0:00:06 > 0:00:09My name is David Malone.
0:00:10 > 0:00:14This is Tynemouth, where I was born.
0:00:18 > 0:00:21And the place where my parents came back to when they retired.
0:00:23 > 0:00:26What I really remember is standing down there.
0:00:26 > 0:00:28Where the guns...?
0:00:28 > 0:00:32- No, where the gate is, and watching the waves go by.- Oh, right.
0:00:32 > 0:00:34- I used to take you there.- Did you?
0:00:42 > 0:00:45I used to go down to this particular sea wall when I was a little lad.
0:00:45 > 0:00:49The angle of the wall to the curl of the wave meant that
0:00:49 > 0:00:53it always trap air inside the wave, compressing the air,
0:00:53 > 0:00:56which would then escape and make this wonderful roaring sound
0:00:56 > 0:01:00as the wave came down the length of the wall towards you.
0:01:07 > 0:01:09I make science documentaries
0:01:09 > 0:01:12and I believe a deeper understanding of waves
0:01:12 > 0:01:16can explain our endless fascination with them.
0:01:16 > 0:01:20When we started out, this film was supposed to be
0:01:20 > 0:01:22about the science of ocean waves.
0:01:22 > 0:01:27But it can't be about just that, because waves also give us a window
0:01:27 > 0:01:30into how the world actually works,
0:01:30 > 0:01:32into the nature of reality.
0:01:34 > 0:01:36Because waves have a life cycle,
0:01:36 > 0:01:40so they're quite unlike the things that we think of as objects,
0:01:40 > 0:01:42like pebbles or cliffs.
0:01:42 > 0:01:43They have a birth and a death.
0:01:43 > 0:01:47They're a process, and that makes them much more like us.
0:01:53 > 0:01:56There's a view that science is merely about totting up numbers
0:01:56 > 0:01:58to make them come out right,
0:01:58 > 0:02:03while how we make sense of the world should be left to the poets.
0:02:08 > 0:02:10I don't think that's right.
0:02:10 > 0:02:13Waves in particular is one of those subjects
0:02:13 > 0:02:17where the science itself is full of meaning.
0:02:43 > 0:02:46Why are waves so fascinating to watch?
0:02:46 > 0:02:49Why is it that human beings will sit
0:02:49 > 0:02:52and be hypnotised by waves for hours?
0:02:52 > 0:02:55We don't normally sit and watch chairs and tables.
0:02:55 > 0:03:00All my life I've gazed at the sea breaking on the shore
0:03:00 > 0:03:03and wondered what makes each wave different
0:03:03 > 0:03:06and why they crash so relentlessly.
0:03:07 > 0:03:10I was surprised to discover that the scientific study of waves
0:03:10 > 0:03:13began only relatively recently,
0:03:13 > 0:03:15and it wasn't idle wave-watching.
0:03:15 > 0:03:18It was truly a matter of life and death.
0:03:25 > 0:03:26Autumn 1942.
0:03:26 > 0:03:30During the Second World War, the first major amphibious landings
0:03:30 > 0:03:34were planned to attack German forces in North Africa.
0:03:37 > 0:03:40The Allies knew that the landing craft carrying troops ashore
0:03:40 > 0:03:42could capsize in waves over six feet high.
0:03:49 > 0:03:52It was essential, therefore, to predict the height of the waves.
0:03:55 > 0:03:58Scientists found they could calculate wave heights accurately
0:03:58 > 0:04:01by measuring the duration and strength of the wind.
0:04:06 > 0:04:08The ability to predict waves
0:04:08 > 0:04:11led to the success of the landings in North Africa...
0:04:13 > 0:04:16..and later on, D-day in France.
0:04:27 > 0:04:30To understand these wartime discoveries about waves,
0:04:30 > 0:04:34'it's easier to start not at sea, but at Flatford Mill in Suffolk,
0:04:34 > 0:04:37'made famous in the painting by Constable.'
0:04:37 > 0:04:43Well, we've got a virgin canvas here, ready for waves to start.
0:04:45 > 0:04:48'Gavin Pretor-Pinney is an author who studies waves.'
0:04:48 > 0:04:52The whole idea of the birth of a wave is a rather intriguing notion.
0:04:52 > 0:04:55- It's got to start somewhere. - I hadn't thought about it before.
0:04:55 > 0:04:59I suppose what I'm interested in is how does a wave get born?
0:04:59 > 0:05:02It does seem a bit like getting something from nothing.
0:05:02 > 0:05:03Cos there you've just got water,
0:05:03 > 0:05:06and somehow you've got to get a wave out of it.
0:05:06 > 0:05:09Well, now the air is quite still.
0:05:09 > 0:05:14But in the case of winds out at sea,
0:05:14 > 0:05:16there is the wind.
0:05:16 > 0:05:18That is the crucial factor.
0:05:18 > 0:05:20That's where the energy comes from.
0:05:20 > 0:05:22- How?- Well, I'll show you.
0:05:22 > 0:05:25I'll get down and I'll be the wind.
0:05:25 > 0:05:27OK.
0:05:27 > 0:05:30On this little flat bit here...
0:05:43 > 0:05:47- Right.- It really very easily happens.
0:05:47 > 0:05:49It doesn't require a lot, does it?
0:05:55 > 0:06:02And these tiny little ripples that I produce by blowing over the surface,
0:06:02 > 0:06:07they're known as capillary waves, these tiny embryonic waves.
0:06:07 > 0:06:11The critical factor is the surface tension of the water.
0:06:11 > 0:06:16When the water is distorted into a slight crest,
0:06:16 > 0:06:21the elastic nature of the surface wants to flatten it down.
0:06:21 > 0:06:26In terms of it being a wave that propagates over the surface,
0:06:26 > 0:06:29this returning, this restoring force, is critical.
0:06:29 > 0:06:31Is that what helps to push it away?
0:06:31 > 0:06:33It helps to make the wave move because,
0:06:33 > 0:06:36where it's lifted up, the restoring force brings it down,
0:06:36 > 0:06:38- and then it overshoots... - Pushing the wave that way.
0:06:38 > 0:06:42It continues down below and as the parts of the water go like this,
0:06:42 > 0:06:45the actual shape of the wave progresses across the surface.
0:06:48 > 0:06:51In the mill pond, as the wind creates a wave,
0:06:51 > 0:06:54the surface tension tries to flatten the water.
0:06:56 > 0:06:59The result is a regular undulation in the surface.
0:07:06 > 0:07:09Naturally, the forces that create waves out at sea
0:07:09 > 0:07:11are very much greater.
0:07:13 > 0:07:17The sun provides the earth with energy in the form of heat.
0:07:17 > 0:07:21This warms the atmosphere and creates the wind.
0:07:21 > 0:07:25It is the energy of the wind that in turn creates the waves.
0:07:29 > 0:07:34Energy is the invisible force that drives the universe.
0:07:34 > 0:07:36Energy can never be destroyed.
0:07:36 > 0:07:38It can only change from one form to another.
0:07:42 > 0:07:46Even after the wind dies away, the energy lives on in the waves.
0:07:52 > 0:07:55These ocean waves are far larger than capillary waves,
0:07:55 > 0:07:59and forces other than surface tension take over,
0:07:59 > 0:08:00pushing the water down.
0:08:03 > 0:08:06- Better get out the way.- Yeah.
0:08:08 > 0:08:13'We can see this if we increase the wind at the mill pond.'
0:08:13 > 0:08:15Right, let's turn it round here.
0:08:20 > 0:08:24That's good. Shall we start her up?
0:08:24 > 0:08:25We shall.
