WEBVTT - Stickiness, Part 2 0:00:03.040 --> 0:00:07.040 Welcome to Stuff to Blow Your Mind production of iHeartRadio. 0:00:12.720 --> 0:00:15.680 Hey, welcome to Stuff to Blow Your Mind. My name 0:00:15.720 --> 0:00:16.800 is Robert Lamb. 0:00:16.760 --> 0:00:19.520 And I'm Joe McCormick, and today we are coming back 0:00:19.600 --> 0:00:23.720 with part two in our series on stickiness. This is 0:00:23.760 --> 0:00:26.920 a topic I got interested in after feeding my ten 0:00:27.000 --> 0:00:31.479 month old various fruits and fruit based smoothies and stuff, 0:00:32.080 --> 0:00:36.480 and noticing the way that a kind of stealth stickiness 0:00:36.479 --> 0:00:41.200 can easily migrate outside of the direct vicinity of eating 0:00:41.600 --> 0:00:46.040 and contaminate surfaces beyond. There's a kind of stickiness fallout 0:00:46.080 --> 0:00:49.800 effect after the initial meltdown. Rob I think you said 0:00:49.880 --> 0:00:51.919 last time, you've had similar experiences. 0:00:52.159 --> 0:00:55.280 Oh, yes, and I'm still finding sticky spots in the house, 0:00:55.360 --> 0:00:57.760 you know. Now here's a question about your daughter. Has 0:00:57.800 --> 0:01:01.960 she used the stickiness to scale walls yet? 0:01:02.360 --> 0:01:05.039 No, she has not figured this out yet, but she's 0:01:05.080 --> 0:01:08.240 crafty and I think she could be getting there very soon. 0:01:10.280 --> 0:01:11.679 More on wall climbing in a bit. 0:01:12.319 --> 0:01:15.640 Yeah, the creature will not be contained. But so in 0:01:15.680 --> 0:01:20.120 the last episode we started off talking about difficulties and 0:01:20.319 --> 0:01:24.280 even defining stickiness rigorously. This is one of those subjects 0:01:24.319 --> 0:01:28.440 where I expected there to be a pretty simple, straightforward, 0:01:28.720 --> 0:01:33.240 well understood physics or chemistry answer to what makes things sticky? 0:01:33.520 --> 0:01:36.080 And it turns out no, the answer is super complex 0:01:36.200 --> 0:01:39.920 and in some ways not fully understood, and we'll be 0:01:39.959 --> 0:01:43.040 talking more about that some at the beginning of today's episode. 0:01:43.040 --> 0:01:45.440 But in the last episode we also discussed one of 0:01:45.480 --> 0:01:50.600 the most glorious of sticky foods, glutinous rice aka sticky 0:01:50.680 --> 0:01:56.040 rice aka sweet rice, the unstoppable amylopectin avalanche. 0:01:56.680 --> 0:01:58.960 That's right, I hope if nothing else, we inspired everyone 0:01:58.960 --> 0:02:02.080 out there to seek out some sticky rice or sticky 0:02:02.200 --> 0:02:06.520 rice derived food products in wake of listening. 0:02:07.200 --> 0:02:09.200 Did you have some sticky rice over the weekend after 0:02:09.240 --> 0:02:11.040 we did the episode? 0:02:11.880 --> 0:02:14.400 I had some mochi, and I really I think it 0:02:14.560 --> 0:02:17.720 enhanced my enjoyment of the mochi, and I'm looking forward 0:02:17.760 --> 0:02:21.720 to having sticky rice the next opportunity I get nice. 0:02:22.440 --> 0:02:25.960 Well, today, we wanted to further explore the concept of stickiness, 0:02:25.960 --> 0:02:28.840 and one place I wanted to start was with a 0:02:29.200 --> 0:02:31.680 chapter in a book that I've been reading. It's a 0:02:31.760 --> 0:02:35.560 very good book called Sticky The Secret Science of Surfaces 0:02:35.960 --> 0:02:40.040 by Laurie Winkless. This is a popular science book from Bloomsbury, 0:02:40.240 --> 0:02:43.480 twenty twenty three. So this is just recently published. And 0:02:43.960 --> 0:02:46.639 this book is not just about stickiness. It's about all 0:02:46.639 --> 0:02:50.560 different kinds of surface interaction, so it covers slipperiness and 0:02:50.600 --> 0:02:53.560 friction and all that stuff too. But there is a 0:02:53.600 --> 0:02:57.360 great chapter early in the book about stickiness. And this 0:02:57.400 --> 0:03:00.160 book is full of interesting stuff about the world that 0:03:00.320 --> 0:03:03.840 I never thought of before. For example, in this chapter 0:03:04.000 --> 0:03:09.320 on stickiness or adhesion, Winkless is talking about how oil 0:03:09.440 --> 0:03:13.320 based paints are made. Typically, so an oil based paint 0:03:13.400 --> 0:03:15.960 is usually going to be a solid pigment of some kind, 0:03:16.040 --> 0:03:19.760 little colored particles that are suspended in a liquid medium 0:03:20.400 --> 0:03:23.440 that might be something like linseed oil. And then it'll 0:03:23.480 --> 0:03:25.800 also have additives in it that will be things like 0:03:25.880 --> 0:03:29.240 stabilizers to help thicken the mixture and disperse the pigment 0:03:29.240 --> 0:03:32.560 particles evenly. But the thing that really caught my attention 0:03:32.639 --> 0:03:35.840 is she gets to an interesting fact, which is when 0:03:35.920 --> 0:03:39.520 you use an oil based paint. Maybe you're painting a 0:03:39.560 --> 0:03:42.040 painting on a canvas with some oil based paint. What 0:03:42.080 --> 0:03:44.320 do you do when you're done painting? You let it dry. 0:03:44.480 --> 0:03:47.960 We say that it dries, but actually the paint does 0:03:48.040 --> 0:03:52.680 not dry drying would mean that it loses moisture through evaporation, 0:03:53.160 --> 0:03:56.760 but moisture does not leave the oil based paint. Instead, 0:03:56.800 --> 0:04:01.000 what oil based paints do is polymerize. This is sometimes 0:04:01.000 --> 0:04:05.000 called curing. So instead of losing water molecules to the 0:04:05.080 --> 0:04:10.520 air through evaporation, these paints steal oxygen from the air 0:04:10.720 --> 0:04:15.040 and use that oxygen to form bonds between molecules, which 0:04:15.040 --> 0:04:18.000 allows the paint to harden into a solid film and 0:04:18.120 --> 0:04:21.599 form these layers of hard solid films. And because oil 0:04:21.600 --> 0:04:25.360 based paints remove oxygen from the air rather than drying 0:04:25.400 --> 0:04:30.360 by losing moisture, they actually get heavier, not lighter, as 0:04:30.400 --> 0:04:33.760 they cure. So Winkles says that paints based on linseed 0:04:33.760 --> 0:04:37.360 oil can sometimes increase their weight by over fifteen percent 0:04:37.560 --> 0:04:42.159 during curing, so a painting would be heavier after it's 0:04:42.279 --> 0:04:45.480 dry than when it was wet if you use one 0:04:45.480 --> 0:04:48.200 of these paints. Now you can contrast this to water 0:04:48.279 --> 0:04:51.920 based paints, which actually do dry by losing moisture, and 0:04:51.960 --> 0:04:55.080 these will leave behind only the solid pigments held in 0:04:55.120 --> 0:04:58.559 place by binder compounds. So when you buy a can 0:04:58.600 --> 0:05:01.600 of water based paint, most of the volume of that 0:05:01.680 --> 0:05:04.080 can is not actually going to end up on your wall. 0:05:04.120 --> 0:05:08.320 It will instead evaporate. And in illustrating this, she writes, 0:05:08.400 --> 0:05:14.279 quote Colin Gooch, technical director of paint manufacturer Racine, told 0:05:14.279 --> 0:05:17.000 me that a four liter can of high quality waterborne 0:05:17.080 --> 0:05:20.560 paint might contain just over one point five leaders of 0:05:20.720 --> 0:05:24.760 volume solids. That's what actually forms the film that stays 0:05:24.760 --> 0:05:27.200 on the surface. The job of the other two point 0:05:27.279 --> 0:05:30.520 five leaders is to keep those solids dispersed. It allows 0:05:30.600 --> 0:05:33.240 us to carry the pigment from the can to the wall. 0:05:33.720 --> 0:05:36.719 This is crazy. I'd never thought about this before either. 0:05:36.839 --> 0:05:41.000 It makes me wonder if I were using oil based 0:05:41.000 --> 0:05:45.360 paints in painting minis instead of the acrylic paints that 0:05:45.440 --> 0:05:49.000 I use. Like what the difference would be like all 0:05:49.040 --> 0:05:50.800 the you know, sort of the fine art of the thing. 0:05:50.880 --> 0:05:53.840 Do you have to factor that in to how much 0:05:53.839 --> 0:05:56.040 paint you're applying. I don't know. I'd love to hear 0:05:56.080 --> 0:05:59.000 it doesn't out there with experience painting anything, you know, 0:05:59.080 --> 0:06:00.719 minis or canvas or houses. 0:06:01.400 --> 0:06:05.719 Yeah, the book doesn't get into how the material the 0:06:05.760 --> 0:06:09.640 differences and the materials affect the craft itself, but I 0:06:09.760 --> 0:06:10.840 expect they probably do. 0:06:11.279 --> 0:06:11.479 Yeah. 0:06:12.000 --> 0:06:14.560 But anyway, coming to the more general topic in the 0:06:14.600 --> 0:06:17.520 same chapter of What Stickiness Is, I wanted to talk 0:06:17.560 --> 0:06:21.840 about some of the things that Winkless explains here. And 0:06:22.120 --> 0:06:26.480 there are two very important concepts for stickiness. One is 0:06:26.600 --> 0:06:31.760 adhesion and the other is cohesion. Adhesion is the attraction 0:06:32.000 --> 0:06:36.800 between two different materials, and it's defined usually by the 0:06:37.080 --> 0:06:39.719 work or the effort that it takes to separate the 0:06:39.760 --> 0:06:43.839 two materials. And then cohesion is the attraction of a 0:06:43.920 --> 0:06:47.960 material to itself. How the molecules of the substance, how 0:06:48.000 --> 0:06:51.640 well they stay stuck together to each other. Now, to 0:06:51.680 --> 0:06:56.080 discuss the different physical models of adhesion, how two different 0:06:56.320 --> 0:07:01.560 substances stick together, Winkless starts by imagining a hypothetical interface 0:07:01.640 --> 0:07:04.960 between two different things. So you imagine a drop of 0:07:05.080 --> 0:07:08.680 some kind of liquid, some kind of adhesive liquid, sitting 0:07:08.720 --> 0:07:11.920 on top of a clean, flat block of solid material. 