A Problem Squared - 091 = Optimal Darts and Smelling Sharks

Episode Date: August 12, 2024

🎯 What is the optimal layout for a dart board?  🦈 How soon after a cut does a shark smell your blood?  📜 And there’s some AYE-YOOO-BEEEE. To see the Percy Arrangement mentioned by Matt follow this link: https://www.globaldarts.de/globalDartsEN/sport/Percysboard.html And for the “Optimal Dartboard Design” reveal, see here! https://journals.indexcopernicus.com/api/file/viewByFileId/1980058If you want to learn more about shark senses, check out Sensory Biologist Dr. Lauren Eve Simonitis‘s Instagram: https://www.instagram.com/oceanexplauren/?hl=en And if you like, leave us a review, pass the podcast onto a friend or give us a rating! Every little helps.  Finally, if you want even more from A Problem Squared, you can find us on Twitter, Instagram, and on Discord

Hello and welcome to a problem squared, the problem solving podcast, which is a lot like a window in that there's it functions in a frame work of some sort. We do. We are part of that framework is top quality introductions. Yep. We are transparent. That's true. That's true. And the, um, message is clear.

You can open one to solve a problem. Yes. You can open a window to solve a problem. And you can also close it. Should you not want any noise like you would our podcast? That's true. I'm Beck Hill. I'm a comedian, a writer and a pain.

See what I did there? That's great. Yep. And that other voice is Matt Parker, who's a comedian, mathematician and silly, silly. Oh, like a sill. A window sill. Wow. Got there in the end.

I was about to glaze over. Nice. On this episode. I've checked the numbers on the optimal dartboard. I look into sharks and blood. Hmm. Sharks and blood. And we might find some any other business through the square window. You're a square window.

Hello Matt. Hello Bec. How are you? I'm good. I'm good. How have you been? I'm good. I'm good.

Thank you for asking. So my big news. I went to the election. Well, the election happened all around us, but I got to go in the UK. There's no like electronic voting or anything like that. You get a physical bit of paper and you write your vote on it. And I got to go to the room on the, at the evening of the election, where they count the pieces of paper to tally up the votes, which was a huge amount of fun.

Yes. I was a count agent. That sounds pretty cool. It's very cool. A count agent sounds like if Dracula was in Men in Black. Yes. I mentioned to my friends that I was going as a count agent and they all got very excited about the costume I should wear. Yeah.

And several vampire related outfits were suggested. I was not swayed by those suggestions. I did contemplate a sash. You've done a YouTube video where you dress up as like a vampire. I have and that was raised because I kept it just in case there's another video where I need to dress up as a vampire. I have. And that was raised because I kept it just in case there's another video where I need to dress up as a vampire. I deemed this not that occasion. I ruled out wearing a sash that says count agent as much fun as that would be. In the end I did put on a suit. I wore a suit. Like a secret agent? No,

not like a earpiece kind of agent. Just like I was cosplaying as an accountant. That's less fun. I think you're getting too hung up on the word agent. Yeah, because I'm good at costumes and if you'd listen to me you would have gotten way cooler reactions. I don't want to startle anyone who's unfamiliar with my work, who was not there for a cool reaction. Now, to be fair, that said, I was in the convoy of some people in very good costumes because the reason I was able

to get into the room where the votes were taking place is I was a count agent for a political party. And the political party in question was the Count Binface party. Yes. Friend of the show. Your friend and mine, previous producer of this podcast, Count Binface. Yeah, I hope Lauren doesn't start to get ideas and run for parliament. We all know we're just, you know, running out of time before Lauren dons some kind of ridiculous costume and starts running for parliament. Yeah, the Duchess of dustbin or something. It's inevitable.

And as they say, the important thing is just to enjoy the time you have and just know that it's fleeting. That is what they say. I say that to all children when it's their birthday. Could they wonder your producer will put a bin on their head and leave you? Yeah. No. So Count Binface is an intergalactic Space Warrior who runs in Earth elections

because it's funny. And I mean, there's a history of novelty candidates in UK elections. I, without throwing too much shade, find them all to be all zany, no substance. They'll just have a funny outfit and then that's it. And because we were at the election that the sitting prime minister was in. So a lot of people will run against the sitting prime minister who traditionally is the very safe seat, they're going to get voted back in again, but there's a lot of media attention and like their speech at the end of the results is

always broadcast on TV. So if people want to run as a novelty candidate, it's a very appealing constituency to go for wherever the sitting prime minister is. So we were surrounded by the novelty parties and that no one had any substance behind them. So I got to go along and I got to be there in the room as that was all happening. Rishi dashed in at the last conceivable second to be officially present for the vote count, did his speech and gone. Okay. Binface, I'm very impressed.

