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How To Prove You're A Time Traveller

Apr 22, 202650 minSeason 1Ep. 45
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Summary

Michael Stevens and Hannah Fry delve into hypothetical time travel scenarios, starting with the challenge of proving one's future origin using Michael's "lost and found" slap bracelet. They discuss the impossibility of surviving on prehistoric Earth due to lack of digestible food and hostile atmospheric conditions. The conversation then shifts to the vast communication delays across the solar system, the catastrophic effects of wormholes on atmospheric pressure, and the historical point at which one person could no longer comprehend all human knowledge.

Episode description

How do you convince people you aren't a witch if you travel back in time, and where can you actually find something decent to eat when you're there?


Professor Hannah Fry and VSauce, Michael Stevens, tackle the most practical and delicious logistics of surviving a trip through history.


Check out one of Hannah's favourite chemistry YouTube channels - https://www.youtube.com/@cnliziqi


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Transcript

Welcome and Time Travel Challenge

B

Welcome to the rest of science. I'm Hannah Fryer.

A

And I'm Michael Stevens.

B

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,'cause you like this one just as much.

A

Well, you know what? 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.

B

Make that the challenge, yeah. See what we can optimize for.

A

We could do just like a clip show. 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 kinda wrong. Unfortunately.

B

Unfortunately it's not gonna be today because it's absolutely amaz it's jam-packed full of amazing stuff.

A

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.

B

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 else.

A

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 two thousand seven.

B

Right.

A

How would you prove that you were from the future?

🎵 Music

B

This episode is brought to you by Cancer Research UK.

A

Here's something strange. Your DNA contains more ancient viral fragments than genes. The genes that build our cells make up only two percent of our DNA. And for years, that is what scientists focused on. They treated the rest, the ancient viruses and stuff, as junk.

B

But now we know that that hidden majority, sometimes called the dark genome, influences how our biology works and how diseases like cancer behave.

A

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 two hundred types of cancer, work that's helped double survival in the UK over the past fifty years.

B

For more information about Cancer Research UK, their research breakthroughs and how you can support them, visit Cancer Research UK dot org forward slash the rest is science.

A

Yeah.

C

It's the Family and Friends event at Shoppers Drug Mart. Get 20% off almost all regular priced merchandise. Two days only. Tuesday, April 28th, and Wednesday, April 29th. Open your PC Optima Map to get your coupon.

🎵 Music

B

Two thousand and seven.

A

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 traveler being able to prove that they're from some wind else in time, I call it the time traveler's credibility problem.

B

Nice.

A

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?

Proving Future Origins Credibility

B

Do I get advanced notice that I'm gonna go? Like can I prep? Can I bring stuff with me? No.

A

No advance notice.

B

Just straight away there.

A

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.

B

Okay, so I'm trying to think 2007. Because the thing is is that there's you could say, oh, in the year twenty twenty there's gonna be a big pandemic, but then people have gotta wait thirteen years for that to happen.

A

Exactly.

B

So that's not gonna work. I don't have any lottery results memorized.

A

Nope.

B

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 um that I am from the future?

A

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.

B

Like Biff's dad in um Biff Biff and his dad in Back to the Future, where they swap roles.

A

Exactly. Uh 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?

B

What do you do, Michael?

The Lost and Found Bracelet

A

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.

B

Yeah.

A

And I've got them on wooden hands because you know, you gotta you gotta have'em modeled.

B

They were pretty fancy in seven in two thousand seven, to be fair.

A

Yeah, exactly, right? Um and this is good for any time travel from twenty let's see, from twenty twenty two all the way back to the year six hundred.

B

Okay.

A

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.

B

Uh 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.

A

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?

B

But could you go back with the exact coordinates of the Titanic?

A

Yes, you could. 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 nineteen fifties, 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 forty-one degrees north, forty-nine west, and some change.

And they'll go, Wow, how did you know that? You must you must be a a sea 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 eighties? You can also t I can also tell you where the HMS endurance earn a shackleton ship is.

B

Oh, nice.

A

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 Astomachion, the method of mechanical theorems, which was lost in twelve oh four and not recovered until nineteen oh six.

We've got the Baltimore Gold Horde, which was lost in eighteen fifty six and found in nineteen thirty-four. The Sutton Hoo ship burial from the seventh century, lost until nineteen thirty eight.