0:07:12.040 --> 0:07:14.240 So you can think of a drop of water sitting 0:07:14.280 --> 0:07:16.040 on a piece of wood, or a piece of metal, 0:07:16.400 --> 0:07:18.920 or a drop of whatever of glue. You know you're 0:07:18.920 --> 0:07:22.000 going to be measuring how well this thing adheres. And 0:07:22.640 --> 0:07:26.920 coming back to the level of uncertainty that I've found 0:07:26.960 --> 0:07:31.200 surprising in this subject, she writes that the general consensus 0:07:31.320 --> 0:07:34.880 is that there are quote three or four ways that 0:07:34.920 --> 0:07:37.040 these materials could interact. 0:07:37.240 --> 0:07:40.200 Yeah, this is a familiar thread, it seems that one 0:07:40.320 --> 0:07:45.120 finds when you start researching stickiness is that, Yeah, we 0:07:45.160 --> 0:07:48.880 don't necessarily know On one l hand, we might not 0:07:48.920 --> 0:07:52.440 necessarily know like the one thing that is making something stick, 0:07:52.480 --> 0:07:56.560 and it may more honestly be various things, and there's 0:07:56.600 --> 0:08:00.320 disagreement on to what extent each thing is contributed to 0:08:01.040 --> 0:08:01.800 the stickiness. 0:08:02.400 --> 0:08:06.120 That's right. So the first one of these models of 0:08:06.160 --> 0:08:11.040 interaction for adherents is chemical adherents, and this means there's 0:08:11.040 --> 0:08:16.000 an actual chemical reaction. There are molecular bonds between the 0:08:16.040 --> 0:08:19.000 adhesive and the surface, so some kind of reaction has 0:08:19.040 --> 0:08:23.440 taken place, resulting in essentially a new compound where they 0:08:23.520 --> 0:08:27.800 meet and winkless. Here uses the example of paint. Quote. 0:08:28.160 --> 0:08:31.000 In paint, this sort of adhesion is enabled by the 0:08:31.160 --> 0:08:34.800 binder molecules that surround the pigment particles. So the pigment 0:08:34.800 --> 0:08:38.120 particles are the little solid particles that give the paint 0:08:38.160 --> 0:08:41.079 its color, and then they have these binder molecules that 0:08:41.920 --> 0:08:45.640 surround those pigment particles and help stick them to the surface. 0:08:46.200 --> 0:08:49.160 She says, quote they react with molecules on the surface 0:08:49.240 --> 0:08:53.840 sharing and borrowing electrons, effectively forming a new compound at 0:08:53.880 --> 0:08:59.280 the interface. So this is actual chemical interaction here. Second 0:08:59.320 --> 0:09:04.800 model of action is mechanical adhesion. Here there's not a 0:09:04.880 --> 0:09:08.520 chemical reaction going on between the adhesive and the surface. Instead, 0:09:08.880 --> 0:09:12.640 Winkless uses the analogy that one sticks to the other, 0:09:13.280 --> 0:09:16.160 like the way a rock climber clings to the surface 0:09:16.200 --> 0:09:19.800 of a cliff by like sticking fingers and toes into 0:09:19.920 --> 0:09:23.960 cracks and crevices in the rock. So the drop of 0:09:23.960 --> 0:09:26.480 the adhesive wants to stick to itself. Of course, it 0:09:26.520 --> 0:09:30.000 wants to stay intact, much like the rock climber's body 0:09:30.080 --> 0:09:33.560 wants to stay intact and stick to itself. And parts 0:09:33.679 --> 0:09:38.520 of this adhesive are jammed into recesses in the surface 0:09:38.720 --> 0:09:42.640 of the solid material. Now you might think, well, okay, 0:09:42.679 --> 0:09:45.559 but what about smooth surfaces. And the fact is that 0:09:45.600 --> 0:09:49.000 basically all surfaces, even if they're pretty smooth as far 0:09:49.000 --> 0:09:51.719 as you can tell at the macro scale, they've got 0:09:51.800 --> 0:09:54.800 lots of little irregularities when you zoom in. If you 0:09:54.800 --> 0:09:58.360 get a high sensitivity microscope, you can zoom in and 0:09:58.400 --> 0:10:02.679 see mountains and ravines the microscale, most surfaces you will 0:10:02.720 --> 0:10:07.000 find in the real world are like this. Third model 0:10:07.040 --> 0:10:12.280 of adhesion is diffusion. This typically happens when the solid 0:10:12.320 --> 0:10:16.120 material in the scenario is a polymer, for example, rubber 0:10:16.520 --> 0:10:20.000 or cellulose or nylon. There are lots of different kinds 0:10:20.000 --> 0:10:24.080 of polymers in the world, and structurally, polymers are long 0:10:24.400 --> 0:10:29.120 molecules with a repeating structure, sort of like the links 0:10:29.120 --> 0:10:33.200 in a chain. In diffusion, these long chains can sort 0:10:33.200 --> 0:10:38.440 of intermingle and tangle with several nanometers of material on 0:10:38.559 --> 0:10:42.000 the other side, on the other object or the other substance, 0:10:42.320 --> 0:10:46.199 even though they're not reacting chemically. And this might be 0:10:46.200 --> 0:10:49.040 a kind of crude analogy, but for a rough picture, 0:10:49.120 --> 0:10:52.280 just sort of like imagine surfaces that have a bunch 0:10:52.320 --> 0:10:54.880 of chains and ropes and strings at the edge of 0:10:54.920 --> 0:10:59.400 them getting tangled up with the edge of the other object. Now, 0:10:59.440 --> 0:11:02.280 remember you said there were three or four. This last 0:11:02.280 --> 0:11:05.640 one seems more debatable, but Winkless notes that the adhesive 0:11:05.679 --> 0:11:10.680 product manufacturer three M also identifies a fourth possible type 0:11:10.720 --> 0:11:15.760 of adhesion, and this is electrostatic. Sometimes, if you are 0:11:15.880 --> 0:11:19.680 about to attach a strip of adhesive tape to a 0:11:19.679 --> 0:11:22.920 piece of paper, you will see the paper actually kind 0:11:22.960 --> 0:11:26.040 of move through the air like it's reaching out toward 0:11:26.160 --> 0:11:28.280 the tape. You know, they want to you know, it 0:11:28.360 --> 0:11:31.920 wants to be found, like the one ring, and it's 0:11:32.280 --> 0:11:34.440 kind of like it's being attracted by a magnet because 0:11:34.520 --> 0:11:37.559 it's sort of is This is because the tape accumulates 0:11:37.960 --> 0:11:40.600 charged particles as you peel it off of the roll, 0:11:41.120 --> 0:11:44.920 and there is attraction due to static electricity there same 0:11:44.960 --> 0:11:47.679 reason you know, you get static electricity on a balloon 0:11:47.840 --> 0:11:50.320 or something and then it lifts your hair off of 0:11:50.360 --> 0:11:51.079 your head. 0:11:51.320 --> 0:11:54.200 Yeah, or occasionally in that scenario where there's some little 0:11:54.240 --> 0:11:57.560 bit of plastic garbage or packaging that you are trying 0:11:57.600 --> 0:12:00.000 to throw away and it just clings to your hand 0:12:00.160 --> 0:12:02.600 and you can't fling it away, even though there's obviously 0:12:02.640 --> 0:12:05.880 nothing sticky on your hands. You weren't just messing around 0:12:05.920 --> 0:12:09.120 with glue, you haven't, you know, you've washed your hands. 0:12:09.320 --> 0:12:11.240 But yeah, it's sticking to you because of the static. 0:12:11.480 --> 0:12:14.320 So that is a real force. But Winkles says that 0:12:14.400 --> 0:12:17.160 she doubts whether this should really be considered a true 0:12:17.280 --> 0:12:22.200 adhesive force that like meaningfully sticks objects together, because while 0:12:22.200 --> 0:12:25.200 it might cause an initial attraction, this is not really 0:12:25.280 --> 0:12:28.120 what would like hold a you know, an adhesive tape 0:12:28.160 --> 0:12:31.520 firmly to the paper, what prevents it from peeling off? 0:12:32.480 --> 0:12:35.920 But it's important to note she says that no single 0:12:35.960 --> 0:12:40.679 one of these forces fully explains stickiness, and she writes quote, 0:12:40.720 --> 0:12:45.120 for any given adhesive product, it's almost impossible to determine 0:12:45.160 --> 0:12:48.439 exactly which model or models might be operating. 0:12:50.240 --> 0:12:53.120 That's that's interesting just even to think of in terms 0:12:53.200 --> 0:12:55.560 of hobbyists, you know, because there's so many different types 0:12:55.600 --> 0:12:57.640 of glues, and you get into any given hobby, you 0:12:57.679 --> 0:12:59.680 might think, well, all clues are the same, but of 0:12:59.679 --> 0:13:03.600 course they're most certainly not. You know, some expand some don't. 0:13:04.320 --> 0:13:09.199 You know, some are more about like essentially melting one 0:13:09.200 --> 0:13:14.079 bit of plastic into another. So yeah, it's I guess 0:13:14.120 --> 0:13:16.560 the thing we keep running up against is like everything 0:13:16.640 --> 0:13:20.120 involving stickiness. There's like this level of language you have 0:13:20.160 --> 0:13:22.319 to get past, as well as sort of the level 0:13:22.360 --> 0:13:25.480 of human perspective, you know, like we're just we're just 0:13:25.520 --> 0:13:27.679 too big. We're not on the same level where all 0:13:27.720 --> 0:13:29.160 of this is actually taking place. 