time. In which case, I believe time travel is the better explanation. We've also got Archimedes Astoma chion, the method of mechanical theorems, which was lost in 1204 and not recovered until 1906. We've got the Baltimore Gold Horde, which was lost in 1856 and found in 1934. The Sutton Who Ship Burial from the seventh century, lost until 1938. I don't know what that one is. What's that one? Uh I can't tell you any more details, Hannah. I'm just helping time travelers. I'm not a history teach er. It was our science writer, uh, Scott Frank. I'll give him a shout at. He's the one who found this. I'm like, they need to overlap. There must always be at least two things for every year. Because you got you can't just prove it with one. You could just got lucky. Can't prove it with one. With one, you're just a good you're just a good looker. But with multiples, especially different types of things like a shipwreck, a gold hoard, and an ancient manuscript. Come on, you're a time traveler. You're from a time when these things have been found. And unlike uh the the result of a sporting event or a lottery, you can immediately have people go out and verify your claim. Hang on. I want to know whether you wear it on your person at all times. No, I don't. Um I I'll admit that. This feels like a flaw in your plan, Michael. I know. It's you know, I don't anticipate accidentally time traveling uh at endpoint. But man, wouldn't it be hilarious if that happened and I was like unprepared and I'm like, man, I specifically made a tool for just this and I don't have it. Yeah, that would be the worst. The the dream is to eventually make an entire like pocketbook that has much more than just a few items on it and that it will allow you to travel through um all of of human history, you know, and that's gonna have to teach you how to speak the languages you might encounter. Um if you you know you need to be able to speak Middle English, perhaps, or who knows what, right? We'll try to put that We also made a slap bracelet that's a ruler. It's got inches and centimeters on it. But since a slap bracelet wraps around You've never looked more cool, Michael. I've never looked more cool. Imagine that it looks it looks more like a medical bracelet. Like, oh, this guy's got some kind of. It does a bit. It just escaped from the hospital. I just came from the hospital. But we also made one that takes advantage of this wrapping effect, and it is not a ruler, it's a pie tape. So instead of having a mark every centimeter and every inch, we put a mark every pi centimet ers and every pi inches. So from here to here, that gap between my two thumbs is four pi centimeters. Why would you want to know that? Well if I wrap that around something , what I'm finding when I look at four pi centimeters, that's the circumference, which means the diameter is uh four centimeters. So you can instantly measure the diameter of circum You can instantly measure the diameter of something. Like imagine you you find a pipe and the ends of the pipe are inaccessible, so you can't like actually just go across the diameter of the pipe to tell. You have to go around it and divide by pie, not with the pie tape. You just go around, the number it reads is the diameter. This is extremely useful. I I do feel like making these tools and then not wearing them is your real downfall here though. I think I think you need to commit. I think you need to start tattooing some of these onto your body. I could tattoo them on my body, yeah. The one fear though is that the the existence of the tattoo itself might make me look like a witch . I mean the knowledge of where these things are might make me look like a witch. If I went back to like the 1100s and I'm like, hey guys, I know where this Archimedes thing is and blah blah blah, uh they might say, mm-OK, either you're from the future or you're in a pact with the devil. I haven't actually solved that problem, have I? I do like the idea of you going to the uh the center in Paris where they have the the definition of the meter and you've been like hang on a second and just whopping out your leg and being like look this is uh I've got the measurement on me. You know my sister who makes a lot of her own clothes she's been discussing for a while now having an inch tattooed onto her Ah yes. Just so that you can do an inch hem. Yeah, it's a really good idea. Uh so Adam Savage is someone I know in real life who has a ruler tattooed on his body. Does he? Is it accurate well no it's symbolic you know um the problem is that your your body changes your skin changes and so the inch changes um but again as a as a sign of like I'm a maker and I'm I'm a measurer and I love quantities and quantification. It's a great tattoo to have. But we struggled with this at the Curiosity Box trying to come up with a shirt that had rulers on it because inevitably the shirt will stretch. The shirt is is a is a material that moves. It's just not useful as a measuring tape. It can be useful for , you know, formulas and conversion tables. That's great. We've done two shirts that have that property. But uh this is so far the best I've been able to come up with. And I'm just now realizing that this is the prototype Look at that. Ah more space for more coordinates. This is for your time travelling children. This is an adult slap bracelet. It is like really long, by the way . You could wear it as a neckerchief. You could yeah let's see if I can. Oh no I can't look at that. Any of you who are listening rather than