Wisconsin Public Television University Place Wonders of Physics  Clint Sprott  UP600 2011   cc >> So, Professor Sprott has asked me to find someone to entertain you before he arrives, so I've gone over to the zoo and I found a great storyteller to come out. Please welcome Reid Miller. (applause) >> Hi, Peter. Thank you very much. Hello, everyone. Welcome to "The Wonders of Physics" this year. As you may have heard, this year, "Wonders of Physics" is connected to the Year of the Arts here at the university. So if you think about it for a second, scientists, like a physicist, has to think creatively like an artist does. And an artist has to know how things work to make art. So, science and the arts are blended. 

I brought along my friend Quackers, because I've been telling a lot of duck stories lately. Will you say hi, Quackers? >> Hi, Quackers. >> One day, a duck waddled into a physics lab, walked over to the scientist and said, "You got any duck food?" The scientist looked down and said, "No, I don't have any duck food! This is a physics lab. I'm doing experiments. I don't have time to waste on you. Get out of here!" So the duck left. The next day, the duck waddled back into the physics lab, walked over to the scientist and said, "You got any duck food?" The scientist said, "It's you again? I told you yesterday, I don't have time for your nonsense. I don't have any duck food! This is a physics lab. Get out of here and don't come back. If you do, I'll nail your beak to the floor!" So the duck left. 

The next day, the duck waddled into the physics lab, walked over to the scientist and said, "You got any nails?" The scientist said, "No." The duck said, "You got any duck food?" (laughter) (Quackers quacking) You know what, Quackers? You're not looking so well. I think your jokes are kind of lame. >> I know. I'm kind of falling down. >> Oh, no! He's not feeling well. Oh, dear, he's kind of gotten sick on telling all these jokes. Is there a doctor in the house? Is there a quack doctor in the house? >> In come I that never cometh yet. The best Doc Quacker you may bet. Here I come from the Continent to cure this duck which Reid Miller hath slain. >> How did you come to be a doctor? >> By my travels. 

>> Where have you traveled? >> I've been to Icky Picky, France, and Spain. Three times to Oconomowoc. And now I've returned to Madison again. >> What can you cure? >> All sorts. I can cast out 14 devils from one's heart. I can cast 21 out. >> Well then, cure my duck. >> Here, Quackers, take three sips at this bottle. Down they thrittle throttle. Arise and quack again. 

(Quackers moans) >> You've killed my duck! >> Oh, Reid, I quite forgot. I took the wrong cork from the right bottle-- The right cork from the wrong bottle! But in my inside, outside, backside pocket, I have another bottle. In it, there is some hokey, pokey, snokey. It's sure to bring a dead duck back to life. If you don't believe these words I say, step in Dairy Dout and clear the way.  >> In come I, little Dairy Dout, with my shirt lap hanging out. Five yards in and it'll be five yards out, when out goes little Dairy Dout. (Quackers gulping) >> Oh-ho-ho! Oh, thank you very much Dairy Dout! I'm all better. Give her a big hand, folks. (applause) >> If you don't believe these words I say, step in Professor Sprott, and clear the way. 

(applause) § §  >> Welcome to "The Wonders of Physics." I have always wanted to be an actor. And I've even played the Quack Doctor in Mummer's plays before. But you know, sometimes I have nightmares that I'm in a play and I've completely forgotten my lines. In fact, that's one reason I went into physics. In physics, we like to work things out from principles and not just memorize them. But do you know this is the Year of the Arts at the University of Wisconsin, so I thought we should find some physicists who know something about the arts, who can come and explain to us how physics relates to the arts. Peter, who's on first? >> Oh, yes, who's on first. What's on second. I Don't Know is on third. But enough about baseball, we did that last year. 

I have found a dancing scientist who recently appeared on "America's Got Talent." Please give a welcome to Jeffrey Vinokur! (applause) § § (musical flourish) >> Welcome, ladies and gentlemen. My name is Jeffrey Vinokur. I'm a real life dancing mad scientist. I am here to talk to you about how the physics of motion. What I have here is a fire extinguisher filled with carbon dioxide gas. I use it to propel myself into motion. If I shoot the gas in one direction, I'm able to move in the opposite direction. I use a skateboard just to reduce the friction. A man named Isaac Newton explained this through his Third Law of Motion, which says that for every action, there's an equal and opposite reaction. If you think of a rocket being fired, the hot gases go in one direction, and the rocket goes in the other direction. 

But did you know that Newton's Third Law of Motion can also help you do dance moves like the moonwalk? By providing a force with my feet in this direction, I should be able to moonwalk in the opposite direction. Hit it, DJ. § §  § § (musical flourish) (applause) Thank you. I got a little carried away there. All right. So, how many of you have seen one of these toys before? Awesome. It's called an Airzooka. What an Airzooka does is it shoots harmless air vortex rings. I'm going to shoot some air vortex rings into the audience. If you feel a gust of wind go by, just raise your hand. 

