good job bit of. news from africa and the world the link to it 70 stories and discussion from the news of easy to our website the interview that comes to much for join us on facebook j w for. the full. welcome to a weekly does of science on tomorrow today. our journey in the footsteps of alexander from home but continues to peruse pacific coast and on into the ocean. so much water so close yet peru's coastal region is mostly desert can water be drawn out of the clouds. we say goodbye to the traditional kilogram and well come to mind bending any one.

of the boats oceans are linked by currents crisscrossing the globe. one that flows up the pacific coast of south america is called the peruke or humboldt current yet the interest german naturalist went out to look in to answer tickets temperature. he was surprised to find it cooler than the more server around it. before you died it was given his name but he responded modestly. call the fishing boys from chile to piii to have known about the current for 300 years my only contribution was to be the 1st to have measured the temperature of the currents waters. our expedition retracing alexander from whom but footsteps now takes us to peru and the current that bears his name.

by the thawing when i'm in the water i enter a new world it's a great privilege being able to observe things that so few other people can feel seen and understanding how nature works underwater is spectacular it's an indescribable sensation traffic that would out if not have been to. far this is where the pacific ocean meets a seemingly endless desert. peru's coastal region is among the driest in the world while its cold ocean waters are among the most productive ecosystems the current

that flows along the western coast of south america would later be named after of xander often on board although it was known centuries before his expedition to the region. in the course of his climate studies rumbled noticed that at the coast of peru the pacific was around 7 degrees celsius colder than in the open ocean. as the cool masses of water flow up from there and arctic current north along south america they bring a large quantities of oxygen with them. but that was. one of the most important features of the cold currents is that they generate an extremely rich ecosystem in the region here we find extraordinary high concentrations of marine life that are typical for these waters compared with other latitudes these waters boast of a far higher degree of biodiversity which makes them very important what that means they know you have to get from where you're going but at.

roselawn bastar works for roos in mar pavement marine institute. here in new product as national reserve he examines the influence of them both current on plant and animal life and divers need to don think wetsuits to go exploring underwater here and his work is not made easier by the strong current. the upwelling zones in their own boat current bring an abundance of nutrients to the surface in the process supplying food for fish and marine mammals the current is an ideal environment for algae. farm about a bit off for most of the algae growing in the. region has adapted extremely well to the cold environment better. than the but much of the algae

constitute a very important component of the overall biological cycle. a lot of organisms feed off them. so we can try to get healthy algae population you also find a high diversity of other species. that biodiversity in and along the current has made peruse coastal waters one of the world's richest sources of fish. for centuries the country offer a hugely lucrative grounds for fishers but more recently they've noticed a significant reduction in their catches and it's the operators of smaller fishing boats like captain mario decreases by over who are struggling the most. just look. we've been out here for over 2 hours and we haven't got a single fish. in the bit. that

they don't use to be so much more to catch in this region until the big boats arrived. although you wouldn't they tell all the smaller species that fish with their trawler nets. there's nothing left for us here and i think this is because we have to go further out to sea. to roos annual fishing all amounts to $7000000.00 tonnes that's over 10 percent of the global catch overfishing by high tech commercial fleets from all over the world is a threat to the ecosystem and it's already making an impact on people's livelihoods . in the once prosperous port city of biter many boats have been left stranded by developments with unemployment rising

one of the few options for making a living is a job on one of the foreign trawlers. how much longer can local fishermen survive. in the peruvian capital lima the country's national marine institute is projecting the future development of the ecosystem in the homeworld current. in addition to keeping count of fish stocks the scientists here also monitor the quality of the sea water and what has been declining due to climate change. among their observations the home boards current no contains less oxygen and is becoming increasingly acidified due to i levels of carbon dioxide.

one object of their research. which is only visible under the microscope a drop of water can contain up to a 1000 plankton organisms seen here during the metamorphosis of larva into juveniles plankton provides food for many marine creatures and is indispensable for the well being of the seas. come out of that nice walk up but on the way it's in our organisms that benefit production and propagation in other food chains and they're also very sensitive to change as a result of the low oxygen content the acidification of the oceans and the growing pollution of our coasts organisms that are unable to adapt quickly enough and dying and we're seeing this right now with plankton. it's a picture far removed from the paradigms of biodiversity that are xander for and on

boarding card on the peruvian coast on a much more human intervention can overseas cope with. any got missed and i think the future is definitely in our hands it ought to be obvious to us humans as intelligent beings that if we want to have a flourishing ecosystem it's up to us to start keeping it healthy. which i don't like you saying a lot of people still don't seem to realise that the contamination we subject our coasts and oceans to is being further exhilarated by climate change. at the court. but we still hope to be able to reverse it then they will have better.