watching, you you just missed the absolute delight of watching Michael Stevens of V Swall Spain slap himself in the neck with a slap bracelet. I'm kind of a Gastani guy. My neck is too thick. Even my pie tape won't tell me the diameter of my neck. It's just not long enough. Well that'll be that'll be for a future item. Look at that. See? Doesn't make it. So close. So close. Uh careful now. You have to lift up your head quite far to get your beard out of the way. I don't need to get in get your top jar vertigo. I know, isn't that funny? Like um my beard is so long now. It's it's changed it's been long for so long. It's changed even my own perception of what my head looks like. I think of my head as being this huge thing, but actually, my head is like a little bean. Look at this guy . Yeah. My daughter looked at our wedding photos the other day and she was like, Dad used to be so small. And it's because my head used to be half the length. I'm slightly disappointed, I've got to be honest with you, that when you when you pulled your beard back there your head was small underneath. I I really really I really wanted you to have a jaw all the way down. I don't I I don't have anything else to share about my object. I'm open to all kinds of questions and comments. Um I did just finish a time travel book, Bid Bid Time Return by Richard Matheson. I love it because the method of time travel is literally just believing strong enough that you've traveled. I mean look some some some forms of time travel Exactly. I I can I can travel through time forward at regular speed, effortlessly. That's just called living. Sleep is pretty good too. With sleep, uh you can uh travel through time with your consciousness, like the the travel seemed to not happen. If you um if you did jump forwards in time though rather than backwards, how could you prove you were from the past? Whoa . That's really tough, isn't it? I don't know. Where's the slap bracelet for that? I know because what would you do? Because your only evidence would be your own ignorance of things, and that anyone can have that. Unless there's something the other way around, unless there's something that we have now that is lost to the future. Okay . In that case, you need to carry around with you a very very, priceless relic that's well known. So that when you jump forward, people will say, Oh, hey, that you know, medieval chalice has been missing since you jumped. And you're like, I know I've got it, 'cause it came with Here it is. Or what about a skill? You know, you could say, um, uh, ask me a phone number. I know six different phone numbers, you know? And people in the future just won't won't know any phone numbers. Or like I can write with a fountain pen . I still 'cause actually I think if you got somebody from, you know, whatever the 1700s, uh, they would probably have skills that modern people I'm sure they could weave a basket, you know? Right. Right. Um make ice cream in the traditional way. Yes. So skills obviously, although they're funny, the skills anyone could learn, you could learn to read cursive, even though it's the year twenty seven hundred. Uh I don't know why I'm anticipating the demise of cursive. I've just always felt that it was confusing. And difficult to read. You're right. It's gonna be difficult to prove. I I have a friend who I was talking to about this time travel idea, and I wanted to do it as a VSOS episode. It became it became a product, but she said it should just be a book. It should be a science fiction novel about time travelers and how they have to, you know, have slap bracelets like this or almanac books they carry. We didn't think about going to the future, in which case, yes, there needs to be like a big collection of important relics that are always kept track of, and you get to carry one with you when you travel through time to prove that you're you you are the time traveler and that you're from the past. Maybe we're overthinking this. May maybe it's just that um all you need is to prove that you know how a slap bracelet works, you know? Maybe that's the skill that's going to be lost to the future. And maybe you get a two in one. Yeah, you could say, hey guys, I remember the joy of a plastic straw . What's that tweet? It's like, look, I just want a straw that somewhere in between dissolves immediately and kills turtles and destroys the rainforest. Just somewhere in between would be nice. Is there nothing in between? Bamboo, you know, maybe, maybe bamboo. Should we have a quick break first? Let's do that. This episode is brought to you by Cancer Research UK. We often think of beating cancer as treatment, but imagine stopping it before it begins. After years of work, Cancer Research UK scientists are launching a clinical trial of lung vax, the first vaccine designed to prevent lung cancer. It builds on Tracer X, the world's largest cancer evolution study, which tracked lung cancer cells over many years to uncover the disease's earliest warning signs. Lung vax is designed to train the immune system to spot these signs early on, destroying faulty cells before cancer develops. So it's not treat ment, but preventative, with the potential to stop lung cancer before it starts. The first stage of the trial starts this year, focusing on people at higher risk. It shows what long-term research makes possible . For more information about Cancer Research UK, their research breakthroughs, and how you can support them, visit CancerResearch UK.org forward slash the rest is science. Snoring? Gasping