0:13:29.520 --> 0:13:31.960 Yes, And I think also when we think about it, 0:13:31.960 --> 0:13:35.280 we're usually thinking, we're trying to think too simply, we 0:13:35.320 --> 0:13:37.440 think about it in one direction. We think, like why 0:13:37.440 --> 0:13:40.480 does X stick to why? Like why does duct tape 0:13:40.559 --> 0:13:43.520 stick to the wall, And we think that there would 0:13:43.559 --> 0:13:46.560 be one answer for that. There is one cause. But 0:13:46.720 --> 0:13:50.000 it might be better to think about stickiness as an 0:13:50.000 --> 0:13:54.520 emergent system that relies on many different things interacting, rather 0:13:54.600 --> 0:14:08.559 than a property one thing does to another. Now, remember 0:14:08.600 --> 0:14:11.800 all of everything I've been saying so far was about adhesion, 0:14:11.880 --> 0:14:15.720 how two different materials cling to each other. Another important 0:14:15.760 --> 0:14:19.720 factor in stickiness is cohesion, the tendency of a material 0:14:19.760 --> 0:14:23.640 to stick to itself. So in order for a sticky 0:14:23.680 --> 0:14:26.240 material like paint to work the way that it's supposed to, 0:14:26.600 --> 0:14:29.520 it has to be both adhesive meaning it sticks to 0:14:29.560 --> 0:14:33.400 the wall, and cohesive, meaning it sticks to itself. If 0:14:33.440 --> 0:14:35.960 either of these properties fails, then it's not going to 0:14:36.000 --> 0:14:40.000 be good paint. Another interesting factor that Winkless discusses in 0:14:40.040 --> 0:14:43.880 this chapter is what's known as surface energy. So when 0:14:43.920 --> 0:14:45.560 you come back to that image of you put a 0:14:45.640 --> 0:14:48.760 drop of some kind of liquids, some adhesive liquids, sitting 0:14:48.840 --> 0:14:52.720 on a flat, solid surface, the nature of the solid 0:14:52.760 --> 0:14:57.120 material that the liquid is sitting on also influences how 0:14:57.200 --> 0:15:00.880 well the adhesive sticks and one of the carearacteristics that 0:15:01.040 --> 0:15:06.640 matters is that solid material's surface energy. So technically, the 0:15:06.680 --> 0:15:10.560 surface energy of a material is the extra energy present 0:15:10.680 --> 0:15:14.200 at the outside of a solid mass compared to the 0:15:14.360 --> 0:15:18.320 energy present inside the mass. And this extra energy is 0:15:18.320 --> 0:15:21.800 there because of imbalances of molecular bonds on the surface 0:15:21.920 --> 0:15:25.680 of the object. But for a more intuitive understanding of 0:15:25.720 --> 0:15:29.160 surface energy, you can think about it basically as equivalent 0:15:29.200 --> 0:15:33.640 to wet ability. Usually, you can predict how well and 0:15:33.760 --> 0:15:37.120 adhesive will stick to a surface by looking at how 0:15:37.200 --> 0:15:41.280 easily the surface gets wet, how well it attracts water. 0:15:41.800 --> 0:15:45.520 And a common test used to measure surface energy is 0:15:45.560 --> 0:15:49.040 to look at what's known as the contact angle of 0:15:49.120 --> 0:15:51.800 a drop of water on the surface of the material. 0:15:52.200 --> 0:15:54.880 That might sound kind of abstract, but it's actually when 0:15:54.880 --> 0:15:58.360 you see it illustrated, it's pretty easy to understand. So 0:15:59.000 --> 0:16:01.840 imagine you put a drop of water flat on a 0:16:01.880 --> 0:16:05.800 solid surface, and it can be it could be wood, metal, cardboard, whatever. 0:16:06.800 --> 0:16:10.120 Watch what the water does. Does it spread out and 0:16:10.240 --> 0:16:14.080 form a wide, flat disk or kind of a lens shape, 0:16:14.880 --> 0:16:17.320 or does it stand up a little bit taller and 0:16:17.360 --> 0:16:21.040 form kind of a flat bottomed hemisphere or does it 0:16:21.080 --> 0:16:23.680 sit way high up in almost kind of a full 0:16:23.760 --> 0:16:26.920 sphere or bead shape. The first one I talked about, 0:16:26.920 --> 0:16:30.840 the wide flat lens of water is what or has 0:16:30.880 --> 0:16:34.280 what's known as a low contact angle. If you measure 0:16:34.320 --> 0:16:37.960 the angle between the water droplet and the flat surface, 0:16:38.080 --> 0:16:41.400 it's going to be pretty narrow, well below ninety degrees. 0:16:41.880 --> 0:16:45.960 A low contact angle means that this surface likes water. 0:16:46.080 --> 0:16:49.400 It attracts water, and it has a high surface energy. 0:16:49.520 --> 0:16:51.160 And you can kind of see that because the water's 0:16:51.200 --> 0:16:55.240 like spreading out. It's the water wants to touch the surface. Meanwhile, 0:16:55.440 --> 0:16:58.480 the bead of water that sits almost like a sphere 0:16:58.600 --> 0:17:01.280 or a ball up on the surface has a very 0:17:01.360 --> 0:17:05.719 high contact angle. It minimizes contact with the solid, and 0:17:05.760 --> 0:17:08.800 this indicates that the solid has a low surface energy, 0:17:09.000 --> 0:17:12.080 and it's a substance that wants to fight off wetness. 0:17:12.119 --> 0:17:14.359 It wicks away the moisture. So you might think of 0:17:14.480 --> 0:17:17.639 like a think of like a waxy leaf, you know, 0:17:17.680 --> 0:17:20.000 where that you see water hidden and it just rolls 0:17:20.119 --> 0:17:22.840 right away. It's like what you know, it almost seems 0:17:22.840 --> 0:17:27.440 like it's impossible for it to get wet. In most cases, 0:17:28.160 --> 0:17:34.359 this quality the surface energy correlates with stickiness. Surfaces with 0:17:34.440 --> 0:17:37.760 a high energy that attract water then and form that 0:17:37.800 --> 0:17:42.360 flat disc shape are also usually easier to stick things too, 0:17:43.040 --> 0:17:46.359 and Winkless writes, this is kind of interesting. Surface energy 0:17:46.480 --> 0:17:50.240 also tends to correlate with the coefficient of friction. It's 0:17:50.280 --> 0:17:52.280 not a hard and fast rule by any means, but 0:17:52.280 --> 0:17:55.640 if a material has low surface energy, if it's slippery 0:17:55.680 --> 0:18:00.600 to liquids, it is often also low friction slippery to solids. 0:18:01.280 --> 0:18:03.960 So I thought that's kind of interesting. As she says, 0:18:03.800 --> 0:18:07.639 it doesn't hold in every single case, but generally, the 0:18:07.720 --> 0:18:11.639 easier it is to kind of like slide smoothly over 0:18:11.680 --> 0:18:15.760 something without rubbing or sticking to it, also that surface 0:18:15.800 --> 0:18:18.359 that you're sliding over is going to be harder to 0:18:18.560 --> 0:18:22.360 like stick sticky things to. But also on the subject 0:18:22.359 --> 0:18:24.840 of surface energy, this coming back to what we were 0:18:24.840 --> 0:18:27.240 talking about earlier. I was really not expecting a book 0:18:27.280 --> 0:18:31.359 chapter about the science of stickiness and adhesion to contain 0:18:31.480 --> 0:18:35.480 much controversy. But you know, again, this just feels like 0:18:35.520 --> 0:18:38.080 one of those topics that you would find already pretty 0:18:38.160 --> 0:18:41.720 much settled and more just kind of standardized textbook explanations, 0:18:41.760 --> 0:18:44.879 like we all know how this works, but once again, 0:18:44.880 --> 0:18:47.520 this topic still does contain a lot of mystery and 0:18:47.600 --> 0:18:51.159 room for disagreement. And one of those areas of disagreement 0:18:51.480 --> 0:18:55.760 that Winkless documents is disagreements between materials scientists and chemists 0:18:56.280 --> 0:19:01.240 about how important surface energy actually is when you're making 0:19:01.440 --> 0:19:05.399 things like glues or adhesives that are supposed to hold 0:19:05.520 --> 0:19:10.440 together to different solid materials. So she cites a professor 0:19:10.520 --> 0:19:12.720 named Stephen Abbott, who is a fellow with the Royal 0:19:12.760 --> 0:19:16.080 Society of Chemistry, who argues that, and these are abbots 0:19:16.119 --> 0:19:20.480 words quote, surface energy is undoubtedly useful for paint, but 0:19:20.600 --> 0:19:24.879 for practical adhesive systems where we're actually sticking stuff together, 0:19:24.960 --> 0:19:28.640 it's basically irrelevant, thousands of times too small to give 0:19:28.720 --> 0:19:31.520 us what we need, and yet people are obsessed with it. 0:19:32.240 --> 0:19:35.400 So he seems almost mildly annoyed by this. Maybe I'm 0:19:35.440 --> 0:19:38.080 reading too much tone into that, but either way, I 0:19:38.080 --> 0:19:41.359 thought it was fascinating that this topic is has so 0:19:41.400 --> 0:19:44.840 many more questions within it than I realized, Like and 0:19:44.920 --> 0:19:48.520 the fact that we have lots of adhesive products that 0:19:48.600 --> 0:19:51.040 work pretty well, Like you know, they're companies that make 0:19:51.400 --> 0:19:54.600 tapes and glues and sticky notes and all kinds of things. 