2012 Physics of the Wisconsin Idea  The Wonders of Physics with Professor Clint Sprott UP718  cc >> Ladies and gentleman, introducing the Analyst of Agronomy, the Houdini of Horticulture, that Physicist of Farming, and the Wizard of Wisconsin, Professor Clint Sprott! [applause]  >> Welcome to the Wonders of Physics. This is the year of the Wisconsin Idea at the University of Wisconsin. The Wisconsin Idea is that the boundaries of the university are the boundaries of the state. Or more generally, that the research we do at the university should have broad applications for society. An example is the weather. We can make accurate predictions of the weather because of all the detailed physics that is in the models that the weather people use to make predictions. We can even predict when and where a tornado is likely to occur. Would you like to see me make a tornado? >> Yeah! >> I thought so. For this, I will need a volunteer. Okay, come down here. 

 What is your name? >> My name's Melissa. >> Hi, Melissa. Where are you from, Melissa? >> I'm from Chicago. >> Melissa from Chicago. Do they have tornadoes down there? >> Oh, yeah. >> Uh huh. Have you ever seen one? >> No. >> Okay, well, we're going to show you a tornado today. Tornados usually occur in the summer. They require some heat. 

So I'm going to make some heat. To do that I'm going to wad up this little paper towel and I'm going to put it in this can. Then I'm going to take some lighter fluid and I'll soak the paper with the lighter fluid. What I would like you to do, Melissa, is to take this and set that on fire for me.  Of course, you know, hot air rises, and as the air rises, cold air has to come in from below. If the cold air coming in is rotating, then as it comes in closer and closer to this center of rotation, it goes faster and faster. § § It's much like and ice skater you've probably seen, that spins around and brings her arms in and goes really fast. Now Melissa, could you take this and put that out for me? [wind sounds] >> Auntie Em! Auntie Em! [thunder] >> I don't think I'm in Wisconsin anymore. Excuse me, where am I? >> You're in the Wonderful Land of Physics, of course. >> The Land of Physics? >> Yes. 

>> How am I going to get home? >> Home? Where's home? >> Chicago. >> Chicago, hum. I have an idea of how we can get you back home, maybe we can use some balloons. You know, I've been experimenting with them. What do you think would happen if we were to light a hydrogen balloon on fire? [crowd murmurs] What do you think would happen if we lit ten hydrogen balloons on fire? [exclamations]  Well, you know, if loud noises bother you, you're going to want to plug your ears. I'm really fond of my beard here, so I've got a little bit of added protection I'm going to put on. And again, we will light our match on a stick. Here we go. Okay now, this is going to be loud. [applause]  Good. 

Got that one too. Alright. [crowd talking]  Now, you know, maybe a hydrogen balloon is not the way that we're going to send you home. I know of a person who can help you out though. And that's the Wizard of Wisc. He's a big Green Bay Packers fan and a real Cheesehead. He lives in the City of Green and Gold. What you'll have to do is follow the Yellow Cheese Road and learn some physics of the way. So off you go. >> Wish me luck. 

I'll need it. § §  >> Transportation is an area that physics has greatly influenced over the recent years. In fact, Wisconsin has played first to many of the advances in transportation. We've had the first city to city auto race, the first snowmobile, and the first outboard engine. Here to tell us more about physics and transportation is our own king of transportation, Mike Randall. [applause]  >> § Why, if I were king § § Just king § Physics is a part of everyday life. It's the study of how things push and pull on each other, how things exchange energy, how things move. To get something moving, you have to push or pull on it. Physicists call that a force. My favorite dead guy, Sir Isaac Newton, came up with three rules about how to move things around. 

He called this three laws of motion. Have you heard of them? >> Yeah. >> Yeah? Maybe some people haven't. I need three volunteers from the audience. We're going to demonstrate this. Okay, you sir in the red jacket, right there. Let's see here. You, young lady right there, in the pick stripes. And you sir, that will do just fine. What is your name? >> Abraham. 

>> Abraham. Let's see, Abraham. And you are? >> Blake. >> Abraham and Blake. I have a special job for you. I'm going to have you guys sit right on that board for me please. Sit cross-legged and face the crowd. What is your name? >> Lexie. >> Lexie. You get to hold on to that. Okay. 

These guys are playing the roll of two large Wisconsin cheese wheels today. [laughter] We are in Wisconsin. You are all playing the roll of scientists, which means you're all observing right now. I want you to observe our two cheese wheels. What are they doing? [inaudible] They're just sitting there, not doing anything. Sir Isaac Newton's first law of motion says that an object at rest, stays at rest, unless acted upon by an outside force. Lexie, you get to be the outside force. I want you to pull on that rope, and let's see what happens. [laughter] Anytime. Go ahead and start-- >> Oh, dear. 

>> How's that going? [inaudible] It's really hard. You know, hang on a second. Stop pulling. I think the problem is, there's too much friction between the bottom of that board and the floor. Do you know what friction is? I think there might be some people who don't know. So we're all going to try this out. Put your hands together for me, and rub. What do you notice? >> It's getting hotter. >> It's getting hotter. Ah, yes. 

