0:00:25 > 0:00:28Welcome to our Tomorrow's World Christmas fair, complete with
0:00:28 > 0:00:33sideshows, replete with magic, mystery and scientific illusion.
0:00:33 > 0:00:37And to probe our mysteries, we have once again a group of hard-eyed
0:00:37 > 0:00:40professional experts waiting and panting
0:00:40 > 0:00:45and ready to start on our magical mystery tour, and our first guide
0:00:45 > 0:00:47will be the impresario of the changing face,
0:00:47 > 0:00:50the charming Miss Judith Hann,
0:00:50 > 0:00:54and she has her own speciality in transformation scenes.
0:00:54 > 0:00:59And then, to mystify us all with his anamorphic art, and I bet you don't
0:00:59 > 0:01:03know what that means, Mr William Woollard, an old friend of audience.
0:01:03 > 0:01:05And now come over here,
0:01:05 > 0:01:08television's first mathemagician whom we have
0:01:08 > 0:01:13lured from his beautiful country seat at Ludlow and he,
0:01:13 > 0:01:18Mr Michael Holt, is going to baffle us with every conceivable
0:01:18 > 0:01:21kind of mystery, so you'd better keep an eye on him.
0:01:21 > 0:01:24Then, lured from the halls of academia,
0:01:24 > 0:01:28which means he's very clever, Dr Stuart Anstis,
0:01:28 > 0:01:31and anyone who's brave enough to participate in his experiments
0:01:31 > 0:01:33will be, literally, electrified,
0:01:33 > 0:01:37and finally, to get us under way with his ghoulie ghosties,
0:01:37 > 0:01:42Michael Rodd to prove beyond peradventure that now you see it,
0:01:42 > 0:01:44now you don't.
0:01:44 > 0:01:48Never a truer word. Who wants to meet a ghost? Follow me, then.
0:01:48 > 0:01:51Right across the fairground, over here.
0:01:51 > 0:01:55Leave some room for me in the middle or the spell won't work.
0:01:55 > 0:01:59Now, we need a little ghostly gloom.
0:02:00 > 0:02:04Young William here is looking into the mirror, but he's not
0:02:04 > 0:02:08thinking about himself. He's thinking about the lovely Susan.
0:02:08 > 0:02:12Now, in all the best stories, Susan would be his girlfriend.
0:02:12 > 0:02:16- Are you William's girlfriend? - No.- That's a pity,
0:02:16 > 0:02:20because we could use this magic mirror to show Susan and William
0:02:20 > 0:02:24what their children might look like if they decided to get married.
0:02:24 > 0:02:26- Shall we do it anyway?- Yes.
0:02:26 > 0:02:28We've got to do some magic words and it goes like this -
0:02:28 > 0:02:32mirror, mirror, on the table, show me their children if you're able.
0:02:32 > 0:02:34Ready? All together.
0:02:34 > 0:02:36- ALL:- Mirror, mirror, on the table,
0:02:36 > 0:02:41show me their children if you're able.
0:02:52 > 0:02:57Very, very weird and there it was, Pepper's ghost
0:02:57 > 0:03:00named after the Victorian gentleman Mr Pepper
0:03:00 > 0:03:02who invented the technique. He was the original.
0:03:02 > 0:03:04It's all done with mirrors, man,
0:03:04 > 0:03:08and his work was used by such magicians as the Great Masculine
0:03:08 > 0:03:10to make people appear and disappear,
0:03:10 > 0:03:13and indeed Mr Pepper himself had great fun doing what we've
0:03:13 > 0:03:16just done, showing Victorian couples what their children
0:03:16 > 0:03:19might look like if they got married. Now, this is how it works.
0:03:19 > 0:03:22William isn't looking into a mirror at all. He's looking through a plain
0:03:22 > 0:03:26piece of glass and on the other side is Susan, and when the light is
0:03:26 > 0:03:30shining brightly on Susan, William can see Susan through the glass.
0:03:30 > 0:03:34But if Susan's light goes out and William's light comes on,
0:03:34 > 0:03:38what Williams sees is his own, much brighter, reflection
0:03:38 > 0:03:40in the pane of glass.
0:03:40 > 0:03:42But what is really interesting is what happens
0:03:42 > 0:03:44when we put both lights on at the same time.
0:03:44 > 0:03:51A strange blend of faces emerges called Pepper's ghost.
0:03:51 > 0:03:55You changed your mind about getting married, perhaps?
0:03:55 > 0:03:58Right, over here, everybody. Come on. Enough of Pepper's ghost.
0:03:58 > 0:04:01Come and look at yourselves in these mirrors over here. Over here.
0:04:01 > 0:04:05There's nothing mystical or marital about these like Michael's mirrors.
0:04:05 > 0:04:07They're just plain distorting mirrors.
0:04:07 > 0:04:09And if you stand in front of them, you can change.
0:04:09 > 0:04:11See, this one gives you legs ten-feet long.
0:04:11 > 0:04:14If you hold your hands up, you get great long, sort of, claws.