Under the bin, they're a politics nerd and a comedy writer. So unlike the other novelty parties, they've got a lot of substance to back up their style. He's really good. Yeah. And the media love interviewing Binface because they say almost slanderous, but very funny things about the state of politics. And so they're a great, the media know they can go to them for a very good sound bite. And I got to watch people count things. So I had a huge amount of fun drifting around people counting stuff. It was a good time. How about yourself? I didn't do any counting. What? I went to the Children's Media Conference in Sheffield. The Children's Media Conference. Is that a bunch of children who secretly run the media

or is it a conference just for children? Oh man, I wish it was the former. Wouldn't that be special? It's just a bunch of people getting together talking about how no kids watch TV anymore these days. That's about to say. They're all just sitting around going, you got any ideas? Yeah. Anyone watching your show? Nope.

Watching yours? No. My favorite panels where there was a panel where they discussed that very fact. What's really interesting is a lot of parents will let their kids watch YouTube and you've kind of got the parent filter on, you know, like the child filter on there. Like children's media in terms of television and stuff is very heavily regulated to keep kids safe. So there's a lot of laws about what you can and can't advertise.

Like the quality in the UK, there's got to be like a certain amount of education has to be provided, especially if it's a nationally funded thing, like CBBS or CBBC, you have to hit a particular quota of what is educational. And obviously fair fair representation. I've done wireless TV than you, but you know, particularly aimed at kids, but occasionally something I'm doing will bump up against imitatable behaviour restrictions. And that's a big one. You can't.

Yeah. Yeah. In fact, one of the one of the preschool shows I was writing on recently, there was a storyline pitch that was very cute where the character gets the sneezes for the whole episode and hilarious, you know, things ensue. You know, they sneeze, they're shot backwards, or they sneeze and a house falls down, or they sneeze and they shoot up into the air, or that kind of thing. But obviously, the idea of that since COVID is pretty, uh, looked down upon. Cause it could suggest that it's encouraging kids not to cover their

mouths when they sneeze or to try and sneeze as big and loud as possible. So there you go. Yeah. So you've got to be used to be careful. And the thing is like these things are in place so that parents don't have to. Be as heavily involved in the vetting process. Like, you know, you can stick your kid in front of CBBC or CBBs and know that they're getting a relatively good quality, relatively

good level of education. Nothing that's going to necessarily scar them for lives or anything. But YouTube doesn't really have that. Basically with YouTube, you say whether your content is kid-friendly or not. It might run through a couple of algorithms to check for things and people can flag stuff, but it kind of relies on the people being the filters or moderators being the filters rather than there being a huge vetting process back and forth about what can and can't go on there. But parents don't realize this. Like it's parents just think, well, it's here and it's here.

No one thinks about the fact that children's TV, so much thought goes into it, so much thought because children are sponges and they will soak up everything. So you've got to be extra careful. Not in a sense that you're sheltering them in any way. I'm a very big believer in not patronising kids. I'm always citing Bluey as the perfect example of something that will understand that kids are capable of taking in very important subjects. But we've got to be careful about how we go about talking about them.

And I just hadn't really realized that a lot of the public don't realize that. And so they'll chuck their kids in front of YouTube and they'll watch six hours of fruit dancing, which is very, very nice and calming and meditative. But anything in large quantities, in large, bingeable quantities is not healthy for anyone. In the interest of, you know, the free market, if we hadn't removed all those restrictions and regulations we wouldn't have had the creative output that is skibbidy toilet. So there's something to be said for unshackling the creativity of children's media. Yeah, yeah, you're right.

And my other favourite panel is just called Put your money where your mouth is. And it's where they get four people to pitch their, their TV shows to a bunch of commissioners and it was brilliant. Well, nice. Yeah. And in what capacity were you at the children's media? I was just a delegate baby. Oh, just hanging out. Yeah.

Just networking. Lots of networking that goes along. People who work in kids media are like the nicest, loveliest people. I did karaoke. I think I mentioned it before, but I'm not drinking at the moment. Um, and I've been really enjoying that. I thought I was going to be a bit nervous at karaoke because they didn't have any good, zero non-alcoholic alternatives at the bar.