during sleep? Feeling fatigued? Ask your doctor about Zepbound, Terzepatite, the first and only FDA-approved prescription medicine for moderate to severe obstructive sleep apnea, OSA, in adults with obesity. Zetbound is a prescription medicine used with a reduced calorie diet and increased physical activity to help adults with moderate to severe obstructive sleep apnea, OSA, and obesity to improve their OSA. Z bound is approved as a 2.5, 5, 7.5, 10, 12.5, or 15 milligram injection. Zetbound contains terzepatide and should not be used with other terzepatide-containing products or any GLP1 receptor agonist medicines, it is not known if Z-Bound is safe and effective for use in children. Don't share needles or pens or reuse needles. Don't take if allergic to it, or if you or someone in your family had medullary thyroid cancer, or if you've had multiple endocrine neoplasia syndrome type 2. Tell your doctor if you get a lump or swelling in your neck, stop subbound and call your doctor if you have severe stomach pain or a serious allergic reaction. Severe side effects may include inflamed pancreas or gallblad der problems. Tell your doctor if you experience vision changes before scheduled procedures with anesthesia. If you're nursing, pregnant, plan-to-be, or taking birth control pills. Taking zet bound with a sulfonyl urea or insulin may cause low blood sugar. Side effects include nausea, diarrhea, and vomiting, which can cause dehydration and worsen kidney problems. Talk to your doctor. Call 1-800-545-5979 or visit Zetbound.lily.com. No one goes to Hank's for his spreadsheets. They go for a darn good pizza. Lately, though, the shop's been quiet. So Hank decides to bring back the $1 slice. He asks co-pilot in Microsoft Excel to look at his sales and costs and help him see if he can afford it. Copilot shows Hank where the money's going and which little extras make the dollar slice work. Now Hank has a line out the door. Hank makes the pizza, co-pilot handles the spread sheets. Learn more at m365 copilot.com slash work . All right, and welcome back. We are having the time of our lives answering and reading your questions about time. Here's one for Hannah. It comes from Alex. Watching a documentary about the dinosaurs got me thinking. If somehow a human ended up on Earth 1 50 million years ago, would they be able to find food they can digest? What is the earliest time when we would be able to find food? This is such a good question. This has never occurred to me. I I like how your mind works Alex because until you mentioned this I just honestly hadn't even thought about it. Um but you are totally right because uh 150 million years ago, this is the late Jurassic period. There's no flowering plants. I mean you can go back and listen to our episode on what's the most vegetable vegetable to to discover that you're just wait wait wait wait I didn't know this. So there was no fruit? No fruit, no grasses there',s no legumes, there's no root vegetables. Surely I could eat a dinosaur. I mean sure. Meat. Meat. Well you can accept that. Well, okay, two things. First off, it would be like chewing on an old goat, right? Like it would be the meat would be so tough. It would be really horrible. One of my favourite foods, go on. Um but also loads of the stuff, loads of the I mean you're you're basically in fern territory. There's there's like conifers um there's loads of it's like big green stuff, you know, like uh you got conifers, you got ginkgos and you've got uh cyc ads, I think they're called. Um and the problem is is that all of the dinosaurs are eating those, fine, but they are totally loaded with carcinogens. So it's all almost certain that the uh the dinosaurs themselves would be carcinogenic. No kidding. So I mean your options are basically eat nothing or cancer. So enjoy. Basically, none of the aisles of the supermarket exist. You've got you've I mean you've sort of got uh fiddleheads, which are like the coiled uh fronds of young ferns, um , and you've got uh something that's like kind of old school pine nuts, like prehistoric pine nuts, like conifer seeds. Um, but the thing is, is that you know, even if you're trying to eat the vegetation and it's not carcinogenic, even if you manage to find some stuff like that. Modern humans, we've we've basically lost the ability to ferment really high fibre, kind of woody plant material efficiently. Yeah. And Jurassic plants, they are way tougher, way more fibrous than than the soft vegetables that we get today. So it would be a lot less like eating salad and more like eating furniture, essentially. It's gonna be it's not gonna be very fun. And then also loads of the foods that we eat now, we've like bred the toxins out of them. You know, things like almonds, potatoes, we've like bred them over the years so they don't kill your kidneys or or your liver. So so I mean you could survive, but you've basically got ro asted dinosaur and pine nuts and that's it. That's all you got. You got you can't even flavour them. You know, chilies don't even exist for another hundred million years. It's um it's gonna be boring. Wow, I had never thought of that before, but yeah, I mean 150 million years ago, you can go further than that before there are even early mammals. And then you're really in trouble because the mammalian diet needed to be there for mammals , which we are, to exist . Now, I feel like I could maybe eat some fish, but you're saying that the food chain is probably pretty contaminated with stuff that's that we're