0:08:37 > 0:08:41LOUD WHIRRING
0:08:54 > 0:08:56WHIRRING STOPS
0:08:56 > 0:08:58So that, you could see...
0:08:58 > 0:09:00God, I can hardly hear now!
0:09:00 > 0:09:06You can see that they soon develop into larger than these
0:09:06 > 0:09:072cm-high capillary waves.
0:09:07 > 0:09:09And they're continuing much more.
0:09:09 > 0:09:13Can you see the bunch of them coming back?
0:09:13 > 0:09:16Capillary waves themselves, when they're tiny, they don't go very far,
0:09:16 > 0:09:20but once they get larger than a couple of centimetres,
0:09:20 > 0:09:21they're known as gravity waves.
0:09:21 > 0:09:24Why are they called gravity waves? Why the change of name?
0:09:24 > 0:09:28There are two forces that try to return the water to the level.
0:09:28 > 0:09:32One is the surface tension that we were talking about
0:09:32 > 0:09:35with the capillary waves. The other is the force of gravity.
0:09:35 > 0:09:38When the waves are greater than a couple of centimetres,
0:09:38 > 0:09:40that becomes the dominant force.
0:09:42 > 0:09:47With these larger waves, gravity works just like surface tension.
0:09:47 > 0:09:53It pushes the wave down, overshoots, and the wave is propelled forward.
0:09:53 > 0:09:55- That's beautiful! Look at that! - That is beautiful.
0:09:55 > 0:09:58A very graceful movement, isn't it?
0:09:58 > 0:09:59It is lovely.
0:10:06 > 0:10:08The thing I was quite sceptical about...
0:10:08 > 0:10:12I mean, I knew it intellectually, but there's something about someone
0:10:12 > 0:10:15getting down on their knees and blowing onto the surface
0:10:15 > 0:10:17of the water making a few ripples,
0:10:17 > 0:10:20and then saying, "And that's how you start a Pacific wave."
0:10:21 > 0:10:26It doesn't quite grab you that some 40ft monster that
0:10:26 > 0:10:31can throw a boat about starts off life as little teeny ripples.
0:10:31 > 0:10:34And yet, as soon as you brought the wind machine out,
0:10:34 > 0:10:36you could see that that's exactly what it was.
0:10:45 > 0:10:49The thing for me about being on the sea is it reminds me
0:10:49 > 0:10:53how different an environment the sea is to the land.
0:10:53 > 0:10:55Most of us live in cities
0:10:55 > 0:10:59where we're cut off from the nature of power and energy.
0:10:59 > 0:11:02For us, you just flick a switch and there's power.
0:11:02 > 0:11:03It flows through wires,
0:11:03 > 0:11:06lights come on, records play and your dinner heats up.
0:11:06 > 0:11:08But we're unaware of what power is.
0:11:10 > 0:11:14When energy was generated by rushing water,
0:11:14 > 0:11:19or even by steam, we had a visceral knowledge of what power was about.
0:11:19 > 0:11:23Water rushed by and cogs turned and hammers went up and down.
0:11:23 > 0:11:24Today it's all hidden from us
0:11:24 > 0:11:29and we live in such a static, calm, quiet environment.
0:11:29 > 0:11:32It's not until you come back out on the sea, you're reminded
0:11:32 > 0:11:36of the real nature of the dynamic, the powerful side of reality.
0:11:39 > 0:11:42For me, what's so exciting about waves
0:11:42 > 0:11:45is that they reveal what is normally hidden from view.
0:11:47 > 0:11:49You can actually see energy in action.
0:11:52 > 0:11:56They provide insight into the forces that rule the universe.
0:11:56 > 0:11:58One of the strangest things about waves
0:11:58 > 0:12:00is they're not really made of water.
0:12:00 > 0:12:04I know it doesn't sound right, but they're really not.
0:12:06 > 0:12:09Think about sound. Think about the words I'm saying.
0:12:09 > 0:12:12You wouldn't describe them as MADE of air.
0:12:12 > 0:12:14You'd say they're vibrations IN the air.
0:12:14 > 0:12:16And it's the same for waves.
0:12:19 > 0:12:22I've come to Cambridge University to find out more
0:12:22 > 0:12:27'about this counterintuitive idea that waves are not made of water.
0:12:27 > 0:12:32'Professor Michael McIntyre, a leading physicist and mathematician,
0:12:32 > 0:12:34'wants to prove it to me.
0:12:34 > 0:12:39'He's fascinated by the relationship between atmosphere and ocean waves.'
0:12:39 > 0:12:42What a fab lab, don't you think?
0:12:42 > 0:12:45Oh, it's a beautiful lab, and Stuart does a great job
0:12:45 > 0:12:48running a facility like this. It's a great tradition in our
0:12:48 > 0:12:52department to do experiments as well as mathematical theories.
0:12:52 > 0:12:55And I think you need both to understand how things work.
0:12:55 > 0:12:58Stuart, can you make a wave break around here?
0:12:58 > 0:12:59Certainly.
0:13:07 > 0:13:09The gentle waves out here
0:13:09 > 0:13:13- aren't moving the water very much except back and forth.- The ducks!
0:13:13 > 0:13:17That gives you a visualisation of how much the water is moving.
0:13:17 > 0:13:20It is moving a bit, but the main motion is an oscillation.
0:13:20 > 0:13:23The ducks are going round in circles.
0:13:23 > 0:13:25Yes, they're certainly not travelling with the wave.
0:13:25 > 0:13:27Not nearly as much.
0:13:27 > 0:13:29So most of the water, then, is just going up and down?
0:13:29 > 0:13:32Well, it's actually going in little circles or ellipses.
0:13:32 > 0:13:35Watch that duck carefully. You see?
0:13:35 > 0:13:38Oh, yes. You can feel that when you stand in the beach.
0:13:38 > 0:13:40When the wave passes, it pushes you one way
0:13:40 > 0:13:43and then drags you back the other. Is that the same thing?
0:13:43 > 0:13:45Yes. That's the oscillatory part of it.
0:13:48 > 0:13:52'Professor McIntyre's ducks show it's not the water that's moving'
0:13:52 > 0:13:54but the energy.
0:13:55 > 0:13:58The water and ducks are essentially stationary.
0:13:58 > 0:14:02They go around in a big circle, almost back to where they started
0:14:02 > 0:14:06from, while the waves of energy move onwards.
0:14:25 > 0:14:27There's a surprising parallel to waves
0:14:27 > 0:14:29in an executive toy.
0:14:32 > 0:14:34The balls in the middle hardly move,
0:14:34 > 0:14:40yet the energy passes through them and out the other side.
0:14:40 > 0:14:44The balls are the medium that transmits the energy
0:14:44 > 0:14:47just as the water does in waves.
0:14:50 > 0:14:52Hello, Dr Porter!
0:14:52 > 0:14:56'Physicist Richard Porter has studied waves for 20 years.'
0:14:56 > 0:14:58Picked a good morning for it, at least!
0:14:58 > 0:15:02- This is beautiful!- 'He researches them as a source of power.
0:15:03 > 0:15:08'I met him at his open-air wave tank, the sea off North Devon.'
0:15:08 > 0:15:12Waves are a form of transport of energy.
0:15:12 > 0:15:14That's the way I would describe it.
0:15:14 > 0:15:16And the water is what? Just the medium?
0:15:16 > 0:15:18The water just acts as the medium.
0:15:18 > 0:15:20In this case, it's the water that acts as the medium for
0:15:20 > 0:15:23transporting that energy in the form of this wave.
0:15:23 > 0:15:25- Like sound going through the air? - Exactly.
0:15:25 > 0:15:28I'm talking to you, and the acoustic wave that you're hearing
0:15:28 > 0:15:32is a wave which happens to propagate through air using particles of air.
