30 years of techno where are we going and where did we come from. in 60 minutes. which a british. tour linked to news from africa. or link to it section stories and discussion on the news and visit our website interview that comes much traffic have joined us on facebook g.w. africa. welcome to tomorrow to day the science show on t w. this time we go to the beach where surfing physics teacher explains what waves are all about. we'll hear from an acoustics experts why the sound of

waves is so relaxing. the waves can also have huge destructive power and scientists are trying to predict rogue waves. the oceans are in constant motion waves poking at the surface of the water but ways are not equally high all over at the equator they tend to be more shallow at higher latitudes they're stronger. a wave can traverse entire oceans but it's not actually the water itself that is moving with the wave confusing let's head to the shore and find out about waves and where they come from. the atlantic coast of portugal and spain towards waves large and small purser 1st of all novels of ability. as an enthusiast. dick waverider he's also

a physics teacher so he knows something about how waves form and what surfers find really epic a perfectly shaped long wave surfing requires practice and patience of all your good stuff the it's often just luck you have to be in the right place at the right time there are so many factors the height of the tide the when the wave periods that play a role and sometimes there's just a tiny window where behalf an hour a day when you get a good way and the rest is rubbish you know. this looks like a good moment because. the surfing science teacher seizes the opportunity. but what power and waves exactly. waves are the transfer of energy. transfer and energy. so far today's waves have been pretty tame let's do an experiment on the beach and

i ask a question it says tom we can see how the wave is being propagated through the length of the cloth because shaking is providing the energy that's being transferred. but what does a wave in a towel have in common with a wave in the ocean. more than you might think. whether it's a towel wave or a water wave bit of the waves transport energy not matter. even though that might not be obvious that seen from the beach the water is just the transport medium. just like the surfer is waiting on their boards the molecules in the water don't move over great distances that the wave propagates much faster so how does the energy in waves come from it. it depends on what kind of points we're talking about . the moons gravitational force keep. the ocean in motion. its attraction produces the rising and falling sea

levels known as and flow. but the waves that interest surfers are generated by the wind what matters is how strongly and how long it loads it gets the water particles moving. here's a simulation the hairdryer makes a wind which makes waves. planes can travel for days and hundreds of kilometers from their place of origin in the middle of the ocean to the coast. long and shallow waves tend to travel faster than the short highly ones which slow themselves down. within the waves water particles follow circular or orbital paths. that this orbital movement extends deep down in the water the deeper the water the

smaller the radius of the circular motion but when to circle in the water particles hit the seabed they're stopped and then. that makes shallower water waves. breakers are typical shallow water waves. they occur when the water particles below the surface are slowed at the bottom of the particles above continue to move on their circular patterns unhindered to. be unchecked water particles move upward making the wave tower up at the shore and then break. to the delight of the surfers. ya block not it makes you happy it's very exhausting

by night time not totally knocked out of but happy if you get all the everyday stress it's just great. but the best brains don't come on demand which is why this evening until yes he got is still in the water waiting for that perfect wave. but waves can also be scary in the past sail is reported towering waves that suddenly a rose out of nowhere on the open ocean but scientists dismiss these accounts until the mid 990 s. that is when a so-called rope weight was documented on an oil rig in the north sea. this freak wave measured 25 metres in height. now researchers are trying to understand and recreate these monsters.

in the ocean waves that are between 8 and 10 meters high are commonplace but at any given time anywhere in the world there are likely to be 10 also rogue waves up to 30 metres in height. they appear suddenly and without warning. scientists recreate rogue waves here in the wave basin of the loop which consumes institute in hanover here the water isn't whipped up by storms or currents the waves are generated by these panels which are controlled by a computer. they enable the scientists to simulate nearly every kind of wave at a scale of $1.00 to $75.00 everything from small harmless ocean swells to gigantic monster waves the way for me to shows the current height of a wave. music airplane is going to simulate the dropping away the 1st rogue wave ever documented it was measured on always dropping the oil. eldrick in 1905 they

did not say we can see it clearly in this north sea story to fit shows 8 to 10 meter high waves on average during the storm then here we see an extreme of that a wave that's 25 meters high a rogue wave and months of. what's unique about rogue waves is that they're $2.00 to $3.00 times higher than the highest waves around them. that also makes them $2.00 to $3.00 times as steep. a rogue wave has almost 10 times as much force as a normal way. for a long time it was a mystery how a wave more than 20 metres high could suddenly arise in a storm of 8 metre high waves at only 2 famished shortly thereafter. the explanation waves don't spread out equally in the water waves with shorter wavelengths in which the troughs and crests quickly follow each other only move

relatively slowly. weights with a long way lengths are faster. they can catch up with shorter ones. when that happens they can combine to create a high away. our if several waves joined together in this way they can become a rogue wave. broke waves are extremely steep a ship has no chance of sailing over the crest of a rogue wave as it can with an ordinary one instead the water crashes over it. the water masses collide with the structures on deck with tremendous force in a real scenario at sea this would break the ship's windows and bend heavy steel elements. scientists can simulate monster waves in a laboratory but why. they really want to know is under what conditions and how