0:04:14 > 0:04:17This one makes you into a dwarf and this one,
0:04:17 > 0:04:22this one gives you a strange mouth. See that, Karen?
0:04:22 > 0:04:25Now, what they can't do is to make you look anything like you really are, but here
0:04:25 > 0:04:27we've got mirrors that can make things clearer than
0:04:27 > 0:04:30they really are. If you come over here, we can see.
0:04:30 > 0:04:32Stand round the front there, round the front, everybody.
0:04:32 > 0:04:33Enough of those mirrors.
0:04:33 > 0:04:36What do you think that is, anybody? Any idea?
0:04:36 > 0:04:41Worms? Lipstick marks, perhaps? No?
0:04:41 > 0:04:43Red slugs.
0:04:43 > 0:04:46Well, if I put it down here
0:04:46 > 0:04:50and put this cylindrical mirror over that circle, what have we got?
0:04:50 > 0:04:54Yes, the ten of hearts and hearts are trumps today.
0:04:54 > 0:04:56Let's try this one. Go round the front again.
0:04:56 > 0:04:59What do you think that is? Yes? Mountains?
0:04:59 > 0:05:02Valley? Moon? A face, you say.
0:05:02 > 0:05:04Let's see. Shall we put it down?
0:05:04 > 0:05:08Get that, Jackie, and put it over the circle and what have we got?
0:05:08 > 0:05:10A witch in a green coat.
0:05:10 > 0:05:14OK, over to here, and this idea of hidden art that can only be
0:05:14 > 0:05:18revealed in a particular way has fascinated artists for centuries.
0:05:18 > 0:05:23- Here's another example of it. Any idea what that is?- Swamps?- Swamps.
0:05:23 > 0:05:26A road? Just a series of lines.
0:05:26 > 0:05:29But look at that, Jackie, from one side.
0:05:29 > 0:05:34Look on the edge. Can you, Jonathan, you have a look? Along the edge.
0:05:34 > 0:05:37- That's right, there are four faces. - Upside down.- Indeed.
0:05:37 > 0:05:40It's an idea that's also fascinated scientists, of course,
0:05:40 > 0:05:41they call it making transformations.
0:05:41 > 0:05:43We remember the astronomer Copernicus,
0:05:43 > 0:05:45because he made an enormous transformation
0:05:45 > 0:05:48thinking of the stars and the planets, imagining himself to be
0:05:48 > 0:05:50standing not on the Earth, but on the sun,
0:05:50 > 0:05:52but let's get back to these pictures.
0:05:52 > 0:05:55Yes. Dougal. Florence.
0:05:55 > 0:06:00- A trumpeter.- Let's see. Yes, it's a monkey blowing a trumpet.
0:06:00 > 0:06:05And one final go over here. What about this view of the Earth from...
0:06:05 > 0:06:08- That's the moon.- Is it? Put the mirror on.
0:06:08 > 0:06:10Come on, Jackie, put the mirror on.
0:06:10 > 0:06:13It's a pink tiger, isn't it? Yes. Something you don't want to catch
0:06:13 > 0:06:15by the tail. Right, finished mirrors,
0:06:15 > 0:06:17over to Judith who's got a competition. Follow me.
0:06:17 > 0:06:19First of all, something really easy.
0:06:19 > 0:06:22- Can anyone tell me what this is?- A face.
0:06:22 > 0:06:25A face, that's right, it is a face, yes.
0:06:25 > 0:06:28Now, a scientist called Gerald Fisher has discovered how
0:06:28 > 0:06:31to turn a face like that into something else.
0:06:31 > 0:06:33Not another face, something really different.
0:06:33 > 0:06:36Now, I want you to listen to what you've got to do.
0:06:36 > 0:06:39I'm going to walk behind these statues and take these things off
0:06:39 > 0:06:42and when you see the face changing into something else,
0:06:42 > 0:06:45and when you're sure you know what it is, I want you to run over
0:06:45 > 0:06:48and sit on the chair underneath the statute.
0:06:48 > 0:06:51If there's somebody there, just sit on top of him, pile yourselves up.
0:06:51 > 0:06:54- Right. Are you ready to go?- Yes.
0:06:54 > 0:06:58No, you wait over there and just watch.
0:06:58 > 0:07:01Anybody can see? No?
0:07:01 > 0:07:03Number two.
0:07:03 > 0:07:05Onto number three.
0:07:05 > 0:07:08Ah, John's seen a change.
0:07:08 > 0:07:09On to number four.
0:07:12 > 0:07:15Five. Can you all see it now?
0:07:15 > 0:07:20And number six. Two left. Jackie's just coming on there.
0:07:20 > 0:07:23Now, as you can see, they've all seen the change at a different time.
0:07:23 > 0:07:25John was the first one. Jackie here was the last.
0:07:25 > 0:07:27We don't see it at the same time.
0:07:27 > 0:07:30To some people it changes into a girl much earlier
0:07:30 > 0:07:33and if any of the men watching at home found that the face
0:07:33 > 0:07:36became a girl much earlier, down at that end, it's tempting to
0:07:36 > 0:07:38read into that something your wives might not approve of!