0:15:32 > 0:15:37- And out there...- And out there, you just happen to have waves -
0:15:37 > 0:15:40the energy which is travelling along the surface of the water.
0:15:40 > 0:15:44So there is no net transport of water.
0:15:44 > 0:15:46Yes. When we're standing on the beach,
0:15:46 > 0:15:49you get the impression that those waves are bringing the water in,
0:15:49 > 0:15:50but that is not right.
0:15:50 > 0:15:54- No, that's not right.- Because they appear to be bringing it in,
0:15:54 > 0:15:55even when the tide's going out.
0:15:55 > 0:15:58That's right, and if they were bringing in water,
0:15:58 > 0:16:01then we'd all be doomed. Everything would flood.
0:16:01 > 0:16:03So that's not what happens.
0:16:03 > 0:16:06What you see is the water coming in and going back out again,
0:16:06 > 0:16:09on a cycle, with the waves coming against the shore.
0:16:14 > 0:16:17When I watch the sea, I love to listen to the sound of the waves.
0:16:21 > 0:16:24I learned from Dr Porter that very little of the energy is lost
0:16:24 > 0:16:27as a wave travels across the ocean,
0:16:27 > 0:16:31but when it breaks on the shore, the energy must go somewhere.
0:16:40 > 0:16:42Some energy is absorbed by the sand,
0:16:42 > 0:16:47some bounces back into the sea, and some turns into sound.
0:16:55 > 0:16:58You've got some water, you've got some air,
0:16:58 > 0:16:59you drop the liquid in
0:16:59 > 0:17:01and you listen to the sound here.
0:17:01 > 0:17:03- Can we do that, then? - Let's have a go.
0:17:03 > 0:17:04Let's see what happens.
0:17:08 > 0:17:12'Tim Leighton is the bubble man or, more formally,
0:17:12 > 0:17:15'Professor of Acoustics at Southampton University.'
0:17:15 > 0:17:16OK, here comes the drop.
0:17:18 > 0:17:20'We've all heard the drop of a leaky tap.
0:17:20 > 0:17:25'But the question is, what exactly is making the noise?'
0:17:25 > 0:17:28It hits, forms this crater - lovely crater -
0:17:28 > 0:17:30closes, pinches off the bubble...
0:17:30 > 0:17:33- That tiny thing there? - That little thing.
0:17:33 > 0:17:37All the ripples on the surface, which are very impressive visually,
0:17:37 > 0:17:38don't radiate the sound.
0:17:38 > 0:17:40It's that tiny little bubble.
0:17:44 > 0:17:49When magnified and slowed down, the bubble constantly moves in and out.
0:17:52 > 0:17:56It's the vibrations of the bubble, be it from a drop of water or inside
0:17:56 > 0:18:00an ocean wave, that produce the noise.
0:18:00 > 0:18:04Hidden away amongst them are pulsations, microscopic,
0:18:04 > 0:18:09and the pulsation is pushing the water in and out, in and out,
0:18:09 > 0:18:12as it expands and contracts.
0:18:13 > 0:18:16Until this moment, I'd never realised there WAS a bubble,
0:18:16 > 0:18:20let alone that its pulsing made the noise.
0:18:22 > 0:18:24When you were talking about bubbles,
0:18:24 > 0:18:27there was the temptation to think it's when they pop.
0:18:27 > 0:18:28- I was thinking of balloons.- No.
0:18:28 > 0:18:31- It's not at all? - I don't think they're kosher bubbles!
0:18:31 > 0:18:37- You've got MY kind of bubbles... - When you're president you're going to ban them!
0:18:37 > 0:18:39..are pockets of gas surrounded by water.
0:18:39 > 0:18:44Now, the other kind of bubble - a soap bubble for example - has gas
0:18:44 > 0:18:49- and then a thin wall of liquid and then gas outside.- Right.
0:18:49 > 0:18:53But it doesn't have that huge mass of liquid around it,
0:18:53 > 0:18:55providing the inertia, so it won't act
0:18:55 > 0:18:58like a really powerful sound source like this.
0:19:01 > 0:19:04The sound a bubble makes depends on its size.
0:19:04 > 0:19:07We can hear this if we release two different-sized bubbles.
0:19:11 > 0:19:14What you can see here is the bubble on the left is giving out the big bubbles.
0:19:14 > 0:19:17That is the regular, "blonk, blonk, blonk".
0:19:20 > 0:19:25The smaller bubble, coming out of the needle on the right,
0:19:25 > 0:19:27gives you a high "plink".
0:19:32 > 0:19:36- If it's a different size, it gives you a different note. - Pretty much, yes.
0:19:36 > 0:19:39It just so happens that these millimetre-size bubbles
0:19:39 > 0:19:43give out plinks at the frequencies we can hear,
0:19:43 > 0:19:48which is why babbling brooks makes a poetical babble that you can hear.
0:19:48 > 0:19:53If the numbers came out differently, the babbling brooks would be silent and we'd have lost all that poetry.
0:19:53 > 0:19:55- But as it is...- So wait a minute,
0:19:55 > 0:19:58if the bubbles were just way too small, we wouldn't hear them at all.
0:19:58 > 0:20:02Yeah, that's right. That's right. The numbers turn out just right
0:20:02 > 0:20:06so that the babbling brook and the waterfall and such like are musical.
0:20:06 > 0:20:09- Fantastic.- Yeah, it's nice, yeah. - That is quite good, isn't it?
0:20:12 > 0:20:17In a wave - obviously I've never even thought of trying to count the bubbles in a wave -
0:20:17 > 0:20:20but we were on the beach a couple of weeks ago,
0:20:20 > 0:20:23and it was just a wall of Atlantic surf, and it was just white.
0:20:23 > 0:20:26It was about, I don't know, eight foot of whiteness,
0:20:26 > 0:20:29- that's all bubbles, isn't it? - Where you see white...
0:20:29 > 0:20:33Just a metre of that must have been an uncountable number of your bubbles?
0:20:33 > 0:20:35Yeah, and each one is giving a noise,
0:20:35 > 0:20:40which is why we think of oceans and waterfalls as being noisy, and it is a very powerful noise.
0:20:40 > 0:20:43- But we don't think of them being noisy, they are.- They are.
0:20:45 > 0:20:51The noise of an ocean wave is made by all the bubbles, all heard at once.
0:20:53 > 0:20:56Slow the sound of the wave down far enough...
0:20:58 > 0:21:04..and we hear the individual notes, each from a bubble vibrating.
0:21:05 > 0:21:10Multiply the bubbles up a trillion-fold and they become the song of the ocean.
0:21:12 > 0:21:15Each bubble is like a little bell giving out a very pure note
0:21:15 > 0:21:22and what you see there is, you've got a wobbly sea surface, and then a couple of thousand bells,
0:21:22 > 0:21:25- and it's obvious where the sound's coming from.- It is now, it is now.
0:21:30 > 0:21:35It's not just scientists who want to know what happens to the energy after it's crossed the ocean.
0:21:36 > 0:21:40- Morning, gentlemen.- Hello, there.
0:21:40 > 0:21:42- Good to see you again. - Morning, mate.
0:21:42 > 0:21:46'Surfers also need to predict the arrival of waves.'
0:21:48 > 0:21:51- Did you know it was going to be flat today?- Yeah.
0:21:51 > 0:21:53How do you predict the waves?
0:21:53 > 0:21:56Is it something you have to do with surfing? I presume it is.
0:21:56 > 0:21:58The earlier you know the waves are going to be good,
0:21:58 > 0:22:01the easier it is to make a decision about where to go surfing.