 Gotcha! (laughter) That's pretty interesting, but this would be a lot more fun if we could see these air vortex rings. That's why I have a fog machine here. I think this will be a lot more interesting. Let's find out. § §  § § (musical flourish) (applause) >> Do it again! >> Wasn't that a lot more interesting? I thought so. The physics here is pretty amazing, too. By very quickly forcing air out this front hole here, the air around the sides encounter some friction and it slows down, while the air in the center keeps moving quickly. This causes the air to start turning in the shape of a donut. But a donut is a food and not a shape, and we physicists call this shape a torus. There's actually a really big torus right behind the wall over here called the Madison Symmetric Torus, where physicists are studying magnetic fusion energy, and that could one day help power the world. 

Okay, I have one more demo to do for you today. It's my favorite one. What I have here is a mixture of cornstarch and water. Cornstarch is a powder you can find in your kitchen. It's used to thicken sauces. When you mix the two together, it forms what's called a non-Newtonian fluid. Basically, by applying a force on this material through motion, it behaves as a solid. (pounds on surface) But if you were to, say, move your fingers through more slowly, it behaves as a liquid because I'm not applying a lot of force. See that? If I were to, say, apply a force on this material with my feet by say, dancing on it, then I might be able to dance on water. But I'd have to use a special dance style called jump style to provide enough force to keep afloat and special European techno music to make this work. 

(laughter) Do you guys want to see me try? >> Yeah! >> Okay, let's give this a try. § §  § § (musical flourish) (applause) As you can see, when I stop dancing, I start sinking. Thank you very much ladies and gentlemen. I hope you enjoyed learning about the physics of motion. Hey, Dr. Sprott, do you like to dance, too? >> Well, in fact I do like to dance. In fact, there was even-- (laughter) a picture of me-- (laughter and "oohs")  I do like to dance. There was even a picture of me in the newspaper dancing once. But you know, when you dance, you do use your feet. It's a great way to build up heat. I think that's pretty neat. 

Don't you agree, Mr. Pete. >> Yeah, congratulations, Professor Sprott. As a poet, you're smoking hot. You know, I did meet someone someone who was studying heat. >> Who's that, Mr. Pete? >> Well, it's a scientist from the Madison Area Science Technology. Please give a warm welcome for George the "Big Bang" Boomer. (applause)  >> "Big Bang Boomer"? Seriously? (laughter) Anyway, we've all seen spectacular special effects of explosions and fires in movies and on television. Since some people consider movies and television to be a form of art, I thought I might explain how that works. So, would you like to see me blow stuff up and set things on fire? >> Yeah! >> Okay, well, most of us associate explosions with things that are hot. So I thought it would be interesting to make an explosion out of something that's really cold. 

In this dewar flask, I have a bunch of liquid nitrogen. That's at more than 300 degrees below zero. I have this pop bottle here. I'm going to pour about a cup of this liquid nitrogen into this pop bottle. That will take a little bit of time, because it likes to boil off. This is going to expand about 700 times its original volume. So that's going to put about 700 cups of nitrogen gas into this pop bottle. I don't think it's going to hold it all, do you? So, I'd have to be some kind of moron to screw a cap onto this. (laughter) And give it a shake, and put it into this frame here.  We'll hear more from that later. 

(laughter) Now, you'll notice that I have a long stick with a match on the end of it. You might wonder why I have a long stick with a match on the end of it. I'll leave that to your imagination, but I'm going to light this match. Maybe. There we go. Now, up here I have a balloon, and I have a flammable explosive gas in this balloon. It's called hydrogen. What can go wrong with hydrogen? So what do you think is going to happen when I touch this to the balloon? All right, plug your ears. (popping explosion) § § (musical flourish) (applause) So, what happened there is when I lit it on fire, I burned a lot of chemical bonds that held the hydrogen together. Some of that energy that was stored in those bonds was released as heat. 

That caused the volume to expand a lot. That ran into the air around it, and that produced a wave that went out across the audience. That's something we call a shockwave. You heard it, and some of you closer in probably felt it. That's how an explosion works. I've been studying storms for 35 years, and I've been a storm chaser for about 20 years. Here you can see a clip of a tornado I caught here in southern Wisconsin a few years ago. I thought it would be really interesting if I could figure out a way to merge my interest in heat with my interest in tornadoes. Would you like to see me make a tornado out of fire? >> Yeah! >> Okay, well, to begin that, I need to apply some of this fuel here to this material. (laughter) Okay. 