not ready for. Absolutely. Absolutely. I mean you probably would be able to, you probably would be able to, but it's not I mean you're really gonna struggle. Also, by the way, it's not just the food, because if you're going back 150 million years ago, the CO2 levels are five to ten times higher than you've got today, so you are gonna be perpetually out of breath, basically. You might be trying to hunt down a dinosaur to eat them, but you're gonna you're gonna be s suffering from CO2 toxicity just just trying to get dino steak. That's wild. How have I never thought of that before? Yeah. Of course. Like it'd be easier to go to Mars than to go live in the like early Jurassic, but you're on Earth and yet it's just not for you yet. The air isn't right. If you're a vegan, sorry. If you're willing to to hunt living creatures, you don't have any chicken. Um you've basically got fish, sharks, reptiles. Other than that, you've got a bunch of like tree bark. Yeah. Bit of tree bark. That's it. Not even any grass. Can't even chew on any grass. So no wheat. No wheat, no grains, nothing. Yeah. It's gonna be it's gonna be you're gonna have a terrible time. And no one around to tell about the bracelet. Um okay, here's a question from Adam. I really like this question because of course everything that's going on with Artemis at the moment, uh that amazing expedition around the dark side of the moon. Adam asks, what would the lag on a FaceTime call be like from space or from the moon? Oh yeah. What would it be like? So you know the the lag that we get in FaceTime calls is caused by all kinds of factors, but ultimately, at the very end, even if your technology is perfect, you're always bound by the speed of light, the speed at which an electromagnetic signal trav els. It's it's it's finite and it's really fast , but when you talk about really long distances, it becomes a big problem. So for the astronauts on Artemis II, at their at their furthest point, well I mean at their furthest point they couldn't contact Earth at all, right? For forty minutes, they were out of contact with Earth because the moon was in the way. They couldn't radio. And uh just as a side note , on the Apollo missions, when people actually left and and walked around on the moon's surface and someone stayed up in the command module, that one person in the module was alone on the far side of the moon by themselves, with no radio contact with anybody. Um and the first guy to do that was Michael Collins, who also I think went the furthest away, but he did it alone. Artemis II crew, they have each other. Michael Collins was alone, and he was the furthest any human has ever been from any other human. Even Buzz and Neil on the moon's surface were further away from him than you can be from another human here on Earth. On the surface, yeah. Because he was orbiting around the dark side. Well, the far side, let's call it, because the dark side is always changing. But yeah, he was he was on the far side of the moon by himself in the command module , and the closest people were the two other guys on the surface of the moon on the other side. By the way. Is that true? Yeah. Wow. Yeah. So so er I mean it would kind of make sense. Every every uh uh crewed mission to the moon has happened during the lunar day. And it makes sense because at night it would be harder to see things, right? You wanna be able to see where you're going. But that what that means is that no human has ever experienced earth sh ine alone . At night on the moon, it's actually quite bright because the earth is you know, w when there's a full earth on the moon, it's like a full moon, but times like twenty, because the earth is bigger and it's brighter. The moon is actually pretty dusty gray, but but Earth is very white because of the clouds and the ice caps. Um, so night on the moon is just not nearly as dark as what we get here on Earth. Oh, that's so beautiful. Yeah, right. I mean , night on the moon with a with a full earth is gonna give you like pretty distinct shadows at night on the moon because of Earth. But look, I'm actually gonna answer your question. The the the light speed delay from Earth to Artemis II is um at its maximum was one point three five seven seconds. That's how long it took a light speed message to get from mission control on Earth to the Artemis spacecraft. And that's just one way. Just because of how far away it is. Incredible. That's how far away it is. Um and so like just to give you guys a sense of the radio delay because of how far Artemis 2 is. Hannah and I are gonna have a conversation with that one point three five seven second delay, thanks to our editors. Okay . Hannah, how are you? I'm good, Michael. How are you? How's the Earthshine ? The Earthshine is fantastic, but I'm not loving this 1.357 second delay . It does slightly get in the way of really having a good conversation . And so there you go. That is the delay between the Earth and the Moon. Hey mom, I'm on the other side of the moon. Yeah, did we fool you? Thanks, editors, for recreating for for demonstrating that that fact. But when you get further than the moon , things get really messy. I mean Mars. Okay, we're gonna yeah, let's go to Mars, all right? Mars is so much further away. Um and it it's also much more variable. The moon is sometimes a little bit closer, sometimes a little bit further away. But I think the difference in its distance is uh literally um creates a light speed delay difference of only about a tenth of a second between when