See, friction is a force that turns the energy of motion, or kinetic energy as scientists call it, into heat energy. Throughout history people have been looking for ways to reduce friction, to make transportation easier. Okay, guys, I need you to stand up and pick that board up for me. In ancient times people used rollers to help reduce friction. So we're going to try some rollers out. Okay. Set that board right back down on there. And go ahead and sit on the board again, just like you did before. Face the front of the room. Okay. 

Lexie, hang on to that for a second. I also want you guys to put your arms like this. Excellent. Okay, Lexie, give it another try. Pull, pull, pull. Go! [applause] Now, how was that? Was that easier? >> Yeah. >> Yeah, those rollers did a great job to reduce the friction. They made transporting these cheese wheels a lot easier, right? Excellent job. Big round of applause for my three helpers here. [applause]  [inaudible] >> Gees. You scared the daylights out of me. 

>> I'm sorry, I didn't mean to. >> It's not your fault. Sometimes we physicists just get wrapped up in our thoughts. My name is Mike Randall. Who are you? >> My name is Melissa, and I'm trying to find the Wizard of Wisc. >> I know the wizard. He's an airplane pilot. Have you tried looking for him in an airport? >> No, but I've been walking for hours and I think I twisted my ankle in the Swiss cheese a little bit. >> I hate it when that happens. >> Yeah. 

Is there an easier way I can get there? >> Well, I have been working on another type of transportation, another way to reduce friction. This is called a hovercraft. This uses a thin cushion of air to lift the board a little bit. It greatly reduces friction, but I've been too cowardly to try it. >> I'm not scared at all. This will get me to the city in no time. >> Really? >> Oh, yeah. >> Okay, well-- We'll give it a try here. [engine noise]  I guess physics isn't a substitute for driving lessons. [applause]  >> There have been many pioneering environmental ideas recently. 

Here at the UW-Madison we've had the very first Department of Limnology, which is the study of freshwater lakes. Also, John Muir, a very famous conservationist and father of our national park system, attended the UW-Madison. Here to tell us more about physics and the environment is our own biodegradable and environmentally friendly, Marty Lichtman. [applause]  >> Hello everybody. Welcome. I have a demonstration here that can show us how the greenhouse effect work. Now, we have two identical fish tanks, and before the show, I filled one with a dense gas called sulfur hexafluoride. It's clear, it's odorless, and it's non-toxic. But it's very dense, so it will stay in the tank. I had the cover on only so that breezes wouldn't blow it out. 

This balloon is just filled with air. It will sink. If I put it in this one, it sinks down, because this fish tank is just filled with air. But if I put it into this one, it will float, because the air in the balloon is lighter than the sulfur hexafluoride that it displaces. Let me set that aside, and I'm going to turn on two lamps to simulate the sun. The light from the sun comes down and it heats the dark earth at the bottom, which we've simulated using this cloth. That light is absorbed, and then it's actually re-emitted in infrared. You might say, wait a minute, the Earth is not glowing. That doesn't make sense. Ah! But it is, and you just can't see it. 

I will show you exactly where that infrared radiation is using another device over here. We call this a carbon arch lamp. It's the same thing used in older lighthouses to make that bright, white light. I'm going to turn this on and we will strike an arch, forming a plasma between two carbon electrodes, making this bright, white light. We'll shine that light on this quartz prism, refracting it out into the colors of the rainbow. We'll shine it on that white card which we'll put up on the screen here. You can see the rainbow shining on my card and you can see a black dot in the middle. What that is, is it's a sensor that detects optical power. I can move that sensor back and forth to see how much power is in different parts of the rainbow. We'll show the measurement on this galvanometer on the screen on your right, over here. 

Let me move it back and forth, and see how much power is in different parts of the spectrum. You can see, as I move it, it changes how much power there is. Let me try and find the peak. There's a big spike there. All right. It's pretty high right there. I think that's the peak. We've pegged the needle. It's way past 50, but now take a look at my rainbow. Can anyone tell me which color we're on? Right here. 

Speak up! >> Red. >> Well, it's pretty close to red, but I don't think it's on red. Anyone else have any guesses? Over there. >> Violet. >> No, violet is all the way on the other side. It looks to me like there isn't light there at all. Actually, I don't see any. Do you guys? >> Together: No. >> Ultra violet. >> Well, ultra violet is actually all the way at the other end of the spectrum. 

This is what we call infrared. We call it infrared because it's a longer wavelength than red, so it's past red when you refract the light out into a rainbow. But this shows that there really is light there, we just can't see it with our eyes. In fact, there's quite a lot. Most of the optical power is falling there. So let's shut this off and go back to our suns. Put this away. Now, what's been going on here? Why did I fill one of the fish tanks with sulfur hexafluoride? That visible light comes down, it's absorbed by the dark cloth, and then it's re-emitted as infrared. Air just passes the infrared and most of it will come out, but sulfur hexafluoride is a greenhouse gas. What that means is that it absorbs infrared radiation. 

