of the film. about 100,000 flights jet around the world every day. flying accounts for 2.5% of all carbon emissions. now, that might not sound like much, but if aviation was a country, it would be among the top ten most polluting nations in the world, and its impact is expected to rise. now there's a global race to get clean aviation off the ground. and some companies think they're close to cracking it. pretty soon, passengers will be flying in zero—emission aircraft. but how did we get here? archive: the new machine is called, optimistically, - the flyer. we've come a long way since the wright brothers�* first flight in 1903. that day, they lifted the world into a new dimension. then we achieved bigger, faster planes. great, but that's also how we ended up with all these emissions. jet engines burn kerosene, which releases carbon dioxide, one of the main greenhouse gases causing climate change. the industry faces an enormous challenge to clean up its act, and that means coming up with new fuels. let's take a look at some of the options. there are biofuels, which are made out of things like plants or vegetable oils, but they still produce some harmful emissions. then there's electric. but although batteries are getting far more efficient, the size that you'd need to power a passengerjet would be way too heavy. and there's one potential solution that's getting people really excited — hydrogen. hydrogen fuel cells combine hydrogen and oxygen to create a flow of electrons around a circuit to power a motor. and as we all know, hydrogen plus oxygen equals h20. the problem is... we can't do much about the fundamental properties of hydrogen. volumetrically, we need to compress it to get sort of in the ballpark of not quite a third of the efficiency of fuels that we use. that means that we need often very large, very heavy tanks, because they need very thick walls to deal with the incredibly high pressures we need them at. what you end up with is an aeroplane that can't have any passengers in. this is the challenge faced by zeroavia, one of several companies working to make hydrogen—powered flight a reality. they retrofit existing planes with hydrogen engines. the company had several successful test flights with this plane last year. in the original frame, we would be able to fly about 19 passengers. it looks like a lot of kit in there. how would you fit in 19 people? yeah, so in the retrofitted configuration, it will be about a dozen people. daniela is one of the engineers working on the engine. actually, the fuel cells are this one. the power is created in these small layers. so you have to build up your layers to create the power to take off an aircraft. this engine could almost provide enough power to get you from london to glasgow, but not quite. if you wanted to scale it up for international flights, would you just make the same thing bigger or is it a totally different exercise? it is scalable until a certain power, but then we'll have to change technology. getting this high power density system that will allow to have a lot of power but minimal weight to be integrated on an aircraft is really a challenge. and that probably means completely redesigning the plane. everything will be shrunk. some parts of the engine, of the fuel cell, will be sitting inside of the nacelle, and also the storage tank, which is, uh, going to be probably the largest, uh, you know, piece of equipment they will actually bring outside, 0k? right. so either on the side of the fuselage, or we will hang it on the wing. making everything fit isn't the only challenge, though. you need to have the maintenance and repair organisation. the whole process needs to be certified. we need to provide the hydrogen infrastructure to the, uh, to the aircraft. zeroavia has a plan for that. in its vision, hydrogen would be produced on site at airports using renewable energy before being processed and transported out to the plane. but what about the cost of all this? at the moment, liquid hydrogen is significantly more expensive than conventionaljet fuel, but backers of hydrogen planes believe it will eventually become cheaper than traditional flight. zeroavia isn't the only company racing to reimagine air travel, though. aerospace giants like airbus and boeing are also developing hydrogen planes. but there are still questions over how sustainable they'll actually be. we're going to be using some fairly exotic materials that are very energy intensive to arrive at. what energy are you using to build the fuel cell? what materials are you using? how much energy are we sinking into this technology to get something out? zeroavia has the backing of the uk government and big investors and has over 2,000 pre—orders from airlines. so there seems to be significant belief in hydrogen despite all of the challenges. but what i really want to know is... are we going to be able to jet off to spain anytime soon in a hydrogen plane? history shows that you need to start small and grow big. and that growth would take a while. but if this could be scaled to the largest of planes, then the difference to emissions would be jumbo. you know, it sounds like, if they can get it right, hydrogen planes could be a massive deal. yeah. it's as much about the infrastructure, though. they've got a lot to do. right, 0k, noted. 