0:19:54.600 --> 0:19:58.359 They stick to one another pretty effectively. And we know 0:19:58.680 --> 0:20:02.640 at least some and may all of the underlying mechanisms 0:20:02.680 --> 0:20:06.560 by which these by which these products work, and they 0:20:06.560 --> 0:20:09.440 do work, and yet you still can't say in every 0:20:09.520 --> 0:20:14.199 case which mechanism or mechanisms are making the difference. And 0:20:14.240 --> 0:20:17.280 part of this is because stickiness is not merely a 0:20:17.320 --> 0:20:20.920 property of one material, but, as we were saying, an 0:20:20.960 --> 0:20:26.280 interaction between two or more materials and the conditions under 0:20:26.400 --> 0:20:30.359 which they interact. And at the later on in this chapter, 0:20:30.720 --> 0:20:36.040 Winkless quotes the same researcher, Stephen Abbott, saying, quote, adhesion 0:20:36.160 --> 0:20:39.600 is a property of the system. It's not a property 0:20:39.640 --> 0:20:43.800 of like the individual substance. But it's all these things 0:20:43.880 --> 0:20:50.399 interacting together. They have adhesive behavior as a whole or not. 0:20:51.720 --> 0:20:54.000 Yeah, I think that's key. That's key to keep in mind, 0:20:54.040 --> 0:20:57.560 and it's it also factors into what I'm about to 0:20:57.560 --> 0:20:59.800 discuss here in a minute, because originally the plan was 0:21:00.119 --> 0:21:02.200 that I thought, well, we'll roll through a few different 0:21:02.200 --> 0:21:05.080 animal examples of which ones are sticky and why are 0:21:05.160 --> 0:21:10.199 they sticky? Foolishly thinking again that we must have have 0:21:10.320 --> 0:21:13.199 this settled. It must be settled how this particular animal 0:21:13.240 --> 0:21:16.400 sticks to a wall. And we do know a lot 0:21:17.200 --> 0:21:20.560 about this topic, but it's maybe not as perfect of 0:21:20.680 --> 0:21:24.720 knowledge as one might expect. And and and I do 0:21:24.840 --> 0:21:27.160 have to, you know, to admit that. Of course, this 0:21:27.280 --> 0:21:29.000 is the case with plenty of plenty of other things 0:21:29.040 --> 0:21:31.760 about animals that we are even very familiar with. I mean, 0:21:32.040 --> 0:21:34.600 even a house cat has its secrets. There are things 0:21:34.640 --> 0:21:38.760 about house cat behavior that we have varying ideas about 0:21:38.800 --> 0:21:43.119 and we haven't completely worked out. But yeah, with stickiness, 0:21:43.160 --> 0:21:45.639 it's easy just to again to completely take it for granted, 0:21:45.680 --> 0:21:48.320 to approach it from our you know, look at it 0:21:48.359 --> 0:21:53.560 through the fog of our scale and our language and think, oh, yeah, 0:21:53.640 --> 0:21:56.280 well it just sticks right. It's like, you know, it's 0:21:56.320 --> 0:21:57.320 it's like a suction cup. 0:21:57.520 --> 0:22:00.520 Well, speaking of suction cups, that brings up an interesting thing, 0:22:00.560 --> 0:22:03.520 which is that on the macroscopic scale, you can get 0:22:03.800 --> 0:22:06.760 stickying forces that have nothing to do with any of 0:22:06.760 --> 0:22:08.639 the stuff we've been talking about so far, because we 0:22:08.640 --> 0:22:12.560 were just talking about like surfaces sticking to one another 0:22:12.720 --> 0:22:15.600 due to properties of the surfaces. But in the case 0:22:15.640 --> 0:22:17.440 of a suction cup, like if you want to stick 0:22:17.440 --> 0:22:19.760 a suction cup to a window and climb a skyscraper 0:22:19.840 --> 0:22:22.640 like Tom Cruise in one of those Mission Impossible movies. 0:22:23.000 --> 0:22:25.679 That's a totally different mechanism. What's going on there is 0:22:25.720 --> 0:22:29.879 the suction cup. By evacuating the air from the space 0:22:29.920 --> 0:22:33.040 between the cup and the smooth surface, you are creating 0:22:33.080 --> 0:22:37.399 a low pressure area inside, which allows the atmosphere to 0:22:37.520 --> 0:22:40.119 press on the outside of the cup and hold it 0:22:40.200 --> 0:22:42.959 against the wall. So when Tom Cruise is doing that, 0:22:43.000 --> 0:22:46.359 what he's really doing is letting the atmosphere, the weight 0:22:46.400 --> 0:22:49.479 of the atmosphere press his handholds against the building. 0:22:50.119 --> 0:22:53.200 Is Tom Cruise still climbing up buildings with the suction cups? 0:22:53.200 --> 0:22:55.240 Is that still happening in the current movies. 0:22:55.920 --> 0:22:57.879 I think he was in the most recent one of 0:22:57.920 --> 0:22:58.600 those I saw. 0:22:58.760 --> 0:23:00.760 Maybe that's the way. I can't remember did that, And 0:23:00.880 --> 0:23:03.000 I think I only saw the first Mission Impossible movie, 0:23:03.080 --> 0:23:05.720 And if you told me that he used suction cups, 0:23:05.720 --> 0:23:08.119 I would just assume, Well, I guess he probably used them. 0:23:08.440 --> 0:23:10.560 It seems like the sort of thing he would do. 0:23:10.680 --> 0:23:13.679 I think in the first one he uses magnets, because 0:23:13.680 --> 0:23:17.480 that's when he's on the top of that train, you know, Oh, no, 0:23:18.040 --> 0:23:21.160 John Voight, and they're fighting for a helicopter on top 0:23:21.200 --> 0:23:21.680 of a train. 0:23:22.080 --> 0:23:25.440 I remember John Voight, And don't they lower him into lasers? 0:23:25.560 --> 0:23:27.440 Is that the movie with lowering endo lasers. 0:23:27.359 --> 0:23:28.520 Lower him in the lasers. 0:23:28.760 --> 0:23:31.920 Yeah, like room full of like laser trip wires and 0:23:31.920 --> 0:23:33.800 they have to like it comes down from. 0:23:33.640 --> 0:23:37.040 The cel Oh I don't know, Yeah, yeah, yeah. The 0:23:37.080 --> 0:23:38.960 first one is where they put Tom Cruise on a 0:23:39.080 --> 0:23:41.959 rope and they lower him down through out of an 0:23:42.000 --> 0:23:45.240 air vent into a room that the floor is lava. 0:23:45.320 --> 0:23:47.480 You can't touch the floor or the alarms will golf. 0:23:47.680 --> 0:23:50.920 And that was so he could steal the knock list, 0:23:51.119 --> 0:23:55.840 you know, the knocklst I had VHS to the first Yeah. 0:23:56.240 --> 0:23:59.800 I guess I only saw it once. Then. Yeah. I 0:24:00.240 --> 0:24:01.800 don't have any strong feelings about it one one or 0:24:01.800 --> 0:24:04.440 the other, but I mean I admire, I admire the 0:24:04.960 --> 0:24:06.520 commitment to amazing stunts. 0:24:07.000 --> 0:24:10.200 Apart from like the coronal mass ejection of star power 0:24:10.200 --> 0:24:12.639 that is Tom Cruise. Most of those movies have a 0:24:12.680 --> 0:24:15.280 pretty cool supporting cast. Oh you know the first one 0:24:15.359 --> 0:24:19.360 it had Ving Raims and John Renau. 0:24:19.840 --> 0:24:23.040 Yeah, yeah, I believe you're right. Yeah, yeah, strong casts 0:24:23.520 --> 0:24:27.560 all right. Well, speaking of star power, and speaking of 0:24:27.640 --> 0:24:31.440 daring stunts. The main creature we're going to talk about 0:24:31.440 --> 0:24:35.040 here today is going to be the gecko. I'm also 0:24:35.040 --> 0:24:36.720 going to get a little bit into Spider Man later, 0:24:36.720 --> 0:24:39.560 but Spider Man's not real. The gecko is real, and 0:24:39.600 --> 0:24:42.840 the gecko is quite amazing, one of the most famous 0:24:42.880 --> 0:24:46.840 sticky animals of all, though to be clear, not all 0:24:46.920 --> 0:24:52.120 geckos have this ability. For instance, the oft domesticated leopard gecko. 0:24:52.840 --> 0:24:54.960 There's actually one of these living in my house. It's 0:24:55.320 --> 0:24:59.200 my son's pet, is a ground dwelling lizard and does 0:24:59.240 --> 0:25:02.120 not have this ability. But geckos are found on every 0:25:02.160 --> 0:25:08.639 continent except Antarctica various species of the infraorder Gekota. Of these, 0:25:08.840 --> 0:25:13.760 some sixty percent have adhesive toepads that enable climbing, although 0:25:13.760 --> 0:25:16.840 this ability has apparently been lost and gained many times 0:25:16.840 --> 0:25:17.640 over their evolution. 0:25:18.160 --> 0:25:21.080 Now, when you hear that a gecko has adhesive toepads, 0:25:21.880 --> 0:25:23.720 first of all, that might make sense because you've probably 0:25:23.720 --> 0:25:27.119 seen a gecko climbing up a flat surface like a 0:25:27.200 --> 0:25:30.760 you know, a window pane or a sliding door, or 0:25:30.960 --> 0:25:33.240 the wall of a building or a tree trunk, or 0:25:33.240 --> 0:25:36.399 even climbing on the underside of things. Again, much like 0:25:36.440 --> 0:25:40.080 tom cruise kind of doing overhang free climbs, going around 0:25:40.080 --> 0:25:43.000 on the ceiling. It is pretty amazing what they're able 0:25:43.040 --> 0:25:46.520 to do, and across the range of surfaces across which 0:25:46.520 --> 0:25:49.919 they're able to do it. So you might just assume, okay, 0:25:49.960 --> 0:25:53.000 well they got you know, toes that feel like glue. 0:25:53.040 --> 0:25:54.520 Like if you were to go put your hand on 0:25:54.560 --> 0:25:57.960 a gecko's toe, it would be a gross, sticky you know, 0:25:57.960 --> 0:26:00.399 almost kind of like a like a sugar seer or 0:26:00.400 --> 0:26:03.919 something like that. But no, no, that's not the case. 0:26:04.400 --> 0:26:06.760 If you go and look at the toe and feel 0:26:06.840 --> 0:26:09.640 the toe of a gecko, the kind that has these 0:26:09.680 --> 0:26:13.200 amazing climbing powers and clinging powers, it feels totally smooth. 0:26:13.359 --> 0:26:16.639 It is not covered in a sticky adhesive like the 0:26:16.640 --> 0:26:17.639 back of duct tape. 0:26:18.000 --> 0:26:20.679 Yeah, it's one of the things that's long fascinated us 0:26:20.720 --> 0:26:23.960 about the gecko. And again, geckos are widespread, so they've 0:26:24.000 --> 0:26:26.840 been there. They're around for great thinkers of different ages 0:26:26.880 --> 0:26:32.080 to potentially ponder them, and in fact, Aristotle mentions them 0:26:32.600 --> 0:26:36.520 in the History of Animals, the fourth century BCE text. 0:26:36.880 --> 0:26:39.399 If you start looking searching around in that text for 0:26:39.560 --> 0:26:41.800 mentions of the gecko, they do come up several times. 0:26:43.359 --> 0:26:47.520 But he also writes of the amazing climbing ability of 0:26:47.560 --> 0:26:50.919 the quote unquote gecko lizard to quote run up and 0:26:51.000 --> 0:26:54.440 down a tree in any way, even with the head downwards. 