0:22:01 > 0:22:03So you can use, you can check on mobile phones,
0:22:03 > 0:22:08I can check out the synoptic weather charts which gives you an idea where the low pressure is going to be.
0:22:08 > 0:22:11And ideally when you get here, you want the wind to be blowing off the land,
0:22:11 > 0:22:14which will make the waves smoother and give us a cleaner wave to surf.
0:22:14 > 0:22:20What we're looking for is one perfect band of energy, really, moving in sets, unaffected by anything else.
0:22:20 > 0:22:23What do you mean by a perfect band of energy?
0:22:23 > 0:22:27Say there's a storm, north of Scotland and it's nice and tight and it creates one swell,
0:22:27 > 0:22:33then that swell travels and over a period of time it becomes formed into nice long lines of waves.
0:22:33 > 0:22:35Pulses of energy.
0:22:35 > 0:22:39And it's that energy you're looking for. Is that what you're surfing, the energy?
0:22:39 > 0:22:42Yeah, we're just looking to ride the energy.
0:22:42 > 0:22:45On the perfect days, the water doesn't really move...
0:22:45 > 0:22:48- That's fantastic.- ..So the energy is just moving through the water.
0:22:59 > 0:23:04And the purest experience is the nearest you get to the pure form of energy.
0:23:04 > 0:23:07So the oscillations as they come to the shore, as they continue in,
0:23:07 > 0:23:10that roundness, that hollowness.
0:23:29 > 0:23:36Surfers know all about the energy of the wave and how its energy has to go somewhere.
0:23:36 > 0:23:39I love the way surfers understand this as well as any scientist.
0:23:43 > 0:23:48Richard Porter has explored why it is that waves contain so much energy.
0:23:48 > 0:23:51If you really want to think about how powerful a wave is,
0:23:51 > 0:23:55you just think about sitting on a boat, just a little boat, somewhere out to sea,
0:23:55 > 0:24:00and imagine you're sitting there and the boat is moving up and down.
0:24:00 > 0:24:03But imagine how much power you'd need to give to that boat
0:24:03 > 0:24:07just to lift it up and down. And that energy comes from the wave.
0:24:07 > 0:24:12If you had to do that on land, it would take a large group of men to lift that up.
0:24:12 > 0:24:16- Well, yeah, machinery to do that. - Whereas, on the boat, on the sea... - It just happens, right?
0:24:16 > 0:24:20So it is a huge, huge amount of energy in a single wave.
0:24:20 > 0:24:24Surface waves are a fantastic way of storing energy
0:24:24 > 0:24:30because they take energy, which occupies a three-dimensional space.
0:24:30 > 0:24:32Like wind or something.
0:24:32 > 0:24:35Wind, it occupies the atmosphere, it's three-dimensional
0:24:35 > 0:24:39and it transmits its energy to these surface waves,
0:24:39 > 0:24:44these waves that you see on the ocean, which exist upon the surface of the water.
0:24:44 > 0:24:46So they've kind of concentrated it.
0:24:46 > 0:24:49Yes. So you've taken this three-dimensional space,
0:24:49 > 0:24:54full of energy and you've transmitted it into a two-dimensional surface,
0:24:54 > 0:24:57and that's a way of focussing the energy.
0:24:57 > 0:24:59Which is what you see out there?
0:24:59 > 0:25:00Exactly.
0:25:04 > 0:25:06Yes. That makes sense to me.
0:25:30 > 0:25:34I've always thought of waves as being on the surface of water.
0:25:36 > 0:25:42Professor McIntyre showed me that there are other types of wave hidden below.
0:25:43 > 0:25:48The energy that creates many of these internal waves doesn't come from wind.
0:25:49 > 0:25:54They owe their existence to temperature and salinity differences IN the ocean.
0:25:54 > 0:26:00In this tank, the heavy blue liquid lies underneath a lighter clear one.
0:26:00 > 0:26:03This sort of thing is more what you see near coasts,
0:26:03 > 0:26:06where a river runs out over the ocean and makes an interface.
0:26:06 > 0:26:08If you look along...
0:26:08 > 0:26:11And I can just see them curve, beginning to go over...
0:26:11 > 0:26:15And they're going the other way, so you can have different waves going in different directions.
0:26:15 > 0:26:20- And they're not affecting each other.- Not very much. And this comes out of the mathematics.
0:26:20 > 0:26:22But is this what you get in the ocean?
0:26:22 > 0:26:28You get waves doing something down below and in addition to the surface waves?
0:26:28 > 0:26:31Yes, you get them at all levels. You get them on any interface.
0:26:31 > 0:26:35There's an air-water interface, there's a water-water interface.
0:26:35 > 0:26:38So you get that kind of wave on the surface, that's what we're used to,
0:26:38 > 0:26:41and then 20 feet or 50 feet or whatever it is,
0:26:41 > 0:26:44you've got this going on, which we don't normally see?
0:26:44 > 0:26:45Yes.
0:26:47 > 0:26:52Professor McIntyre's work shows that surface waves are just the start.
0:26:52 > 0:26:59Beneath them are larger internal waves which run in different directions to those on the surface.
0:27:03 > 0:27:08There are some very important waves in the ocean which break sideways, known as Rossby waves.
0:27:10 > 0:27:17The thing can move sideways and there's a fundamental sideways wave motion, called Rossby waves.
0:27:17 > 0:27:20I walked in here this morning just having one kind of wave!
0:27:20 > 0:27:23- I've got about five now.- But if you want to understand the ocean,
0:27:23 > 0:27:27- you have to have at least five. I can mention more if you like. - Please don't.
0:27:27 > 0:27:29Let's take Rossby waves, cos they're fundamentally important.
0:27:29 > 0:27:32To understand how jets form you have to understand Rossby waves
0:27:32 > 0:27:35and how they break and they do it all sideways.
0:27:35 > 0:27:38- Is that what it is? - If you think of the gulf stream,
0:27:38 > 0:27:42it's essentially a jet with Rossby waves on it and they're breaking all the time.
0:27:42 > 0:27:46That means they're throwing off eddies, sideways,
0:27:46 > 0:27:49and that's a kind of wave breaking, from a Rossby wave perspective.
0:27:49 > 0:27:55And that wave breaking is fundamentally how the jets sharpen and maintain themselves.
0:27:55 > 0:27:57How they stay narrow.
0:28:00 > 0:28:04Rossby waves allow the Gulf Stream to flow like a river
0:28:04 > 0:28:07within the Atlantic ocean, for thousands of miles.
0:28:09 > 0:28:15Without these sideways eddies, the main current would break up,
0:28:15 > 0:28:20the warming effect of the Gulf Stream would disappear and Europe would freeze over.
0:28:28 > 0:28:31We have seen how energy travels through water in the ocean
0:28:31 > 0:28:35but other waves of energy are found throughout the universe.
0:28:37 > 0:28:42The world is actually filled with waves, it's just that we can't see them, generally.
0:28:42 > 0:28:46Right here, there are quantum waves, light waves, sound waves.
0:28:46 > 0:28:50There are sound waves distorting the air between me and you right now, but we can't see them.
0:28:50 > 0:28:55They happen on a time scale that we can't appreciate or physically at a scale we can't appreciate.
0:28:55 > 0:29:00The one place where you really see this other reality is in the water.
0:29:01 > 0:29:06That's where you can see the waves doing what they do, making the world work.
0:29:07 > 0:29:12And once you realise that, you realise that the familiar world,
0:29:12 > 0:29:17the static world of rocks and cliffs, is just one side of reality,
0:29:17 > 0:29:21there is this other reality where everything is actually in motion, in process.