it's at its closest and furthest from Earth. But for Mars, that uh radio message delay is going to be anywhere from three minutes at its closest to twenty-one minutes. Three minutes. We're not talking about seconds anymore. That's not a conversation anymore, is it? That's that's that's voice notes. You're you're in voice note territory. That's right. It's voice note territory. It's like, okay, even when they're I mean, three minutes is actually pretty long to wait, to be like And then you wait three minutes just for them to get the message. Then they have to reply, and then once they send, you have to wait three more minutes. So it's at least six minutes minimum. Or up to 40. Up to 40. And once you get to Jupiter, that's 33 to 53 minutes one way. Wow Pluto, five hours . Is it? Goodness me. Five hours. I do know what though, that also really demonstrates how much closer we are to the sun. I mean, the sun is nine minutes light speed, right, from us. Yeah. So, and then if we are five hours to Pluto, I mean that's a really good way to think of the scale of the solar system um and just how close we are to the sun in comparison to the other planets. Wait, how long was Jupiter? An hour, basically. Jupiter, yeah, it was between half an hour to an hour, depending on where each planet is in its orbit, right? And then the the nearest star that isn't our sun, that gets you out of the hours into the years, right? Four years to Proxima Centauri, the nearest star to Earth. And what's so interesting to me about Proxima Centauri is that it's the nearest star. It's about four point two five light years away. And yet it's so dim we can't see it with the naked eye. It's like, guys, I'm right here, I'm the closest to you, and yet we cannot see it unless we have a tool. Four years really doesn't feel like very long time. I mean if you were sort of if you were giving it an update on what was going on on Earth and be like, hey, we've got a new president. Oh no, wait, strike that. We've got a new president. It would be uh That's a good point. Yeah. You would tell them the results of the election, and by the time they got the message, there would have been another election, and then by the time they responded and you got their response, more than eight and a half years would have passed. And so you would have had a you would have been having the third election already. By that point it's just not really worth keeping them in the loop, is it? No, you wouldn't. And and this isn't something that technology is gonna fix. Uh well, I mean it could I guess, but this is the limit of the speed of light. We would have to discover something very brand new about space-time. Uh for example, create wormholes for instantaneous communication across these light-year distances. Otherwise, the separation is essentially total. I tell you what, actually, talking about wormholes, we had in another question about wormholes. Um the downsize of wormholes, let's uh let's say. Um this was Anders TX on YouTube. This is one of the comments on YouTube. Um great question. If we had wormholes connecting to each other's homes, would there also be a rush of air through the wormhole due to pressure differentials? Like if you were connected from somewhere at sea level to another location at high air elevation like Denver or Mexico City? Um and the answer, absolutely yes they would, it would be a complete nightmare. Um You guys are really good at thinking about the the the real caveats of um of instituting this, you know, time travel wormhole what, are the downsides? Um, okay, so of course air moves from from high pressure to low pressure. At sea level, air pressure is 14.7 psi, right? In Denver, which is at 5,000 odd feet, not far from you, Michael, right? It's 12.1 PSI. Mexico City, by the way, it's about eleven point one PSI. So if you open a wormhole in London , right where I am, to to where you are, near Denver, you've got a difference about, you know, two point six PSI, which doesn't sound that small, but in fluid 's terms, it's gonna be an absolute monster because you've got this binnui principle, you've got this pressure drop of like seventeen thousand pascals, essentially the air would rush through the wormhole at roughly 150 meters per second? I mean you're talking it's way worse than a category five hurricane, essentially. It was not just like a little rush of air. It would be this absolute deafening structural failure-inducing blast. Um, it would just strip the wallpaper off your walls, it would sort of suck you through through the wall before anything. So yeah, I mean I would say careful. Careful with what you wish for. It would it would rip the snap bracelet right off your arm. Put it that way. You know it's it's another way to think of it too is that y you're pretty near sea level right now, Hannah, more or less. Yeah. Pretty much. I'm in I'm in Colorado high enough up that the air pressure where I am is about the same as the air pressure in a Hoover that you would use today . And by Hoover I mean vacuum for those of you who are Americans. And and that's that's kind of like blew my mind when I learned that, to be like, wow, so this is what it's like to be inside a vacuum cleaner at sea level . That's literally true. And it yeah, that pressure difference is what it takes to hoover See see the other thing is though you you'd also have this temperature issue because if you have you know the air rushing around, right, it will go under this expansion because when you get an air that sort of expands