0:26:55.160 --> 0:26:59.040 So even Aristotle thought that this was pretty interesting, though 0:26:59.080 --> 0:27:02.160 I don't believe he offers any possible explanation for it, 0:27:02.200 --> 0:27:03.960 is just kind of an observation about you know, I 0:27:04.000 --> 0:27:05.840 think he's comparing it to another creature. Here. 0:27:06.480 --> 0:27:10.719 The quest to understand how gecko toes cling to all 0:27:10.800 --> 0:27:13.919 these different surfaces and allow it to walk straight up 0:27:14.000 --> 0:27:17.840 vertical walls of any roughness or smoothness, to cling to 0:27:17.920 --> 0:27:22.120 ceilings and overhangs. This goes way way back, and people 0:27:22.160 --> 0:27:25.520 have put forward tons of hypotheses over the years. Again, 0:27:25.560 --> 0:27:28.560 coming back to our mission, impossible digression was due to 0:27:28.960 --> 0:27:31.720 talking about suction cup climbing, and for a long time 0:27:32.200 --> 0:27:35.200 a lot of people thought that the geckos did climb 0:27:35.240 --> 0:27:38.639 by essentially using suction cup grips. But that's not the case. 0:27:39.040 --> 0:27:43.040 Yeah, At different points they you know, hypotheses included sticky 0:27:43.080 --> 0:27:46.800 secretions like we've mentioned, suction cups, also tiny hooks. You know, 0:27:46.840 --> 0:27:51.240 these are all decent hypotheses to work with but it 0:27:51.280 --> 0:27:55.280 didn't take too long for various naturalists and ultimately scientists 0:27:55.359 --> 0:27:57.679 and thinkers in general to realize, well, none of these 0:27:57.720 --> 0:28:01.520 are really explaining it. Something else is goinging on, and 0:28:01.600 --> 0:28:03.920 it seems like it's something maybe more you know, more 0:28:03.920 --> 0:28:08.159 physical certainly than chemical. But once again, like it's our 0:28:08.680 --> 0:28:10.720 perspective and our language kind of get in the way 0:28:10.760 --> 0:28:14.560 of like simple understanding of what the get go is doing. 0:28:15.000 --> 0:28:17.840 And I find my experience with researching this it was 0:28:17.920 --> 0:28:20.679 kind of like like the Powers of ten sort of 0:28:20.840 --> 0:28:24.440 experiences ZUSA in you know, yes, because you start off 0:28:24.520 --> 0:28:27.479 with like a simple question, well, why can gecko's climb walls? 0:28:27.640 --> 0:28:30.200 And the answer is, well, because they have special flexible 0:28:30.359 --> 0:28:33.119 adhesive ridges on their toes. And if you wanted, you 0:28:33.119 --> 0:28:35.560 could stop there and be like, okay, question answered, I 0:28:35.560 --> 0:28:39.400 can go home now. But but then you might ask 0:28:39.480 --> 0:28:43.240 the follow up question, well, how do their adhesive toes work? Well, 0:28:43.280 --> 0:28:46.560 the answer is the toes have special tiny hairs like 0:28:46.640 --> 0:28:49.160 even you know, far smaller than what we think of 0:28:49.240 --> 0:28:53.440 as hairs called ceta on them. And then you might say, okay, 0:28:53.520 --> 0:28:55.440 I got it. I can go home now, that's what's 0:28:55.480 --> 0:28:55.840 doing it. 0:28:56.800 --> 0:29:00.280 But wait, yeah, how are the tiny hair What do 0:29:00.360 --> 0:29:02.520 the tiny hairs do? Or how are they sticky? How 0:29:02.560 --> 0:29:03.720 do they stick well? 0:29:03.800 --> 0:29:08.120 Each of these has even smaller bristles called spatula on them. 0:29:08.360 --> 0:29:11.000 Right, So, one way I've seen this described is all 0:29:11.040 --> 0:29:13.760 these tiny little hairs. If you can zoom way way in, 0:29:13.960 --> 0:29:16.920 like smaller on a scale smaller than you can see 0:29:16.960 --> 0:29:18.880 with visible light. You have to use like a scanning 0:29:18.920 --> 0:29:23.720 electron microscope, you can see that each hair like frayse 0:29:23.920 --> 0:29:26.600 like a rope that just goes out to like millions 0:29:26.640 --> 0:29:30.600 of little fibers that are beyond microscopic. They're down on 0:29:30.640 --> 0:29:35.640 the nanoscale. They're super super tiny, frayed out to uncountable ends. 0:29:35.960 --> 0:29:38.640 Yeah, I mean, there's so many that a given gecko 0:29:39.320 --> 0:29:42.160 i've read have somewhere in the neighborhood of two billion 0:29:42.200 --> 0:29:45.560 of these on the pads of their toes combined. 0:29:45.880 --> 0:29:49.760 Okay, so on their toes they have these ridges. The ridges, 0:29:49.760 --> 0:29:51.920 by the way, are called lamelli, and then on the 0:29:52.000 --> 0:29:55.880 lamelly they have the setae, and the setae are little hairs, 0:29:55.920 --> 0:29:59.000 and those hairs fray out into these little frayed bristly 0:29:59.120 --> 0:30:02.200 ends called spatchel. But what does the spacially do. What 0:30:02.240 --> 0:30:03.800 are those how do they work? 0:30:04.240 --> 0:30:08.440 Well? The answer here is well, it's complicated, but the 0:30:08.840 --> 0:30:12.680 basic idea is that their stickiness seems to depend on 0:30:12.760 --> 0:30:15.760 a combination of intermolecular forces. 0:30:16.080 --> 0:30:19.160 Yeah, it does seem like there are maybe multiple forces involved, 0:30:19.240 --> 0:30:22.240 though the sources I was looking at zeroed in on 0:30:22.440 --> 0:30:25.840 the most agreed upon explanation having to do with what 0:30:25.920 --> 0:30:27.720 are known as Van Derval's forces. 0:30:28.040 --> 0:30:31.320 Yes, van der Waals force named for Johannes Diedrich van 0:30:31.360 --> 0:30:35.240 der Waals who lived eighteen thirty seven through nineteen twenty three. 0:30:36.400 --> 0:30:38.800 There's an excellent two thousand and two article I've been 0:30:38.960 --> 0:30:43.160 shouse that I that I One of the sources I 0:30:43.200 --> 0:30:46.400 turned to for this section is you can find on 0:30:46.480 --> 0:30:50.280 science dot org has the just perfect title how Geckos 0:30:50.360 --> 0:30:56.880 stick on de valls at Waals spelling for walls. So yes, 0:30:56.920 --> 0:31:00.320 that as of two thousand and two is to gused 0:31:00.320 --> 0:31:04.880 in this article like that is the primary hypopsis for 0:31:05.040 --> 0:31:09.520 how the gecko's toepads are ultimately sticking to the wall. 0:31:10.240 --> 0:31:12.400 But another one that was being looked at at this 0:31:12.560 --> 0:31:15.520 time in an article I'm going to side here is 0:31:15.560 --> 0:31:19.160 this idea that it could have been water based capillary forces, 0:31:20.160 --> 0:31:22.800 so like a thin film of water between pads and 0:31:22.840 --> 0:31:27.120 the climbing surface. Quote. Because water molecules are polar, their 0:31:27.120 --> 0:31:30.520 electrical charges aren't evenly distributed. They might stick to some 0:31:30.760 --> 0:31:32.960 polar molecule in gecko's feet. 0:31:33.200 --> 0:31:36.080 Oh okay. Now on the opposite side of that, what 0:31:36.120 --> 0:31:38.640 I've been reading about gecko's feed is that they seem 0:31:38.680 --> 0:31:43.600 to be composed largely of water repelling hydrophobic materials. But 0:31:43.880 --> 0:31:46.000 that again, I think it's complicated. 0:31:46.400 --> 0:31:50.800 Yes, yeah, Now to come back to vander Walls here, 0:31:51.920 --> 0:31:56.440 science writer Eleanor Nelson put together a great explainer on 0:31:56.480 --> 0:31:59.360 this whole topic for ted D several years ago. You 0:31:59.360 --> 0:32:01.320 can look this up. There's a video on ted ED 0:32:01.360 --> 0:32:03.800 about the gecko to search for ted ed gecko and 0:32:03.880 --> 0:32:06.160 you can watch it as great visuals to help explain 0:32:06.200 --> 0:32:09.960 all this. But she stresses that what we're talking about 0:32:10.000 --> 0:32:14.280 here isn't attraction between charged molecules positive or negative, but 0:32:14.360 --> 0:32:20.240 rather attractiveness between uncharged molecules that experience patches of negative 0:32:20.280 --> 0:32:23.720 and positive charges due to the movement of atoms with 0:32:23.800 --> 0:32:28.920 different electro negativities in the same molecule. So we're talking 0:32:28.960 --> 0:32:33.160 about flickering patches of weak attraction. It's not strong in 0:32:33.240 --> 0:32:36.720 isolation like each of those you know, tiny spatula are 0:32:36.760 --> 0:32:40.120 not you know, pulling things across the room or anything 0:32:40.360 --> 0:32:44.080 remotely like that. But when you have two billion of 0:32:44.080 --> 0:32:47.920 these on a single gecko exploiting the force, it adds up. 0:32:48.040 --> 0:32:50.320 In fact, it adds up so much that a gecko 0:32:50.400 --> 0:32:53.880 can hang by a single digit, you know, from a 0:32:54.000 --> 0:32:57.480 like a ceiling, you know. And it has complete control 0:32:57.520 --> 0:32:59.480 over this as well, so you know, because they can 0:32:59.520 --> 0:33:02.960 manipulate the angle and surface area of those tow ridges 0:33:03.360 --> 0:33:06.920 in just the right way to activate and release that 0:33:07.080 --> 0:33:08.240 stickiness on demand. 