invisible traces we leave behind. viruses that i excelled into the egg for example . which have turned our world upside down. join us as we play detective on tomorrow today the science show on d w. images like these have become the new normal people queuing to get tested for covert 19. the tests are meant to get the band demick under control and better understand the spread of the disease. there are 3 spaces prochoice the antibody test detects a pasta infection and requires the blood song called. the blood is tested for antibodies that would have been produced. by the immune system during the illness. the other 2 tests are meant to detect a current infection of cells kovi to. the antigen test requires a swab from the back of your nose or throat and detects proteins from the surface of the virus. the results are quick but not as accurate as a p.c.r. test here you also need saliva or a nasal swab. these tests are intermediate to identify genetic material called r n n e. the p.c.r. test is the most reliable. but it takes up more time and resources and so it cannot be easily used for mass testing. but pool testing for the virus could change that mathematicians in rwanda have now developed an algorithm to do just that. in the fight against the pandemic we wonder coronavirus task force relies on comprehensive contact tracing. to get an up to date picture of how much the corona virus has spread rwanda regularly tests a cross-section of the population using an ingenious strategy called pool testing. the brains behind this strategy is professor wilfred to define who is director of research at the african institute for mathematical science or a i.m.s. global network. if you go to the community and. it doesn't tell you how many people are actually infected because you're going to everybody so you always sample i'm sort of go from go some poor. to the truth to reality you know my magical models. the calculations involve complex algorithms and define has translated them for us into an example from everyday life. the idea to be on board bursting is really simple so imagine that you have 9 cups of beans and your 2 are not all of those as bobbins only not artichoke which corporals them by being as you was cool beans and dearest so you might find out the abuse that this bit of those who are these are not only takes a long time will be to go to a world group and so use a lot of gas if you are doing my own cooking mon ports of beans. the mathematician resorts to a simple yet effective trick he combines being samples from different parts of all the beings in this sample pool are good you no longer has to test each part individual he only has to perform additional tests if there are better beans in the sample that brought. the principle can be applied anywhere you can create groups for testing that's why it can also be used to combat covert 19. in rwanda sets of 10 and 20 samples are combined and tested simultaneously. if the pull test result is negative all the subjects in the pooled sample are declared as not having coded 19. if the pooled result is positive then each sample is retested individual. the advantages of their pulling out portions just to reduce the cost spots to the for the adults to do the turnaround time for the bar for results and also to test the massively in the community also the group does. which are that course run for the community so those are the men advantages for these. but if the virus has spread dramatically pooled samples test positive too often and retesting becomes costly and time consuming so far however africa has low numbers of cases compared to western countries and the method is proving useful there this is really hurtful for the african countries but not only the african countries even for the roping countries since we developed these and published the. pulling up close tonight a paper route so we have been approached by a similar countries. ghana and kenya are now applying the strategy to group testing enquiries have also come from the us and the university of edinburgh in scotland is using the method to test its students the method actually originated in 1903 american economist and researcher robert dorfman was the 1st to develop tool tests to screen u.s. army soldiers more efficiently for syphilis since then the strategy has been further developed and is also used to test for other sexually transmitted diseases malaria and blood banking there's a lot of interest in this approach i think it's it's a no brainer that we need to be. optimizing the use of resources. to develop the method the cameroonian collaborated with his rwandan colleague tessa and a.m.'s founder neal to rock it's a pan african response to the continent's challenges. it's really extraordinary that you can write. on the board so many questions and no tell you how. this is so spread in a population how what happens when you draw a ball. out what happens to cars how computers work so all of these are markets on the. resort of people just investigating doing analysis trying to understand better how things are around and work. the a ins network places great value on training young scientists across the continent so they are confident that the next albert einstein will come from africa training young people to how to obvious knowledge and this ability to use mars to solve problems is wonderful and i'm very proud to be associated with this vision to be helping to drive it forward. for example as the room proof that this is vital thing to do. did you know that p.c.r. technology which detects the virus is the basis for many other tests. it's used to amplify specific d.n.a. richard such can be analyzed. p.c.r. also produce a breakthrough in forensic technology many possible to determine this information from the smallest human traces this genetic fingerprint can be invaluable