0:07:38 > 0:07:41Haha! Well, I don't know about that, Judith,
0:07:41 > 0:07:45but certainly, wild horses wouldn't get me to confess how soon I saw it.
0:07:45 > 0:07:49Come with me and see what we have over here.
0:07:49 > 0:07:53We had a very quick look at Mr Michael Holt, the mathemagician,
0:07:53 > 0:07:56but now watch closely and see what he has to show you.
0:07:56 > 0:07:57Thank you, Raymond.
0:07:57 > 0:08:01Now, would somebody like to try on a waistcoat and...
0:08:01 > 0:08:04Oh, here you are. Would you try on this waistcoat?
0:08:04 > 0:08:07We've met, haven't we? It's Sanjay, yes? Right.
0:08:07 > 0:08:10And here is the coat. Your arm out, that's it.
0:08:10 > 0:08:13In with that arm and in with that arm.
0:08:13 > 0:08:17Now, here is a challenge which you might like to try at home
0:08:17 > 0:08:20and that is to see if you can take the waistcoat off without
0:08:20 > 0:08:23taking the jacket off, without taking your arms out of the sleeve.
0:08:23 > 0:08:25Off you go. See if you can try, come on.
0:08:25 > 0:08:27HE CHUCKLES
0:08:27 > 0:08:30No? Do you give up?
0:08:35 > 0:08:37Well, look, shall I show you?
0:08:37 > 0:08:41- Shall I show you how to do it? - I can't do it.- You can't do it.
0:08:41 > 0:08:44Well, very well tried, anyway. Very well tried. Would you sit down?
0:08:44 > 0:08:46- That's it. - APPLAUSE
0:08:46 > 0:08:48Give him a good hand. That's terrific.
0:08:48 > 0:08:50- Now I'll show you how it's done. - MUSIC PLAYS
0:08:50 > 0:08:52You see, you undo the waistcoat like this
0:08:52 > 0:08:55and we've got the right kind of music for this.
0:08:55 > 0:08:57And you take this arm here
0:08:57 > 0:09:00and you put it through the waistcoat like that, you see?
0:09:00 > 0:09:03And then you feed the waistcoat all the way through, but I'm going
0:09:03 > 0:09:04to turn round so as you can see
0:09:04 > 0:09:06what's happening at the back, like that.
0:09:06 > 0:09:10And you just feed the coat through, making sure you haven't got
0:09:10 > 0:09:11anything in the pockets.
0:09:11 > 0:09:13If you've got an awful lot in the pockets,
0:09:13 > 0:09:15you're never going to do this.
0:09:15 > 0:09:17And then you get the waistcoat right over onto the side
0:09:17 > 0:09:20and you just slip the elbow through, like that.
0:09:20 > 0:09:23Now, we've now got the waistcoat entirely on this
0:09:23 > 0:09:26side of the jacket, you see. Here it is. All here.
0:09:26 > 0:09:29Now, all I have to do is put the waistcoat right down
0:09:29 > 0:09:32the sleeve here. That's it, it's going down.
0:09:32 > 0:09:36And then try and get it down right past the elbow.
0:09:36 > 0:09:39Put my hand up the sleeve here to pull the waistcoat down, like this.
0:09:39 > 0:09:40And here we are.
0:09:40 > 0:09:44And I pull it out. Oh, Christmas!
0:09:44 > 0:09:47Ah! There we are. Thank you very much.
0:09:47 > 0:09:49And there you are.
0:09:52 > 0:09:57Now, I would like somebody to help me bring out these three dice here.
0:09:57 > 0:10:01Could I have you, you, Mark. And could I have you, Sue, isn't it?
0:10:01 > 0:10:04Out you come. Will you bring the dice out here?
0:10:04 > 0:10:08I'm not going to watch what you do while you turn them.
0:10:08 > 0:10:12Turn them round. Michael is going to see fair play.
0:10:12 > 0:10:17And then would you stack them up into a tower? Have you done that?
0:10:18 > 0:10:21- Nice big tower, that's it. - Yes, nice big tower.
0:10:21 > 0:10:23What do you want us to do now?
0:10:23 > 0:10:26Can I just turn around and show you what I want you to do next.
0:10:26 > 0:10:29What I'm going to do, can I move around here.
0:10:29 > 0:10:34What I want you to do is to look at the bottom face, then
0:10:34 > 0:10:37look at the hidden faces in there, the two,
0:10:37 > 0:10:41and the two hidden faces in there, add them all up, that face,
0:10:41 > 0:10:44that one and that one and the bottom one, add them up
0:10:44 > 0:10:46but don't tell me what the total is
0:10:46 > 0:10:50and I am going to try and find out. All right? You know what to do?
0:10:50 > 0:10:53I'm going to turn my back and I won't watch what you do.
0:11:00 > 0:11:02Let everybody see.
0:11:04 > 0:11:07I don't think your maths is very good!