Then I'm going to take another match and I'm going to attempt to light it. Don't try this at home, kids.  I have this frame that I'm going to put on.  § §  Then, in the other hemisphere. § § I'll put it out before the Fire Department gets here. § § (musical flourish) (applause) You'll notice that before I put the sleeve on, the fire oscillated in and out. What was happening was the fire was preventing oxygen from getting into the fuel, so you'd have periods where the fire was at a maximum where the fuel had gone in, and that prevented, so it died down. When I put the sleeve on, it acted like a chimney. It gave a place for the hot gases to rise out of. It left the base open for air to come in. 

When I rotated the base, the rotation was caught in the updraft, and that caused a vortex of fire. Anyway, thank you for having me here, Professor Sprott. I hope I've inspired some of you to learn about physics and the arts. You've been a great audience. Thank you. (applause) That's somebody else's problem. (laughter) § § (musical flourish) >> Well, I do have one other demonstration that involves heat right here. I have a long hollow pipe that has on the top several hundred very tiny holes. It's connected back here to a source of natural gas. That's like the gas that you have in your homes, if you have a gas stove or gas furnace. 

It's a gas that we call methane. I'll light the flame. There we go. You see it makes a nice long flame. Down at this end, I have a loudspeaker, much like you have on your stereo set at home. It's connected back here to an audio oscillator. When I turn it on, you can see an interesting thing. You can see that the flame is high in certain places, and low in between. When I change the frequency, when I go down to a lower frequency, you can see the distance between the large flames gets longer. When I go up to a higher frequency, the opposite happens. 

They get closer and closer together. This is an illustration that sound in fact is a form of wave. >> Ah-ha! That sound, that noise, that song. It's my flugelhorn. Oh. No, that's just a Ruben's Tube. George borrowed my flugelhorn and I have no idea where he put it. Oh, well. I'm here today, my name's Don, by the way, to talk to you about sound and music, and how those relate. Do you mind if I take over, Professor Sprott? >> Go ahead. 

Well, in order to have music, we need instruments, right? In order to have an instrument, we need three things. The first thing we need is vibration. It can be the buzzing of a mouthpiece, the plucking of a string, the hitting of a drum. The second thing we need is resonance. I'm going to spend a lot of time talking about that in just a second. The the third thing we need is amplification. Otherwise, the noise will be quieter than a mouse. I said I'm going to talk a lot about resonance. This has a lot to do with the physics of noise. What is resonance? Resonance is the frequency at which things vibrate. 

Lots of things can vibrate. We can have a vibrating string. We can have vibrating air in a tube, like we had with the Ruben's Tube. But I'm going to show you an example instead of a vibrating piece of metal. Okay, who knows what this is? What is it? A tuning fork, right. We use these to make sure all our instruments are playing the same note when we think they are. That way, it sounds good when we all play together. I have a tuning fork here. It's kind of a big one. (explosion) (audience reacts and laughs) § § (musical flourish) (applause)  Now, it's not entirely unheard of for us to have explosions in music, because an explosion, a shock wave is just a really, really loud sound that's really, really short. 

Think for example of the "1812 Overture." We have cannons that go off in the middle of it. Of course, we also time them so they don't go off during someone else's performance. (laughter) But oh, well. Where was I? Tuning forks. I have a large tuning fork here, which will be a lot less loud, I assure you. A large tuning fork here. We can listen to this, and it's going to make a low tone. So if we listen to it, you can hear it. It's a clear tone. (single low tone) Nice and low. 

If we look on this, up on the oscilloscope up there, we can see. (single low tone) On our oscilloscope, we see something like three peaks in this particular tone. The distance between those, as we were talking about with the flame over here, is called the wavelength. If instead we take something that's smaller, like this smaller tuning fork, and listen to it. (single higher tone) It's much higher in tone. If you look at it up there, we see that there's five peaks. It's a much shorter wavelength. The way you can think of this is that in general, large objects tend to have a low sound and have a long wavelength, where small objects have short wavelengths and have a soprano sound. Soprano is a fancy word for high, so I don't break the alliteration while I talk. All right, but it's not just the size of things that determine how they resonate, how they vibrate. 

It also has to do with the distribution of mass, which is a fancy way of saying, you know, how the object is shaped, where it's heavy and whatnot. Now, for a demonstration of this, we had our small tuning fork before, which made a tone like this. (single high tone) Compare that to one where I've added some weights. This is a slightly different pitch, and you might be able to hear it if you have good ears. (single high tone) Could anyone hear the difference? >> Yeah. >> Some people could. If you've got hearing before that went off, you know, you might be able to tell the difference. This would serve you well if you do go into music. Although you can go into music if you don't have perfect pitch anyway. But let's listen to them both at the same time and see if everyone can tell the difference between them. 

(two tones) Do you hear that effect, that mwah-wah-wah? You can see the amplitude of these two waves together oscillate. It gets big and small, and big and small, and big and small. Think about this like you're out on the ocean, and you're in an inner tube. You have two boats that go by. The first boat that goes by, its wave will lift you high and low, high and low. Let's say you're sitting in the high position, when the other wave comes by. Now, we can do one of two things. One, it can also be high, in which case you'd go really high. That's like the two tuning forks making a really loud sound. One could be high and one could be low, in which case you'd stay right where you were. 