Either it was a free bar. So your choices were all the free booze or water or like, I don't know, soft drink. And I didn't want to be full of sugar. And so I was like, oh gosh, I'm going to have to do karaoke on just water. Turns out karaoke is just the level of natural high that I need. Cause once I got that first song under my belt, Oh boy, I was there till the bitter end. Amazing. And that's how children's TV is made. Our first problem comes from the rog or the roj. Let's go with rog. Not any rog. The rog.

The rog. Do you think it's Dwayne the rog Johnson? I do. I've been sat staring at a dartboard for the last 40 minutes. I understand that it's ordered the way it is to promote skill by having large numbers and small numbers near each other. But is there a better way to place the numbers to achieve this? So basically they just want to know about optimal layout and who figured it out in the 18th century and how. I mean, they're, they just want to know about optimal layout and who figured it out in the 18th century and how.

I mean, they're close. The current number system we think was the late 19th century, potentially early 20th century. In my cursory research, there's no primary references for who did it. The kind of accepted wisdom was it was a carpenter named Brian Gamlin in 1896, but that is not not settled fact, but it has been, we can say unambiguously for over a century. It's been the current numbers on the dartboard.

And when this question came in, I was like, that is an interesting problem. Uh, because I'm kind of, I'm aware that the positions of the numbers on a dartboard is a very mathematical thing. And I'm kind of conscious of that as just being something that is in the mathematical world, but I've also never looked at it very closely. Yeah. So it was kind of my, Oh, I'm sure that's interesting. I've just never dedicated any time to looking into it.

So when the rogue got in touch and said, I've been living under a rogue, uh, I don't know why dance works. I was like, brilliant. I'll look into that. And it reminded me cause I just put out my video where Grant and I play pool against Jen and Rolly. And in the background of that video, very astute viewers will spot someone out of focus playing darts.

That person is the good Beck Hill. Yeah. I think it was about three hours I spent playing darts trying to perfect my throw. We didn't rush the filming and you found a dart board in the corner of the pool hall and just got busy. I did improve. I did get better than what I'd been before, but I did then reach that point where my arm was just getting tired. My arm was aching for days after that. I remember you complaining for days after that.

Yeah, I did anyway though. I mean, that's true. But this was a valid complaint, your arm. After you saw it, after your arm. Yeah. Because then we finished filming and we were all like, oh, now we want to play some darts. We've been watching you play all day.

We want to have a go. And you're like, oh, more darts. So we spent like another hour or two playing darts. It was great. I loved it. I had a great time. Good darts. Good darts all around.

So I think that's it. I think we've answered it. I loved it. I had a great time. Good darts all round. So I think that's it. I think we've answered it. I have wondered about this as well. I've wondered who chose the order. Cause you know, a QWERTY keyboard is, you know, there's been some thought that's gone into why the letters are where they are. And it makes sense. I just assumed that it was like throwing darts at a dartboard as to how they chose the numbers.

Oh, look at you go. Oh, that cliche was a bullseye. Turns out potentially it's way more thought through than they thought. Sort of. So no one's a hundred percent sure what the original logic was. That said, now that people have come up with theories about what properties a dartboard should have in terms of the number arrangement. The classic one that's been around for over a century is very good. So even though it would have been worked out without the

benefit of computers or modern mathematics or a lot of the techniques we're using now, it is a very good layout for a lot of the kind of properties we want to have in a dartboard. So just, I mean, for people who don't play darts to kind of give you a quick darts catch up, you're throwing a pointy bit of metal at a circle across the room. And the, the circle is divided up into slices as one would a pizza. 20 slices. 20 slices, 20 slices. And each slice has a number.

So the numbers from one to 20 are arranged around the outside of the board, one per slice, as you would a terrible clock. If you get your dart into a slice, you get that number of points. Now there's a few other things like there are different regions within each slice where you might get double or even triple the value. Yeah, like Scrabble. Yeah, like Scrabble. So you get double dot score or triple dot score.

There's also the bullseye and like a ring around the bullseye right in the middle, which are worth like 50 points. It's actually more beneficial if you're going for points to go for the triple 20. Yes. Cause that's 60. It's a bigger number. Which always shows me. There is a scenario in which it's preferable to aim for the bullseye.

And that is if your aim is absolutely terrible because as your aim gets worse, the location you should aim for changes and if you're going to be lucky to get into the board, aim for the middle of the board because it will just maximize your chance of getting something. So there is a scenario in which the bullseye is good. That said, if you've got any kind of control, even vaguely of where the darts gonna go, then the bullseye is probably not for you. Well when you're playing darts you do you're trying to count down from 300

aren't you? So you start with, it varies either 301 or 501, you start with a big number and one and then each time you score with a dart, so you get to throw three at a time. And then the other person has a go. Each time you throw a dart, wherever it lands, you subtract that value off your score, first person to zero wins with two caveats. You cannot exceed zero. If you score too many points that you can't subtract them all off your current running total. That shot just doesn't count.