0:33:08.600 --> 0:33:11.840 Yeah, it is amazing, especially when you notice like the 0:33:11.880 --> 0:33:14.960 motor activities that the gecko has to coordinate to orient 0:33:15.120 --> 0:33:17.960 these little harris correctly to always cling the right way. 0:33:18.920 --> 0:33:21.520 But I wanted to clarify one thing because it took 0:33:21.520 --> 0:33:23.280 me a minute to understand what was going on with 0:33:23.320 --> 0:33:28.240 the Vandervals forces. The vanderwalls or Vanderval's forces are something 0:33:28.280 --> 0:33:30.800 that is different from like the attraction you get in 0:33:30.840 --> 0:33:34.840 a polar molecule like water, which is permanently polarized in 0:33:34.920 --> 0:33:36.880 terms of a charge, so it's always going to be 0:33:36.920 --> 0:33:39.920 able to attract one way or another because it's got 0:33:39.920 --> 0:33:42.160 a you know, negative charge on one side, positive on 0:33:42.200 --> 0:33:46.760 the other. The Vanderval's forces are, Yeah, they're due to 0:33:47.400 --> 0:33:53.080 the fluctuations in the orientation of electrons around an atom 0:33:53.160 --> 0:33:56.720 that are just random. So they just randomly change over time, 0:33:56.800 --> 0:33:59.680 even when an atom is electrically stable, so this atom 0:33:59.720 --> 0:34:03.600 is not polarized, but things just sort of flicker in 0:34:03.680 --> 0:34:06.360 and out of existence. A charge attraction going one way 0:34:06.440 --> 0:34:09.640 or the other flickers in and out of existence because 0:34:09.880 --> 0:34:14.120 of just random fluctuations of where the electrons are lined up. 0:34:14.520 --> 0:34:19.040 And that in cases where where atoms are packed close 0:34:19.160 --> 0:34:23.800 enough together can actually have an attractive effect, but usually 0:34:23.880 --> 0:34:27.240 atoms are not packed close enough together for that to matter. 0:34:28.000 --> 0:34:30.440 Yeah, this is a if you're still foggy on this, 0:34:30.840 --> 0:34:32.920 I do recommend that ted Ed video because they have 0:34:32.920 --> 0:34:36.640 a nice animation that kind of that illustrates what's going 0:34:36.680 --> 0:34:39.000 on here. At least for me, it helped clarify the 0:34:39.000 --> 0:34:39.520 whole thing. 0:34:40.040 --> 0:34:42.319 Yeah, and so the reason the spatuely are able to 0:34:42.360 --> 0:34:45.000 take advantage of the Vanderwolts force is because they're so 0:34:45.239 --> 0:34:47.239 tiny and there's so many of them. 0:34:47.960 --> 0:35:00.160 Forests of them, I've seen it described a right. So 0:35:00.239 --> 0:35:04.080 coming back to the two thousand and two time period here, 0:35:04.440 --> 0:35:07.279 there was a paper that came out in a two 0:35:07.320 --> 0:35:10.680 thousand and two edition of Integrative and Comparative Biology titled 0:35:11.239 --> 0:35:16.520 Mechanisms of Adhesion in Geckos. This was by Keller autumn 0:35:16.560 --> 0:35:20.640 at All and in this they were exploring the vendor 0:35:20.680 --> 0:35:25.239 val and the water based capillary forces explanations to you know, see, okay, well, 0:35:25.680 --> 0:35:28.200 let's look at these two possible ideas and see which 0:35:28.200 --> 0:35:33.720 one seems to seems more evident when put to the test. 0:35:34.080 --> 0:35:37.960 And they used the aid of semiconductors, so they ruled 0:35:38.000 --> 0:35:42.840 out water droplet hypothesis as it depends on polar surfaces. 0:35:43.080 --> 0:35:46.200 They found in their experiments that geckos could equally climb 0:35:46.200 --> 0:35:49.839 a non polar surface. In this experiment they used a 0:35:49.880 --> 0:35:54.840 semiconductor called gallium arsenide, which is a compound of gallium 0:35:54.840 --> 0:35:58.840 and arsenic. By the way, it is also interesting that 0:35:58.880 --> 0:36:03.560 gecko feet can not adhere to teflon. You may have 0:36:03.800 --> 0:36:07.040 heard this or seen some headlines about this over the years, 0:36:07.080 --> 0:36:11.400 but according to Sarah Chodesh on Popular Science back in 0:36:11.400 --> 0:36:16.480 twenty eighteen, teflon disrupts the Vanderval's force effect here that 0:36:16.640 --> 0:36:19.600 enables them to climb other or seems to be one of, 0:36:19.680 --> 0:36:22.320 if not the primary factors in their ability to climb 0:36:22.320 --> 0:36:26.000 other surfaces. Quote. Vanderval's forces depend on being able to 0:36:26.040 --> 0:36:29.480 induce a positive and negative end of a molecule or atom. 0:36:29.640 --> 0:36:32.600 But the layer of fluorines in Teflon just have this 0:36:32.760 --> 0:36:36.920 permanent negative charge to them. The electrons stay in one place. 0:36:37.400 --> 0:36:39.560 Teflon's not having any of it. Yeah. 0:36:40.239 --> 0:36:42.880 So anyway, that twenty and two study backs up the 0:36:42.960 --> 0:36:46.640 vandervals explanation. In their own words, their findings at the 0:36:46.680 --> 0:36:50.239 time provided quote direct evidence that Vanderval's force is the 0:36:50.280 --> 0:36:54.520 mechanism of adhesion in get Go ceta and that water 0:36:54.560 --> 0:36:58.680 based capillary forces are not significant. So again not to 0:36:58.719 --> 0:37:01.040 say it couldn't be doing something, but it's not the 0:37:01.120 --> 0:37:02.120 significant factor. 0:37:02.920 --> 0:37:06.719 Yes, though it's interesting. In uh the chapter in Winkless's 0:37:06.760 --> 0:37:11.200 book on gecko toes, she talks about, how you know, 0:37:11.280 --> 0:37:14.719 it seems like most researchers in this area kind of agree, Yeah, 0:37:14.719 --> 0:37:19.839 it's Vanderval's force. That's that's the explanation or the main explanation. 0:37:19.920 --> 0:37:22.120 But she says, they all kind of have this bit 0:37:22.160 --> 0:37:25.319 of hesitation when they talk about it, like maybe there's 0:37:25.320 --> 0:37:28.080 something else going on too that we haven't fully figured 0:37:28.080 --> 0:37:29.240 out yet. Yeah. 0:37:29.320 --> 0:37:33.200 I kept thinking about like the experience of trying like 0:37:33.239 --> 0:37:35.640 a fancy cocktail somewhere and you're trying to pick out 0:37:35.640 --> 0:37:38.359 the ingredients just on taste. You know, generally you can 0:37:38.440 --> 0:37:40.279 you can pick out some of the major flavors. But 0:37:41.440 --> 0:37:44.479 are you gonna, you know, absolutely put your money down 0:37:44.719 --> 0:37:47.759 that there are only three ingredients in this cocktail and 0:37:47.800 --> 0:37:51.960 you're there are not four, they're not five, and so forth. 0:37:52.360 --> 0:37:55.120 That's right. What's that tingling in the back of your mouth? 0:37:55.400 --> 0:37:57.240 Could that be an absentthe rense? 0:37:59.239 --> 0:38:03.279 So one sample of this concerning gecko feed This comes 0:38:03.360 --> 0:38:06.520 up in a twenty fourteen article that I was looking 0:38:06.560 --> 0:38:11.600 at role of contact electrification and electrostatic interactions in gecko 0:38:11.600 --> 0:38:14.440 adhesion by A. Zadi at All published in the Journal 0:38:14.680 --> 0:38:19.200 of the Royal Society Interface, and this one discusses the 0:38:19.360 --> 0:38:24.759 CE driven electrostatic interaction. This refers to the contact electrification phenomenon, 0:38:25.200 --> 0:38:29.440 and I understand that this is still controversial. For example, 0:38:29.480 --> 0:38:31.799 in a twenty twenty three paper by song at All, 0:38:32.200 --> 0:38:35.319 in published in the journal Friction. The author's cite the 0:38:35.480 --> 0:38:39.240 controversial aspect of the CE driven explanation, though to be clear, 0:38:39.480 --> 0:38:43.440 it's ultimately more about the level of contribution that's controversial, 0:38:43.640 --> 0:38:46.879 because again it's like saying, well, yes, I think there's 0:38:46.880 --> 0:38:50.680 absinth in this cocktail, but maybe it's just a drop. 0:38:50.800 --> 0:38:53.320 It's like three drops of absinthe I'm not saying it's 0:38:53.400 --> 0:38:57.960 anything more than that, Whereas there might be someone else arguing, actually, 0:38:58.040 --> 0:38:59.799 I think they put an ounce in there, and then 0:38:59.800 --> 0:39:04.560 the fighting and controversy. But anyway, in this song at 0:39:04.560 --> 0:39:09.360 all paper the way they explain it, it seems like 0:39:10.480 --> 0:39:14.040 CE may be part of the situation, but their study 0:39:14.080 --> 0:39:18.000 suggests that its impact is low, perhaps contributing only around 0:39:18.400 --> 0:39:21.840 three percent of the adhesiveness, and this may also be 0:39:21.960 --> 0:39:24.719 why it doesn't help them out with something like teflin, 0:39:25.040 --> 0:39:29.040 which again essentially cancels out Vanderval's force, which, as far 0:39:29.080 --> 0:39:31.920 as we can tell, seems to be the primary factor 0:39:32.120 --> 0:39:35.440 in play here. However, they note that quote long range 0:39:35.480 --> 0:39:39.360 electrostatic forces may play other roles in a distance range 0:39:39.440 --> 0:39:43.640 where the Vanderwals interaction cannot function, So again there could 0:39:43.680 --> 0:39:46.640 be certain situations where it's more important to some degree 0:39:46.719 --> 0:39:47.440 than other times. 0:39:47.880 --> 0:39:50.319 But it does seem clear that whatever else is going on, 0:39:50.400 --> 0:39:53.360 the main ingredient, the whiskey in the cocktail is the 0:39:53.480 --> 0:39:58.360 vandervals interaction. Yes, and another interesting thing here, Rob you 0:39:58.440 --> 0:40:02.279 alluded to this earlier, but it's something that you can 0:40:02.360 --> 0:40:06.600 notice if you watch a gecko actually climbing, which is 0:40:06.680 --> 0:40:10.440 the question of wait, how do they make their toes 0:40:10.600 --> 0:40:13.960 stick and then unstick? So they've got this really powerful 0:40:13.960 --> 0:40:18.560 sticking force, and in some cases the sticking force it 0:40:18.600 --> 0:40:21.080 can hold so much more than the weight of a 0:40:21.080 --> 0:40:24.480 gecko's body. There's one estimate in Winkliss's book about a 0:40:24.520 --> 0:40:26.799 test showing that a gecko I can't remember, I didn't 0:40:26.800 --> 0:40:29.480 write down the number, but it's like a gecko's grip 0:40:29.520 --> 0:40:33.440 could hold hundreds of pounds up on the wall, despite 0:40:33.440 --> 0:40:35.640 the fact that the gecko itself only weighs like half 0:40:35.640 --> 0:40:38.279 a pound. Now, on one hand, you might think, well, 0:40:38.280 --> 0:40:40.719 that's kind of overkill, but of course that would be 0:40:41.239 --> 0:40:43.920 testing it in sort of ideal conditions in a lab, 0:40:43.960 --> 0:40:46.359 whereas in nature a lot of times the surfaces it's 0:40:46.360 --> 0:40:48.680 climbing on are going to be dirty, which will reduce 0:40:48.760 --> 0:40:52.720 the adhesive potential, might be wet, which would potentially reduce 0:40:52.719 --> 0:40:56.520 adhesive potential. Some of their toes might be injured or something. 