That infrared radiation gets trapped in the SF6, emitted back down to the cloth, back up, back down, and a lot of it stays in there. So the temperature in this fish tank should get hotter. But now how can we actually see that, since we can't see infrared with our eyes? I happen to have a camera which can see infrared radiation. Let's get this out here. Get that set up on the screen there. Let's take a look at you guys first. [laughter]  Give a wave. What you're seeing on the screen there is the infrared radiation coming off of your bodies. All of you are glowing, just at a wavelength that you can't see. In fact, anything that has some temperature will glow at some wavelength, just not necessarily one that you can see with your eyes. 

Let's take a look at our fish tanks and see-- Oh! Hey, let's check this out. [laughter]  Ladies and gentlemen, a geyser. Actually, if you look at the geyser over here, you can see quite a lot of heat on the Bunsen burners on the bottom there, and then the heat traveling up the tube. There's hot water all in the tube there. We're going to take a look at these fish tanks. Actually, what I'm going to do is I'm going to shut off these lights so that they don't wash out my picture, but if I look at the light even though the light is off, it's still glowing. Because it's very hot, it's glowing in the infrared spectrum. Let me take a look at the fish tanks and see what we can see. Since I'm facing the other way from you, the one on the right is the one with the sulfur hexafluoride. You can see the red spot on the bottom there, on the cloth. 

It has a much larger red spot than the one that had air in it. Red and white are the hottest colors in this image, so the one with the sulfur hexafluoride we can see, after a few minutes, it's already gotten quite a hotter. It's a small temperature difference, but after only a couple of minutes, it's still noticeable. You can imagine what would happen if this process was repeated all day long, day after day after day. It would build up quite a bit. I should mention that the reason we call it the greenhouse effect is it's an analogy to a garden greenhouse where you have glass that passes the visible light, the plants and whatever else is in the greenhouse absorbs that visible light, re-emits it as infrared radiation, but the glass traps that infrared radiation inside making the greenhouse warmer than if the glass weren't there. There's one other cool thing we can do with sulfur hexafluoride. I wonder what would happen if I stick me head in and take a breath. Let's find out. [deeper voice]: Let the beat drop! [laughter] § Somewhere over the rainbow! § § Skies are blue § [voice normalizing]: So the speed of sound in sulfur hexafluoride is only 44% of what it is in air. 

When I breathe it in, I get longer wavelength resonance setting up in my nasal passages, making my voice seem to appear lower. [applause] Hello. >> [high voice]: § I represent § § The lollipop guild § § The lollipop guild § Hello. >> That must be helium in your balloon. It does quite the opposite of what SF6 does, because it's a lighter gas. The speed of sound in helium is 2-1/2 times higher than in air. Which makes it set up shorter wavelength resonance in your nasal passages. >> That's really interesting and all, but I'm actually trying to find the Wizard of Wisc. >> Oh, the wizard. You know, all this talk about greenhouse gases and SF6, SF6 is not usually one that we're concerned about because there's not much abundance of it in the environment. 

We're typically more concerned about methane, and especially carbon dioxide. It's the carbon in the carbon dioxide which is why we're all trying to lower our carbon footprints. The Wizard of Wisc is no exception. He rides his bike in order to try and lower his carbon footprint. There's a picture of it actually. He also has a carbon dioxide-powered tricycle. It's this right here. It's his rocket tricycle, but it's powered by a carbon dioxide fire extinguisher. I think he might be a little confused about the whole carbon footprint. It actually emits quite a bit of carbon dioxide when we use it. 

But it's a rocket cycle, so it's quite fast. I think it should take you to him in no time. >> Okay, which way should I go? >> Well, um, I think it's that way. Or maybe that way. I don't know. >> Really helpful. >> It's a little bit loud, so you in the front row might want to cover your ears. Good luck! § § [applause]  >> What's the difference between a magician and a physicist? A magician, you can't ever get him to tell his secrets, but a physicist you can never get him to shut off. [exclamations] I think I've seen that somewhere out west. Energy is an area that has been greatly influenced by our physics research. 

In fact, the Department of Energy funds many energy research programs here at the UW-Madison. Here to tell us more about energy and physics is our own energized and electrifying Kenny Rudinger. [applause]  >> Where would we be without energy? It would be very difficult for you to be here today, because your cars wouldn't have had the energy to take you here. It would be difficult for you to sit here and watch, because you wouldn't have gotten any energy from the food that you ate. Energy can take on many different forms. One of those forms is light. We have some light bulbs here to demonstrate that for us. Let's turn them on. Let's find a switch. That didn't do it. 

Neither did that. Let's see, hum. There's a cable here. Where does that go?  Oh, it goes to this bike. A bicycle is a clever device that you sit on and you peddle, and you turn a gear that will then turn a wheel, to make you and the bicycle move down the street. What we've done here is we have taken this bicycle and we have taken the back wheel off. Instead, we put a device on it that we have plugged the light bulbs into. To demonstrate how this bicycle works, I need a volunteer who likes to ride bicycles. You, sir. What is your name? >> Blake. 