0k, we're going from the air to the sea now. you might not think of the world's oceans as a great source of green energy, but when you think about it, the tides move an enormous amount of water around the globe every single day, and we are discovering new ways to harness this tidal power. and adrienne murray has been to the remote faroe islands, which are between scotland and norway, to see what they're doing to help harness renewable energy. rugged and remote, the faroe islands are an isolated archipelago found in the north atlantic. powerful currents flow around its 18 islands, and in this sea channel called the vestmannasund, mechanical creatures lurk beneath the water's surface, called dragons. designed by swedish marine energy firm minesto, it's among a wave of new technology that hopes to revolutionise tidal power. this huge yellow thing behind me is a tidal kite. it looks a bit like a glider because it's designed to fly through the water, and once it's installed on the seabed, it will be generating electricity using the current that flows through this stretch of water. weighing 28 tonnes and with a 12—metre wingspan, the newest dragon can deliver 1.2 megawatts of power. it's sort of like kitesurfing, but underwater. so we tether it off to the sea floor, foundation on the sea floor, and then it flies in a figure of eight. as underwater currents flow by, the kite's wings generate a hydrodynamic lift force, spinning the turbine and generating electricity. this design�*s very different to other types of tidal technology. so what's the advantage of a design like this one? we can install and operate and produce power in low flow currents with lightweight machines. although it looks big to the eye, this is actually a very small tidal turbine. we've designed the system as such to be maintenance friendly — you simplyjust tow them in, replace modules and then put them back in. we've also, over the years, removed more and more components from the system and fit them onshore instead. the less old components you have that could become damaged, it's easier to access it and it's much cheaper also. it's the gravitational pull of the moon, and to some extent the sun, which gives the tides their rhythm. and unlike wind, solar or hydro, tidal power isn't reliant on weather. while tidal barrages have been around for decades, their cost and the ecological impact has been a barrier. now, from the scottish islands through to canada, a new generation of tech firms have introduced tidal stream turbines. 0cean energy is still largely untapped, so what are the barriers that have prevented it from taking off? it's a relatively small and new industry, so very few machines in the water, and then you have to compete with wind farms and solar pv, etc. we're now addressing a resource that's so much larger, so we're opening up a market that didn't even exist before. if all goes to plan, there could be arrays of subsea kites around the faroe islands, installed in groups similar to wind farms. so this machine here, that's the first utility, or the array device. there will be many of these in parks, orarrays, as you call them, uh, around the world. the faroes aren't connected to any other country's power grid, so it has to be self—sufficient. and in the past, it relied heavily on oil imports. now, though, it's going fully green, and this battery station helps to regulate electricity supply. we have the biggest battery, i think, in the danish kingdom. we don't have any subsea cables to neighbouring countries. so we need to maintain the stability of the power system at all points in time on a millisecond level. much of the country's power will come from wind, hydro and solar, but that's also where its experiment with tidal energy comes in. it's predictable. we know exactly when it's there, 100 years ahead. if we install tidal turbines in different spots, we will have a baseload generation from tides, and that is extremely valuable. if we can unlock the potential, it can really dramatically change the energy mix in the islands. maybe 30 to 40% of the annual usage in the islands could be provided by tides. now this dragon has begun to fly, and it's sending energy to the grid. it's just one machine, but potentially a big leap forward for harnessing energy from our seas. this is the richard cloudesley school in london... that was adrian. now time for a look at this week's tech news. has a has announced it will lay off 10% of its global workforce, the largest round of cuts yet to affect the firm's estimated 140,000 employees. the cuts, weeks after tesla revealed it delivered fewer vehicles expected last quarter. nasa has confirmed a piece of spacejunk nasa has confirmed a piece of space junk that nasa has confirmed a piece of spacejunk that damaged nasa has confirmed a piece of space junk that damaged a man's home came from the international space station. it was a tremendous sound, it almost hit my son. i was shaken. i was completely in disbelief. what are the chances of something landing on my house? ., ., house? nasa said the metal finder house? nasa said the metal cylinder was _ house? nasa said the metal cylinder was a _ house? nasa said the metal cylinder was a fragment - house? nasa said the metal cylinder was a fragment of l cylinder was a fragment of discarded equipment from the space station. thank goodness it wasn't from the loo. the uk government is set to make the act of creating a sexually explicit deepfake criminal offence in england and wales. people contravening the new law could face an unlimited fine or jail time. could face an unlimited fine or jailtime. bake images could face an unlimited fine or jail time. bake images made with al tools have recently been used to target a number of celebrities, including pop star taylor swift stop and finally, apple has lost its crown to samsung as the world's leading smartphone provider. market research company idc set a 10% dip in iphone shipments last quarter and more competition from android handsets allowed the south korean firm to reclaim the top spot. this is the richard cloudesley school in london... right, there we go. ..although this is no ordinary lesson. not only are these pupils getting to play video games during school time, they're also helping to test some exciting new software. it's very fast. they're helping to test the latest version of a suite of programs collectively known as motioninput. developed over four years by over 200 students at university college london, motioninput allows anyone to control their computers using any part of their body they can move. this could be by moving