Yeah. So if you had 50 left to get, that would be the one time where a bullseye would work. The other rule is you need to finish on a double. Oh, I didn't know that. Your final shot has to land in one of the double value spots around the edge of the board. And that is an interesting twist. Like that one little game mechanic makes both darts in general and the arrangement of the numbers a slightly more interesting game because it adds a lot of complexity because as you're

counting down, you've got to make sure you can end, boom, double score. And if you miss and you get another score, you've then got to work out a new way to end on a double. You're doing maths while you're throwing stuff. It's such a great game. You're throwing pointy things while doing mental arithmetic. What a game. I can see why it's so enduring. And why it's done in the UK, at least frequently in

pubs where you have a drink. Drinking famously helps both throwing pointy objects and doing mental arithmetic. In the Rogues problem is the assumption that you want to have numbers next to each other

to be very different in value. And that's because there's this notion that you want to make the game a challenge because the game would be effectively the same if it started like at one at the top and counted up to three, four, five, all around to 20, like, like a terrible clock. And the downside to if they just went up in numerical order is you'd have one region of the board with very, very low values and you have another region of the board with all big values. So if you were aiming for, let's say 19 and you think, wow, I mean for

19, because there's a chance I'm not super accurate. I might go one to the left or one to the right. And by aiming at 19, if you're slightly off, you get 20 or you get 18. You're still getting a very big score. So the idea behind the layout is to penalize inaccuracy. So the idea is if you throw a dart and you miss the slice you were aiming for, you're going to get a very different score to what you would have got. So the idea is if you throw a dart and you miss the slice you were aiming for, you're going to get a very different score to what you would have got if you'd hit the one you wanted. Yeah.

What if you're trying to achieve being inaccurate has to mean you no longer achieve that to make it an interesting game. Yeah, like in a video game, like in Mario or Sonic, you have the platforms between spikes. You're not going to put all the platforms together and then just a whole bunch of spikes. It's the inverse of darts, because in darts you throw the spikes at the game, as opposed to throwing the game onto the spikes. If you take that idea and you run with it, the idea is you want to penalize inaccuracy. So the whole point of the game is to be accurate at throwing the pointy thing. There's some things you do when you don't want. So one of the common criticisms of the current

layout, like it's very, very good, but it's got a few hotspots, let's say, where not all the regions of the board have the same kind of average value. So what you can do is if you're a little inaccurate, you can pick up like a hotspot and aim for it. So, I mean, if you're dead accurate, you aim for, um, triple 20, cause that's your maximum points, like you're saying, but 20 is flanked by one and five. So if you miss by a bit, you, you're getting barely any points. So if you're not sure if you're going to exactly hit it, or you might be off by a

bit, then it's actually preferable to aim for seven because seven has 19 on one side and 16 on the other. So ironically, if you were accurate, you're only going to get seven each time. If you're a bit all over the place, the average value from those three is 14. And so that's like the high, that's the highest average of three consecutive slices on the board. And that whole region on the board, if you're randomly hitting between seven, 19 and 16, you'll average 14 points per dart. And that kind of region of the board, the region that runs from it goes 8, 16, 7, 19.

That's your hotspot on the board. If anyone's listening who's not that great at darts and in a pub, you're told, Hey, why don't you join in a game of darts? The secret is ignore 20. If you aim for 19, that's your best kind of higher than average region of the board and the region around 19 is where the, there's the best concentration of big value slices that you might hit. So now we've got two things we would like from an optimal dartboard.

And one is that you want to have a big difference between two consecutive slices. So you're penalizing missing. Secondly, you don't want to have a hotspot. You don't want to have a region which has an above average value. Interestingly, those two requirements are in contrast with each other. Because if you're having really big variations somewhere on the board, you've got to have another region where a bunch of similar valued ones are kind of clumped together.

So there's a push and a pull between these two criteria. What you need to do is find some way to measure those two things. And then you go try and find an arrangement, which gives you a balance of the two. So what you actually end up doing is go try and find an arrangement which gives you a balance of the two. So what you actually end up doing is you try to find an arrangement of the numbers such that it's got the smallest maximum difference between any two consecutive slices. And by measuring that you end up with a nice balance, but also big enough differences.