rapidly, right, into a much lower pressure environment without losing heat, then its temperature just drops really significantly. So the air as, it blew out into Denver, because it would go from it would go from London to Denver, right? That would be the direction of the airflow. Um or to Colorado more generally, you know, it would probably drop by tens of degrees instantly. So you would have this this category five, worse than category five, blast of freezing air shooting shooting into your room. Yeah. And you would have condensation so clouds could form or or disappear. Uh depending on yeah the the humidity in the areas, they would have their own weather. Yeah, I hadn't thought of that. I mean you would also have me, Michael, I would be there. I probably wouldn't be in one piece. Uh I would probably be frozen and uh and and m much mutilated by the journey, but nonetheless I would be there. So there's upsides and downsides, that's what I'm saying. There's one more question that came in from Jacob Fletcher, and I think this is quite a nice one. This round s it all off very neatly, actually. Um, going back to your snap bracelet containing the information. At what point did it become impossible for a single person to learn everything that humans had collectively learned, Michael? I love this question. And of course it's difficult to actually answer. But the first thing I thought about was a smaller question, which is uh one that XKCD tackled in what if um and many other people have have taken their own um approaches to. And it's the question of at what point could a person have actually truthfully said that they had read every single book in English ever written. Because today that's impossible. And that in and of itself is almost one of the saddest facts. That you and I will never read every book ever written. Even if we read really quickly, and that's all we ever did as a full-time job, if we never slept, we still couldn't catch up. But if you look at the past, there was a time when there were fewer books that had been written. Now, there's a there's a distinction we need to make between written and printed . Printed becomes much easier to answer because we know a lot more about what was printed on a printing press. And the first book in English that was printed on a printing press was printed in 1473. And it was called the uh Requie of the Histories of Troy. That book um printed in 1473, great. Go ahead and read it and you've read every book ever printed in English. So yeah, you're right. At that point you read that, you're done. You read that and you're done. Uh but books get published, and there's this great uh there's this great book content creator named Tom Ayling, uh, who I follow on all the different platforms, and and he he went through this like year by year because we know about how many books were published every year in English. So he's like, you can actually keep up with this process. I I I'm not gonna get into the the hairy details of it all. But um Tom Ailing actually did something really interesting. He said don't even start reading with the first um English book printed. Just don't don't even start reading until the year fifteen hundred. At which point there were two hundred and ninety-four books in English that had ever been printed. Different titles. I could do that. I could do that. You could do that. And every year there's like, you know, it looks like maybe 20 new ones printed. And he's like, you could actually catch up and have read every English book that had ever been printed until 1530. In that year, there weren't 15 or 18 books printed, new books . There were 96. Ooh, that's gonna be tough. That's one every three days. That's tough. At which was the last year a person could have ever claimed that they had read every single book ever printed in English. 1529. So unfortunately, we're not there. But that's that's an answer to a question that's much more specific. We're talking about reading a book in English that has been printed. Reading in any language or reading anything in English that's been written, that's that's where it starts to become basically impossible for this to have ever even existed. To have read everything ever written, you would have to talk about some time period just after the invention of writing, because once people were writing, they were writing. Okay . Just just the accumulation of tax records alone would have meant that that you would have had to have lived in the stone age to have actually read everything. You wouldn't get access to everything because there were people writing in China, in um Mesoamerica, in Europe. You'd have to somehow get all this stuff. And it depends on how we define writing. Does does this also require that you have read all the notches put on bones to represent numbers of, you know, oil jugs shared. But the question that is being asked here by Jacob Fletcher is when did it become impossible for a single person to learn everything that humans had collectively learned. And that , I think, my answer is never. To have learned everything that humans collectively knew? I mean, we don't even know everything we collectively And what I mean by that is that we've got knowledge, but then there's also the meta memory of it all. Do we know what we know? And we don't always. We've got to refer back to written records. We've kind of externalized our memories. And so I think to know everything that humanity has known collectively becomes basically how do you define collective knowledge? But