the eyes, individual limbs or body parts, or even by gestures, facial movements, or speech... page down. ..giving a raft of potential new input methods to disabled people. crucially, motioninput doesn't need any additional specialised equipment. our work with the motioninput software was developed in partnership with intel, and it's focused on al for your pc, so it runs completely on your own laptops and pcs. it has its own engine internally to do the evaluation of how people can be seen to be moving, and it uses just the webcam. the ucl students have been working with the richard cloudesley pupils to help identify potential bugs or development issues with the software. you ready? so do the calibration again. safiya is using the eye gaze application to play different types of games using eye movements. you're a better driverthan i am. afterwards, i asked her what she thought. so what's it like, playing games this way with this new software? speaking software: it is good. it helps me to focus. and is it easy to use? yes, it is easy. it helps me experience every action of the game. and is it better than playing other ways you might have done before? yes. i've only tried the nintendo wii. this new controller helps me play better. that's the young ones suitably impressed. over at ucl, the students working on different elements of motion input were keen for someone slightly less youthful to have a go and see how it works using bodypoint. first up, everyone's favourite block—builder and basher, minecraft. so i'm just moving around here in minecraft by using my right arm as a mouse and my leftarm... it's kind of like a joystick. i think i've cracked it now. oh, it's so cool. go on this look button so you can look around. i was also able to play minecraft using eye tracking. this is amazing. i'm literally using my eyes and my head... ..to look around. the cow, agh! you can attack the cow. oh, i don't want to attack the cows. laughter so this is basically like a steering wheel. as well as minecraft, i was able to take rocket league for a spin. the gestures are really cool. i like that a lot. so if ijust raise my eyebrows... ..i'm making the carjump. the accessibility elements of motioninput are all available to download for free on the microsoft store. the future aim is to commercialise the non—accessibility applications of the software into industries such as manufacturing or healthcare. but in the short term, it's all about the games. now, many of us have a movie that we just love, that we'll watch time and time again and could recite loads of the lines from. ghost? yep. star wars? 0bviously. well, how about if the next time you press play, it had the same people in it, it was about the same topic, but there was a different storyline, different dialogue and different music? would it be the same movie? well, there is a new "generative" documentary about the musician brian eno that does just that, and ben derico has the story. applause inside theatre hey. that version of the film was just for you. that will never be seen again anywhere else in any other time. this is documentary filmmaker gary hustwit. if you didn't catch that, he just said that his new film about brian eno, the one we all just watched, will never be seen again. it's not an error with the file or a mix—up in the screening. this is the intended result. that's because this film is being billed as a generative documentary, a movie that, with the help of generative software, can rewrite itself before every screening. like, we're so locked into this concept of, film and television always has to be the same. it's linear, it's static, it never changes. that's a technical constraint that's from 130 years ago. we don't have those constraints with digital technology any more, so why are we still sticking with them? when you create something, you're doing this thing that humans are very good at, which is imagining. for the uninitiated, brian eno is a bit of a legend, notjust for the music he's created — he's produced acts like u2 and david bowie — but for his philosophy, his ideas about creativity and how art can be made, particularly with the help of generative technology. a lot of the ways that brian creates music and art are also reflected in the way we created the film, because we're not making a normal documentary where we craft each scene and, you know, time it out. we're creating kind of a structure in software that will create our film. you can think of it like this. up here, we have a pool of pre—cut scenes, hundreds of hours of never before seen archival footage and exclusive interviews with eno. down here, we have an empty structure looking for pieces to fill up the slots. some parts of the film are always the same. pieces here are pinned in place, but for the rest, the software makes selections, slots them into place based on instructions from the filmmakers, and edits together a new film that it will never generate again. it can make approximately 52 quintillion versions of the film, which is 52 with 19 zeroes after it. brendan dawes is a generative artist himself and the developer of the film's bespoke generative software. the way to think of it is kind of like a collaborator. i give it some direction, but then it's like, "actually, i've done this," and i go, "wow, ok, "let's go down that path and that route." i'm specifically looking to be surprised, surprised and delighted. i'm pleased if people are more confused than they were before, because i think the biggest problem is trying to deal with what i call the appetite for certainty. i think we normally want to have control as filmmakers of every second, so there's a little bit of surrendering that control. but the result is things that i never would have thought to connect myself. when i see it when our generative system does it, you know, it's like, "oh, my gosh, "i didn't even think about that connection." that could be making unusual story choices, likejumping around out