They kind of cancel out. That's what happens when we have that low sound. When these two things go, they go high sound, low sound, high sound, low sound, and we get that mwah-wah-wah beating effect. All right, now we don't make music just with tuning forks, and tuning forks aren't the only thing that resonate. You might've seen, if you've ever been to a wedding or some formal event, when someone wants to get your attention, they'll rap on the glass and make a nice loud clear tone. This is another example of resonance. Here, I'm seeing the glass resonate as I strike it, giving  it vibration. Now, you might wonder about the sound that comes out. That's the exact frequency at which the glass vibrates. Now, does glass vibrate really well? If I were to take the glass and drop it from here, would it hit the ground and bounce and vibrate and jiggle? >> No. 

>> No, what would happen beside being yelled at? >> It would break. >> It would break, that's right. If we were to drop a glass, it's going to hit the ground and shatter, because glass doesn't vibrate really well. If we try to get it to vibrate too much by dropping it or hitting it too hard, it just shatters. The same thing can happen if we send in sound on the frequency of its resonance. In order to do this, we have a device up here. This device has a speaker hooked up to an amplifier that can produce a particular sound. In front of that, we have a glass. Now, I don't have quite the ear that's required to get the exact tone. However, the creator of this device, Steve Narf, who's backstage, does have the ear for it. 

Let's give him a round of applause and let's get him out here. Let's see if we can get him to break this glass. (applause) I have to warn you ahead of time, it's actually quite loud, so you're going to want to plug your ears. Also cross your fingers, because it's really hard to do. All right, so let's cross our fingers and plug our ears. (single high tone) Wow. Let's thank him. (applause) That looks like that got up to about 143 decibels, which is loud enough that if you were inside the box with that glass, you might have actually hurt your ears. It's a little bit louder than a jet engine. Out here, it's much quieter, thankfully. 

Here we have a slow motion of a very similar break. You'll notice as we play this, that it starts off by shaking. You can notice that by the little piece of paper attached. As we increase the amplitude, it shakes more and more and harder and harder. Eventually, it shatters, because we can't get it to shake any more. § § (musical flourish) (applause) So now hopefully, you know quite a few things about resonance, which is one of the three things we need for instruments. At this point, I'd pick up my flugelhorn and show you how it all works together, but again, I can't seem to find my flugelhorn. >> I found your mouthpiece. >> Oh, hey, Ella. Well, my mouthpiece was next to the rest of it, so wherever my mouthpiece was hidden, I'm sure the rest of it is nearby. 

Why are you smiling? Smiling's not good. >> Remember that big bang a few minutes ago? >> Yeah, George set it up and left it out here. >> I have your mouthpiece. (laughter) >> Hopping habaneros of Hades! Did George blow up my flugelhorn? Mouthpiece, right. (buzzes mouthpiece)  My mouthpiece isn't going to help, because we need three things. We need the first thing, something to vibrate. That's what the mouthpiece does. Then we need something to resonate. A flugelhorn is a long length of tube. Then we need something to amplify it, like a bell. 

Oh, yeah, no, that might work. We have a long length of tube here and a bell at the end. Do you think this might work? Let's try to improv. (plays various notes) That kind of sounds like, you know, third trumpet or something like that. (laughter) >> Well, I can do something with this that you can't do with an ordinary trumpet. Check this out. (plays tone that oscillates) § § (musical flourish) (applause) So, were you down at the World Cup recently? Okay, she's showing an interesting effect here. Ella is showing us the Doppler Effect. The Doppler Effect says that if we have a source of sound that's coming towards us, it's at a higher frequency, and when it's coming away from us, it's at a lower frequency. Think of it like you're standing on the side of a road and you have a car coming. 

When it comes toward you, it's a higher frequency. It passes you and it goes lower. >> Should I make my improvaphone march on out of here? >> I think maybe we should. Thank you, everyone. (applause)  >> You know, there are a lot of ways to make music. These days, we often use electronic instruments of one sort or another. In fact, maybe some of you have seen or have even owned one of the synthesizing keyboards that can emulate many different musical instruments. I actually have several electronic devices here that make sound. The first one is a simple audio oscillator. It's now making a tone that is a thousand cycles per second, one kilohertz. 

It's a very pure tone, not very musical, perhaps. But when I turn it down to a lower frequency, you can hear it goes to a lower pitch. When I turn it up to a higher frequency, it goes to a higher pitch. This suggests an interesting experiment we can do right here in the room. What I'm going to ask you to do is to hold up your hand if you can hear that sound. Keep your hand up. I'm going to turn up the frequency. Whenever you stop hearing it, lower your hand. (tone increasing in pitch)  At this point, about half of the hands are up and half are down. If you look around, you'll notice whose hands are up. 