What you can do though, to really force the need for differences, is as well as looking for the difference between two consecutive slices, you also look at and try to minimize or maximize the square of the same thing. And by squaring it, you're adding more emphasis on bigger differences. Because squaring, just big numbers get bigger, small numbers don't get as bigger. So by also squaring the same thing and checking that separately, you're then providing extra emphasis on the importance of big differences. So those are actually the four criteria. You want to find the biggest average difference between two slices.

You want to find the biggest average squared difference between two slices, consecutive ones, and then you also want to minimize the maximum value of that for any given board and you want to minimize the maximum version of the squared value of that. So mathematically, that's how you lay it all out. I'll be honest. You have lost me. I've missed the board. Yeah. So, I mean, what's interesting about this is this is some fairly advanced

mathematics, not like ridiculously abstract mathematics, but it's not just standard maths you will have learned at school, this is niche slash unusual mathematics. So the original layout was absolutely not done this way. There's no way the original designer sat down and went, oh I need to make sure that this measure on the cyclic arrangement has this property. They just would have been eyeballing it and going, oh, here's a way that I can do it such that the differences are pretty good and there's no overly significant hotspots. Is it a bit like in baseball, there are many different ways in which you can check different stats? Like there's many different stats that you can work with to work out different ways in which you can check different stats. Like there's many different stats that

you can work with to work out different ways of playing the game and moneyball. Let's just say moneyball because that is my shorthand. However, baseball wasn't invented with those things in mind. Yeah, it's a yes. I will say it's a bit like back in the day, baseball scouts would just be like, I like the gumption on this kid. I got a feeling they're going to be good at playing the baseball. Whereas now we're like, oh, we can calculate all the different factors and determine who is the optimum person at playing baseball. And when the dart ball was designed, it was before we had that kind of process.

So it was just someone going, this feels right. This is probably a good one. And it turns out they were right. It is, it's very good. Whereas now we can exactly quantify precisely how good or bad it is. And which is the best. Got it. Okay.

Now there's a new criteria in town. Recently, people have started saying, oh, on top of everything else we want a dartboard to do in terms of the number arrangement, we also want it to alternate odd, even, odd, even all the way around the board. Huh. Do you want to have a guess why, why we would want to alternate odds and evens around the board. Is it because... It's not immediately obvious.

Has it got anything to do with the whole having to end on a double? You are spot on. Yay! It's to put people ending on a double. And quite pleasingly, when I was reading a bunch of research about dartboard arrangements, I saw that was cited to Easterway and Haig. I then realized I know Easterway. That's my friend Rob Easterway.

He wrote a book called The Hidden Mass of Sport. You've met Rob. I was going to say, I knew that name. That's my mate Rob. And in all the literature I was reading, it didn't say why we want this odds even thing, so I just messaged Rob and Rob very kindly recorded a quick message for why they came up with the idea to alternate odds and evens. Hi Matt.

When John Hague and I were examining the number patterns on dart boards, it occurred to us that one way to penalise players who don't throw accurately is to make the numbers round the board alternate between odd and even. And the reason for this is that you have to finish a darts game with a double, so if your target is currently 24, then to finish the game you've got to get double 12. And at the moment on the current boards, if you aim for the 12, its neighbors are five and nine, which are both odd numbers. And that's bad news because your target score, if you happen to miss the double 12 and get a five or nine, your target is now an odd

number. So you can only finish on a double if you spend another dart, reducing that back to an even number, throw it to one, so you've now got an even target, and go for that again. And a weakness of the current dart board is that the 16 is next to the 8. So if you miss double 16, you might land on 8, and that's still an even target, so you've still got an out. So they could improve the difficulty of the current board by making it odd even. Huh? That's really interesting. Yeah.

So you were, you were absolutely correct. And so Rob had this idea, put it in his book and now that's been folded into the literature, it feels like when it was designed a hundred years ago, they had an awareness of that because while there are a bunch of evens that are next to each other, it does largely go alternating odds and evens, just not completely. And we now know that it's impossible to do everything at once. You cannot alternate odds and evens while getting an optimal arrangement of the

numbers in terms of how big they are. So the actual maths was done by Dave Percy at the University of Salford up in Manchester and they did a lot of research into the optimal arrangement of a dartboard and in 2011 they found the best arrangement. They published it the next year and I really struggled to find any of their, the 2012 paper. I couldn't find it easily online, but quite conveniently, they announced the discovery of the optimal dartboard at the mass jam conference that I help organize.

