"On this week's show..." " Argh!" "Oh, no." "..Jem looks at what makes stuff sticky... ..Dr Yan puzzles commuters..." "Whoa!" "..and Dallas goes supersonic." "Oh, my God..." "Whoa!" "That's Bang Goes The Theory, revealing your world with a bang." "Welcome to Bang Goes The Theory, the show that reveals the science behind our world, especially the stuff we might take for granted." "In fact, that's what science is all about - asking tough questions and then finding the answers by experimenting." "Like glue, for example." "You learn to stick things at about the age of four and never really give it a second thought." "But I figured it's time to find out why some things are sticky and others aren't." "Yes, and knowing Jem as we do, he's not going to find the answer to that question in a book." "Have you ever wondered what it is that makes one thing stick to another?" "At the moment, I simply can't think about anything else, cos the only thing holding my boots to that board... is my home-made glue." "Whoa!" "Ooh..." "Oh!" "Aaagh!" "Oh, no." "Agh!" "Aagh!" "Oh!" "Oh!" "OK." "That was pretty strong, but quite frankly, I'm keen to make something a little bit stronger." "So what is it that managed to stick the sole of my boot so hard that I could hang off it..." "until I wriggled." "It's nothing much more exotic than a few pear drops." "It turns out that to a great extent, it's all down to things called electrostatic forces, which are a common phenomenon to anyone who's ever rubbed a balloon on their head." "When you rub a balloon, it gives it a small electrical charge, and you can see that electrical charge attracts an opposite charge on my hair, or...on that polystyrene, or whatever." "Now, on a molecular scale, everything is a little bit electric, and it's the attraction between those electrical charges that holds together almost every substance we know." "So what stops two apparently smooth surfaces from electrically bonding?" "Imagine these are massively magnified versions of two surfaces you want to join." "As you can see, they don't really touch in enough places to stick together electrically." "So what you need to do... is put something down this gap here that will exactly form itself to the contours of this surface, and do the same with this surface, and hold itself together strongly down the middle." "Now, that would be a glue." "What you need for a glue is something that goes in as a liquid, and then turn itself into a solid." "With that in mind, I now fancy making a whole bunch of diy glues from things around the home... and dangling some other presenters from them to see which one's the strongest." "That's the glues, not the presenters." "'That sweetie glue from earlier... '..was so sticky because sugar molecules have electric charge, 'which means they want to stick to anything with an opposite charge." "'To make the glue a bit more forgiving, 'l'm mixing the pear drops with toffee.' l'm going to put it on this fairly small piece of wood and then stick it...get on there, I hope I've got this just right..." "Hopefully, what's happening in there is those sugar molecules are finding electrical charges in the wood fibres, sticking on there rock hard, then solidifying so they go rock hard in the middle and the whole thing almost becomes one." "That's the plan." "Now somebody's got to actually hang off that." "Milk could make a very good glue too, because the proteins in milk also have lots of electrical charges." "If I can isolate them, I think a darn good wood glue could be made." "For separating the proteins out of milk, nothing beats a nice, sharp vinegar." "I'm pouring in the vinegar because vinegar contains acid." "And acid will separate out the milk proteins that I need." "Oh, look at that!" "Urgh!" "They're the milk proteins." "And you can see, once separated out from the milk, they're looking quite good already." "I'll add a bit of bicarb... and some water." "Now, that, believe it or not, should make a very strong wood glue, and when the water evaporates out of that, should hold it extremely well." "Now, I've had enough of cooking for the time being." "I fancy making a glue that's a bit sportier... out of this - a ping-pong ball." "These things are made of a pretty durable solid, one I feel I can dissolve with a household solvent... nail varnish remover." "It doesn't just dissolve nail varnish, it'll dissolve ping-pong balls pretty nicely as well." "What you've got is a solid that's been dissolved, which means you can then paint it on a surface." "It can exactly fit that surface, make all those important electrical