0:11:07 > 0:11:09THEY WHISPER AND CONFER
0:11:09 > 0:11:12Right, are we agreed?
0:11:12 > 0:11:14We had a little bit of trouble making sure
0:11:14 > 0:11:19we had the right total, are we all agreed that that is the total?
0:11:19 > 0:11:22We are. I'll now hide it.
0:11:22 > 0:11:25Sit down, then and we'll see if the mathemagician...
0:11:25 > 0:11:27- Can I turn around? - You can.
0:11:27 > 0:11:30Right, thank you very much. Here are the dice.
0:11:30 > 0:11:33And I've got to look at them and I will try and read your mind.
0:11:33 > 0:11:38I know it's like the key of a door less one. It's 20.
0:11:38 > 0:11:42- Is that right? - Yes!- There you are.
0:11:43 > 0:11:46Now, you want to know how that's done? I'll tell you.
0:11:46 > 0:11:48It's absurdly simple.
0:11:48 > 0:11:52You see, I know that the opposite faces of a dice add up to seven.
0:11:52 > 0:11:54Four and three. Add up to seven.
0:11:54 > 0:11:57And so do all the other faces.
0:11:57 > 0:12:02So all I have to do is add up the faces on three dice making 21
0:12:02 > 0:12:05and then I take away what is on the top dice,
0:12:05 > 0:12:08the top face of the top dice and it is as simple as that.
0:12:08 > 0:12:11Now, see if you can work out the next trick.
0:12:11 > 0:12:17Now look, this is an ordinary gyroscope top
0:12:17 > 0:12:20and if I pull this string, with a bit of luck
0:12:20 > 0:12:25we will be able to spin it up like that.
0:12:25 > 0:12:30Take it in your hand. Now turn it about. Does that feel funny?
0:12:30 > 0:12:34What does it feel? Does it feel as if it wants to move itself?
0:12:34 > 0:12:38Feels kind of alive, does it? If you turn it like that?
0:12:38 > 0:12:40Very strange things, gyroscopes.
0:12:40 > 0:12:44They don't like being moved, do they?
0:12:44 > 0:12:47Right... Now, here we've got a disc of paper
0:12:47 > 0:12:50and if I spin that up very fast
0:12:50 > 0:12:53that is now being a gyroscope, too.
0:12:53 > 0:12:57But not a stiff gyroscope like the metal top.
0:12:57 > 0:13:00Watch what happens when I turn this.
0:13:02 > 0:13:05Isn't that extraordinary?
0:13:05 > 0:13:07You see how it's all distorted?
0:13:07 > 0:13:11Now that may give you some idea of the problems which face
0:13:11 > 0:13:16engineers when they have to make things spin very fast
0:13:16 > 0:13:19and these things then start to behave like gyroscopes.
0:13:19 > 0:13:20Suppose, for instance,
0:13:20 > 0:13:24that disc of paper was the spinning rotors of a helicopter.
0:13:24 > 0:13:26Well, none of us would want to go for a ride
0:13:26 > 0:13:29in a wobbly helicopter like that, would we?
0:13:29 > 0:13:33What have we got here? A circle with an ordinary pendulum.
0:13:33 > 0:13:37If I flick it, it swings backwards and forwards, doesn't it?
0:13:37 > 0:13:39If I turn this motor on...
0:13:39 > 0:13:42it jumps about all over the place.
0:13:42 > 0:13:44If I turn the motor off,
0:13:44 > 0:13:45and hold it up here,
0:13:45 > 0:13:48what would you expect to happen if I turned the motor on now?
0:13:48 > 0:13:49What would happen?
0:13:49 > 0:13:53It would go around, would it? Shall we try it? Shall we?
0:13:53 > 0:13:56Hold it up, turn the motor on. And it doesn't go around.
0:13:58 > 0:14:03If I flick it slightly, it becomes a very stable upside-down pendulum.
0:14:04 > 0:14:07That's remarkable, we can explain that mathematically,
0:14:07 > 0:14:09but no-one has yet been able to explain that physically.
0:14:09 > 0:14:13There's no physical, watertight explanation.
0:14:13 > 0:14:15Let's leave those noisy pendulums alone
0:14:15 > 0:14:18and try two other pendulums, these swings.
0:14:18 > 0:14:22If you stand over there, we have Susan and Sue on the swings.
0:14:22 > 0:14:25They are going to sit right still without swinging at all
0:14:25 > 0:14:29themselves, I'm going to swing one of them
0:14:29 > 0:14:32and let's see what happens to Susan over there.
0:14:32 > 0:14:35Don't move, either of you. I'll just swing Sue here.
0:14:35 > 0:14:40They're connected by that loose strap up ahead. What happens?
0:14:42 > 0:14:47Sue starts slowing down and Susan speeds up. Mind your head.
0:14:50 > 0:14:54And then Susan starts slowing down and Sue speeds up again.
0:14:58 > 0:15:00Susan has now stopped.
0:15:00 > 0:15:04And now Sue is slowing down and off goes Susan again.