Ah, so I was there in the room back in 2011 when Dave Percy was like, hey, check it out. This is the best arrangement because knowing what you want and actually finding it is difficult, it takes a computer to do. But they wrote some probably very good code to then search and find it, and that is now that is the best arrangement. That's it. So the Percy board is the best possible arrangement. I will link in the show notes to a paper written in 2022 by a researcher in Turkey who does a fantastic summary of the history of the mathematics of dart boards. They show that

the Percy one is optimal while looking at some other ones and the way you can balance and all these things I've been talking about how you can measure, you know, the nature of the distribution of the numbers, they break it all down in terms of the maths going on behind the scenes. And they do find two other alternate arrangements. I'll put a picture of the classic arrangement of the dartboard and the Percy arrangement and maybe even these two other alternate ones if people want to have a look at those so you can see what the options are but at the end of the day if you want to have the alternating odds and evens and you want to have the optimal distribution and you

Try to balance them out. The Percy one is the best arrangement So I will make sure we have a link to Arm Percy's design. And it's very similar. Like eight of the 20 numbers are in the same place as they are on the standard board. So it's not dramatically different. It's just kind of shuffling a bunch of them around a little bit to, to just kind of tweak and improve it. So it's technically a little bit better, but not dramatically better than the classic one.

Can you buy the boards or can people just cover up the numbers in tape and renumber them? They did do a limited run of them in like 2012 or 2013. I don't know if they're still available. You might have to get out, you know, some pliers and move and rearrange the numbers on your board, but I will give you the guide so you can, you're right, tape over the boards you've got and sharpie on these improved numbers. I have one more question to ask Matt. We're talking about the arrangement of dartboards and this is the problem that the ROG sent

us. So first of all, ding. To me, as far as I'm concerned, that's a, that's a ding. I think you've fully, fully answered that. Is there a better way to place the numbers? Yes. Yes, there is. Is there a tactic that people should play by if they're playing with a standard board? It depends how good you are.

So, um, my friend, Zoe Griffith did a thing a while ago, which was looking at, if you gradually increase the level of uncertainty in your throw, where the best spot to aim for moves to. So it depends how accurate you are. I will also say that there are still some assumptions around the best arrangement because it assumes that aiming for anyone slices equally easy, but some are sideways and some are vertical. And actually it's easier to aim side to side.

It's easier to aim if you're not good at darts, whereas metering your power to aim up and down is harder. And the height of the player too. And the height of the player. So we're assuming all slices are equally easy to aim for, and that's not true. And as we discovered with, you know, Rob's contribution, we might come up with new measures for what we want from a dartboard.

So maybe my idea of the equality board where it helps bad players, but penalizes good players, we could decide actually that's our new most important criteria and would have to recalculate and look at new arrangements that achieve that. So it's the optimal arrangement based on what we want from a dart board at the moment, but there are still some things we're not factoring in, such as the orientation of the board. Yeah. Well, you can get a lot of those, um, interactive ones now where they sort of

project stuff on there so you can play games where they, they do change the layout of it, depending on what sort of game you want to play. Yeah. I think the board should be able to spin. Yeah. Somewhere between Wheel of Fortune and Darts. Matt, can we invent that? I think we just did.

Next problem comes in from The Chris. I mean, they just wrote Chris, but I assume they'd like to be in from The Chris. I mean they just wrote Chris but I assume they'd like to be known as The Chris. Now they're following the Rog. Yeah. The Chris says sharks can apparently smell blood from quite a way away. They're not sure what that means as they can presumably only sense something that is in the water that is around them. Good point, the Chris. Their main problem though is if they cut themselves, how long would it be before a shark got a whiff of them and could home in how long have they got to get out of the water or stated alternatively, how quickly does blood spread in the sea? Okay, the Beck, have you got a solution for the Chris?

I do the Matt. I'd heard several sort of things about sharks can smell blood from a mile away or they can smell it a quarter of a mile away. And my first thing was like, how do they know? That led me down a series of rabbit holes. I suppose I'm going to go from the problem backwards. So how quickly does blood spread in the sea? Blood in the sea, very similar to a fart in the air. It's all to do with diffusion. So if things were sort of sitting relatively still, but sort of diffusing, then obviously the further away it is, the fewer particles there are. And if you and I were in a room with completely still air and one of us farted, but there was no movement in the air,

it would take quite some time for some of those very dispersed particles to make their way to my olfactory system for me to then recognize it. And therefore deduce that you had delta rise. Well, if you recognize it, you dealt eyes to it. I think that's the expression. Yeah, that's what they say. Yeah, that's the, that's the same, but obviously air and water move. So at first I thought, okay, like waves, but waves actually only really affect