>> Blake. All right, Blake. Why don't you sit on the bicycle, and go ahead and start peddling. § § That's a lot of work, isn't it? But you were able to light the bulb. >> Yeah. >> Now, try again.  § § Look at that. You are able to get a much brighter light and it's not nearly as much work, is it? >> No. >> All right, thank you very much. Let's give him a round of applause. 

Thank you. [applause] So what happened? When he peddled it turned the gear which then turned this device at the back of the bicycle called a hub dynamo. What a hub dynamo does is it converts mechanical energy, that is the energy from peddling, into electrical energy. The electricity that is generated then, goes through one of the bulbs, lighting it up. We have two different bulbs. We saw the first bulb, the incandescent bulb, required a lot of effort and didn't light up very much. The second bulb, the one of the right, is an LED, or a light-emitting diode. That one didn't require nearly as much work and was very, very bright. The reason for that is, the incandescent bulbs, these older kinds of bulbs, are much less efficient at converting electrical energy into light as opposed these LED's which are much more efficient. The LED's will take much more of the energy that you've put into it and convert that into light. 

That's why we're switching today, from old incandescent bulbs to LED's and compact florescent bulbs, saving us energy and money. >> Hello there. My name is Melissa and I'm trying to find the Wizard of Wisc. But I'm a little curious about what's going on with all these ping pong balls and mouse traps. >> That's a great question. Let's take a look. We're talking about energy, and we just saw with this bicycle, different forms of energy that you can have. This is a demonstration of another kind of energy that you can have. Before I explain exactly how this works, we need to talk about atoms. You and me and everything around us, everything in the world, all the matter in the world, is made up of atoms. 

Atoms are made up of protons, neutrons and electrons. If you take an atom and split it apart, you can release energy. If you hit an atom with a neutron, you split it apart, releasing energy, and sometimes other neutrons as well. Those neutrons can hit other atoms, causing them to split apart releasing more energy and more neutrons, in a process that's called a chain reaction. This chain reaction is the process by which we get power at nuclear power plants. When we split these atoms apart, this is a process called nuclear fission, and if we have a chain reaction of them, we can generate power. This is a model of that. Each mouse trap represents an atom and each ping pong ball represents a neutron. We're going to drop a ping pong ball in from the top, it's going to hit a mouse trap. It's going to make that mouse trap go off which is going to send a ping pong ball flying. 

That's going to then hit another mouse trap that's going to send it's ping pong ball flying in a chain reaction. Much like the chain reaction when there's nuclear fission going on at a power plant. There's a string there. Take hold of that and everybody watch very carefully. It's going to happen pretty quickly. Melissa, go ahead and pull the string. [exclamations] [applause]  >> That was sweet! >> Would everybody like to see that again? >> Together: Yeah! >> All right, I'm going to need 200 volunteers to help me reset the traps. [laughter] On second thought, we can just watch a video in slow motion that we make earlier.  Pretty cool, huh? >> Oh, yeah. >> Nuclear fission is one way that we can get energy from atoms, by splitting them apart. 

But there's another way too, by bringing them together in a process called nuclear fusion. The Wizard of Wisc worked on a nuclear fusion project right here at UW for over 25 years called the Madison Symmetric Torus If you're looking for him, look for a large aluminum donut, and he'll be sure to be nearby. >> All right, I'll try to keep an eye out for one of those things. Thanks. [applause]  >> Can you hear me now? Can you hear me now? >> Yes! >> Can you hear me now? >> Together: Yes! >> Can you hear me now? >> Together: Yes! >> Okay. How many of you remember a telephone that had a cord on it? Oh, maybe you've still got some. Okay. How many have ever used a telephone with a dial on it? That's a few hands. How many have used a telephone that had a crank on the side? You had to crank it to use it. Maybe one, two, a couple. 

Okay, now how many of you have went down to the Western Union Telegraph office at the railroad station and sent a telegraph? Nowadays, most people, when they want to communicate, they just use cell phones and two-way radios. Communications is an area that physics greatly influences. Here to tell us more about that is our own 5G professor, Professor Michael Winokur. [applause]  Oh, I think he forgot again. Hang on a minute. Professor Winokur. Professor Winokur! >> Pete? Sorry Pete. Pete? Oh, he'll get over it. Look what I found on the Yellow Cheese Road. I thought it appropriate that we should try to communicate with him and find out why he's here and what he's all about. 

Communication only involves manipulation of energy, so as a first attempt I thought I'd try some directed energy from this Tesla coil, and see if we could wake him up. What do you think? Yeah? I hope there's no equipment malfunction, but if there is, it's okay. My CPR is current and up to date. I'm down to the control panel. Are we ready for this? >> Yeah.  >> Ahh, I needed that. I feel good. [applause] >> Hey, it talks. Now we can communicate. With all this energy, there's no way I'm going to stand here and talk. 