0:29:25 > 0:29:29It is this that makes water waves so fascinating for me.
0:29:29 > 0:29:34They're not made of water, so a wave isn't really a tangible object.
0:29:34 > 0:29:36Waves are process.
0:29:48 > 0:29:52Michael McIntyre recognises that process is the important side of reality,
0:29:52 > 0:29:55yet it's often hidden from us.
0:29:55 > 0:29:57If we want to understand anything in depth,
0:29:57 > 0:30:00we usually find we need to think of it both as objects
0:30:00 > 0:30:03and as dynamic processes and see how it all fits together.
0:30:03 > 0:30:08I always tell my students, "What is understanding?" Understanding means being able to see something
0:30:08 > 0:30:13from more than one viewpoint, make it all consistent, do it in equations, in words, in pictures.
0:30:13 > 0:30:16make it all hang together consistently.
0:30:16 > 0:30:21Very often we say, "OK, that's an object but if you zoom in you'll see a process."
0:30:21 > 0:30:24Do you like that Heraclites quote,
0:30:24 > 0:30:29that everything flows and nothing persists, or nothing endures?
0:30:29 > 0:30:33Well, I'd agree with him, certainly.
0:30:33 > 0:30:36Our whole understanding of the cosmos says that that's the case.
0:30:36 > 0:30:38And waves are the archetype for that.
0:30:38 > 0:30:43That's why we thought we would make this film on waves, as the science of change.
0:30:43 > 0:30:48Because, you can understand that quote and the idea of process,
0:30:48 > 0:30:52intellectually, but it's very difficult to see it most places, isn't it?
0:30:52 > 0:30:56I mean you can't stare at a table and see it as a process. It's an object.
0:30:56 > 0:31:01- But waves, it's right there, isn't it?- Yeah, ordinary waves on the surface of the sea,
0:31:01 > 0:31:04they're highly visible, so they give us all sorts of new ideas.
0:31:09 > 0:31:17Understanding waves reveals the processes that govern the universe and therefore govern our lives too.
0:31:17 > 0:31:24Almost by definition, waves are about the transformation of energy and so are people.
0:31:26 > 0:31:30We harness energy to keep us alive, from cradle to grave.
0:31:30 > 0:31:35Without this constant throughput of energy, we'd just be a pile of atoms.
0:31:39 > 0:31:43Our lives are in continuous change.
0:31:47 > 0:31:51As you get older, especially once you've had children,
0:31:51 > 0:31:55you start to think that life maybe really is a process.
0:31:55 > 0:31:59It stops being just you as a static thing in your life
0:31:59 > 0:32:05and suddenly there's a process of your parents getting older and your children coming along,
0:32:05 > 0:32:08and life seems somehow to be moving,
0:32:08 > 0:32:13like a wave, it's shifting along and you're going with it.
0:32:13 > 0:32:17And for me, it was quite a fundamental change.
0:32:26 > 0:32:33To have children, to grow older, it's all part of our life-cycle, a dynamic process of change.
0:32:39 > 0:32:46Seeing our lives as process is part of a philosophical debate that's long intrigued me.
0:32:46 > 0:32:50The debate is over whether it is more fundamental, more true,
0:32:50 > 0:32:53to view the world as objects or as processes.
0:33:01 > 0:33:05I think most of the time, we see the world as a collection of objects.
0:33:10 > 0:33:14This is because so many processes are invisible.
0:33:19 > 0:33:22Take the creation and erosion of a coastline.
0:33:22 > 0:33:27It happens over thousands of years, a period of time inaccessible to humans.
0:33:32 > 0:33:37To us, on the beach, the coastline appears static and inviolable.
0:33:40 > 0:33:44Except for waves, virtually everything around us is like this,
0:33:44 > 0:33:50and that's perhaps why humans are hard-wired to perceive the world as full of objects.
0:33:53 > 0:33:59But Richard Porter, who constantly studies waves, has a different perspective.
0:33:59 > 0:34:02Making mountains is a slow process,
0:34:02 > 0:34:05but, clearly, it's a very powerful process.
0:34:05 > 0:34:10And this is a fast process on that timescale,
0:34:10 > 0:34:14- but it's a timescale that we can actually observe.- It's a human one.
0:34:14 > 0:34:21And waves are a way of doing that, to remind people, actually, the world isn't a static place,
0:34:21 > 0:34:25that it is full of this energy, which is doing things.
0:34:25 > 0:34:32Yes. I think that waves in some ways
0:34:32 > 0:34:38are almost uniquely placed in that they are essentially things
0:34:38 > 0:34:42that are created and destroyed in equal measure.
0:34:42 > 0:34:45They're always being created. They're always being destroyed.
0:34:45 > 0:34:49And you think of all of the other types of natural forces that you see at work,
0:34:49 > 0:34:52and you don't quite see that level of dynamism that you have.
0:34:52 > 0:34:55You tend to see one end of the process or the other.
0:34:55 > 0:34:59With wind, you see wind generated and then it disappears off somewhere
0:34:59 > 0:35:01and you don't really get to know where it goes.
0:35:01 > 0:35:06But you've got this continual sort of, these waves coming in, continuously.
0:35:06 > 0:35:09It is this permanent exchange of energy.
0:35:21 > 0:35:26Professor Markus Kirkilionis uses maths to model the natural world.
0:35:26 > 0:35:30He pushes the concept of waves further than anyone else.
0:35:30 > 0:35:34- Hello, Professor Kirkilionis.- Nice to meet you.- Nice to meet you too.
0:35:34 > 0:35:38We've talked a lot to physicists and I can see why they're interested in waves,
0:35:38 > 0:35:42why are they important for maths? Do you see waves when you look around,
0:35:42 > 0:35:45when you look in the world, do you see other waves?
0:35:45 > 0:35:48Oh, I see waves everywhere, to be honest, yes!
0:35:48 > 0:35:52Just look at this marvellous city.
0:35:52 > 0:35:55It has spread for centuries.
0:35:55 > 0:35:59If you would now give me a map of London,
0:35:59 > 0:36:04let's say 500 years ago and we would gradually, every 50 years, look at it,
0:36:04 > 0:36:08you would actually see a wave-like structure evolving.
0:36:08 > 0:36:10If you compare such a city,
0:36:10 > 0:36:15with all its processes that are going on all the time,
0:36:15 > 0:36:18you have a lot of similarity to all this,
0:36:18 > 0:36:23to the waves in the ocean at a very windy day, where a lot of things are going on.
0:36:23 > 0:36:29What is interesting for us in a wave is usually it's dynamic behaviour, that it does something,
0:36:29 > 0:36:33it transmits something, like information or energy and...
0:36:33 > 0:36:38And also its very, being is slightly more tenuous. That's the thing that's interesting to me.
0:36:38 > 0:36:42You look out at buildings and there's this notion that we don't need to worry about them,
0:36:42 > 0:36:44they're just going to be there forever.
0:36:49 > 0:36:51The energy within a process is always changing.
0:36:51 > 0:36:55The energy within an object is locked in place.
0:36:55 > 0:37:00But perhaps this constancy of an object is just an illusion.
0:37:00 > 0:37:07Whether we can call something a static thing or a dynamic thing,
0:37:07 > 0:37:11that really depends on the timescale you are observing it
0:37:11 > 0:37:15and that's a general principle that is, of course, also valid in mathematics.
0:37:15 > 0:37:19But is it still worth having the distinction between objects and processes?
0:37:19 > 0:37:24I mean, take St Paul's. Now is that an object for you?
0:37:24 > 0:37:30Well, I think for us humans, it is naturally an object first,
0:37:30 > 0:37:35because our lifetime, compared to St Paul's, is much shorter,
0:37:35 > 0:37:40so we will not see any change in this object.