It tends to be the little children. Because it is the case that as you get older, you lose your ability to hear the very high frequencies. Fortunately, you don't have a lot of use for those, so it's not a great loss. But if you lose too much, of course, that's serious. Over here, I have another example of a device that is rather musical. It's something called a theremin. It was invented in 1920 by a Russian physicist named Leon Theremin. It was originally intended as a proximity detector for military use. But he discovered that it made a very good musical instrument. It works because it has two oscillators. 

One fixed in frequency, and the other oscillator, I can change it's frequency by just bringing my hand closer. (tone varies in pitch) What you're hearing is the beat frequency between the fixed oscillator and the variable oscillator. If I were a good musician, I could play you a tune-- (tone varies in pitch) without even touching the instrument. But I have something even better for you. We have an old video clip of Leon Theremin himself playing the theremin that he invented. § §  This shows one use of electricity in the arts. I have one final example of an electric circuit that makes a sound. I'm sort of proud of this circuit because it's something that I invented just this past year. When I turn it on, you hear a sound, not very musical perhaps. But when I turn up this knob, I reach a point where a sound comes in that's half the frequency, one octave below the sound that you were previously hearing. 

If I continue to turn it up-- (buzzing sound) you will hear what we call the sound of chaos. Chaos is a very irregular, unpredictable variation. I'm particularly interested in chaos, because that's the area of my own research. To show you some other examples of how electricity is used in the arts, I would like to introduce my esteemed colleague Professor Michael Winokur. (applause)  >> Thank you for that kind introduction, Professor Sprott. I've just come from the electricity lab. If the sound of physics isn't frightening enough, perhaps you would like to take in a horror show, hopefully not this one! (laughter)  >> Can you hear me?! Give my creation life! (laughter) >> Electricity has long been used in the movies to shock and frighten audiences. You may not know it, but Thomas Edison, inventor of the electric light bulb, was involved with the movies. His name even appears in the first Frankenstein film back in 1910. Electricity is nothing more than electrons in motion. 

It still amazes me that one of nature's smallest things, the unseen electron is responsible for some of the most dramatic displays of energy and power. A single electron's force is small, too small for you to feel. But there is strength in numbers, if you know how to move them around a bit. So for our first electricity demo, I've brought my monster's head for you. I think it's back here. (laughter) But my monster needs help. He needs a body. I'll give it back. Preferably one with a head with long, fine hair. Anybody want to...? This little girl had her hand up early. 

Come on down, dear. I think that'll work.  Okay, your name is? >> Mariah. >> Mariah, that's a lovely name. We're going to do a little experiment here. We're going to transfer electrons between your hair and the balloon. All I'm going to do is rub, rub, rub. Hold still. (laughter) We get to see the electrons' force. § § (musical flourish) (applause) Thank you, Mariah. 

This is an example of a static electricity. The electrons don't go back, but they stay put. We're going to park my monster over here, so he can watch the rest of the show. § § (musical flourish) (laughter) Close enough. Over in the corner, we have a device called Jacob's Ladder. § § (pipe organ music) To make it work, we need to push the electrons from one metal electrode to the other. Scientists call that push voltage, or electric potential. Once the electrons find the weak link in air gap in between and jump back, creating an electric arc. To start the process, I merely flip the switch.  The electricity heats the air, and the hot air rises, drawing the electric arc with it. 

The bright color that you see is merely due to air molecules in the gap that are excited by that electricity. You can do a similar experiment at home with a nine-volt battery and your tongue! (audience groans) You will feel that electric current. Ask your parents. It could be a tad unpleasant. But I suppose you'd like a little bigger demonstration of electricity. Is that not so? >> Yes! >> In our laboratory, we have the ability to create lightning, just like in nature. In nature, during a thunder storm, air currents move vast quantities of electrons between the ground and the clouds. They, too, find the weak link and jump back. You see the lightning. We have a short video capturing nature in the act. 

(no audio)  But here, we have a device called the Tesla Coil. (suspenseful organ music) (laughter) Underneath, there's a motor that turns paddles that play the role of the air current. They move the electrons from one side, from the left to the right, step up the voltage to a million volts in this coil. They collect at this tip and escape through the air to the metal ball, back to the ground and the earth. Shall we see? >> Yeah! >> I'll just go over here, turn on the power, engage the solenoid. (loud electrical buzzing)  § § (musical flourish) (applause)  Now, you folks in the front rows may smell something sickly sweet. >> Yes. >> Yeah, that's smell is ozone. Lightning produces lots of it. It won't hurt you too much, if you only breath a little bit. 