0:15:04 > 0:15:08Great idea for having in a park. Stop. End of swings.
0:15:08 > 0:15:11Let's go across to Raymond.. Off you get, kids. There we go.
0:15:11 > 0:15:14Raymond has another stall going over here.
0:15:14 > 0:15:16Look what's coming now.
0:15:16 > 0:15:21Now, the trouble with these mechanical toys,
0:15:21 > 0:15:24although they're very charming, is that they run into things.
0:15:24 > 0:15:26And when they run into things,
0:15:26 > 0:15:29they get stopped and it always happens under the piano,
0:15:29 > 0:15:32or behind a cupboard, or something awkward like that.
0:15:32 > 0:15:38So let's put this little pussycat in a cage and then see how he makes out.
0:15:38 > 0:15:41Let's start him up before we put him in.
0:15:43 > 0:15:46This is the most difficult part of all.
0:15:46 > 0:15:49Right, now...
0:15:49 > 0:15:51In it goes. Now...
0:15:53 > 0:15:54See? You can't stop him!
0:15:59 > 0:16:05Do you see? What he does is he climbs up the wall
0:16:05 > 0:16:10of the ball and manages to keep going.
0:16:10 > 0:16:17And that has all to do with something called feedback control.
0:16:17 > 0:16:21It's a very simple example of it, but without feedback control,
0:16:21 > 0:16:24there would be no television, no space flight,
0:16:24 > 0:16:26and indeed, no living creatures,
0:16:26 > 0:16:31because robbed of feedback control, none of us could even exist.
0:16:31 > 0:16:34To learn more about it, over to Dr Stuart Anstis.
0:16:34 > 0:16:39Here's a nice piece of feedback. Tucked away inside this little box
0:16:39 > 0:16:40is an electronic eye,
0:16:40 > 0:16:43looking through this large, square lens at this picture tube.
0:16:43 > 0:16:46But it's not only looking at the television tube,
0:16:46 > 0:16:49it's also controlling the picture on its face in a most remarkable way.
0:16:49 > 0:16:52Unfortunately, at the moment, the eye is confused by all the studio lights
0:16:52 > 0:16:55and so let's get, Stuart, first of all,
0:16:55 > 0:16:57to cover the eye up with a black cloth,
0:16:57 > 0:17:00so it can only see the screen, and if we get the gallery to take the
0:17:00 > 0:17:03studio lights down, we might be able to conjure up some electronic magic.
0:17:03 > 0:17:06Right. Now, can everybody see that line on the screen?
0:17:06 > 0:17:09That white flashing line? Yes, of course you can.
0:17:09 > 0:17:12Now, so can the electronic eye, but more than us.
0:17:12 > 0:17:13It's rather cleverer than our eyes.
0:17:13 > 0:17:17It can not only see the line, it can actually tell the line where
0:17:17 > 0:17:19to go, so that it can go on seeing it.
0:17:19 > 0:17:21So if I try to cover up that line with my hand,
0:17:21 > 0:17:25then the line won't allow me to do that.
0:17:25 > 0:17:27The eye will control it to stop it happening.
0:17:27 > 0:17:29So you see, I get an outline of my hand.
0:17:29 > 0:17:33Even if I open my fingers and close them like scissors,
0:17:33 > 0:17:35there the line very cleverly follows the outline.
0:17:35 > 0:17:39It never gets concealed. Now, have a go at that, William.
0:17:39 > 0:17:41That's a very nice name you've got.
0:17:41 > 0:17:45Put your hand in gently. Open the fingers, very gently.
0:17:45 > 0:17:46And close them again.
0:17:46 > 0:17:49You see? The line still follows your hand, take it out.
0:17:49 > 0:17:52In you go again. Open the fingers, close them.
0:17:52 > 0:17:55Take this shape, this cut out of a face we've got, push it in cos
0:17:55 > 0:17:59that line always wants to run away. It's frightened of reflected light.
0:17:59 > 0:18:04In goes the face. And there we can see the outline of that cut-out face.
0:18:04 > 0:18:06Now, can you hear anything else happening?
0:18:06 > 0:18:09BUZZING As that face goes in?
0:18:09 > 0:18:10TONE CHANGES
0:18:10 > 0:18:13- What can you hear? - A noise.- A noise, yes.
0:18:13 > 0:18:16Now, that noise depends upon the shape of that line.
0:18:16 > 0:18:18Stuart's keeping it on the screen for us. There it is.
0:18:18 > 0:18:21Now, have you ever heard the sound of your own face?
0:18:21 > 0:18:24You haven't, have you? No, neither have I.
0:18:24 > 0:18:26But if we're very careful, you might be able to achieve that.
0:18:26 > 0:18:29Kneel down... See, the line's frightened,
0:18:29 > 0:18:31it runs away as soon as you go near it.
0:18:31 > 0:18:34Now, if you put your head carefully between the electronic eye
0:18:34 > 0:18:37and the line, the screen, there's your face.
0:18:37 > 0:18:40Stick your tongue out. And again.