attractions so it's bonded to the surface, and then the solvent, if it's like this one, dries off fairly quickly, leaving just the solid behind, but a solid that's bonded." "Unless all that solvent evaporates, this will never turn back into solid ping-pong ball material, which it needs to be if it's going to hold together." "And we're away." "How do you know this stuff, Jem?" "How do you know which materials to pick?" "How do you know that acetone dissolves ping-pong plastic?" "Well, there are certain underlying principles to these things, but mainly, it's just thinking and tinkering." "I have a question." "I understand the electrostatic principle you talked about." "Theoretically, if you had two completely smooth, flat surfaces, would they stick together without glue?" "Not only would they, but they DO." "At the National Physical Laboratories, they have ultra-flat machine surfaces, like reference flat surfaces." "They mustn't put them together, because they would struggle..." "Pop!" "..to pull them apart." " Awesome." "OK, now for something the British have often been accused of - rather snidely in my opinion - and that's only being good at sports where we sit down." "But frankly, I don't care - rowing, cycling, equestrian events and one other, land speed record attempts." "This is an Astra Hawk." "It's the same sort of plane that the Red Arrows use." "And guess what?" "I'm going for a ride." "The Empire Test Pilots' School has been training the guys who test high-performance aircraft like this for 65 years." "And with their help, I'm going to go supersonic." "You're going to go pretty high." "38 or 39,000 feet." "Then we're going to have to dive at the ground, put a lot of energy in, unload and keep going." "We need gravity on our side." "This won't do it on its own." "No, we do need gravity." "If you're on your bike and you want speed, you go downhill, so it's the same principle?" "You could help by pedalling, when we do it." "OK." "Rhys, you've flown these before, haven't you?" "Err, once." "Fine." "'So we're going try and hit the sound barrier, 'but what does that actually mean?" "Well, it's all to do with pressure." "'From the moment we get airborne, 'this plane will be continually squashing the air ahead 'as we ram into it." "That'll create a constant high-pressure wave, 'which will race away from us, travelling at the speed of sound.'" "Ready?" "Let's do it." "OK." "Full power." "Here we go." "Wow." "Whoo-hoo!" "'But when we reach the speed of sound ourselves, known as Mach 1 , 'that pressure wave can't get away, 'and just like snow piling up in front of a snowplough, 'there'll be a build up of pressure ahead of us," "'and that's the sound barrier.'" "'lt's difficult to believe we're already nudging 600mph." "'lt feels almost as if we're just floating.'" "0.4..." "'Though we're not quite at the speed of sound, 'small streams of air are already rushing over parts of the plane 'at supersonic speed, 'causing pockets of intense pressure that buffet the plane about." "'We're in what's known as the transonic zone." "'At this speed, early aviators 'just didn't have enough oomph to go any faster, 'so to them, it was almost like a physical barrier." "'Not so my plane." "'We're climbing to our highest point now, 'ready to make the dive that'll take us through the sound barrier.'" "OK." "Ready to roll, then?" "OK." "Stand by." " Oh, my God, whoa!" "We're going down at an angle now." "Oh, my God!" "'Pulling out of that ludicrously steep dive creates some serious G." "'lt's like there's three extra Dallases sat on top of me.'" "Oh..." "'But guess what?" "'ln all the excitement, I forgot to look at the dials." "'l've no idea if we really went supersonic." "'Oh, dear, we'll just have to go again.'" "Whoa!" "That is..." "Oh!" "'Here we go again, 'aiming for the target of Mach 1 , the speed of sound.'" "'Mach 1 .02." "'l am through the sound barrier 'and suddenly, everything's gone quiet.'" "Once through the sound barrier, the buffeting from those pressure pockets vanished as they gathered together to form a giant pressure wave at the tip of the nose, a supersonic shockwave." "Well done." " Thank you." "Now, this shockwave makes a very specific shape." "It forms a hollow cone, a bit like that." "There's your pressure wave caused by the plane there." "It's when this wave brushes against the ground like that that you get the sonic boom, this big bang that people hear, which can actually break windows." "The shockwave could interfere with air moving over the wings, so supersonic aircraft are often designed with their wings swept