I gotta go. >> That's pretty heartless of him. >> I heard that. You are so right for now, but not for long. >> I'm sure the Wizard of Wisc can fix him up with a nice new heart, but if he'd stayed I could have told him that communication that often involves energy in the forms of light or sound. Two things which our Telsa coil seems to produce in rather large quantities. But we really, really need to control it better. In fact, we need to do three things. First, we need to use energy to create a disturbance. Then we have to send that disturbance, that signal, out over a distance. 

And more importantly, or most importantly, three, we have to maintain that signal even in the event that there is noise or interference. Perhaps some of you parents know a little bit about noise and interference. [laughter] I think I'll talk about sound first. Sound uses the air molecules, we just have to impart some energy to them. To do that I have a demonstration here that shows you how it works. We squeeze the air molecules together and then we spread them apart. We do that over and over and over again. Let's get this set up. I think that's set there. Here's a piston. 

Sort of like your bicycle pump. When I push down on the plunger, the volume will get smaller. The molecules of air will move closer together. They're getting squeezed. The pressure will go up. When I lift up on the plunger, the air molecules will have more space so the volume will increase and the pressure will go down, and they will sort of be spread apart. To monitor that process I have a pressure gauge down here, and a computer readout up there. The top display gives you a number in units of kilopascals, I'm sure they'll live. Plus, there's a chart along the bottom for you to follow and see the graph of the pressure. If I hit start, you see a number. 

Let's squeeze down, and lift up. Squeeze down and lift up. The pressure goes up, the pressure goes down. Back and forth. Did you here that? >> Yeah. >> You've got good ears. For you to really hear that pulse, I'd have to do that about a hundred times a second. It's not going to happen. Not today anyway. But now I have my disturbance. 

Now I have to send that energy out to you through the air. I want to show you that, but it's hard to see the air. So we have another demonstration back here. It's just a simple device. It's a long coil of wire, wrapped 'round and 'round and 'round and 'round. We have a fancy name for it. We call it a Slinky. [laughter] We are going to do what happens in the air. There's a metal bar back here that's attached to the Slinky, and when I pull it back it will spread the coils of wire apart. When I let go it will squeeze the coils of wire together. 

You'll see what happens to the energy in this disturbance when I let go. Are we all ready? All right, watch carefully.  [applause] So this squeezing and spreading is happening in the air, and this special kind of wave, because the energy moves along the wave, and the motion moves along the wave, is called a longitudinal wave. We can actually visualize the motion of the air molecules with sound in this device. I'll just turn on the light over here. This is just a tube, sort of like a pipe organ tube. There's a speaker on the far end. It will set up a standing wave in here. With this standing wave, there'll be an interesting property. In the places where the pressure is high, the molecules are squeezed together, the air will be moving slowly. 

Where the pressure is low and the air molecules are far apart, they'll actually be moving very quickly. We'll be able to visualize it because there's all this brown stuff on the bottom. There's some wine bottles that we had, we ground up the cork really fine so that the dust is very powdery and light. When I turn on the speaker then you'll be able to see the standing wave and the motion. Let's turn that on. Watch carefully. It moves quick here, and not at all there, and about 2/3 of the way down. Are you ready? [machine hums] So that's what's happening-- [applause] in the airwaves as they move out to you. So we've got two of the three things. We've created the disturbance, we've sent the energy out to you. 

Now we what to maintain the signal in the event that there's noise. Now for this last part, or this third part, I have a couple more demos. I need a volunteer. Somebody close. You put up your hand. Come on out here.  Your name is? >> Wyatt. >> Wyatt. The Wizard of Wisc sent me a special message by the mail, and you're going to read it. You can read, right? >> Yes. 

>> Oh good, Wyatt. All of you are going to participate, because you're going to make some noise while he's reading the special message, and we'll see if someone in the back row can hear that message. Are you ready? Let me get the message out. I'll put that there. Everybody start making noise.  Okay. In the back row, did anybody hear that? >> No. >> Okay, so now we're going to keep the signal together in such a way that maybe someone in the back row can hear it. We talked to our friends at Kraft and got the world's biggest cheese noodle. I think they got carried away with the orange food coloring. 

What do you think? We're going to try that again. You're going to speak in here, a little bit louder, and there's going to be a volunteer in the back row who's going to listen. Do we have a volunteer? All right, we're good. You guys are going to make that noise again while Wyatt says the secret message. All right, go!  What did he say? >> I like physics, I like physics, I like physics. >> Cool! [applause] How many of you folks like physics? Thank you Wyatt, and back there. The sound tube is a lot of fun. We leave it out after to show so the kids can have good time with it. Now sound it usually pretty good for communicating in the room, but it travels really, too slow, to go long distances. If you think about it, a one word conversation by cell phone to California, if you were to use sound energy, would take about four hours. 

Can you imagine what your cell phone bills would be like? I can. No, thank you very much. We have other forms of energy. I happen to have a green light on top of my hat. Light energy travels at about a million times faster. That means it takes almost no time at all. We just have to control the sound in the same way. Back here we have a demonstration that shows you how we're going to do that. We have a light pipe and we're going to examine the physics of refraction, that's the bending of light, and reflection, like a mirror, but there's no mirror in this plastic rod. We'll see what happens as I change the angle at which the light comes into one end of the plastic rod. 