I'm gonna say it was it's never been possible because of the definitions of these words, which is an un an unhappy answer, but that's why I also gave you the like when could you have read every book kind of an answer? Let me think about this though, because I wonder whether there was a point I'm just wondering about I don't know, cats . Right? Where cats have different lived experiences. Of course they do. Each one is like their own individual entity. But if you think about the sort of spectrum of what cats know, rightight. It's a pretty tightly, tightly packed distribution, right? There's not like if you took an average cat, right? Sort of imagine the full distribution of everything that all cats know. Take an average cat. There's it's pretty much going to be overlapping, isn't it, really? There's like there's maybe a couple of little things that some clever cats have learned here and there. But they're just quite a simple species. So I do wonder whether there was a point where actually the only things that we knew as humans were foraging for food, finding mates , taking care of our young, looking for shelter, you know, where where actually there was such simplicity to our knowledge that there just wasn't very much to learn at all. Yeah, you're right. I'm not really happy with the answer that I gave. I think you're right that if we include sort of instinctive knowledge, then it could be possible to know oh it gets cold at night or um y those kind of things. Once you get tool use, I think you're right. As soon as you start getting tool use. Yeah, once you get into yeah, technology tools, things that we aren't born already knowing, things that we have discovered and invented, then I guess it's tough because you could say, well, yeah, do you know how to nap a stone to create like a stone blade um do you know how to make paper do you know how to um interact with a d with a dog like these things people invented, oh man, I think there really is an answer to his question, at least a hand-wavy one where you're like, well, you know , the the fermentation of of liquids into alcohol happened around this point, and that could be a skill that you learned and you could also learn. Um, but it's but hold on, it's gotta be things that we collectively know. And that's what I'm getting stuck on. Because to know how to use a musical instrument that was invented in China and Egypt and um in in the Americas. That's not collective knowledge. Only certain groups have that knowledge. So what does it mean, the collective knowledge of humanity I guess if someone were to write a book of everything that humans like invented and discovered, could you know everything in that book? And and at at what point was there just too much in it for someone to even be familiar with everything in it? You know, I also think that actually human knowledge and technology, I mean I one of my guilty it's actually not a guilty pleasure at all, it's a what's the opposite of guilty, proud pleasure. Yeah. Is watching videos about primitive technology. Uh huh. Uh do you remember the guy who was in Australia who would be there just in his shorts and and like every single tool he would build he had a knife and that was it. That was all he was allowed to have. He would build the most unimagin ably sophisticated I mean practically entire villages, right? Pottery, um, you know, uh roof tiles, fires, I mean weapons, all sorts of stuff. Um I think that the sort of collective knowledge of things that humans invented and created, it's it's very, very quick, I think, that that that it becomes this vast wealth of uh of stuff that you would have to potentially learn. Yeah. Again, I think that you're gonna need to look at some like stone age time period to even be able to wrap your head around all of the skills, techniques, and observations that humans collected and weren't just simply born with, like knowing to drink when you're thirsty. You know, if that kind of stuff counts, then then you can go back pretty far and we all had that knowledge. But do you know I met the primitive technology guy. Did you? Yeah. When when Adam and I were doing Brain Candy Live in Australia, he came to the show and that was it was awesome. Did he have to announce himself or did you know immediately who he was? 'Cause you don't really see his face that much on camera, do you? No, no, no, no. But uh he had been in contact with Adam Savage and so that's how it like happened and Adam met him and I just kinda tagged along and was like, Hello, me too. Hello . Imagine Vsaur tagging along and being like me too. Rather than the central character. I was like, sorry to butt in, but I just wanted to to to shake your hand. Yeah, that's what it was. It was really cool. The other thing that I've become I'm quite obsessed with is like ancient chemistry. Yeah. Yeah. My Sassai mornings, that's uh that's that's the treat that I give myself. A little bit of a lie in and watch Now could there come a point where the past is so big and new discovery is so slow that our species is actually forgetting things faster than we're learning new things. That'd be a good like science fiction future premise for a book.. Yeah Because there's certainly a lot of things people used to know that we literally no longer know. That we've outsourced, basically, to technology instead, really. Yeah, that we've outsourced. Or we literally have lost. Like we don't know what they did. We don't know what they put in this concrete to make it so strong. Um well that was a I