B

I don't know what that one is. What's that one?

Wearable Wisdom and Its Flaws

A

Uh I can't tell you any more details, Hannah. I'm just helping time travelers. I'm not a history teacher. It was our science writer, uh, Scott Frank. I'll give him a shout out. 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.

B

Because you got you can't just prove it with one. You could just g' got lucky.

A

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.

B

Hang on. I want to know whether you wear it on your person at all times.

A

No, I don't. Um I I'll admit that.

B

This feels like a flaw in your plan, Michael.

A

I yeah, I know. It's you know, I don't anticipate accidentally time traveling uh at any point, 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.

B

Yeah, that would be the worst.

A

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 like teach you how to speak the languages you might encounter.

Um if you y you know, ha you need to be able to speak Middle English, perhaps, or who knows what, right? We'll try to put that together. 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.

B

I've never looked more cool than Michael.

A

I've never looked more cool. Imagine it looks it looks more like a medical bracelet, like oh this guy's got some kind of

B

It does a bit. It just escaped from the hospital.

A

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 centimeters and every pi inches.

So from here to here, that gap between my two thumbs is four pi centimeters. Why would you wanna 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.

B

So you can instantly measure the diameter of something.

A

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 pi, not with the pie tape. You just go around, the number it reads is the diameter.

B

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.

A

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 eleven hundreds and I'm like, hey guys, I know where this Archimedes thing is and blah blah blah. uh they might say, mm, okay, either you're from the future or you're in a pact with the devil. I haven't actually solved that problem, have I?

B

I do like the idea of you going to the uh the centre 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 thumb.

A

Ah yes. Thank you.

B

I like that idea.

A

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.

B

Does he? Is it accurate?

A

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 um at the Curiosity Box trying to come up with a shirt that had rulers on it.

Because

A

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. The real ones we made were adult sized. Look at that.

B

Ah more space for more coordinates.

A

This is for your time traveling children. This is an adult slap bracelet. It is like really long, by the way.

B

You could wear it as a neckerchief.

A

You could Yeah uh let's see if I can. Ugh Oh no, I can't. Look at that.

B

Any of you who are listening rather than watching, you you just missed the absolute delight of watching Michael Stevens of V Swall Spame slap himself in the neck with a slap bracelet.

A

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.

B

But careful now, you have to lift up your head quite far to get your beard out of the way. I don't want you to get in g get your top shelf vertigo.

A

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.

B

Yeah.

A

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 of the

B

I'm slightly disappointed I've gotta be honest with you that when you when you pulled your beard back there your head was small underneath. I really I really I really wanted you to have a jaw all the way down.

Proving Past Identity in Future

A

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 Yeah 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.

B

I mean look, some some some forms of time travel are not necessarily completely impossible, right? It's just they're going backwards that's gonna be difficult.

A

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.

B

If you um if you did jump forwards in time though rather than backwards, how could you prove you were from the past?

A

Whoa.

B

That's really tough, isn't it?

A

I don't know.

B

Where's the slap bracelet for that?

A

I know, because what would you do? Because your only evidence would be your own ignorance of things, and that anyone can have that.

B

Unless there's something the other way round, unless there's something that we have now that is lost to the future.

A

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

B

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.

Um I still'cause actually I think if you got somebody from, you know, whatever the seventeen hundreds, 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.

A

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.

B

And difficult to read. You're right. It's gonna be difficult to prove.

A

I have a friend who I was talking to about this time travel idea and I wanted to do it as a V Sauce 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.

B

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 gonna be lost to the future. And maybe you get a two in one.

A

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's somewhere in between dissolves immediately and kills turtles and destroys the rainforest, just somewhere in between would be nice.

B

Is there nothing in between? Bamboo, you know, maybe, maybe bamboo. Should we have a quick break first? Let's do that.

🎵 Music

B

This episode is brought to you by Cancer Research UK.

A

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. This, the first vaccine designed to prevent lung cancer.

B

It builds on TracerX, the world's largest cancer evolution study, which tracked lung cancer cells over many years to uncover the disease's earliest warning signs. Lungvax is designed to train the immune system to spot these signs early on, destroying faulty cells before cancer develops.