often such waves will occur in nature. what is the likelihood of a freak wave forming. previous estimates had suggested that the probability of finding a way higher than 10 meters in a heavy storm would only be 0.03 percent. but measurements show that giant waves occur much more frequently the actual chance of waves forming that are at least 10 meters high is closer to one percent. and that's the classical approach adheres to the theory that every wave has a certain energy that the energy of one wave can sometimes overlay that of another to form a particularly high wave and that the component waves each with their own energy can thereafter continue on their way for. newer approaches theorize that energy can

also be transferred from one wave to another and that this 2nd wave moves on with somewhat more energy and the 1st one with a somewhat less that was when you can. separate the waves would take on energy from their neighbors and grow at their expense into rogue waves that can endanger even big ships at sea. this is not a rogue wave but it's a nami tsunamis are not generated by wind at the surface but on the sea bed usually by earthquakes when tectonic plates colline releasing massive amounts of energy and displacing huge volumes of water. bar at it seats anomalies are still relatively small waves traveling fast. but when they reach the shore they slow and

the water piles up into towering waves dozens of meters high which can destroy everything in their path. waves are only powerful they're also pretty loud. they can get up to 100 decibels that's as noisy as a jackhammer 10 meters away. and. the sound is generated when the waves break but despite the volume the sound of waves is generally perceived as relaxing. the. waves break on the shore it day and night and have been doing so for millions of years. nobody seems to mind the noise in fact most really enjoy the sound

why is that. if anyone knows the answer then scientists at the frown hoover institute for building physics based in stuttgart germany. this is our echo chamber music to test absorbers. peter punched ed and his colleagues research how people experience the sounds that surround them the field is called psychoacoustics they also develop products. here they're working on a booth with sound absorbing properties where one can conduct private conversations without being overheard. this chamber is anechoic that is totally soundproof it's used to test things but it's not actually pleasant to spend time man. this is it's perhaps rather too quiet we're not built to hear nothing at all it's we can't close our ears in contrast to our eyes now is our

original vigilance systems warning us of dangers seen our hearing is always switched on designed to receive signals and issue warnings to protect us from harm . for good falzon to violently superfast and. this kind of sound is better than silence if we want to relax. just like. that has to do with the structure of waves. it's not a uniform constance noise with the same volume but rather it rises and recedes regularly it's. like the surging is a very relaxing kind of sound for us very familiar and with positive associations. for. prostitution are such that your own and white pink and brown noise are characterized by equal intensity at different

frequencies the sound of waves exemplifies that when you give voice to. the sounds of produced as water slaps on to water and displaces and had went out without movement there would be no noise machine or new vehicle kind toward. people like certain kinds of sound with or without ocean waves technically generated white noise is sometimes even deployed in workplaces it can disguise other sounds. and it can be soothing. and seek to take this kind of noise doesn't carry information so after a while our brains infer that they don't need to do anything until in the noise out all register it's. we should even that's why it feels relaxing. by listening it's not real silence there is something that says but it's not

threatening it's not telling us anything so we can just relax your attitude as who in 6.2. waves might still primal anxiety and let us sleep easy but one of the ocean is far away. is highway noise and effective substitute. is one for when traffic noise isn't all that different when the vehicles are just passing by at a constant speed and not starting and stopping on the stuff once again the sound is continuous over time and of a constant volume because the cars are driving at around the same speed but i live in the fog so i get on with life on the think is when the cards. so in a sense listening to a highway should be a good long or by except our brains link the sounds to the cause of them and the associations are anything but mellow traffic speed concentration stress

i. the sound of waves by contrast feels friendly reminds us of the cation or allows our minds to simply go blank. we are just on facebook what do you think of when you hear the sound of waves. mirer from venezuela loves the sound of waves and says nothing is more relaxing than to sea and it's waves. and he writes from indonesia that the sea is amazing almost alive it's always rippling sometimes slowly sometimes strongly and sometimes it's terrifying. for pius the sound of waves is very familiar. he wrote to us and he's so heavey that he's a skilled swimmer and that's what he knows. as the wallet from indonesia is more interested in the ocean waves as

a source of energy and says we might be able to use them to replace fossil fuels and that's true. there have been many attempts to use the forces in the ocean waves to generate electricity we've been successful with other forces of nature solar power for example is most advanced in china india and japan according to the international renewable energy agency. other countries are focusing on wind and then. here to china is in 1st place but it's proven very difficult to harness the energy of waves. immensely powerful forces. huge wind generated waves. not the tides controlled by the moon's gravity. was an area of 360000000 square kilometers about 70 percent of the earth's surface