0:18:40 > 0:18:42Stick your tongue out.
0:18:42 > 0:18:44That's your face, I can see your tongue out.
0:18:44 > 0:18:47Now, that, for the very first time, live on television,
0:18:47 > 0:18:51the sound of William's face with his tongue out.
0:18:51 > 0:18:55This feedback business works the other way round, as well.
0:18:55 > 0:18:58Not only do we need the right information to enable us
0:18:58 > 0:19:00to do whatever we do normally,
0:19:00 > 0:19:03if we feed ourselves the wrong information,
0:19:03 > 0:19:05we can make life impossible,
0:19:05 > 0:19:08we might even find we were unable to stand up, for instance.
0:19:08 > 0:19:10Now, how are we going to prove that?
0:19:10 > 0:19:14Well, here in the studio, we've got a room with a trolley in the middle
0:19:14 > 0:19:18of it and the trolley is on wheels, but this is no ordinary room.
0:19:18 > 0:19:22The walls of this room are not connected to the floor.
0:19:22 > 0:19:25And with the help of the strong arm of Stuart Anstis, I can show
0:19:25 > 0:19:30you that we can move the walls without moving the floor.
0:19:30 > 0:19:34In other words, this room behaves in a way that our mind will find
0:19:34 > 0:19:36difficult to cope with.
0:19:36 > 0:19:39Right, Stuart, let's see who's had a heavy tea.
0:19:39 > 0:19:42Come on, Martin. Try an experiment and we see
0:19:42 > 0:19:45if we can make you behave in a strange fashion.
0:19:45 > 0:19:49Stand in the trolley, on the rubber. Now, face the other way.
0:19:49 > 0:19:51That's right, turn yourself round.
0:19:51 > 0:19:56And look up perhaps at one of those pictures. Lovely. Now then...
0:19:56 > 0:19:59You tell me what you think is happening.
0:20:02 > 0:20:05I don't want you to sway. Stand still, whatever happens.
0:20:08 > 0:20:10You're swaying, aren't you?
0:20:10 > 0:20:13Now, what do you think it is that's moving?
0:20:13 > 0:20:15- The floor?- The floor!
0:20:15 > 0:20:19Well, turn round and have a look and see what is happening.
0:20:19 > 0:20:22The floor isn't moving, is it? What is?
0:20:22 > 0:20:23- The wall.- That's right.
0:20:23 > 0:20:25So now you know what's going on, turn round and see
0:20:25 > 0:20:27if you can stand still again.
0:20:27 > 0:20:30Look up at the wall, hands by your side.
0:20:32 > 0:20:34Do you think he's standing still?
0:20:34 > 0:20:37He's not, is he? It's jolly difficult. Well done, Martin.
0:20:37 > 0:20:40Even when you knew what was happening,
0:20:40 > 0:20:43you found it impossible to stand still and I can hardly blame you.
0:20:43 > 0:20:47Come on, Helen. We'll try something else with you.
0:20:47 > 0:20:49Have you had a heavy tea?
0:20:49 > 0:20:51You have? Oh, dear. We might have a problem here.
0:20:51 > 0:20:53Step up, then.
0:20:53 > 0:20:55Hands by side. Don't touch the rails.
0:20:55 > 0:20:58Now, Stuart's made a few adjustments.
0:20:58 > 0:21:01You see if you can tell me what's happening.
0:21:05 > 0:21:09You tell me if you think she's going to fall over.
0:21:09 > 0:21:10She's not doing very well, is she?
0:21:10 > 0:21:13What do you think is happening, Helen?
0:21:16 > 0:21:19It's very confusing, isn't it? Let's try something else.
0:21:19 > 0:21:22If I told you I was moving, would you believe me?
0:21:25 > 0:21:27Really and truly?
0:21:27 > 0:21:31Yet everybody else can see I'm the one that's standing still.
0:21:31 > 0:21:34You're the one that's moving!
0:21:34 > 0:21:36Feels funny, doesn't it?
0:21:36 > 0:21:38Yes, they did it to me on Tomorrow's World not so long ago.
0:21:38 > 0:21:40Thank you very much.
0:21:40 > 0:21:42Have you ever wondered why your ears are where
0:21:42 > 0:21:44they are on the side of your head?
0:21:44 > 0:21:46You haven't? It's something I ponder every day.
0:21:46 > 0:21:49But not all living creatures do have ears where ours are.
0:21:49 > 0:21:52Some, like the cricket, for example, have theirs on their legs.
0:21:52 > 0:21:56Well, that, for the time being, is what we've done to Sophie here.
0:21:56 > 0:21:59Now, with her, we can find out what the cricket's world would sound like
0:21:59 > 0:22:02or what our world would sound like if we had our ears around our ankles.
0:22:02 > 0:22:06If Sophie will jump, if Stuart will hold her satchel,
0:22:06 > 0:22:09jump a little bit, Sophie. Hear that sound?
0:22:09 > 0:22:10It's quite deafening!