0:40:56.640 --> 0:41:00.520 Some of the lamilly might come off. In nature, you know, 0:41:00.600 --> 0:41:02.960 it's better safe than sorry. When you're a gecko, have 0:41:03.440 --> 0:41:06.720 a lot of sticking power. But yeah, anyway, the question 0:41:06.840 --> 0:41:09.319 is how does it stick and unstick and climb in 0:41:09.320 --> 0:41:11.360 different directions? And a lot of this comes down to 0:41:11.760 --> 0:41:15.800 how it lifts and attaches its toes to the surface 0:41:16.239 --> 0:41:18.799 and how it orients them. So like you, if you 0:41:18.880 --> 0:41:22.800 watch a gecko crawling up a wall, it will tend 0:41:22.840 --> 0:41:26.680 to sort of like peel its peel its toes up 0:41:26.960 --> 0:41:28.960 and then lay them down with all of the toes 0:41:29.000 --> 0:41:31.600 facing upward on the wall. But if you see a 0:41:31.600 --> 0:41:35.319 gecko climbing down a wall, it will rotate its back 0:41:35.360 --> 0:41:38.800 feet so that its toes are facing up. Because the 0:41:39.800 --> 0:41:43.920 ceta and the spatually on them, they sort of only 0:41:44.000 --> 0:41:46.640 grip effectively when laying in one direction. 0:41:47.480 --> 0:41:50.040 Yeah, one way to think about all this is that again, 0:41:50.160 --> 0:41:54.040 our understanding of what's going on when a gecko climbs 0:41:54.800 --> 0:41:59.440 has not reached a level of perfection, but their exploitation 0:42:00.200 --> 0:42:03.840 of it has reached perfection, like they are the perfect 0:42:04.239 --> 0:42:08.480 manipulators of this force. So it's pretty amazing to watch. 0:42:08.880 --> 0:42:13.200 Now, whenever evolution achieves something this ingenious, you will bet 0:42:13.280 --> 0:42:15.960 that human engineers come running to see, how are they? 0:42:16.440 --> 0:42:18.839 How are they doing that? What's going on there? Could 0:42:18.880 --> 0:42:21.080 I make robots that could do something like that? 0:42:21.360 --> 0:42:26.640 Yeah? Yeah, So of course biomimicry has gazed longingly at 0:42:26.640 --> 0:42:29.840 the gecko for a while now. There have been various 0:42:29.840 --> 0:42:33.840 efforts to create artificial ct with some working prototypes and 0:42:33.960 --> 0:42:38.160 robotics and even human climbing suits popping up in headlines. 0:42:38.200 --> 0:42:39.880 I think there was a DARPA project that made the 0:42:39.880 --> 0:42:43.799 news in twenty fourteen. These have certainly not reached a 0:42:44.000 --> 0:42:47.319 level of perfection yet, but you know, there are some 0:42:47.400 --> 0:42:50.960 interesting applications out there potentially for this, and they're not 0:42:51.000 --> 0:42:54.520 all of them involved like super soldiers climbing the windshield 0:42:54.960 --> 0:42:59.640 or robots cleaning you know, high rise buildings, for instance. 0:42:59.640 --> 0:43:01.960 It's been put far that they could be used in 0:43:02.000 --> 0:43:05.000 low gravity environments. They could even be used, you know, 0:43:05.080 --> 0:43:07.719 to collect space debris in orbit, that sort of thing. 0:43:08.200 --> 0:43:11.200 So the amount of weight that can be supported by 0:43:11.320 --> 0:43:14.080 a gecko's toes and the range over the range of 0:43:14.080 --> 0:43:17.640 different surfaces that they can crawl over is truly astounding 0:43:17.680 --> 0:43:20.560 and sort of a superlative in nature. But there are 0:43:20.600 --> 0:43:23.880 lots of other animals that can crawl up walls, and 0:43:23.960 --> 0:43:27.000 I wonder do many of them make use of similar 0:43:27.320 --> 0:43:29.240 mechanisms or forces well. 0:43:29.520 --> 0:43:32.200 Spiders climb in a similar way and also depend on 0:43:32.600 --> 0:43:36.880 tiny set that make use of Vanderval's force. Though they're 0:43:37.120 --> 0:43:40.080 ultimately like masters of these structures, they also use them 0:43:40.080 --> 0:43:45.720 for other purposes as well, like like sensing sense sounds, vibrations, 0:43:45.760 --> 0:43:49.640 and air currents. But this does lead us back to 0:43:49.680 --> 0:43:54.360 the topic of Spider Man, because, as everyone knows, Spider 0:43:54.360 --> 0:44:00.160 Man can do whatever a spider can, and it's this. 0:44:00.239 --> 0:44:03.319 He can liquefy your innards and slurp them out through 0:44:03.320 --> 0:44:04.520 his mouth orifice. 0:44:05.120 --> 0:44:07.640 Maybe he can, and he chooses not to, But I 0:44:07.640 --> 0:44:09.640 guess that's more of a Isn't there a man There's 0:44:09.640 --> 0:44:11.560 a man spid. I know there's a batman and a 0:44:11.800 --> 0:44:15.880 man bat there's also like a spider man monster creature, 0:44:15.920 --> 0:44:18.200 but I don't know if that's man spider or not 0:44:18.719 --> 0:44:21.200 off the top of my head. But it gets it 0:44:21.200 --> 0:44:24.239 gets so complicated when you start comparing Spider Man to 0:44:24.560 --> 0:44:26.759 spiders because, of course there are all these things that 0:44:26.800 --> 0:44:29.440 don't match up. For example, it's easy to think of 0:44:29.480 --> 0:44:31.400 Spider Man. What does Spider Man do well? He swings 0:44:31.440 --> 0:44:35.480 around on webbing through the through the streets, though he 0:44:35.520 --> 0:44:38.239 does so in a way that's not particularly spider esque, 0:44:38.560 --> 0:44:42.360 and while in some adaptations of Spider Man he's using 0:44:42.960 --> 0:44:46.600 like organic like mutations, like he has like he's you know, 0:44:46.640 --> 0:44:49.040 he's been by a radioactive spider and now he can 0:44:49.320 --> 0:44:52.680 he can shoot webbing out of his wrists. Most versions 0:44:52.680 --> 0:44:55.600 of Spider Man you encounter he has these little gadgets 0:44:55.600 --> 0:44:58.560 that he built that shoot some sort of nylon like webbing. 0:44:58.680 --> 0:45:01.040 So he's this weird mix of like, Okay, I'm part 0:45:01.120 --> 0:45:04.160 Spider but also I have like super crazy sci fi 0:45:04.280 --> 0:45:07.319 weapons as well, and all of these combined to make 0:45:07.360 --> 0:45:09.080 me able to do whatever a spider kit. 0:45:09.520 --> 0:45:11.719 It's not really satisfying that way, is it. He's one 0:45:11.719 --> 0:45:14.040 foot in each world. He's half a Charles B. Griffith 0:45:14.120 --> 0:45:17.839 script where yes it was atomic radiation. But he's half 0:45:17.920 --> 0:45:21.400 Batman and we already have Batman. He makes gadgets. 0:45:21.480 --> 0:45:23.399 Yeah, I mean, I guess I'm not a Spider Man 0:45:23.440 --> 0:45:27.799 purist or anything, but I like the mutant version. I 0:45:27.880 --> 0:45:29.640 like the idea that he's shooting it out of his wrist, 0:45:29.760 --> 0:45:33.000 even though that doesn't really match up. Like spiders don't 0:45:33.440 --> 0:45:36.840 they have spinnerets, they don't have wrist openings or whatever. 0:45:36.920 --> 0:45:40.120 So you know, it's still not one to one. 0:45:40.160 --> 0:45:42.879 I guess Spider Man fans, please don't hate me. I'm 0:45:42.880 --> 0:45:45.239 just joking around. I don't know much about Spider Man. 0:45:45.600 --> 0:45:49.120 I mean, Spider Man is great. But one of Spider 0:45:49.120 --> 0:45:53.120 Man's abilities that is or seems to be universally accepted 0:45:53.120 --> 0:45:56.080 as an ability brought on by the radioactive spider bite 0:45:56.320 --> 0:45:59.440 is his ability to climb walls and stick to ceilings 0:45:59.719 --> 0:46:02.080 with out the aid of his wedding. How does he 0:46:02.160 --> 0:46:05.960 do this well? On one hand, we have to admit 0:46:06.000 --> 0:46:07.600 like this is a fool's errand to try and make 0:46:07.640 --> 0:46:11.960 sense of this. Spider Man climbs walls because he's Spider Man, 0:46:11.440 --> 0:46:16.000 and any kind of like scientific explanation to this comes 0:46:16.080 --> 0:46:20.000 after the fact they were not thinking long and hard 0:46:20.040 --> 0:46:22.839 about the anatomy of a spider when they came up 0:46:22.880 --> 0:46:26.719 with this character. As fun as this character is, so 0:46:26.880 --> 0:46:31.040 any attempt to scientifically explain everything about him is is. 0:46:31.360 --> 0:46:33.279 It can be very fun, but it's not going to 0:46:33.280 --> 0:46:35.960 get you to a place of absolute certainty. 0:46:36.440 --> 0:46:39.920 You might as well ask, exactly scientifically, how do the 0:46:40.000 --> 0:46:42.640 crabs in attack of the crab monsters eat your brains 0:46:42.680 --> 0:46:44.600 and gain your knowledge exactly? 