(laughter) But something comes with lightning, something sudden. Can somebody help me out? (crashing thunder) A sharp crack of thunder. For our last electricity demo, we have a device over here called a capacitor. Can you all help me out and say capacitor. >> Capacitor. >> Good job. A capacitor is a simple device, two metal plates held really, really, really close together. With it, we will create thunder, I hope, a sharp crack of thunder. When I push this button, we will move 10,000 million million electrons between the two metal plates. When I release it, they will all go back through the aluminum foil. 

At 5,000 volts, almost there. Are we ready? >> Yeah. (loud popping sound) § § (musical flourish)  You've been a great audience. I hope you've learned a few things about electricity. Electricity sometimes seems like magic, but there are other accomplished physicists here who know something about that. (applause)  >> You know, Professor Sprott, I was backstage waiting to come out and tell everyone about magic, and my needles were going crazy. What are you guys doing out here? >> I bet it was our million-volt Tesla Coil. >> Right, and electricity and magnetism are very closely linked to each other. There was a current flow from the top of the Tesla Coil up to the ball, it created a magnetic field. You know, let me show you what that might look like. 

It'll look like magic in the meantime. Can everybody see all my magnet needles up here. I'm going to wave my hands over them and they start to dance. Can anyone tell me how I might've done that? I've got a magnet in my hand. Magnetism is one of the forces that can act at a distance, which means the two objects don't need to be touching each other in order for a magnet to push on another object. Because of that, we can do some really neat things with magnets. One of my favorites is this box right here, which is just filled with glycerin and iron filings. I shook it up so that the iron filings are fairly evenly distributed throughout the whole thing. Then, when I slide this magnet into it, you start to see the iron filings move and line up along what are called the magnetic field lines. It gives you an idea of what a magnet is actually doing. 

It's pulling things toward it. It's pulling anything that is subject to a magnetic force toward it, along its field lines. You know, when you see magic in a movie or on TV, it's probably because somebody in the special effects department really knows their physics. Take for example, levitation. I've got this aluminum cylinder. It's not levitating. It's subject to the laws of physics, just like everything else out there. But I can levitate it. I take it and put it in here. I can let go and it just hovers. 

I kind of feel like I should pull out my wand and do an incantation. § § (musical flourish) (applause) As you may have guessed, that wasn't magic that made it levitate. It was magneticism. I have a wafer right here that's made out of something called yttrium barium copper oxide. It's a type of ceramic that if we made an atomic model of it, looks like this. This is repeated again and again and again throughout the ceramic. This ceramic has this special property that when it gets cold enough, electrons can move through it very, very easily. And those moving electrons can make a magnet. This is what's called a super conductor. All it takes is a little bit of movement by an electron to create a current that keeps going and going and going. 

If I take this little magnet and place it on there, it just sits on top of the wafer of yttrium barium copper oxide. I pour some liquid nitrogen onto it and what happens is that as the ceramic gets colder and colder, it's easier for the electrons to move, so the magnet starts to levitate. It floats right off the top of the wafer, almost like magic. § § (musical flourish) (applause) There we go. >> You know, that does remind me of magic. I bet many of you have been to a magic show, and you've seen a magician levitate a lady. I wonder why they always use a lady? I don't know. But anyway, something I bet you didn't know is that I'm a magician. >> You're a magician? >> You bet. >> In addition to everything else? >> In addition to everything else. 

In fact, it's often come in very handy. In fact, just the other day, I went to the hardware store and I asked them for a 3-foot-long piece of rope. They said, "Well, we don't have a 3-foot-long piece of rope, but we have these two little short pieces." I said, "Well, heck, that's no problem." § § (musical flourish) (laughter) I said, "Well, heck, that's no problem, because I'm a magician." Any magician can take two short pieces of rope and change them into one long piece. (applause) Now, I didn't really do that at all, I just made that up. But I did go to the hardware store and ask for a piece of rope. They said, well, you want the kind of rope that has two ends on one end and two ends on the other end? Or maybe you want the kind that has two ends on one end and one end on the other end? I said, no, no, no. I just want the regular kind of rope, the kind where when you tie a knot in it, you have a rope with three knots in it. § § (musical flourish) (applause) >> That's quite impressive. You know, I've dabbled in a little magic myself. Do I have a volunteer from the audience who's not too attached to their head, who would like to give me a hand? How about the young gentleman in orange, right here. 

Are you ready to come up? I'm also going to ask one of our physicists, Marty Lichtman to come out and give us a hand. What's your name sir? >> Austin. >> Austin, all right. Austin, we're going to come right back here. I'm going to have Marty and Professor Sprott lift up this tablecloth of magic, and I'm going to chop your head off. You ready to do this, Austin? § §  >> You do know the difference between a magician and a physicist? They both do interesting demonstrations, right? But the magicians, they never tell you how they do their tricks. They physicists, you just can't get them to shut up about it. (laughter) >> Okay, I think I've done it. Ready? § § (musical flourish) (applause)  >> So, Austin, how are you feeling? (laughter) >> Separated from my body. >> He feels separated from his body. 