0:22:10 > 0:22:12Right, back you go on the target, Sophie,
0:22:12 > 0:22:15and Stuart will help you put your ears where they should be.
0:22:15 > 0:22:17Meanwhile, over here, we've got
0:22:17 > 0:22:20William with ears in an even stranger place, on his hands.
0:22:20 > 0:22:22How does that feel, William...
0:22:22 > 0:22:23Matthew! ..to have your ears on your hands?
0:22:23 > 0:22:26- Not very different. - Not very strange.
0:22:26 > 0:22:29Wave your arms around, so we can hear what it feels like.
0:22:29 > 0:22:30Move one past me as I speak.
0:22:30 > 0:22:33Move one past my face as I go on speaking.
0:22:33 > 0:22:36VOLUME FLUCTUATES Can you hear my voice dying away
0:22:36 > 0:22:38- and building up again?- Yes. - You can? Right.
0:22:38 > 0:22:41Now, all of you, how would you like best to have your ears?
0:22:41 > 0:22:45On your hands, like Matthew here, or where the rest of us are?
0:22:45 > 0:22:48Come with me, Matthew. On your ears.
0:22:48 > 0:22:51- Where would you like to have your ears?- Where they are.
0:22:51 > 0:22:54I just want a trial to see. Are you ready, Sophie? Right.
0:22:54 > 0:22:57All these boxes are empty, except for two.
0:22:57 > 0:22:59They've got something ticking in them.
0:22:59 > 0:23:00What you're going to have to do
0:23:00 > 0:23:03when I say go is to run down the side of the table, as
0:23:03 > 0:23:06fast as you can, try and find a box that's got something ticking in it.
0:23:06 > 0:23:07Now, be very quiet, everybody,
0:23:07 > 0:23:10cos we've never done this experiment before. Excuse me, Stuart.
0:23:10 > 0:23:12And we're not quite sure it's going to work.
0:23:12 > 0:23:15Right, when I say go, off you go. Find the ticking thing.
0:23:15 > 0:23:17Listen with your ears, Sophie.
0:23:17 > 0:23:19Listen with your ears.
0:23:19 > 0:23:23LOUD TICKING Any luck?
0:23:23 > 0:23:26BOX RATTLES She's right! She's right!
0:23:26 > 0:23:29So it seems better, doesn't it, to have your ears up here?
0:23:29 > 0:23:32Just before we make sure, let's run another test.
0:23:32 > 0:23:35Matthew, you go back to your target. Sophie, go back to Stuart.
0:23:35 > 0:23:37You've got to close your eyes,
0:23:37 > 0:23:39mustn't open your eyes during this one,
0:23:39 > 0:23:41so you can't see where you're going,
0:23:41 > 0:23:44and they're going to spin you round, so you don't know where you are.
0:23:44 > 0:23:46Blow a trumpet.
0:23:46 > 0:23:50Everybody? John? You have a go. Stand on this target.
0:23:50 > 0:23:53When I say blow, you blow your trumpet and these two are going
0:23:53 > 0:23:56to try and find their way to you with their ears.
0:23:56 > 0:23:57Now, Matthew, it would be better
0:23:57 > 0:24:01if you hold your arms out sideways, like a bird, give you a better sound.
0:24:01 > 0:24:04Right, are you ready? Right, blow.
0:24:04 > 0:24:06BLOWS TRUMPET
0:24:06 > 0:24:09Now, we've crossed over Matthew's ears.
0:24:09 > 0:24:12We've connected his left hand to his right ear
0:24:12 > 0:24:14and his right hand to his left ear.
0:24:14 > 0:24:16But he still seems to be doing very well.
0:24:18 > 0:24:22Judith is stopping him bump into things.
0:24:22 > 0:24:24Oh, a dead heat!
0:24:24 > 0:24:27Open your eyes. Absolutely dead heat. Well done!
0:24:27 > 0:24:31Well, I think you deserve to have the things you found in those boxes.
0:24:31 > 0:24:34Those things that were ticking. Let's open it and see what they were.
0:24:34 > 0:24:36Shall I open it for you?
0:24:37 > 0:24:40Right, here's a Christmas riddle for you.
0:24:40 > 0:24:45What musical instrument starts life encased in a mixture of horse
0:24:45 > 0:24:47hair and cow dung
0:24:47 > 0:24:52and ends up being played by someone standing 30 or 40 feet away?
0:24:52 > 0:24:54Who knows?
0:24:54 > 0:24:57Yes, of course. A church bell.
0:24:57 > 0:25:02This one weighs 500 weight, but guess how much Big Ben weighs. Any guesses?
0:25:02 > 0:25:0813 tonnes, 1,000 weights, three-quarters and 15 pounds,
0:25:08 > 0:25:10so that's a pretty big bell.
0:25:10 > 0:25:15But you know, to the scientist, a bell is a machine for transforming
0:25:15 > 0:25:19the energy of something moving into the energy of musical sound.
0:25:19 > 0:25:22One large lump of metal, the clapper,
0:25:22 > 0:25:26hitting another large lump of metal, the bell.