ecosystems are extremely diverse and dynamic. so maybe we will manage to see a major recuperate. despite all the interference. and adapt to those changes but mostly. the humble and current home to boundless life is a cause of the sterile desert on the land beside it it seems like a paradox but the current cools the coast and keeps a dry well generating fog that passes overhead that's now proving to be a fantastic resource we meet the cloud catches up through. thick fog makes apple trees happy. that the fog passes this way and then that catches at. the end that passes through

it but the tiny drops of water remain behind they gather at the bottom and passed down the tube to the tank. this water means life with this system we're solving the water shortage problem in many places and much of look at this. he came up with the idea almost 2 decades ago he was studying engineering in lima at the time. there was a fence of plastic netting around his home one evening he noticed this phenomenon and realised it could be put to good use. but there were lots of drops gathered at the bottom of the net especially when the wind came from the east so i collected them in a trough and to the nets and fed the water into tanks the next morning the tanks were full of crystal clear water. carlos a potter gross oranges avocados and grapes. he's delighted to be able to do so in

a region where there's no rain talking in southern peru. the area gates has crossed with water captured from the clouds. and then you look at it it's foggy most of the time up on the mountain if we had 2 or $300.00 cloud catcher nets up there my neighbors and i would have a lot more water we would all benefit which i feel. almost the entire length of peru's 2400 kilometer coast is does that. about 10000000 people a 3rd of the country's population don't have access to a secure supply of drinking water. cloud catches has been set up out in the desert near the town of. more than $100.00 families have said.

and they need affordable clean water. if they thought up on the other thing these cloud catches the model here cost the equivalent of $70.00 to $90.00 euro's each. of the sauna a 20 square meter net can yield as much as 200 liters of water a day. it makes watering the vegetable patch a fun job today. when mr cruz put up the nets i decided to stay. i had wanted to leave because my olive trees were all dried out then i saw the water and i changed my mind him again. now when rivera is proud of his olive harvest it in no burger was one of these are the 1st we're going to eat them ourselves when we have more we'll sell them i mean we don't and. it's poverty and the dream of having one's own plot of land that

drive people to move into the does it. during the focus season they'll have access to water but what happens in summer from december to march when there's almost no fog the satellite is a planning a reservoir for folks water so they won't have to buy so much. but if you're back in talking on color supporters plot. about crews and colleagues from the peruvians without water project checking the direction of the wind to ensure the nets are in the right position. cruz has given lectures at universities and won awards around the world for his pioneering work he's determined to help more poor communities and drive regions look at their most what do plants need to grow is arid enough you know they need water and we get it from the clouds and it's free the families here don't even have enough to eat they can't afford to buy water

the only music you know. about crusoe sattar over a 1000 fold catches in peru with more planned until everyone who needs to capture clout. consider a standard drop of water like the one used in metz and 500 other millions her or gram. it contains 56 trillion asked him that 5 with 210 s. there were 2 hydrogen atoms and one oxygen atom in every war somalia killed our viewer khalifah keys has a question about all this. what is an atom. everything around us everything we can see feel smell or taste is made up of atoms and of course we are 2. terms are the building blocks of

matter. the terms and their spatial arrangement give matter it's properties such as consistency and color. the way we think about atoms today is largely influenced by physicists niels bohr's model according to which electrons orbit the atoms nucleus. a bit like planets orbiting the sun. was better can't be seen with the naked eye the fitness of a human hair. that is $500000.00 times the diameter of a carbon atom. in the center of the atom is a tiny nucleus containing neutrons which have no electric charge and protons which have a positive charge. 2 2 the electrons orbiting outside it are negatively charged the only out of not to have any neutrons is hydrogen it

consists of one proton and one electron. just as stars have different numbers of planets orbiting the atomic nuclei have different numbers of electrons in orbit. in the neutrally charged atom the number of electrons equals the number of protons. and the number of protons determines the chemical elements so far we know of 180 mm and many of their properties are displayed in what's known as the periodic table of the elements. if our old line is red why our current even if you. do you have a science question that you've always wanted answered we're happy to help you out send it to us as a video text over its mail if we answer it on the show we'll send you a little surprise as a thank you can i just ask. you'll find as i did have you dot

com slash science or drop us a line at d w underscore site tech on facebook d w dot science. if you pose a specific extremely large number of silicon atoms together to create a sphere of a certain size it will weigh exactly one kilogram scientists have succeeded in doing that and why to define what a kilogram is in terms of a natural constant in this case the ever gartrell constant. it's a way to check the accuracy of another new definition in terms of the planck constant this has read. simply been adopted as the official definition of world wide difficult stuff but it is important anyway to take the measure of things. it's a weighty matter welcomed the new kilogram we now take a look at a project based on that new official definition. since 2017 thomas relation his team at the technical university. have been working on

a new set of scales together with germany's national maturity institute they've developed 2 prototypes based on the new definition of the kilogram. for 130 years a metal cylinder in paris was the world's benchmark of the kilogram but not anymore as you call me. the kilogram was the last remaining unit based on a physical object a piece of metal and all other as our units are based on constants of nature. and. in that speech because of this redefinition weights are no longer derived from the international prototype kilogram stored in a safe in paris. of use. instead they are derived from a fundamental constant constant but 1st things 1st.