back safely within the cone." "It's design features like this that help the fastest aircraft routinely break Mach 2." "But put those aircraft on the ground and suddenly, it's a whole new ball game." "Enter the Bloodhound car, longer than a double-decker bus and with the engine power of 160 Formula One cars." "This is just a mock-up, but in summer 2012, it's hoped the real thing will reach an incredible 1 ,000mph." "At the wheel will be RAF pilot Andy Green, the current land speed record holder." "We're not just putting a small increase on the land speed record." "It's a 31% increase on the previous record." "That's the biggest single percentage increase in history." "The bit from 650 to 800 is the challenge." "It's like a waterskier struggling to get out of the water, and suddenly they pop out and they're on top." "Once we're on top - 800mph - it's all looking rosy." "We have to work hard to get there." "Why can't we take what we know about aircraft aerodynamics and just apply them to a car?" "It's a good point." "You can do twice the speed of sound in an aeroplane at 40,000 feet, and I have done it." "You cannot do it down at ground level, the air is too thick." "The aeroplanes physically don't have the power to plough through it." "So we're not only building the world's fastest car, this will be faster than any jet fighter at ground level." "That's why we need a jet fighter engine and a rocket engine, powered by a Formula One motor, just to make that happen." "But the biggest engineering effort has gone into working out the ideal shape for Bloodhound's body, one that will be aerodynamic up to the speed of sound, but will also cope with the dramatic effects of going supersonic." "So basically you have to... lt's like having two completely separate cars joined together." "We have a subsonic problem and a supersonic problem, and this car tries to join those together in a single car." "How do you manage that?" "Below the sound barrier, we worry about skin friction and the air going over the car, like your car at home." "So normal aerodynamics that we're familiar with?" "But the form drag, the supersonic drag, dwarfs it." "What's form drag?" "As you go supersonic, the air doesn't know you're coming." "It can't flow around the car, it just goes bang." "That's your sonic boom." "and the car punches through it." "Where it's been, there's no air." "You have very low pressure. lt's like a vacuum sucking the car back." "Because there is no wind tunnel up to testing the Bloodhound, the team have used advanced computer modelling to perfect a body shape that minimises both types of drag." "So this is kind of slightly, dare I say, less dramatic at the back." "Just that flat end, why will help the car aerodynamically when it's going at supersonic speed?" "Supersonically, the air can't flow around the car, so it doesn't make any difference if that's cut straight off." "So basically, all your form drag... measurements have been done on a computer." "You've never..." "This is unknown territory?" "The first time we know this works at 1 ,000mph is when it goes at 1 ,000mph." "Wow." "Are you confident?" " l'm excited." "Earlier on, I volunteered to drive it." "Now I'm sort of like, "Actually, you know what, maybe I'll just watch."" "By summer 2012, Team Bloodhound will be ready to race on a dry lake bed in South Africa." "Work has just begun building the real car and here on Bang, we'll be following the progress of this awesome engineering adventure every step of the way." "Amazing." "As a guy with an aeronautics background, Dallas, I'm not only very jealous, I'm utterly gobsmacked." "It's amazing, and we at Bang will be all over the Bloodhound project." "What I love about the Bloodhound project, other than it's the best thing ever, is that it's not just about a bunch of guys driving fast." "It's not just about breaking the record." "It's as much about the engineering process." "The Bloodhound team are so keen to tell that story and get everybody involved, apart from driving it, obviously." "They won't let you do that." "It is really fascinating as a project, even if we don't have an engineering background, like yourself, Jem." "You know what else is really cool?" "They were looking for people to help them get the stones off the run site." "I guess at 1 ,000mph, you need that attention to detail." "It's fairly important." "Time for our weekly dose of Dr Yan now." "Face it, none of us need a perky little scientist bothering us on our commute to work, but that doesn't stop him." "He's at Marylebone Station, obstructing the flow of commuters