towards the surface of the sea. You know how you see people in like a wave machine pool and they just kind of go, and they bob up and then come back down. They don't necessarily get pushed along by the wave. You know, you only intend to get pushed along the wipe by a wave if you're at the right point of the wave breaking and you can manage to catch it. Otherwise it just kind of like passes by you, you sort of raise and then fall again. On a traditional ocean wave, you would do like a little circle loop as the wave goes past you. So it's not exactly up and down motion, there is side to side, but it all brings you back

to where you started. You will not go anywhere on a non-breaking ocean wave. What does move water currents? And that usually comes down to temperature, water temperatures in the same way you get with air. So when the temperatures are different and different parts of the water, warmer water will move towards, and also if you're near where like rivers and stuff are coming out as well, that will

start to affect the movement of the water in those situations, also stuff coming out from under the ground. And then just animals, schools of fish swimming through will interrupt the water currents and stuff as they're swimming through. So I then realized that yeah, how quickly blood spreads in the sea, it really boils down to where you are in the sea. Where's the water going? How much blood is there?

Et cetera, et cetera. And I tried to find how they actually tested, how did they come to the conclusion of exactly how far away a shark is? How do they. Like, how do they know it's a mile or quarter of a mile or whatever? Well, given that they say both a quarter of a mile and a mile, it means we probably don't know exactly, but we do know one thing for sure, and that's that sharks use the imperial measurement system.

Yeah, yeah, yeah, exactly. But I'm imagining you would put... So let's say, let's say just for ease of sake, you, you're working in metric. You'd put a whole bunch of sharks in a long row, 10 meters apart. And then you put blood at one end and you see where the point is, where what's the most distant shark that comes to the blood. It is a very shark intensive way of doing the research, but I think is where what's the most distant shark that comes to the blood.

It is a very shark intensive way of doing the research, but I feel like it would be the most accurate. Yes. I was hoping there would be something like that out there. Nope. I couldn't find anything. All I could find was either things that were pushing the idea that it's a mile. And then a lot of zoologists or marine biologists dispelling this and saying, no, it's not true.

Wow. It's another problem on a problem squared where the messiness of biology and no one agrees and there's always an exception. Yeah, now they do have a very good sense of smell. So according to Louis Villazan, who's a zoologist, they say sharks actually have roughly the same sensitivity as other fish and can detect smells at between one part per 25 million and one part per 10 billion, depending on the chemical and

the species of shark at the top end. That's about one drop of blood in a small swimming pool. So that's pretty impressive. Okay. But not a mile. Hugely unbelievable. It's not a mile. And it's also when you think about like how a dog can pick up a pretty decent scent. My hamster can tell if food has entered a room. Oh wow. He's little. He's only got a little nose. But then again, most of us can, you know, you can usually tell, oh, someone in the neighborhood

is making bacon. Yeah, there's a barbecue nearby. Yeah. So like it's, that's actually not, you know, it is impressive, but it's also, it's not like if you put a drop of blood in a swimming pool, a shark will go nuts. I think that's what a lot of people seem to imagine. So if we're looking at the maximum speed when they're attacking in water, sharks can, can travel at 19 kilometers per hour. That's pretty swift.

So if you had a cut and currents were able to carry that a kilometer away. You got three minutes to get out of there. If you want like a math C type answer, that's what it is. And I do. And now I'm happy. But twist. No. I know. Sharks don't really care about human blood. Sharks don't like humans. We're not tasty to them. They don't really care. So it's not like smelling a barbecue. It's like smelling a salad bar. Yeah, exactly. They're a bit like, uh, sharks generally don't like people to eat. We have a lot of bones. We're sort of more bone than we are flesh.

We're no seal. No, exactly. And like, and the type of bones that we have aren't great. Apparently our flesh isn't delicious. We're not like big, chewy, fatty seals with all that. I'm okay with that. Yeah. So sharks generally don't like eating people. Sharks tend to attack because either they're territorial or they think a person is a seal because they tend to come up from under them

and a seal can sometimes look like a human, vice versa, if you're swimming on top of the ocean. So most of the time when sharks attack, it's not because they're like tasty humans. They're like, oh, delicious lunch. Oh, no, this isn't what I wanted. Your blood's not going to attract them in any capacity, or at least according to Dr. Lauren Simonitis. Overall, you don't really need to worry about whether you're bleeding or not.