This is a green laser with a very special type of lens on it. I'll come in from the bottom so it's perpendicular, and you can see the green light. As I move the laser and change the angle, the light bends more and more. That's refraction. Pretty soon it bounces in and out, back and forth. I can maintain the light signal all the way to end of the rod. [applause] Any of you who've used communications with fiber optics, it exploits physics in that way. But we're not just limited to sound or visible light, we can in fact transmit light of any energy, or almost energy, through space and distance. We had so much fun with the Tesla coil, I'll show you that we can actually use it to transmit energy through the air that you can't see, but we can light up this florescent tube. Do I have a volunteer for this? Come on down here. 

Don't hurt yourself. That's my job. Now hold it down at the metal. Your name is? >> Cavey >> Cavey, cool. You're going to hold on to this. I'm going to turn on the Tesla coil. You won't feel a thing, but even if do, as I've been telling everyone, not only do I know adult CPR, but I know child CPR too. Just stay there. That's good enough. You can step back a few feet. 

We want to transmit a distance. Okay, let's try this time. [exclamations]  [applause] Thank you, Cavey. Are you feeling okay? >> Yeah. >> All right. >> I just heard some really loud, crazy noise. Did I miss anything cool? >> Just our little discussion of communication and physics. >> Would that help me find the Wizard of Wisc? >> Hum, oh, yeah! I know, the Wizard of Wisc, he's an amateur radio operator. We just happened to have a radio here, so if you hold on to this, I will try to find out his call number and send out a signal with radio waves, and see if we can communicate with him. Let's go. 

[beeps]  Whiskey nine alpha victor. Whiskey nine alpha victor. Are you out there? Are you out there?  No, I guess not. But if you see a house with a really tall antenna outside, you just might find the Wizard of Wisc inside. >> Okay, I'll keep an eye out. Thank you. >> Good luck [applause]  >> I'm sorry. I looked all over the building and I couldn't find Professor Winokur. When we talk about the military, that's not something you normally think about when we talk about physics. But being an old Navy sailor, I knew how important physics is to keep my 100,000 ton aircraft carrier afloat. 

Here to tell us more about the military and physics is a own general of relativity, Blaine Law. [applause]  >> Thank you sailor. How are you folks doing today? >> Together: Good! >> Seems my recruits look younger and younger every year. This fellow right here is about as small as a frog hair split three ways and sanded smooth. I've been tasked with come here today and talking to you all about how physics has influenced the military over the years. A bunch of egg-heads in lab coats have been making my job much easier. We're pretty appreciative of that. One of the first ways that physics helped in the field of military science was in the development of something known as ballistics, or the way that projectiles travel. Imagine a few thousand years ago some caveman picked up a rock and he chucked it. He thought that was pretty neat. 

I wonder what happens if I throw it a bit harder. So he tried that too, and he noticed that it went a little bit further. This is what's called experimental science. He made an idea, checked it out, saw what happened and eventually, through trial and error, he got pretty good at chucking rocks. A little while later somebody came up the bow and arrow, right? They found out that an arrow travels a lot like a thrown rock. It just goes a lot further. It still took a lot of trail and error before they could get pretty accurate with it. This idea doesn't really work so well nowadays. When we launch an 80 pound ordnance a couple miles down field where you've got friendly forces nearby, we can't really be guessing and checking much. Luckily, in the late 1600's this fellow named Sir Isaac Newton comes along and he developed a cure for a projectile dysfunction. 

We've been launching stuff ever since. It's been wonderful. To kind of demonstrate to y'all how this works, and our mastery over it, I'm going to be firing a small cannon at a moving target. I'm going to be firing the cannon, so I'll need a volunteer. I appreciate everybody's willingness and I know if I point a cannon at the audience, many of you would be great moving targets. You're really excited, aren't you? Headquarters said I can't recruit any of y'all for this, but that's all right. We have a detainee that has offered his services. It's little flying monkey we caught sneaking around in her earlier this morning looking for some Army secrets, I'm guessing. It looked about as obvious as a cat trying to cover it's poop on a marble floor. [laughter] We're going to stick him up right here. 

Oh, he's feisty. He don't want to stay. We're going to put him up here on this ledge and I'm going to get my cannon zeroed in on him. He's a trouble maker all the way. Before we can proceed with this experiment, according to Wisconsin state law, university guidelines and Army statute 3.14, we have to have the explicit consent of any and all willing research participants. He may seem less than willing, but we're going to give him the opportunity to defend himself. So Mr. Monkey, do you object to us firing a cannon at you? [crickets chirp] Did y'all hear anything? About as quiet as a gerbil fart, wasn't he? [laughter] He's still looking pretty nervous. I'm afraid he's going to keep jumping off of there. He looks like a cat in a room full of rocking chairs. Hopefully, he'll stay tight just long enough. 