is covered by water. most of it is in the oceans which could be a mark of force of climate friendly energy but how can we harness that power tidal amplitudes very dramatically your brand the globe and parts of western europe they're particularly pronounced. the 1st tide mills were built in the middle ages or even earlier they were driven by the daily changes in water levels. in the 1960 s. this idea was picked up again and engineers built the 1st big tidal power station in printing in france. turbines inside hard liberace's are driven by the admin flow of the ocean. but the engineers encountered a problem. i'm only few days are suitable for this type of power plant and the barrage has also disrupt the coastal ecosystem. but that didn't stop them they

saw other ways of using marine energy this time focusing on the strength of waves. wind generation surface waves tend to be large and strong as high latitudes of the northern and southern hemispheres. in scotland in the 1970 s. scientists developed a series of new mechanisms intended to convert the energy of surface waves into electricity many believe that wave energy converters were on the verge of a breakthrough. to. one such device was called the salters dark named after its inventor stephen salter from edinburgh the duck was tested in wave but never on the open sea. eventually these ideas fell by the wayside. in the early 2000 came a new attempt with this snake like offshore device its link cylindrical sections

flex and bend in the waves and convert the motion into electricity but it never got past the prototype stage. german engineers are currently testing another system the ne most project involves flotation modules connected to pulleys on the seabed by flexible cables as they're pulled by the motion of the waves a generator transforms the mechanical energy into alec tricity it's been tested as an addition to offshore wind farms. so far most of the approaches to topping marine power have got nowhere one reason the formidable technical hurdles. wave heights change continually does the force of the waves to stand up to the biggest waves the machinery has to be very robust but this equipment produces too little energy. when waves are gentler there are many different ways of harnessing wave power but they're all still too expensive to be viable. and one of my tidal

energy developers shifted to anchoring the turbines on the sea floor bother than in barrages but underwater repairs are expensive. the latest class i plant forms have turbines mounted underneath that are more accessible and thus easier to fix when the corrosive salt water damages the machines. although the energy of the wild and salty seas has repeatedly proved difficult to harness many engineers remain optimistic that a breakthrough is just around the corner. if our blood is red white object glad to meet you. now it's time for our viewer question this week it comes from morocco i know you took a look at the ways in the ocean and asked where the water is really transparent.

the water in this class looks transparent. the ocean looks blue book of water on today so why the difference. to understand that we need to delve into physics color is an effect of light and without light everything turns black. the light from the sun may look white but it's actually a mixture of a range of wavelengths some of them are invisible to the human eye like ultraviolet rays other parts of the spectrum are visible to us and we see them as red orange yellow green blue violet. and that mixed together we can see the light as white. so why do. different things have different colors. because they absorb different parts of the light spectrum the rest is reflected and picked up by the receptors in the eye. the

material the jacket is made of absorbs blue green and yellow light red like to be reflected so the jacket looks red. so what's going on with water. close to the shore where the water is shallow but like most and passes through without being absorbed or reflected. by one light rays fall on a larger body of water the red orange community yellow components of the light are absorbed more strongly and the new light is preferentially reflected. so that's why the ocean looks blue it's not because it reflects the sky. divers can observe the effect of absorption as they descend into the depths 1st the

red light disappears then the green and then the yellow what remains is blue light that hasn't been absorbed by the water further down that too is absorbed and you get to a point where no visible light at all has penetrated. so the color of the water seems to have depends on the quantity of it large volumes of water no clue. but a small amount of water appears transparent. you know the science question then just ask you'll find us at d. w. dot com slash science and on twitter and facebook. here's a fun fact waves have a strong effect on animals and plants take the barnacle. you know those little alfred pods that adhere to stones or shells in the water they rely on the waves to bring them by nutrients and the way to determine how long their penises are where

the waves are strong bond holders have a shorter penis when the flow is gentler it grows longer and in any case mailbombing holes have the longest penis in proportion to their body length from any animal. that's all for today next time we'll see what's happened to the vision of hyperloop travelling at a 1000 kilometers per hour is that the transport of the future find out next week by.

techno after the one found it was the fever for a lens newly found freedom. can. the old timers and new comers. from the month trade to gentrification authentic city and consumer is them 30 years

of technology where are we going and where did we come from. the few. earth. home to millions of species a home worth saving. on those are big changes and most start with small steps global ideas tell stories of creative people and innovative projects around the world like to use the term climate boost green energy solutions and reforestation. they created interactive content teaching the next generation about environmental protection and were determined to build something here for the next generation global ideas the multimedia environment series on d.w.

. about. 15 years since the moon landing. he was the 1st man to walk on the moon. as a small boy she dreamed of the stars. as a pilot she flew anything no matter how dangerous. a church or go to the pole. as an astronaut she took part in the greatest adventure in history. legend was simply

a schumann who was neil armstrong. was his destiny starts july 20th on t.w. going to. cut. this is deja vu news live from berlin the biggest show of people power in sudan since a violent crackdown in the early. months protesters take to the streets nationwide to demand civilian rule but at least $740.00 killed and scores more wounded in clashes with security forces also on the program. an unprecedented an unexpected

and shake as donald trump becomes the 1st sitting u.s. president ever to cross the north korean border will the historic photo op yield results.