as we speak." "What I'd like you to do is take one of these pictures each." "Brilliant." "Thank you very much." "What I'd like you to do is look into the middle of this disc." "OK?" "Now, I'm going to start spinning it, but keep your gaze on the point in the middle." "Don't worry, I'm not going to hypnotise you." "You can do this at home." "Get anything in your hand, like a remote, and look in the middle of the spiral." "Don't look away." "Look at the middle of here, and I'm going to start spinning it." "Keep looking right in the middle." "Now, your brain interprets this spinning pattern as movement inwards, as if everything's being sucked through a hole in the middle." "Keep up the illusion long enough, and something weird happens, as you're about to find out." "Keep looking, and when I say go, I want you to quickly look at what you're holding in your hand." "Keep looking, just a few more seconds." "Almost there." "OK...go!" "Whoa!" "It got bigger!" "It's still getting bigger." "Still going." "It's almost going off the piece of paper." "That is weird." " Really weird, isn't it?" "Obviously, these bombs aren't actually getting bigger." "It's just your brain playing tricks on you." "Have you ever seen this before?" " No." "That's so cool." "It's an illusion that was discovered about 2,000 years ago by the ancient Greeks." "You can see it also if you look at waterfalls for too long, which is cool." "Today, we call it the motion after-effect." "It's not just a cool illusion - there's a lot we don't know about the brain, and studying effects like this can help us figure out what's going on." "What did this particular effect tell us?" "It seems like there are parts of the brain that are specifically tuned to movement in any direction." "It's a good job we have those, that's why we're good at getting out of the way when something's coming towards us." "But if you look for a long time at movement in any one direction, scientists think the pathway in your brain that detects motion in that direction starts to be adapted to that motion." "It basically gets used to it, and fires less and less in response." "When you look at something still, after having done this, your inward-sensing pathways are firing less, as they've adapted, than your outward-sensing ones, OK?" "That's why it appears to be growing." "Ah." "Very interesting." "Does that make sense?" " Yeah, it does." "But that's not the only thing that this effect can tell us." "This is where it gets interesting for scientists." "I'd like you to do it again, but look with just one eye." "Oover one eye, and look right in the middle again." "What I'd like you to do - when I say go, I'd like you to look at the picture with the other eye." "Swap hands and look with the eye you weren't looking with before." "Looking right in the middle, and now swap to the other eye." "Yeah. lt exploded again." "Still happened." "Oh, my God." "The bomb's getting bigger." "Yeah." "That shows that not only is this illusion definitely in your brain rather than your eyes, but also that it's in a part of your brain that predominantly processes information from both eyes together." "And knowing that allows scientists to work out where in the brain it's happening." "Which is sort of quite cool." " Yeah, that's weird." "Good job it's not permanent!" "Otherwise you'd be going home and be like "Oh, everything's getting bigger!"" "Now for my big glue test." "I made three home-made glues from milk, sweets and ping-pong balls, and used them to glue handles onto a wooden board." "Now I need Dallas and Yan to find out which one breaks first, by dangling them over a swimming pool." "Thing is, I can't help thinking they're going to get wet, cos either the glue breaks and they fall in, or the glue doesn't break and they get tired, let go and fall in." "Shame." "Ah!" "It's a nice day for it." " Yeah, sun." "Thank you for arranging this." " Well, you say that now." "I don't know if you'll feel..." "The water is only five degrees, and you may end up in it." "Hang on a sec." "You've made all these glues." "Presumably, you'll know which is the strongest?" "We haven't got to the stage yet of doing the final tensile tests." "The glues have been clamped up for the same length of time in the same temperature in the same room, and now they're ready for testing." "Good morning, gentlemen." "Thank you for joining me here today." "I'm here to ensure it's fair and square." "So we've got our milk-based, toffee-based and ping-pong-ball-based glues." "Dallas, you won the toss." "What are you going for?" "I'll go with ping-pong, purely