I've got this zeroed in on him pretty well, but I'm pretty sure when this cannon goes off he's going to jump down again. Do y'all think, if I fire this and he's moving down, is it going to go over him or under him? >> Over. >> Who thinks over? Who thinks under? Let's do our own experiment. Here we go, fire in the hole!  >> No! Fly. Fly. I'll get you and your little military secrets too. [laughter] >> I've got big Bertha here. I know you guys have been eye-balling this since the show started. I'm going to show you how cannons work. A cannon has three main components. 

A hammer is generally not one of them, but you never know. The three main parts are the cannon, or the artillery itself, this is the thing that is generally a constant. We don't want it going anywhere. We have some kind of projectile. This is the thing we want as far away from us as we can get it. And then we need something that's going to give us some kind of a reaction, or something that's going to propel it. What do you think we normally use in cannons and artillery to make it boom? [indistinct] Gun powder. That's right. They don't trust me with gun powder after the show back in '08. Y'all saw Pete with that beard? He was pretty sore when he lost it that year, but-- What they do trust me with is liquid nitrogen. 

Y'all ever seen this before? >> Yeah. >> Pretty fun stuff, isn't it? The neat thing about nitrogen is, at room temperature it likes to be a gas, but when we make it as cold as a well diggers behind in January, it condenses itself down into a liquid. I'm going to pour this into the cannon, and the cannon is already at room temperature. You see all that smoke coming up off of there? >> Yeah. >> That's the nitrogen turning back into gas. As it transforms itself from a liquid into a gas, it expands. It takes up more space. We have a finite space here in this cannon shell. So what do you think is going to happen when I plug that sucker up? Something really cool, right? [pounding] Parents will thank me if I tell you not to do this in your back yards. Wait 'til you get to university and study physics. 

You can spend the rest of your life blowing stuff up. >> Fire when ready, Gridly. >> Roger that. [boom and exclamations] >> Ah-ha! [applause] Just like in rehearsal. >> He's gotten pretty good at catching those since that beard incident. [laughter] Did y'all notice anything funny about this cannon when it went off? That's right, it went backwards. Recoil. Watch your feet there. Why y'all suppose that happened? Newton's Law. That's right, I heard somebody say it. 

Y'all learned from that lion-man earlier that for every force, there's an equal and opposed force, right? So the same pressure that's building up and forces that plug forward, is also trying to force our cannon backward. The cannon didn't roll nearly as far as that plug went. Why is that? Shout it out. >> Less mass. >> Less mass, that's right. Actually, the cannon has more mass, so the same force acting on it won't move it quite as far as the plug moved. Think about that next time you're driving down the freeway and you spot a bug on your windshield. The bug is applying the same force to your car, but your car is a little bit more massive, so it gets the better end of that deal. What do you think you're doing in here lady? We've got a lot of ordnance going off. >> Oh, I don't know. 

I think I'm a little lost. I'm looking for the Wizard of Wisc. I'm trying to get to the City of Green and Gold. >> I know the Wizard. He was a major in ROTC when he was back in high school. You can see him sharpening his sword here. They hadn't invented guns then. [laughter] Now I know I've got a cannon big enough to launch you straight to the City of Green and Gold, but in compliance of university policy, state law and Army statue 3.14, I'm going to need you to sign some waivers for me. >> No, that's okay. I think I'm just going to walk. 

>> You wait right here. I'll be right back. >> No. [applause]  >> How many of you have even had an x-ray? How about an MRI? How about a CAT scan? No, not the kind with the tail and all the fur on it. Medicine is an area that has been greatly influenced by our physics research. In fact, John Cameron, one of our professors here at the UW-Madison, was the founder of one of the very first ever medical physics departments. Here to tell us more about medicine and physics is our own Madam Curie of physics, Amy Lowitz. [applause] >> Hi, everyone. I've been doing some research for the Wizard, studying all the different ways that physics has contributed to the field of medicine, helping doctors learn how to diagnose and treat patients. A great example of one of the ways that physics plays into medicine is waves. 

Waves come into medicine in all sorts of different ways, but one of the ways that you probably experience the most in your everyday life is sound. The way that you hear is that waves travel through the air and into your ears, and that's what allows you to hear. A typical young adult can hear frequencies from about 20 Hertz to about 20,000 Hertz. That's 20,000 waves hitting your ears every second. I'd like to do a little experiment to explore that a little bit more. I'd like everyone in the audience to raise their hands and I'm going to play a tone. I'd like you to keep your hand raised until you can't hear the tone anymore. Once you can't hear it anymore, then lower your hand. Let's give it a try and see what happens. [tone, getting higher]  Look at that. 

What you may have noticed is that, for many of you, your parents lowered their hands before you did. That's because, as we age, most humans lose their ability to hear the highest frequency sounds. That doesn't' mean there's not a sound. It just means that it's at a frequency that you can't hear it. Can anyone think of an example of something that makes a sound that you can't hear? Anybody? Just call it out. >> A dog whistle. >> That's right. A dog whistle is a great example. I just happen to have one right here. Let's give it a try. 