A

So it's not treatment, 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.

B

risk, it shows what long term research makes possible.

A

For more information about Cancer Research UK, their research breakthroughs, and how you can support them, visit Cancer Research UK.org forward slash the rest is science.

🎵 Music

Jurassic Period Food Challenge

A

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 150 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?

Dangers of Prehistoric Diet

B

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

A

Wait, wait, wait, I didn't know this. So there was no fruit?

B

No fruit, no grasses, there's no legumes, there's no root vegetables.

A

Surely I could eat a dinosaur.

B

I mean, sure. Me. 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.

A

One of my favorite foods. Go on.

B

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 gingos and you got uh cycads, 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.

So I mean your options are basically eat nothing or cancer. So enjoy. Basically none of the aisles of the supermarket exists. You've got you've I mean you've sort of got a 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, m 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 l 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 your kidneys or or your liver. So so I mean you could survive, but you've basically got roasted 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.

Breathing Ancient Earth's Air

A

Wow, I had never thought of that before. But yeah, I mean a hundred and fifty 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.

B

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 hundred and fifty million years ago, the CO two 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 suffering from CO2 toxicity just just trying to get dino steaks.

A

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.

B

Yeah.

A

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.

B

Yep. Bit of tree bark. That's it. Not even any grass. Can't even chew on any grass.

A

So no wheat.

Speed of Light Communication

B

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 asked, what would the lag on a FaceTime call be like from space or from the moon?

A

Oh yeah.

Lunar Mission Communication Delays

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 travels. 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 40 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 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.

B

Because he was orbiting around the dark side.

A

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. No no humans have ever been on on on the moon at night. by the way Yeah.

B

Wow. Yeah.

A

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?

B

Yeah, you wanna be able to see where you're going.

A

What that means is that no human has ever experienced earth shine. 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.

B

Oh that's so beautiful.

A

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 going to answer your question. The the the light speed delay from Earth to Artemis two 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.

B

Just because of how far away it is, incredible.

A

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 two 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?

B

I'm good Michael, how are you? How's the earth shine?

A

The Earth shine is fantastic, but I'm not loving this 1.357 second delay.

B

It does slightly get in the way of really having a good conversation. Mm-hmm.

Interplanetary Voice Note Distances

A

And so there you go. That is the delay between the Earth and the Moon.

B

Hey mom, I'm on the other side of the moon.

A

Yeah, did we fool you? Thanks editors for recreating for for demonstrating that that fact. Um but w 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 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.

B

Ha ha.

A

Three minutes. We're not talking about seconds anymore.

B

That's not a conversation anymore, is it? That's that's that's voice notes. You're you're in voice note territory.

A

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, hey, hello, uh, are you okay? 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.

B

Up to forty.

A

Up to 40. And once you get to Jupiter, that's 33 to 53 minutes one way. Pluto, five hours.

B

Is it? Goodness me.

A

Five hours.

B

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. 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 planet. Wait, how long was Jupiter? An hour, basically.

A

Jupiter, yeah, between half an hour to an hour, depending on where each planet is in its orbit, right? Um 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

B

So...

A

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.

B

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

A

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 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.

B

By that point it's just not really worth keeping them in the loop, is it?

A

No, you wouldn't. And and this isn't something that technology is gonna fix.

Wormhole Atmospheric Chaos

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.

B

I tell you what, actually, talking about wormholes, we had in another question about wormholes. The downsides of wormholes, 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. 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 uh 5,000 odd feet. Um, not far from you, Michael, right? Uh it's 12.1 psi. Uh Mexico City, by the way, it's about 11.1 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 of out, you know, two point six PSI, which doesn't sound that small, but in fluid dynamics terms. It's gonna be an absolute monster because you've got this bannouy principle, you've got this pressure drop of like seventeen thousand pascals, essentially the air would rush through the wormhole. at roughly a hundred and fifty metres 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.

A

And 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.

B

Yeah, pretty much.

A

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 up all the debris.

B

See see the other thing is though, uh you you'd also have this temperature issue because if you have

A

Oh yeah.

B

You know, the air rushing around, right? it will go under this 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 so the air as it blew out into Denver,'cause it would go from

It would go from London to Denver, right? The air that would be the direction of the airflow. Um or to C 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.