So to go back to the question, if you cut yourself, how long would it be before a shark got whiff and could hone in? How much do you look like a seal? That's the answer. Unless someone is throwing chum for things that sharks like to eat, like other fish or other marine animals, unless you're having a little swim through all that stuff, you're relatively safe. So I'm not saying please go and actively swim amongst sharks unprotected, but I am saying the whole danger of them is severely overblown.

What was interesting was when I was trying to find out how they tested this fact, which now we know isn't a fact, was they did do some tests to see how sharks smell help with their navigating. And they found that a shark will know the source of blood. So if it could smell the blood of prey, and that had come along on a current, it can tell which nostril it hit first and can turn towards that smell. And then using the nostril on each side, steer themselves. They're actually really good at navigating via smell. So I thought that was really fascinating. You were reassuring for a while there.

Now you're back to terrifying. Well, if you are scared, cuttlefish ink is a reasonable shark repellent. Like cuttlefish have a natural shark repellent in their ink. Sharks are not a fan. There's been studies and tests to see whether they can start using or manufacturing a sort of synthetic version of cuttlefish ink to help just ward sharks away from heavily populated areas

so that they're not crossing over into each other's territories and causing issues. That's great. Do you know what I think you can smell coming a mile away? I think I can feel it in my right nostril. Hang on. Yep, now it's hit my left. Yeah, yeah, yeah.

There's a ding in the water. We're going to need a bigger pod. Yeah, a bigger pod. That was the correct answer. Well done. Ding, ding. There's some gag in there about whales and pods, but you know. Oh yeah.

We leave it to the listener to assemble that joke themselves. Yeah. A ding, ding, ding, ding. Well done. Thank you. It's time for any other blindsness. Oh, good work. Thanks.

I was trying really hard to think of other window words. Several of you, and we appreciate every single one of you, wrote in, in response. Well, okay. A very large group of people wrote in response to our do dogs have four legs or two arms and two legs. A decent percentage of those people were telling us the same facts. And it is interesting facts. So I appreciate everyone who said this, because we were talking about what would then be worn on those legs slash arms.

And someone pointed out in the German language, the word for gloves, which we were using as part of our argument, translates to hand shoes, shoes for your hands. which we were using as part of our argument, translates to hand shoes, shoes for your hands. So implying that hands are just feet where you'd normally put your shoes. I don't know, I don't know, I don't know 100% by the argument that this lends any additional weight to the arms or legs argument. But I do accept is a very interesting and fun fact. And we always enjoy a fun quirk of the German language around here. I would argue that maybe arms are a type of leg because you've been known to wear

socks on your hands when you're riding a bike. As gloves. I was improvising gloves. Were they gloves or were they just hand shoes? They were definitely hand socks. We also heard from Michael who said, Hi, Beck and Matt. Just listened to episode 88 and had to ride in solidarity with Beck. Plain salted chips are without doubt the superior flavour, beer pringles, regular chips, kettle

fried, whatever. No. I have some friends whom I love dearly and whenever we go over their five-year-old always says uncle Monkle. I'm guessing that's Michael. We got your favorite, salt and vinegar. And don't get me wrong, I like salt and vinegar, but it's not the best flavor. That's wisdom from the mouth of children right there. I think they're just gently trying to correct Michael's, you know,

accidentally thinking that plain salt are the best. They're doing their best to correct him. I would say that this sort of nonsense coming from the mouth of babes is why we need to regulate children's media better. Oh, wow. Wow. Call back. Don't be so salty. Ah nice. Thank you so much for listening, especially those of you who are right about the best flavour of crisps slash chips. We would like to thank in particular our Patreon supporters who support us financially and allow this show to continue. We love all of you, every single one of our listeners, but it is nice to be able to financially justify the amount of time and effort that goes into

the show. So without any further ado, we will thank three of our Patreon supporters at random by mispronouncing their names. And on this episode, those three supporters are J U Stimber I Richler, Stephan Wilm-Eroth, B Nuk-Asner. Thank you so much for supporting us. Thank you very much to everyone though for listening and for telling everyone to listen to this podcast. Word of mouth is also the best way to support us if you'd like to.

And thank you to my lovely cohost, Matt Parker. Oh, thanks. To myself, Beck Hill, the other host and to our fantastic glassy gal. Would you describe her as the void in our double glazing? Yep. Let's go with that. Our producer, Lauren Armstrong-Glata. Lauren Armstrong-Glata. No, I've got nothing. I'm so sorry.

I'm so sorry, Lauren. Hoo boy. Really regretting opening this episode by saying as a writer. She's going to quit and go into politics. That's a wrap, folks.