[high pitched whistle] [dog barking] There goes Toto. Waves aren't just for sound. Waves can do work too. One way that you can demonstrate that is with an ultrasonic washer like I have here. Normally, ultrasonic washers are used for cleaning delicate instruments. The way they work is that they vibrate back and forth very fast at such a high frequency that you can't hear it, but that helps remove particles from delicate instruments. Today, I'm going to use this ultrasonic washer to show you how waves can do work, To help me, I have this bottle of soda water. Some of you probably have experience of shaking a bottle of soda water and then opening it and having it explode. This is going to do the same thing, but faster. I'm going to open my soda water very carefully, and I have a special cap with a small hole drilled in the center. 

I'm going to put my special cap on the soda water, place it in the ultrasonic washer, and let's see what happens when I turn it on. [exclamations and applause]  So that's pretty cool, but not that useful. Waves can do useful things too in medicine. One of the best examples of that is medical imaging. That's x-rays, ultrasounds, MRIs. All of those are examples of medical imaging. The way ultrasounds work is that they use sound waves that are, again, too high-frequency for you to hear, and those waves pass through the body. Anytime they go from a medium that's higher density to a medium that's lower density, or vice versa, the wavelength changes. That change is wavelength shows up as a color difference on the ultrasound picture. I can show you that wavelength changes using this wave table that I have here. 

As I send waves traveling down the wave table, you can see that as they travel from the wide part of the wave table near me, to the narrow part of the wave table at the other end, the wavelength gets much longer when it makes that transition. That change in wavelength would show up on an ultrasound as a color change. I'll get back to more on that in a few minutes. Oh, hello there. >> Hello. My name is Melissa and I've been looking for the Wizard of Wisc forever. Could you possibly help me? >> Hum, I might be able to help you with that. You see, I happen to have a key to the Wizard's house, but I forgot where I put it. >> Oh. >> I know it's in one of these blocks of cheese, but I can't remember which one. 

Maybe we can use medical imagining to help us. >> Okay. >> Let's start with the x-ray machine. This apparatus that I have here is an x-ray machine, and the way x-rays work is that x-rays are made up of photons, which is the same stuff that makes up the light coming out of the ceiling lights, but at a higher frequency so you can't see it with your eyes. But just like the ceiling lights make shadows with the objects in the room, if there's anything inside this block of cheese, it'll make a shadow on the x-ray screen and we'll be able to see it. Let's give it a try and see if we can see anything. I'll place the cheese inside the x-ray machine and close the door, and then I'll turn it on and let's see what happens. Uh-oh. That looks like a mouse. [squeaking] That's not what we were looking for. 

Well, it definitely wasn't in the block of cheese. Let's try he other block of cheese and this time let's try the ultrasound. Like we talked about before, color changes on an ultrasound represent a change in density. If there's anything inside this block of cheese, it should show up as a color change on the ultrasound. The way it works is that I have my ultrasound probe right here. This is where the sound waves come out of, and I'll use a special gel that will help conduct the sound waves from the probe into the cheese. I'll apply a little bit of my special gel and spread it out with my finger, and let's see if we can see anything. Well, it's a little hard to tell, but you can see that white line kind of through the center of the image there. It looks like there might be something in there. Let's see if we can find anything. 

Hum. Looks like a key! [applause] I'm pretty sure that's the key to the Wizard's house. I know he's been experimenting with ways to transport his body across empty space. I think his lab is just ahead. >> Transport his body across empty space? Oh, boy. [applause]  >> The Wizard, the Wizard, the great and powerful Wizard of Wisc! I can make myself disappear! And I can make myself reappear! And who are you? >> My name is Melissa and I'm trying to get home to Chicago. >> Why, that's no problem. I've been to Chicago many times. I can easily take you there. But with your knowledge of physics you should be able to get there all by yourself. 

>> Wait a second. You're Professor Sprott, aren't you? >> Pay no attention to the man in the box. >> You were using this piece of glass to reflect your image. [applause] >> That's right. This is called the Pepper's Ghost illusion and magicians often use this. Magicians use many principles of physics. I hope we've convinced you today that physics is all around you and you're using it every day. I'd like to do one last demonstration for you, but before I do that I want to acknowledge Professor Jim Latimer who, in collaboration with Frank Ferriano, has written yet another version of the Wonders of Physics theme music. It runs about three minutes and we will play it in it's entirety at the end of the show. We began by making for you a tornado, and I'd like to end by making a cloud. 

We do that using some of this liquid nitrogen that we've used in earlier demonstrations, except here I have a very large container of it. 25 liters of this very cold liquid. Nitrogen is normally a gas. You're breathing nitrogen right now. About 80% of the air you're breathing is nitrogen. If you cool it to 321 degrees below zero Fahrenheit, 196 below zero Celsius, it becomes a liquid. If we force nitrogen gas into this container, that will force the liquid up into this pipe. The pipe has several dozen small holes of the top. The liquid nitrogen will come out, still very, very cold. It will cool the air and that will cause the water vapor in the air to condense into tiny droplets of liquid water. 

That's what we call a cloud. With that, I thank you all for coming. [applause] § §