in the past all weights used to calibrate scales worldwide whether it was in pharmaceutical companies biotech labs or supermarkets all derived from a platinum iridium cylinder located just outside paris stored securely under 3 glance bell jars be extremely precious object was kept in the safe of the international bureau of weights and measures from $889.00 until this year it was the defining unit of mass worldwide but for some unknown reason the paris kilogram decreased in weight by 15000000. of a gram so scientists decided to take action in a historic move they redefined the kilogram. this time they're not using a metal object but a constant of nature the planck constant denoted by a small age described for the 1st time by max planck around 1900 so what is the

planck constant. and before you can think of it has the smallest possible unit of energy consider the energy coming out of a car battery or an electric socket on the walls and if you were to divide that into lots of small amounts the smallest possible amount would be applied constant. it's a fundamental constants of nature it's involved in many aspects of physics. when one reason why we can't take the planck's constant as the definition of this mass is because the planck constant can be expressed in terms of the kilogram and 2 other units that's why we were able to establish a relationship between the value of the cube a gram and the plant constant. this can be done using a watch balance for example it's a highly complex instrument that's been used since the 1980 s. to measure the planck constant as precisely as possible. there are only

a handful of these scales worldwide this one is in the united states at the national institute of standards and technology. the high precision scale is based on the principle of electromagnetic force compensation this is how it works the gravitational force of a test mass is balanced with an electromagnetic force the magnetic field is provided by a permanent magnet a coil of wire is immersed in that field. it's like a coil in a loudspeaker the coil is in the permanent magnetic field and electrical current is run through it to generate a force that force is used to balance the downward force of the weight it's a way to measure weight using an electrical current. mission in other words the electrical current is adjusted until the upward force on the coil perfectly balances the downward force of the weight the 2nd step is. called the

velocity mode a precision laser called an interferometer shown here in green is used to measure the position and velocity of the coil. the aim is to measure the voltage that is created in the process. then we need gravitational acceleration small to be 9.81 meters per 2nd per 2nd if you know all these things very precisely you can calculate the numerical value for h. the math isn't complicated in reverse if you know the value of h. the planck constant you can specify a kilogram. the planck scales from germany will work in exactly the same way they're basically all what about alan's on the left is the laser interferometer on the right is the balance based on the principle of electromagnetic force compensation but it's

a lot smaller than its american counterpart. if i reverse the principle of the water balance and say i know the value of age then i can use my playing scales to calibrate any weight because it will. simply lay my object on the one side and then relate the electrical values to the plumb constant and from that i can calculate the mass on the scale. of. the 2 planck scale prototypes from the technical university elma now will eventually be put to industrial use currently they can be used to determine whites in the range of between one milligram and 100 grams but it will be another 3 to 5 years before the 1st planck scale goes to market the paris kilogram meanwhile has already lost its status as the international benchmark and it's now been consigned to a museum. along with the kilogram the 2nd and the meter they are all sorts of are the units of

measurement we asked our viewers what units of measurement do you. seth wrote the indigenous people of mexico use the media which is equal to the volume of an empty sardine can. from indonesia says in java we often use the volume of an empty coconut shell to measure rice maize and other goods one shell usually holds one kilo. this unit of measurement is still in use today. in argentina eduardo says we use the meter kilo celsius liter and hector personnel or we eyeball it that always works. he says or says farmers in colombia use the tab key talk the distance you can travel while smoking a cigar so where is the fun one and a half to go from danya is stuck here spam thanks for your comments.

that's all for today next week we head to columbia as we continue our journey in the footsteps of humbugs he wrote that slavery was the greatest of all evils to have before then humankind with us of the town of palenque a established by escaped slaves 400 years ago until then good bye.

the bauhaus turns 100. 100 years of modernist architecture. 100 years of functionalism n.p.r. isn't. what's behind the legend. we ask the experts about. 30 minutes on the w. . orld or. not

nothing out of the jam well i guess sometimes i am but most end up in winter that mr jermyn thinks deep into the german culture of looking at the stereotypes a question that is think the future of the country that i know i'm ok. yes you did seem ridiculous grandma there you go it's all about a bar if i make a joke join me to make a german fun d.w. . post. i'm still the by work not hard and in the end this is a me you're not allowed to stay here anymore we will send you back. for you from. earlier with this. with the smugglers would lie and say. what's your story

ready. i'm a woman i was a women especially a victims of violence in terms of its. part and send us your story we are trying always to understand this new culture. or another visitor or another yet you want to become a citizen. in for migrants your platform for reliable information. that. the milk and i'm getting close to the breaking news the old explosive device it's about topics that affects a whole lot of pollution climate change and the turn. lead. police to check out.

this is d w news live from budget g 7 leaders me seen in the french town hall barrett splits on how to deal with iran the leaders of the g. 7 nations have had a full day of bilateral meetings in talks with african media has been a surprise visit from the wrong as foreign minister took a sentence today also coming up violence on the streets of hong kong police pull their guns on pro-democracy protesters and i at least one live shot of the authorities send in water cannon for the 1st time.