I must have done a pretty good job. But as you guys may have guessed, I didn't actually chop Austin's head off. He's still talking to us and moving. What it is, is it's called an optical illusion. I will let Marty explain to you what happened while I reattach Austin's head. >> Well, Ella, I think the easiest way to explain it to everyone is if I just walk in front here. Oh, look at that. I grew an extra pair of legs. >> Oh, it must be the pair of legs I'm missing. Yeah, and you know, the table also grew an extra leg. 

Because what you see as the back leg is actually a reflection of this leg in front, in a mirror that goes straight down the middle. >> Austin, thank you very much. § § (musical flourish) (applause) >> I don't know, I think he should've quit while he was a head. (laughter) >> With that joke, I think I'll leave you. Have a good time. § § (musical flourish) (applause) >> Thanks, Ella. I've just come from the laser lab, where we play with a lot of light. Light is really important in the arts. We started out the evening hearing some stories. These days, as George mentioned, most of us get our stories through movies and television. 

There are two aspects to the way that we use light in movies and television that make the illusions real and wonderful. Those are persistence of vision and color mixing. The first I want to talk to you about is persistence of vision. I have here a box that I call a laser oscilloscope, which will help me explain. If I turn this on, and we turn down the lights, you can see up there on the screen, there's a single dot from a laser. I have a couple of mirrors here that the laser is bounced off. If I move them, I can move the dot around. Also, if I use some of this fog, then I can show you. I'm going to turn this off, and I can show you where the laser is coming from. Okay? I'm going to put this back. 

I have a couple of motors attached to these mirrors. If I turn up the motors and start them moving, I can start that dot moving around. I can make some really cool patterns. These are called Lissajous figures, which is a mathematical term that means fancy stars. But if the motor moves fast enough, you start to see solid lines and curves. I promise you, that really still is just one dot. What's going on here is that the laser light stimulates the photoreceptors in your eyes. If the dot comes back around fast enough, the photoreceptor is still stimulated by the time it comes back, and you see a solid curve, even though it really is just one dot. That's persistence of vision. >> I've been following you! >> Oh, no! My evil nemesis, my shadow. 

I can never seem to get rid of you. >> That's because you can only travel at the speed of light, where I, Shadow, can travel as fast as I like. >> Hold on, Shadow. You know the speed of light is pretty fast, actually. So, here, take for example this ruler. This is 30cm long. You know, light could travel that distance in one-billionth of a second. If I shine a beam of light from here to the back of the room and back, about a hundred times as long, 30 meters, it could travel that distance in one ten-millionth of a second. Not bad, huh? >> That is pretty fast. That's 186,000 miles per second, or 300 million meters per second. 

>> That's right. >> But I'm faster. Watch how fast I go down and back. >> Let's see it. § § (musical flourish) (laughter) >> I've got to admit, that was pretty good. So, I'm not quite as fast as you. But when you surprised me, I was talking to the audience about persistence of vision. There's something else I wanted to show them involving persistence of vision. But I need to be pretty fast in order to demonstrate it. Now, when we used the laser light, you could see it when it was shining on the screen, but you couldn't see it in the middle of the air, until I sprayed the fog and it reflected off the fog. 

The same thing happens when you're at a movie theater, right? The light comes out of the projector, and you don't see it until it shines on the screen, unless maybe there's some dust in the air near the projector. Do you think in the future, maybe we could have some sort of movie theater where there's no screen at all? >> A movie theater without a screen? No way. >> Well, I can do it for you right here, but I need to be pretty fast to do it. Let's give this a try.  >> It's Einstein! § § (musical flourish) >> So, what's going on here, is you're actually only seeing one line at a time reflected off of this rod. It's very similar to how an older television set would work. But if I move fast enough, he photoreceptors in your eyes don't respond quickly enough and you think you're seeing the entire image at once. (applause) As long as we've got the lights off, let's talk a little bit about the colors that light is composed of. White light is composed of all the colors of the rainbow. § § What I've got here is a projector making white light that's shining through this triangular prism. 

The prism splits up the light, it refracts it into all the components of its spectrum. Now, when you watch your television, your TV can actually only make three colors, red, green and blue. It can't make the yellow. It can't make the orange. It can't make indigo. It can't make violet, or anything in between, except for red, green and blue. So how is it that when you watch TV you see all these beautiful images? Well, there's a trick to that, too. Let me show you what happens if I mix blue light with green. I get teal. If I mix blue and red, I get magenta. 