0:37:40 > 0:37:44Also, the physical forces inside the building, you know, all the atoms,
0:37:44 > 0:37:50together, they form something solid which will not change in time,
0:37:50 > 0:37:53at least not over the time we both can observe it.
0:37:53 > 0:37:59And that is a principle that applies to a lot of mathematical objects as well.
0:37:59 > 0:38:01It does work at a mathematical level?
0:38:01 > 0:38:05Yes, so typically in the mathematical equations,
0:38:05 > 0:38:09you can distinguish between solutions that are constant in time -
0:38:09 > 0:38:12we call them equilibrium solutions or steady states -
0:38:12 > 0:38:20and other solutions to the same equation that are non-constant - we call them transients, very often.
0:38:20 > 0:38:25- And the wave would be typically a transient...- Ah yeah, yeah.
0:38:25 > 0:38:31And you can study these objects, for example, in terms of their stability.
0:38:31 > 0:38:36So there is this distinction between stability and instability in the world.
0:38:37 > 0:38:40Which means the division between object and process,
0:38:40 > 0:38:44between a cathedral and a wave,
0:38:44 > 0:38:47is actually based on a bedrock of mathematics.
0:39:08 > 0:39:12It was mathematics that was central to the work on wave heights
0:39:12 > 0:39:14during World War II.
0:39:16 > 0:39:19A young oceanographer by the name of Walter Munk
0:39:19 > 0:39:24found a way to predict the waves for the invasion of North Africa.
0:39:29 > 0:39:31Munk realised that the height of the waves
0:39:31 > 0:39:37was directly correlated to the wind energy injected into the waves.
0:39:37 > 0:39:39So what were the things that he was looking for?
0:39:39 > 0:39:42So he worked out there were three crucial factors
0:39:42 > 0:39:44in determining the size of the waves.
0:39:44 > 0:39:47One is the strength of the wind
0:39:47 > 0:39:49blowing over the surface of the water.
0:39:49 > 0:39:51So the strength of the storm winds.
0:39:51 > 0:39:55- The second is the duration that that wind is blowing for.- Right.
0:39:55 > 0:39:58And the third is what's known as the fetch,
0:39:58 > 0:40:03which is the area of sea that the wind is blowing over.
0:40:03 > 0:40:06So the longer the fetch is,
0:40:06 > 0:40:09the greater the distance that this wind is blowing across.
0:40:09 > 0:40:12And these three factors all determine
0:40:12 > 0:40:15how much energy the wind gives to the surface of the water.
0:40:15 > 0:40:19Imagine the kind of responsibility -
0:40:19 > 0:40:24he was 26, 27, and he had the responsibility of determining...
0:40:24 > 0:40:29Of picking dates for these amphibious landings in North Africa.
0:40:29 > 0:40:32You know, that's a lot of weight on your shoulders.
0:40:32 > 0:40:36'After the war, Walter Munk carried on with his research.
0:40:36 > 0:40:38'He was the first to suspect
0:40:38 > 0:40:42'that the energy contained in a wave is remarkably persistent.'
0:40:42 > 0:40:45One of the things he became very interested in
0:40:45 > 0:40:52was the progress of ocean waves, having been generated in a storm
0:40:52 > 0:40:54and before arriving at some shore.
0:40:54 > 0:40:57- Ah, so he's filling in the middle bit.- The middle bit, yeah.
0:40:57 > 0:41:02- How far they would travel on their own steam, as it were.- Right.
0:41:02 > 0:41:08So from storms that generated the waves off the coast of Antarctica...
0:41:08 > 0:41:11- He was trying to follow them? - He followed them, yes.
0:41:11 > 0:41:13There are six stations off the coast of Antarctic,
0:41:13 > 0:41:20they went up past New Zealand and then past Samoa, Hawaii.
0:41:20 > 0:41:26Each of these measuring stations were a few thousands of miles from the last one.
0:41:26 > 0:41:31In the North Pacific - the last of their measuring stations -
0:41:31 > 0:41:36since there was no island there they used this boat known as FLIP.
0:41:39 > 0:41:42- No, you're kidding me! - And it does actually flip!
0:41:42 > 0:41:45It was like a Thunderbirds-type thing.
0:41:45 > 0:41:48Only the Americans would come up with a boat like that.
0:41:48 > 0:41:51Does it really tip up?
0:41:51 > 0:41:55One end of the boat goes into the water and the other end sticks out.
0:41:55 > 0:41:58That must be slightly alarming.
0:41:58 > 0:42:01The reason for this is that they want to
0:42:01 > 0:42:03try and get the boat as steady as possible
0:42:03 > 0:42:06when there's no land to tether it to.
0:42:06 > 0:42:14And the way to do that is to kind of anchor the boat in the water.
0:42:14 > 0:42:17- Deeper down.- Deep down, below the motion of the waves.
0:42:17 > 0:42:20So it's like sticking a big pendulum...
0:42:20 > 0:42:23the weight's at the bottom so is going to be fairly steady.
0:42:23 > 0:42:25- Yeah.- That's clever.- The depth...
0:42:25 > 0:42:28I don't think I'd have liked to be on that boat though.
0:42:28 > 0:42:31I mean, you'd be in the middle of the sea and it'd starts tipping up.
0:42:31 > 0:42:36- You've got to make sure you tell everybody when you're going to tip it. Very important.- My God!
0:42:36 > 0:42:37And did it work?
0:42:37 > 0:42:41Yes, they were certainly able to measure them there
0:42:41 > 0:42:44and that was quite late on in the progress of the waves.
0:42:44 > 0:42:48- And where would they end up? - They eventually ended up on the coast of Alaska, having...
0:42:48 > 0:42:53- The coast of Alaska, all the way from Antarctica?- Yeah.
0:42:53 > 0:42:57It was a 7,000 mile journey. Astonishing, really.
0:42:57 > 0:42:59How does he know that they're the same waves?
0:42:59 > 0:43:05Well, that was really the tricky part of the study.
0:43:05 > 0:43:08It was all to do with knowing what they were looking for
0:43:08 > 0:43:11so the work that had been done during the war
0:43:11 > 0:43:18for measuring how waves develop and change with distance from the storm
0:43:18 > 0:43:19was crucial in this.
0:43:19 > 0:43:24Because that told them what size the waves ought to be
0:43:24 > 0:43:26by the time they reached this area.
0:43:26 > 0:43:30And remember, once those waves reached the shore of Alaska
0:43:30 > 0:43:32at the far end of this journey,
0:43:32 > 0:43:37which took them, incidentally, about two weeks to make this journey...
0:43:37 > 0:43:40- 7,000 miles in two weeks?!- Yeah. - That's moving along.
0:43:40 > 0:43:43They do, don't they, yeah.
0:43:43 > 0:43:46But once they reached the other end,
0:43:46 > 0:43:52the energy has been spread in this fan-like way over such a large area
0:43:52 > 0:43:56that the wave is very, very small by the time they reach it -
0:43:56 > 0:43:59just a matter of millimetres in height.
0:43:59 > 0:44:04So by the time it gets to Alaska, it's very shallow but...
0:44:04 > 0:44:05Very, very broad.
0:44:10 > 0:44:14Munk was the first man who actually thought to follow waves
0:44:14 > 0:44:16and find out what happened to them.
0:44:16 > 0:44:20He followed them over 7,000 miles, an absolutely epic piece of work.
0:44:20 > 0:44:25But what he didn't look at was what happened to waves when they come to the end of their life cycle.
0:44:25 > 0:44:28When they arrive at the other edge of the sea.