0:46:45.320 --> 0:46:47.399 But like I say, it's a fun exercise, and I've 0:46:47.400 --> 0:46:51.880 been enjoying this book marvel Anatomy by Sumeruk and Wallace, 0:46:52.440 --> 0:46:55.120 and the authors point out several things about Spider Man's 0:46:55.160 --> 0:46:57.600 adhesive abilities and how they match up or don't match 0:46:57.680 --> 0:46:59.960 up with the natural world. One of the main ishu 0:47:01.200 --> 0:47:04.480 that they keep talking about, though, is Okay, Spider Man 0:47:04.640 --> 0:47:07.480 can climb, and perhaps he does this because he has 0:47:07.520 --> 0:47:10.640 little CD on his hands at least or I guess, 0:47:10.680 --> 0:47:13.240 over his entire body, and it allows him to adhere 0:47:13.280 --> 0:47:16.480 to walls. But also he's wearing a full body costume. 0:47:17.080 --> 0:47:21.200 Spider Man is almost never naked when he's clinging to 0:47:21.320 --> 0:47:25.080 walls and so forth, so it raises questions like would 0:47:25.200 --> 0:47:29.640 vander walls work through a pair of spider gloves or 0:47:29.680 --> 0:47:31.960 would that weaken it to some degree. 0:47:32.280 --> 0:47:34.120 I don't think it would work, because the whole thing 0:47:34.120 --> 0:47:36.720 about Vanderval's force is you've got to be incredibly close, 0:47:36.800 --> 0:47:39.960 closer than solids can usually get to each other. That's like, 0:47:40.120 --> 0:47:42.919 that's why the gecko's foot works. It's the tiny little 0:47:43.000 --> 0:47:45.120 thing that can get in there in the cracks and 0:47:45.160 --> 0:47:47.600 crevices in the surface, unlike anything else. 0:47:48.080 --> 0:47:51.040 Well, the author suggests that, well, maybe the ceed poke 0:47:51.200 --> 0:47:54.800 through the costume, but that raises all sorts of questions, 0:47:54.840 --> 0:47:56.640 like then when he takes the costume off, when he 0:47:56.680 --> 0:47:58.799 peels off the sweaty Spider Man costume at the end 0:47:58.800 --> 0:48:00.640 of the day, does it just rich them all off 0:48:00.680 --> 0:48:03.239 and he has to regrow them or I don't know. 0:48:03.280 --> 0:48:06.000 It's a wonder fabric that Iron Man made for him, 0:48:06.000 --> 0:48:07.919 so it lets them out. 0:48:08.080 --> 0:48:08.520 I don't know. 0:48:09.200 --> 0:48:12.520 Again, it just raises more questions than anything. 0:48:13.480 --> 0:48:16.800 I think Spider Man should have finger gloves like a bandit. 0:48:17.320 --> 0:48:20.920 The authors here suggest that maybe Spider Man can actually 0:48:21.000 --> 0:48:25.960 quote consciously control the intra atomic attraction between molecular boundary layers, 0:48:26.880 --> 0:48:30.120 which I suppose sounds reasonable, though I mean this raises 0:48:30.160 --> 0:48:33.080 the question about to what extent this still makes sense 0:48:33.120 --> 0:48:36.880 as a sixties at comic book. Radiation Advancement of natural 0:48:36.880 --> 0:48:41.120 World spider abilities, but I'll take it. I'll take it. 0:48:41.160 --> 0:48:43.840 Sounds good to me. Now. They do point out that 0:48:43.920 --> 0:48:46.760 another character, Spider Woman. I don't know if you're familiar 0:48:46.800 --> 0:48:49.960 with Spider Woman. She was introduced in nineteen seventy seven. 0:48:51.080 --> 0:48:54.440 She just kind of like a red outfit. But she 0:48:54.600 --> 0:48:59.040 is said to be able to climb via secreted biological 0:48:59.120 --> 0:49:03.560 adhesive substances that are on her hands and her feet 0:49:04.120 --> 0:49:09.000 that I guess swiftly penetrate tiny pores in the climbing surface. Also, 0:49:09.480 --> 0:49:13.560 she wears gloves and booties as well, so this secretion 0:49:13.680 --> 0:49:17.200 would have to like rapidly soak through the fabric in 0:49:17.239 --> 0:49:19.680 these cases as well or through the booties and then 0:49:19.719 --> 0:49:22.520 allow her to stick to the walls. And again this 0:49:22.600 --> 0:49:25.240 raises more questions because when you look to the natural world, 0:49:25.480 --> 0:49:29.879 you do see adhesive secretions in some organisms, but they 0:49:29.920 --> 0:49:32.759 tend to be defensive rather than climbing aids. These are 0:49:32.800 --> 0:49:36.360 things that you would extrude when threatened, so that whatever 0:49:36.480 --> 0:49:38.319 was trying to eat you might decide, oh, I don't 0:49:38.360 --> 0:49:39.000 want any of this. 0:49:39.960 --> 0:49:43.440 Yeah, well, maybe I'm not thinking creatively enough, but it 0:49:43.480 --> 0:49:47.760 seems like if you had to secrete enough sticky stuff 0:49:47.960 --> 0:49:49.640 to hold you to a wall every time you wanted 0:49:49.640 --> 0:49:51.400 to climb. That'd just be a lot of stuff that 0:49:51.480 --> 0:49:55.120 sounds like you're secreting, Like do you get dehydrated? Do 0:49:55.160 --> 0:49:57.319 you run out of energy doing that? Well? 0:49:57.360 --> 0:50:00.799 I mean, Spider Man is leaving nylon thread all over 0:50:00.840 --> 0:50:03.320 the city, all over New York as he's fighting crime, 0:50:03.440 --> 0:50:06.200 and I guess somebody has to clean that up. They 0:50:06.200 --> 0:50:08.200 probably didn't think about it much in the sixties, and 0:50:08.200 --> 0:50:10.480 I guess it was acceptable in the eighties, but nowadays, 0:50:10.800 --> 0:50:14.799 like it's what's the what's the environmental impact of this 0:50:14.880 --> 0:50:15.520 crime fighting? 0:50:16.160 --> 0:50:18.560 But once again the genius of the gecko. The gecko 0:50:18.600 --> 0:50:19.600 climbs without goop. 0:50:20.280 --> 0:50:24.440 Yes, yeah, And the authors here they do include a 0:50:24.440 --> 0:50:27.960 bit on one of Spider Man's many enemies. You've perhaps 0:50:27.960 --> 0:50:30.000 heard of, the lizard. I think the lizard was in 0:50:30.200 --> 0:50:32.600 at least one of the movies. I can't remember which 0:50:32.600 --> 0:50:36.920 Spider Man this was, which Spider Man regime, But this 0:50:37.080 --> 0:50:40.200 is a man, a scientist who turns into a great, 0:50:40.239 --> 0:50:44.520 big green lizard and chases Spider Man around. And in 0:50:44.640 --> 0:50:47.520 many of the depictions, the lizard can climb around on 0:50:47.640 --> 0:50:51.279 walls and on the ceiling. In this particular book that 0:50:51.320 --> 0:50:53.680 I was referring to, they discuss it as more of 0:50:53.719 --> 0:50:55.680 a claw thing, which I think makes sense for a 0:50:55.719 --> 0:50:58.400 super villain, you know, big nasty claws. Can you know 0:50:59.640 --> 0:51:03.239 claw into the concrete? Is the creatures climbing around. But 0:51:03.320 --> 0:51:08.040 I've also seen some descriptions that discuss the lizard as 0:51:08.120 --> 0:51:09.759 having gecko abilities. 0:51:10.400 --> 0:51:14.080 Oh okay, so either way claw or gecko, that would 0:51:14.080 --> 0:51:17.799 be San's goop. That would be a mechanical grip of 0:51:17.840 --> 0:51:20.560 some sort or of Vandervohal's force. Yeah. 0:51:20.640 --> 0:51:24.400 But again, I think with a super villain like the Lizard, 0:51:24.440 --> 0:51:29.640 it makes more sense that his climbing ability is visibly destructive, 0:51:31.360 --> 0:51:33.480 though it raises the question like, where's the love for 0:51:33.600 --> 0:51:37.200 the gecko? Then in the creation of Superheroes, I was 0:51:37.239 --> 0:51:39.839 looking around looking at the various databases, and it looks 0:51:39.880 --> 0:51:43.200 like they're a couple of minor Marvel Gecko characters, or 0:51:43.200 --> 0:51:46.840 maybe it's two versions of one character that have existed. 0:51:46.880 --> 0:51:49.600 And it looks like DC Comics also has a Gecko 0:51:49.760 --> 0:51:52.319 or the Gecko. But I don't get this sense that 0:51:52.320 --> 0:51:55.600 these are based on anything, you know, true to the 0:51:55.640 --> 0:51:59.759 get go. But comic book fans out there let us 0:51:59.760 --> 0:52:02.719 know perhaps you have more detail on these Geckos. 0:52:03.400 --> 0:52:06.960 Who is Gordon Gecko? Is he some kind of gecko supervillain? 0:52:08.320 --> 0:52:11.360 I don't know. Maybe it's part of the shared cinematic universe. 0:52:11.640 --> 0:52:13.320 Okay, I think that's all we got for today. 0:52:13.560 --> 0:52:15.160 All right, We're going to go ahead wrap it up here, 0:52:15.160 --> 0:52:16.719 but yeah, write in let us know what you think 0:52:16.719 --> 0:52:21.560 about stickiness in general, the examples of stickiness that we've discussed, 0:52:21.840 --> 0:52:26.480 and yes, even fictional sticky comic book characters and so forth. 0:52:26.880 --> 0:52:29.239 Just a reminder that we're primarily a science podcast here 0:52:29.280 --> 0:52:31.000 at Stuff to Blow Your Mind, with core episodes on 0:52:31.040 --> 0:52:35.000 Tuesdays and Thursdays, listener mail on Mondays, a short form 0:52:35.040 --> 0:52:38.160 monster fact or artifact episode on Wednesdays, and on Fridays. 0:52:38.160 --> 0:52:40.160 We set aside most serious concerns. Who just talk about 0:52:40.160 --> 0:52:42.160 a weird film on Weird House Cinema. 0:52:42.320 --> 0:52:45.920 Huge thanks to our excellent audio producer JJ Posway. If 0:52:45.920 --> 0:52:47.440 you would like to get in touch with us with 0:52:47.520 --> 0:52:49.920 feedback on this episode or any other, to suggest a 0:52:49.960 --> 0:52:52.080 topic for the future, or just to say hello, you 0:52:52.120 --> 0:52:54.799 can email us at contact at Stuff to Blow your 0:52:54.800 --> 0:53:03.240 Mind dot com. 0:53:03.360 --> 0:53:06.319 Stuff to Blow Your Mind is production of iHeartRadio for 0:53:06.400 --> 0:53:10.239 more podcasts from iHeartRadio, visit the iHeartRadio app, Apple podcasts, 0:53:10.320 --> 0:53:26.680 or wherever you listen to your favorite shows.