on the grounds that I know how much Jem loves ping-pong, so I assume he'll put extra effort into that one." "That's not very scientific, Dallas Oampbell!" " lt's not," "But how scientific can you be in this?" "It's three unusual materials." "OK." "My big worry, if I'm honest, is not to do with the glues at all, it's my weak upper-body strength." "I feel my upper body may give out before the glue." "So, Yan, you're left with either milk or toffee." "What's your weapon of choice?" "It could go either way, but I have a feeling you want something where the molecules are long and thin and stretched out like hairs so that they stick stuff." "Maybe the milk is still in blobs, and not enough like a bit of spaghetti." "So I'll go for toffee." "Which means Jem, you're left with milk." "You have the upper hand, you prepared these glues - are you happy with that?" " l'm not disappointed." "Oh!" "The table tennis thing is just a red herring." "Dallas, you know how hard you can hit a table tennis ball, and you know it never breaks." "Hmm." "No chance to change your mind now." "You've picked your glues." "Got to stick with it, pardon the pun!" "'Let's get on with it." "It's not just the water that's cold." "'The boys are starting to freeze too, especially Dr Yan." "'ln an attempt to keep his weight down, he's ditched his shoes." "'A few warm-up exercises gets them ready for their hanging challenge.'" "Guys, are you psyched?" "Are you ready?" "I'm very psyched." " Let's get you in the dinghies!" "Don't fall in." "This looks really good." "Three men in three boats." "Are you ready?" "Hold on to the handles." "Don't pull on them yet!" "'Remember, these handles are stuck in position using home-made glues." "'Which one will fail first?" "'Will the boys take a dive if their arms give out before the glues?" "'" "Move the dinghies!" "And you're on, boys." "'Dallas is concentrating like nobody's business." "'Almost 30 seconds already on the clock, 'and there's no sign of any glue weakening." "'l don't hear any creaking, no cracking." "'Looks like they're all holding fast." "'Hang on, Yan's gone on to one handle." "'Dallas is definitely struggling.' ln your own time." "Hang on with two, Dallas, if you need to." "Oh, I heard a crack." "I'm hearing something go." "That's my arm going!" "Dallas, hang on!" "I'm going...!" "No, he's going to fall into the pool!" "Don't fall in - oh, he's fallen in." "'He's in the soup." "He's the first down, 'his arms proving weaker than the ping-pong ball glue 'after barely 60 seconds.'" "OK, I need you to tug on yours like the clappers." "Are you all right there, Oampbell?" "'We're past 90 seconds, and there's still no sign of a glue failure.'" "Those glues are amazing!" "They just do not go." "Oan you feel the glue going at all?" "Argh!" "Oh!" "'Another one bites the dust in just under two minutes.'" "Last man hanging." "You can bring it in now- oh!" "Ah!" "Oh..." "There you have it - in one-minute 50, two minutes, each of our boys lost their grip on the handles and fell down." "Each of our glues, the table tennis, the toffee and the milk all stood the test of..." "well, at least two minutes." "We should give Liz a hug." " Don't wet me!" "Well, I got that one wrong." "I genuinely thought one of those at least would break." "All it was was the edge of a piece of wood like this, stuck to a piece of ply with home-made glue, and they were unbreakable." "It is amazing, but thinking about it, it's not that surprising." "Anyone who's tried to remove a cornflake from your cereal bowl that's been welded on knows how sticky things can get." "Fair enough, but are you sure it doesn't just boil down to the fact that you're too wimpy and couldn't hold on long enough for the glues to break?" " l was. I was wimpy." "We could have hung forever, and it wouldn't have broken." "Really?" "We were just not heavy enough to apply enough force to break them." "When I took them back to the workshop and tested each individually in my frustration at none of them going, you would be amazed at the force it took." "I mean, which do you think was the strongest?" "Being a biologist, I'm going to "stick" to milk." "Not being a biologist, being a ping-pong fan, I'm going to stick with..." "ping-pong." "Which one?" "Liz, you just take it." "The ping-pong glue was exceptionally strong, but the milk glue was stronger than the wood itself." "The wood broke before the glue did." " Excellent." "Well, that's it we will see you next week." "Say goodbye, boys." " Bye!" "Bye!" "No, he's going to fall into the pool!" "Don't fall in - oh, he's fallen in."