of chronological order, orjuxtaposing two seemingly unrelated scenes. those choices can lead to wildly different versions of what is supposedly the same film. for example, gary says the audience reaction to the project, which premiered at this year's sundance film festival, was different every night. the mood shifted based on the choices the algorithm made. like, the first time that the film screened here at sundance, i felt it was, like, very energetic, and there were lots of laughs. but then the second time, it was more introspective and more personal. um, itjust depends on the scenes that end up getting chosen that night. and you can see those choices happening as you're watching the film. there's text that displays on screen showing the algorithm at work. these sorts of moments can make it easy to chalk this whole thing up to technology, a magic algorithm that somehow creates cinema out of thin air. but the algorithm only succeeds in creating moments of serendipity because of the work of human filmmakers who have worked filming, editing and mixing the material before feeding it into the software. it's not just about the tech, um, it is about the filmmaking craft, and we're using it as a tool to kind of extend what we could do. the system is trained by our intelligence as filmmakers, not some artificial intelligence. a film like this gives us an opportunity to think about what cinema actually is, and where new technology fits into the process of how we make movies. for me, i enjoyed the version of the film i saw. it had all the hallmarks of a good music documentary, although the story did seem to meander a bit from time to time. but for the man the film is about, he's happy with that ambiguity. eno spoke to the audience at sundance from his home in the uk over the theatre's speakers. hustwit and his crew seem to be betting on this idea. in march, he and brendan launched anamorph, a generative film company that will aim to create more films like this one. it's an idea, and there are other people who are going the crew seem to be betting on this idea. in march, he and brendan launched anamorph, a generative film company that will aim to create more films like this one. it's an idea, and there are other people who are going to have other ideas about how to use this tool that we've created, so we're super—excited to kind of keep collaborating and keep doing new projects and see what the possibilities are. i interviewed brian eno once. he was brilliant, as much a scientist as an artist, with a terrifyingly big brain. just like you. bigger. that's all we've got time for. yeah, thanks for watching. we'll see you soon. bye! hello. if you're not impressed with whatjune has brought us so far weather wise, i suspect this weekend will do very little to change your view. further showers in the forecast, albeit with some spells of sunshine in between. a rather cool feel for the time of year. the earlier satellite picture from friday shows clumps of shower cloud circulating around the centre of an area of low pressure. and this will be our weather maker throughout the weekend with bands of showers or longer spells of rain, albeit with some spells of sunshine in between. you can see we start saturday morning with some slices of sunshine, but some showers from the word go. some of those are going to be heavy, perhaps thundery. the showers could show up just about anywhere. some brisk winds across both the north and the south of the uk. in fact, through the english channel, we could see gusts of 40 miles per hour or more, at least where it's windy. the showers will move through pretty quickly with light winds. parts of northern ireland, southern scotland, northern england will see slow moving showers and those temperatures at best between 13 and 17 degrees. so our low still with us through saturday night. and this little weather system here will bring a clump of heavy and persistent rain southwards across scotland, getting down into parts of northern ireland's and perhaps the far north of england by the start of sunday morning. we'll start sunday with temperatures around eight to 11 degrees. a sunshine and showers story again for most of us on sunday. but with this band of more persistent rain sinking its way down across northern ireland, affecting southwest scotland into the north of england, those showers where they do crop up across southern and eastern parts of england particularly could again be heavy and thundery. 14 degrees for stornoway, maybe 19 degrees for hull and for london. so perhaps just a little bit warmer. into monday sunshine and showers once again, although with quite a lot of cloud, i suspect across northern and western parts. 21 degrees possible across the south—east corner. and as we look further ahead, well, there are some signs that at least for a while, things might try to settle down with this ridge of high pressure just trying to topple its way in, but signs are it may not last, it may not hold on for all that long with areas of wet weather returning by the end of the week and while temperatures may climb a little, there's certainly no heat wave on the way. live from washington, this is bbc news. vladimir putin announces his conditions for a ceasefire in ukraine — demands ukraine and its allies swiftly reject. the us supreme court strikes down a federal ban on bump stocks — attachments that increase the firing capacity of guns. and cyril ramaphosa is re—elected president of south africa after his party strikes an unprecedented coalition deal with the opposition. hello, i'm carl nasman. the us supreme court on friday struck down a federal ban on bump stocks, the latest move in america's battle over gun control. bump stocks are gun accessories that allow semi—automatic rifles to fire bullets more quickly, similar to a machine gun. in a 6—3 vote, the court's conservative majority ruled that using firearms with the attachment does not meet the definition of a machine gun under