0:44:31 > 0:44:33For thousands of miles,
0:44:33 > 0:44:38a wave has a perfectly regular undulating shape.
0:44:38 > 0:44:40Then as the wave nears the shore,
0:44:40 > 0:44:43it rears up into a crest just before it breaks.
0:44:43 > 0:44:47Something has caused it to change.
0:44:48 > 0:44:51Essentially what happens is, as it comes in towards the shore,
0:44:51 > 0:44:54it feels the presence of the beach that much more
0:44:54 > 0:45:00and there is suddenly a great difference between what is happening at the top of the wave
0:45:00 > 0:45:03and what is happening at the bottom of the wave.
0:45:03 > 0:45:05Theoretically, what that does is
0:45:05 > 0:45:08the wave at the top wants to move faster than the wave at the bottom
0:45:08 > 0:45:10and that's what causes this over-turning.
0:45:10 > 0:45:14Because the speed of the wave is dependent upon the depth.
0:45:17 > 0:45:18For the most part, out in the ocean,
0:45:18 > 0:45:22the depth is so deep that it's all moving at the same speed.
0:45:22 > 0:45:24But when you come towards the shore...
0:45:24 > 0:45:26The bottom slows down for some reason.
0:45:26 > 0:45:28So the bottom has such an impact all of a sudden
0:45:28 > 0:45:31that the change in the height is crucial.
0:45:34 > 0:45:36'I was curious to see what happens
0:45:36 > 0:45:39'when the energy of a wave dissipates,
0:45:39 > 0:45:43'with the help, once again, of Professor McIntyre's rubber ducks.'
0:45:43 > 0:45:45So down there it's mostly the energy which is moving?
0:45:45 > 0:45:48Well, the energy is going much faster.
0:45:48 > 0:45:50- See how much faster the crests are than the ducks?- Yes.
0:45:50 > 0:45:53That slow drift will take them close to the beach
0:45:53 > 0:45:57and watch carefully from now on...
0:45:57 > 0:45:58That green duck - look.
0:45:58 > 0:46:02Suddenly, it gets swept all the way up to the beach.
0:46:02 > 0:46:07That's where the wave motion becomes, as it were, water motion or energy propagation.
0:46:07 > 0:46:08So when it curls over there,
0:46:08 > 0:46:13it ceases to be just the energy that's moving
0:46:13 > 0:46:15and the water does actually move?
0:46:15 > 0:46:18Is it basically that you are trying to conserve the energy?
0:46:18 > 0:46:22The energy has to go somewhere and it has to grab the water, basically?
0:46:22 > 0:46:24Not much energy reflects back out.
0:46:24 > 0:46:26So most of it has to accumulate
0:46:26 > 0:46:30and that's why you get the sudden violence of the wave breaking.
0:46:30 > 0:46:31Look at that. I love that.
0:46:36 > 0:46:39It's a wonderful visualisation
0:46:39 > 0:46:43- of gentle wave motion becoming violent wave motion.- It is.
0:46:43 > 0:46:48You can suddenly, from up there, see it get vertical and then falls over.
0:46:48 > 0:46:53- Yes.- I always think waves are a bit like a man carrying a heavy weight that you tip forward.
0:46:53 > 0:46:54He can keep going.
0:46:54 > 0:46:58He can keep carrying the weight as long as he keeps going forward.
0:46:58 > 0:46:59But if he ever has to stop...
0:46:59 > 0:47:00Splat!
0:47:06 > 0:47:10It's a law of the universe that energy cannot be destroyed
0:47:10 > 0:47:15so as the wave reaches the shore, its energy has to go somewhere.
0:47:17 > 0:47:21There are a surprising number of options.
0:47:23 > 0:47:27There it is, it's travelled all the way across the Atlantic, happily minding its own business.
0:47:27 > 0:47:31It gets to the beach and if it was sentient it would be going,
0:47:31 > 0:47:33"Oh, my God, we're running out of water!"
0:47:35 > 0:47:39Well, it has to do something different, hasn't it?
0:47:39 > 0:47:40Yes, it has to do something.
0:47:40 > 0:47:45You cannot make the energy vaporise. So it's going, "OK lads, what do we do now?" There's no water left!"
0:47:45 > 0:47:51Things are changed. The energy is experiencing something different when it reaches this region here.
0:47:51 > 0:47:53- So what does it do?- Well, it breaks.
0:47:53 > 0:47:55- Right, so that uses some of the energy.- Yes.
0:47:55 > 0:47:58And you see all of the foam
0:47:58 > 0:48:01and you hear the noise of the waves breaking -
0:48:01 > 0:48:02that's more of the energy.
0:48:02 > 0:48:04You're just dissipating energy.
0:48:04 > 0:48:08And then presumably, it thumps down onto the sand and that uses a bit?
0:48:08 > 0:48:10Exactly, so the sand will absorb energy,
0:48:10 > 0:48:14there'll be friction associated with moving the sand.
0:48:14 > 0:48:16- It shifts tonnes of sand along with it.- Exactly.
0:48:16 > 0:48:19That takes an awful lot amount of energy as well.
0:48:29 > 0:48:33Each individual wave was born thousands of miles away,
0:48:33 > 0:48:34travelled across the ocean,
0:48:34 > 0:48:38and breaks on the shore in a chaotic confusion of energy and mathematics.
0:48:42 > 0:48:47In that moment, the wave dies and the energy moves on...
0:48:52 > 0:48:54..as heat from friction,
0:48:54 > 0:48:57as shifting sand and kinetic energy,
0:48:57 > 0:49:00and sound energy from the bubbles.
0:49:02 > 0:49:05I wonder if the energy that powers a wave
0:49:05 > 0:49:08is similar to the energy that keeps us alive?
0:49:17 > 0:49:19Think of the boat on the sea.
0:49:19 > 0:49:22The boat is an object that doesn't change.
0:49:22 > 0:49:25The waves upon which it rides are nothing but change.
0:49:25 > 0:49:29The continued existence of the boat depends on it resisting change.
0:49:29 > 0:49:34The continued existence of the waves are that they continually change.
0:49:34 > 0:49:37Now think of the man on the boat.
0:49:37 > 0:49:38Which one is he most like?
0:49:40 > 0:49:44'If you look at a human being, is a human being an object or a process?'
0:49:44 > 0:49:46Or do you even buy the distinction?
0:49:46 > 0:49:49I would buy the distinction.
0:49:49 > 0:49:54It corresponds to different points of view you can naturally have.
0:49:54 > 0:49:58I think a body - the man, of course -
0:49:58 > 0:50:02is an organism, is a living thing.
0:50:02 > 0:50:05So it is something that is a process
0:50:05 > 0:50:09because it has to constantly exchange energy, material,
0:50:09 > 0:50:12with the environment in order to persist.
0:50:12 > 0:50:16I mean, we are constantly feeding, we have metabolism
0:50:16 > 0:50:18and of course, we're exchanging all our atoms.
0:50:18 > 0:50:21But still we are maintaining our shape
0:50:21 > 0:50:26and we can recognise after ten years that we are the same kind of person.
0:50:26 > 0:50:30And the same of course holds in a sense for the wave.
0:50:39 > 0:50:40I am 48 years old
0:50:40 > 0:50:42and there are few atoms inside me
0:50:42 > 0:50:45that I would've possessed when I was born.
0:50:50 > 0:50:54The oxygen, water and food we consume is all borrowed.
0:50:54 > 0:50:58In the same way, an ocean wave borrows the water it passes through.
0:51:04 > 0:51:10This idea of human life as a dynamic process intrigues Raymond Tallis,
0:51:10 > 0:51:16former professor of geriatric medicine, poet and philosopher.