A

Yeah. And you would have condensation so clouds could form. Mm-hmm. 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.

B

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.

Reading Every English Book

There's one more question that came in from Jacob Fletcher and I think this is quite a nice one. This rounds 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?

A

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.

A

Um printed in 1473, great. Go ahead and read it, and you've read every book ever printed in English.

B

So yeah, you're right, at that point you read that you're done.

A

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 could actually keep up with this process. I I I'm not gonna get into the the the hairy details of it all, but um Tom Ayling 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.

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.

B

Ooh, that's gonna be tough. That's one every three days. That's tough.

A

You you can't catch up. So 1529 was his estimated year at which was the last year a person could have ever claimed that they had read every single book ever printed in English.

Limits of Collective Knowledge

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

That's where it starts to become basically impossible for this to have ever even existed. To 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 have been able to get access to everything'cause there were people writing in China, in um Mesoamerica, in Europe, you'd have to somehow c 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 to have learned everything that humans collectively knew? I I mean, we don't even know everything we collectively know.

B

Yeah.

A

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.

B

Let me think about this though, because I wonder whether there was a point I'm just wondering about I don't know. 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

Right.

B

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 go there's it's pretty much gonna be overlapping, isn't it really? There's like there's maybe a couple of little things that s some clever cats have learned

here and there. But I mean th 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 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.

Lost Wisdom and Future Forgetting

A

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,

B

Mm-hmm.

A

Then it could be possible to know, oh, it gets cold at night or um yeah, those kind of things.

B

Once you get tool use, I think you're right. As soon as you start getting tool use.

A

Yeah, once you get into yeah, technology tools, things that we aren't born already knowing, things that we have discovered and and invented, then I guess it's tough'cause you could say, Well, yeah, d 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 that 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?

B

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 is watching videos about primitive technology.

A

Uh-huh.

B

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 bu he had a knife and that was it. That was all he was allowed to have. He would build the most unimaginably. 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.

A

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 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.

B

Did you?

A

Yeah. When when Adam and I were doing Brain Candy Live in Australia, he came to the show and that was that was awesome.

B

Did he have to announce himself or did you know immediately who he was? You don't really see his face that much on camera, do you? No.

A

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.

B

Imagine Vsaw tagging along and being like me too. Imag rather than the central character.

A

Sorry to butt in, but I just wanted to to to shake your hand. Yeah, that's what it was. It was really cool.

B

The other thing that I've become uh quite obsessed with is like Ancient chemistry. My Saturday mornings, that's uh that's that's the treat that I give myself. A little bit of a lie in and watching videos about um ancient chemistry techniques, ancient technology. I I tell you what, we'll link we'll link some of my favourite channels in the description below.

A

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.

B

Yeah.

A

Because there's certainly a lot of things people used to know that we literally no longer know.

B

that we've outsourced basically to technology instead, really.

A

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.

Concluding Thoughts and Challenges

B

Um well that was a I absolutely delightful field notes. We went backwards in time, we went forwards in time, we went through wormholes and round the other side of the the other side of the moon. Um I hope you enjoyed it too. Told you it wasn't gonna be boring. Told you it was gonna be uh this is not gonna be the one where we've got zero views on YouTube, Michael. We'll have to save that one for another time.

A

That one is coming. We're gonna crack that nut. We're gonna figure it out. Everyone's trying to beat the algorithm and we are gonna try to be beaten by the algorithm.

B

No, that is that there is that is quite a nice game theory idea, isn't it, of like whether we could actually do it. Whether we could get everybody to collectively agree to not watch one video.

A

Yeah, how would you uh, but see, there's gonna be the reverse psychology of it, the psychological reactance of it where if you tell people not to watch it, they're gonna make them wanna watch it more.

B

Yeah, no.

A

honestly would have to be like an advertisement that we desperately want everyone to watch. Like this is an ad for a really boring product and we were paid to do this and please watch it and people are like, no. Literally no.

B

We'll think on that. We'll ponder on that. If you have any suggestions in the comments of um of how we can get zero views, then uh then let us know. I would be well up for that. It'd be great. Um but anyway, uh anything else that you have? Uh, let us know in the comments or send them to us at therest is science at goalhanger.com. We love hearing from you.

A

And we'll see you next time.

🎵 Music

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