0:25:26 > 0:25:32And actually, what that makes is a most unmusical crash.
0:25:32 > 0:25:35Just listen. BIG BEN SOUNDS
0:25:35 > 0:25:40Now did anyone hear an unmusical crash? Be honest.
0:25:40 > 0:25:44No, you didn't, did you? Not one of you.
0:25:44 > 0:25:49It doesn't sound noisy. It sounds beautiful and musical.
0:25:49 > 0:25:53Because our brains are so quickly overwhelmed by the sheer
0:25:53 > 0:25:57music that the bell makes that we miss the awful noise.
0:25:57 > 0:26:00So now, let's play a recording of the bell backwards,
0:26:00 > 0:26:03so that the crash comes at the end,
0:26:03 > 0:26:06instead of the beginning, and
0:26:06 > 0:26:07then let's listen and see if we can
0:26:07 > 0:26:09hear this crash I'm talking about.
0:26:09 > 0:26:12Listen. BELL SOUNDS BACKWARDS
0:26:12 > 0:26:15Did you hear it?
0:26:15 > 0:26:19And what the body of the bell is designed to do is to soak up
0:26:19 > 0:26:22the energy of the crash as quickly as possible
0:26:22 > 0:26:28and channel all that energy into beautiful musical notes.
0:26:28 > 0:26:32Now, we're going to play you a recording of Big Ben a little
0:26:32 > 0:26:38bit at a time and we'll show you the sound on this screen, too.
0:26:38 > 0:26:39Look. Watch.
0:26:39 > 0:26:41THUMP
0:26:41 > 0:26:44Do you see? Just like an explosion. THUMP
0:26:44 > 0:26:50That's that tremendous impact of that huge clapper hitting that huge bell.
0:26:50 > 0:26:56Now, by modern electronic means, you can in fact find 30 or 40 notes in a
0:26:56 > 0:27:01big bell like this and I can show you what I mean by ringing the individual
0:27:01 > 0:27:06notes in this bell, not with a great big clapper,
0:27:06 > 0:27:10but by a tiny electronic vibrator here.
0:27:12 > 0:27:15LOW NOTE HUMS
0:27:15 > 0:27:16Can you hear that?
0:27:16 > 0:27:18Now that's the low note.
0:27:18 > 0:27:22Now, let's increase the frequency of the vibrator and see
0:27:22 > 0:27:24if we can get the next...
0:27:26 > 0:27:29NOTE GETS HIGHER
0:27:29 > 0:27:33See? That's an octave above. Another pure musical note.
0:27:33 > 0:27:36Now we can get some harmonics. MULTIPLE NOTES HUM
0:27:36 > 0:27:39See, I'm using this little vibrator
0:27:39 > 0:27:42instead of the big hammer and picking out the individual
0:27:42 > 0:27:45notes of this bell, which has already been tuned.
0:27:45 > 0:27:48MORE NOTES HUM Listen to that.
0:27:48 > 0:27:51- Do you think we can find any more? Let's try.- Yes!
0:27:51 > 0:27:54HIGH NOTE HUMS There's a high note.
0:27:54 > 0:27:57MORE NOTES HUM That's a lovely note.
0:27:57 > 0:27:59HIGHER NOTES SOUND
0:27:59 > 0:28:03Now, of course, we can hear them all at once, the old
0:28:03 > 0:28:06fashioned way, by striking the bell and now,
0:28:06 > 0:28:12we shall hear all those individual notes as one beautiful chord.
0:28:12 > 0:28:13Listen.
0:28:13 > 0:28:16BELL HUMS You can hear the individual notes.
0:28:16 > 0:28:17But of course, you don't
0:28:17 > 0:28:22need a great big piece of metal like that to produce such beautiful music.
0:28:22 > 0:28:24Ring out, wild bells!
0:28:25 > 0:28:30THEY PLAY GOOD KING WENCESLAS
0:28:30 > 0:28:32Come on, let's all join in, come on.
0:28:32 > 0:28:35Let's all stand around. Come in, let's have the whole cast.
0:28:35 > 0:28:38Yes, thank you, William, bringing in the music.
0:28:38 > 0:28:41Michael, the other Michael.
0:28:41 > 0:28:42Stuart, right.
0:28:42 > 0:28:44Have you all got your music?
0:28:44 > 0:28:48What better note on which to end our programme.
0:28:48 > 0:28:53On behalf of all of us in the studio, a magical Christmas to you all.
0:28:53 > 0:28:56Right, ready?
0:28:56 > 0:28:58One, two!
0:28:58 > 0:29:01# Good King Wenceslas last looked out
0:29:01 > 0:29:05# On the feast of Stephen
0:29:05 > 0:29:09# When the snow lay round about
0:29:09 > 0:29:12# Deep and crisp and even
0:29:12 > 0:29:16# Brightly shone the moon that night
0:29:16 > 0:29:20# Though the frost was cruel
0:29:20 > 0:29:23# When a poor man came in sight
0:29:23 > 0:29:29# Gathering winter fuel. #