If I mix red and green, I get yellow. And if I mix all three, I get white in the center there. Well, what's happening is you also only have three kinds of color receptors in your eyes. Ones that are most sensitive to red, ones that are most sensitive to green, and ones that are most sensitive to blue. When you look at true white-white, like the white that's being produced on the left there, all three of those photoreceptors are stimulated, the red, green and blue. Same thing happens when I trick you, by showing only those three colors, the red, green and blue. You think that you're seeing true white light. >> But watch what happens when I cast a shadow. >> There's three of them! >> That's right. So as my hand moves in front of the light from each projector, that light is blocked and subtracted out from the image on the screen. 

>> Subtraction, that reminds me of something. You know, Professor Sprott's been working on some sort of painting back there. The way that paint is mixed is actually very different from the way that light is mixed. I think it's more up your alley, Shadow. >> Absolutely. When we mix light colors, we see that they add. But when we mix paint colors, they subtract. Here I have yellow and blue. >> Oooh! Wow! >> I get green. Remember when we mixed green and red light, we got yellow. 

But now-- (loud buzzer) Ick. We mix all the colors, so they've all subtracted out, and it's just dark. >> Okay, thanks. Hmm, mmm. Mmmm. (laughter) Mmm, ah. § § (musical flourish) Delicious. (laughter) Professor Sprott, now that you know about how paint colors mix, you should make a pretty great artist, so we'll leave you to your work. Say goodnight, Shadow. >> Goodnight, Shadow. 

(applause) § § (musical flourish) >> You know, Professor Sprott, I see you've been busy painting over there throughout the show. >> Well, I have. Would you like to see what I've done? >> Yeah, I think we'd all like to see it. >> I've been working on something that illustrates both physics and art. >> Uh, I don't see anything. Do you? >> Yeah! >> No! >> Well, that's where the physics comes in. >> It does? § § (musical flourish) (applause) >> That's because this is painted with fluorescent paint. A fluorescent material is one that absorbs light at one frequency, and then re-radiates at a different frequency. In this case, we have back here an ultraviolet that is shining on the paint. That causes the paint, each different paint, to emit a different color. 

So when I turn the light off, the picture seems to go away, because the fluorescent paint itself is simply white. It does emit those particular colors. I would like to claim that I painted that, but it was actually painted by one of our longtime assistants, Rebecca Nonn. She's very talented. I only wish that I were able to do things like that. But I did become interested in art once, quite by accident. I was solving on my computer some mathematical equations and the patterns that were generated looked to me very artistic. And in fact, that was confirmed by an art professor who said, oh, yes, these have quite a lot of aesthetic value. He said I ought to write a book about it. And I did. 

In fact, I wrote several books, the most recent of which just came out recently, called "Images of a Complex World." It's filled with hundreds of examples of these artistic patterns, which in fact come from solving equations whose solutions are chaotic. These are called strange attractors. This book is full of them. If you're interested in this, you can have a look at it on the table outside the lecture room on your way out. Now, to conclude the show, we have a special treat. Twenty-one years ago, I was doing one of these shows and I looked out into the audience, and I saw Professor Jim Latimer of the School of Music. I recognized him because he's also the director of the Capitol City Band, which many of you have probably heard play. He came down after the show and I jokingly said, "Hey, why don't you write some theme music for The Wonders of Physics." And he did. The next year, 1992, he came to our show and he premiered the theme music that he had written for "The Wonders of Physics." We've been using it ever since. We have a special treat, because it happens that today Jim Latimer is with us. 

Jim, would you stand up? (applause)  Thank you, Jim. I asked Jim, what the heck is a musician doing at a physics show. He said, oh, I've always been interested in physics. In fact, I'm a ham radio operator. That's also how I got interested in physics, through ham radio. In honor of the Year of the Arts, in collaboration with Frank Ferriano, Jim Latimer actually composed a new version of "The Wonders of Physics" theme, and it was premiered by the Madison Marimba Quartet just this past Christmas. It runs about three minutes. We're going to play it in its entirety at the very end of the show for those of you who would like to stay around and listen. Sometimes science is portrayed as being in competition with the arts. But I hope we've convinced you that the two are very closely related. 

All of the arts rely on principles of physics, and scientists enjoy and profit from the arts, just as much as anyone else. Thus, I want to encourage you to learn all you can about science. But also, if you have artistic talents, you should develop those as well. Even if you're like me and have limited artistic skills, you can still enjoy the artistic talents of others. Now I'd like to end the show in the same way we have ended every one of the shows over the past 28 years, by making for you a cloud. For that purpose, we use a tank containing 25 liters of liquid nitrogen. We force nitrogen gas into this tank. That forces the liquid nitrogen to come up into this pipe, and leave through these tiny holes on the top. The liquid, and also the gas, is still very, very cold. It cools the air above, and the water vapor in the air will condense into tiny droplets of liquid water, and that's what we call a cloud. 

So with that, I will put on my hat and let you hear the new version of "The Wonders of Physics" theme music. I thank you all for coming. § § (applause)