0:51:16 > 0:51:17Do you think that the reason that
0:51:17 > 0:51:22making a metaphor between human beings and waves has a believability about it
0:51:22 > 0:51:27is that we're not finished objects, we're kind of in flux?
0:51:27 > 0:51:30I mean, you can't make much metaphor out of a human being and a cup
0:51:30 > 0:51:33because it's finished, there's nothing else happening.
0:51:33 > 0:51:35Whereas, with a wave you can.
0:51:35 > 0:51:38I think that's profoundly true, actually.
0:51:38 > 0:51:42It seems to me that a wave is only completed when it's destroyed
0:51:42 > 0:51:47and a life is only completed, in a sense, when it's destroyed.
0:51:48 > 0:51:51What is arrival for a wave?
0:51:51 > 0:51:55It either bumps into a barrier, in which case it bounces back
0:51:55 > 0:51:57and continues or it's dissipated.
0:51:57 > 0:51:58It breaks and it's gone.
0:51:58 > 0:52:01And it seems to me that the arrival for a wave...
0:52:01 > 0:52:05well, the arrival for a life, is dissipation.
0:52:05 > 0:52:07Right. It's building up to that?
0:52:07 > 0:52:10Yes. That's a bit pessimistic, isn't it?
0:52:10 > 0:52:12One mustn't take it too tragically, I guess.
0:52:12 > 0:52:15How do you think about your own mortality?
0:52:15 > 0:52:17Well, I'm not in favour of it.
0:52:17 > 0:52:22It seems to me that it is obviously the central fact of our lives,
0:52:22 > 0:52:23that they are finite.
0:52:23 > 0:52:26But the fact they've been produced by processes
0:52:26 > 0:52:28means that they're going to be
0:52:28 > 0:52:32destroyed by processes. Those who live by the laws of physics,
0:52:32 > 0:52:34die by the laws of physics, basically.
0:52:34 > 0:52:35And then for that reason,
0:52:35 > 0:52:38one has to accept it with as good a grace as possible.
0:52:44 > 0:52:46At death, the energy that has kept us alive
0:52:46 > 0:52:49leaves us as heat and entropy.
0:52:52 > 0:52:56I believe that this dissipation of energy at the end of life
0:52:56 > 0:52:59is equivalent to the breaking of a wave.
0:53:02 > 0:53:04If you've ever seen the moment of death,
0:53:04 > 0:53:07it's a very strange thing.
0:53:07 > 0:53:11One minute, there's an energy there, and then its gone.
0:53:11 > 0:53:14Nothing else has changed, and yet everything has changed.
0:53:14 > 0:53:20Because the energy that WAS that person has moved on.
0:53:26 > 0:53:30It's easier to consider death as a necessary evil
0:53:30 > 0:53:34if you think through what would happen if our lives never changed.
0:53:36 > 0:53:37Imagine your perfect day,
0:53:37 > 0:53:41where everything is exactly as you want it to be.
0:53:41 > 0:53:44Now imagine it repeated the next day.
0:53:44 > 0:53:46And the next and all the next week.
0:53:46 > 0:53:49How long would it be before your perfect timeless paradise
0:53:49 > 0:53:52became absolutely hellish and you wanted out?
0:53:52 > 0:53:55You see, we want that process of change.
0:53:55 > 0:53:59Think of it this way - would you really want to be able
0:53:59 > 0:54:03to keep your parents forever and never having them die?
0:54:03 > 0:54:06But the cost would be you could never have any children.
0:54:06 > 0:54:08We don't want that, we are transitory beings.
0:54:08 > 0:54:14We want the joy of the new, and the cost is, we have to let the old go.
0:54:22 > 0:54:25My mother and father have been coming to this spot
0:54:25 > 0:54:26ever since I was born
0:54:26 > 0:54:29to look at the ruined priory nearby
0:54:29 > 0:54:32'and to watch the waves.'
0:54:32 > 0:54:35I was just thinking how I must have been, what,
0:54:35 > 0:54:38two and half the first time I went to the priory.
0:54:38 > 0:54:43- Two and half?- Don't you think? - Really.- Oh, yeah. I used to take you down there.
0:54:43 > 0:54:46I remember feeling the railings being quite rough,
0:54:46 > 0:54:49and you'd stand there and you'd kind of see the wave coming in.
0:54:49 > 0:54:52And you'd see it coming...!
0:55:00 > 0:55:04'A few months after we filmed this scene, my mother died.'
0:55:04 > 0:55:06'I've actually got lots of photographs of my mum,
0:55:06 > 0:55:11'but the only film I have of her we shot for this film,'
0:55:11 > 0:55:16and I decided to film her because I realised it was maybe my last chance
0:55:16 > 0:55:18because she was dying.
0:55:20 > 0:55:24'I realised even as we were filming it'
0:55:24 > 0:55:27that there I was making a film about how things are transitory,
0:55:27 > 0:55:31and how things have to move on,
0:55:31 > 0:55:35and yet here we were taking a photograph of her,
0:55:35 > 0:55:40taking a film of her so that somehow I could hold that moment.
0:55:40 > 0:55:44Illogical as I knew it was, I still wanted to do it.
0:55:48 > 0:55:51'And so it's just the way it's worked out that this film'
0:55:51 > 0:55:55and the priory and the waves
0:55:55 > 0:55:59have all become inextricably linked for me.
0:56:03 > 0:56:07Perhaps I could add something. There is also the compensation of death,
0:56:07 > 0:56:11which is to say, without a conclusion there is no sense of form.
0:56:11 > 0:56:15There is no sense of rounded meaning.
0:56:15 > 0:56:22In many ways, meaning itself cannot be...boundlessly open.
0:56:22 > 0:56:26We need closure. We need narrowing. We need sealing off to some extent.
0:56:26 > 0:56:29A piece of music would not be enjoyable if went on forever.
0:56:29 > 0:56:33And that's why an endless succession of waves, all identical,
0:56:33 > 0:56:35would not be very attractive,
0:56:35 > 0:56:38however individually beautiful the waves were.
0:56:38 > 0:56:41You have to have inflection. When we listen to a clock,
0:56:41 > 0:56:45we don't hear "tick tick tick tick". We hear "tick-tock tick-tock",
0:56:45 > 0:56:49as if we have to divide in something into a beginning and an end
0:56:49 > 0:56:52just to give us some sense of structure and closure.
0:57:10 > 0:57:14What's come out of this film for me is I started out thinking
0:57:14 > 0:57:19there was this beautiful poetic metaphorical connection between
0:57:19 > 0:57:24waves as a process and us and our transitory lives.
0:57:24 > 0:57:28I was sure that that was important, but I thought in a poetic way.
0:57:30 > 0:57:34What I've learnt is that it's not just poetry,
0:57:34 > 0:57:35It's not just a metaphor,
0:57:35 > 0:57:40that just as it is the energy in a wave which
0:57:40 > 0:57:43forces all of the atoms of the water
0:57:43 > 0:57:46into that beautiful and unlikely shape of a wave,
0:57:46 > 0:57:50so in us, it's the throughput of energy in our lives which keeps
0:57:50 > 0:57:53us and our atoms in this unlikely shape.
0:57:53 > 0:57:57And that just as when the energy moves on from a wave and it breaks,
0:57:57 > 0:57:59so it is for us.
0:57:59 > 0:58:01And so what I've learnt is that
0:58:01 > 0:58:05we're not just metaphorically like a wave.
0:58:05 > 0:58:11In some really important and scientific way, we ARE a wave.
0:58:28 > 0:58:32Subtitles by Red Bee Media Ltd
0:58:32 > 0:58:37E-mail subtitling@bbc.co.uk