information at the scene for crime. on t.v. shows solving crimes always look so easy clues however tiny are soon analyzed and lead directly to the perpetrator. in real life things often look quite different. this is the state police forensic science institute in kiel normally crime scene technicians go to a crime scene. time it's come to them their food is the photographer could come in with us to take a few pictures of the crime scene that will make it easier for us afterwards to. the 1st step is to look for fingerprints cupboards have been ripped open the interior is a mess it looks like someone has ransacked the mobile home. under the table there's a knife with a bloody blade. everything has to be documented and photographed where it's found later it will be studied in a lab. a crime weapon but no victim whose blood is it. what investigators do what a crime scene is gather evidence as much as possible. even things that look irrelevant can prove to be extremely important. person in by whatever we found a small piece of paper on the floor between the front and say it's a candy wrapper. we secured it because it doesn't belong here it looks more like it might have fallen out of a pocket and under the table we found a knife that appears to have traces of blood so the knife is of interest not only for fingerprinting but also for day in and alice has and possibly for any fibers sticking to it as well would have floated off the fact that. there's a fingerprint on the candy wrapper but it's faint and incomplete this clue would once have been impossible to analyze today however it can be enhanced by a process called sputtering. the wrapper is exposed to vaporized silver in a spotter in kotor the silver condenses on the wrapper highlighting the fingerprint the technique was developed here at this institute just a few years ago. a photograph of a fingerprint is then digitally enhanced it's now so detailed even sweat pours can be seen as tiny white dots on. lines of the print yes i think there is indeed a fingerprint here right above the lettering that means the spattering has performed a small miracle by carting the wrapper and so over the fingerprint is raised against the background and we can see it more clearly. so. i think we should apply the tape to the back of the sate. meanwhile fiber specialists have taken over the crime scene. first and foremost we have to secure the evidence wherever there might be any 5 bits of course we try to imagine where the pair of the trader was and have a crime was carried out that's our main focus but in principle we have to secure everything because we can never really imagine exactly what happened. and we just have to figure this. even the slightest contact with upholstery is another to transfer fibers garments shared fibers all the time the nearby and if the 2 of us were wearing pullovers and i hugged her or we rubbed against each other on the bus my fibers would get on her and hers would get on me and. everybody carries a distinct a mix of fibers around with them mostly fluff from their own clothes. fibers from a crime scene can't lead to the perpetrator by themselves crime scene technicians also need to compare them with the clothes of a suspect. then they can tell whether or not it's fibers match ones from the crime scene. this involves picking out relevant fibers among thousands of others. the 1st thing i do is look at all the colors through the microscope magnified say $250.00 times i look at both the colors and the shapes of the individual fibers to say if it's them or not. i think i'm like a bloodhound on the lookout for a single fiber in this case i'm only looking closely at the red ones i mentally block out the other is otherwise i go crazy doesn't when he finds and. once the visible clues have been identified and analyzed it's the turn of the invisible ones the expert in invisible clues needs breathing equipment and total darkness. the chemical he sprays lights up for a few seconds wherever it's in contact with traces of blood hand prints appears next to the door and smears of blood along the side of the vehicle. is going to go through it all the evidence here is compatible with a person exiting the mobile home and moving perhaps injured unsteady on his or her feet and finding support along the side of the vehicle this is. it turns out things are not what they appear the police officer had left the wrapper in the mobile home and the fingerprint was hers. the fibers were indeed from that red pullover but it belongs to a colleague in the lab. and the blood on the knife came from the butchers around the corner so there was no crime it was a dummy run and a training exercise and internal police matter still the perpetrators are making a getaway taking the scene of the crime with them. for almost 200 years now photographs have captured fleecy moments originally in black and white and soon it became possible to duplicate photos using a negative to make more prints each point of light became a dot in the image a lot of data to capture a moment but. first here's fade with time but what about our digital photos. oh boy i can run from guyana had a question about past. how long can data be stored. humans have recorded their languages and their knowledge in the form of drawings and symbols since prehistoric times. on the analogue data carriers from back then play tablets or stones much of the information survived for thousands of years. as a result these ancient days are carriers can be read and decoded today. modern storage devices can carry a lot more data even though there are a lot smaller. but the lifespan of most c.d.'s and d.v.d.'s is estimated at less than 100 years. data that's stored on the kind of huge servers operated by large companies should theoretically last forever as long as the days is repeatedly copied and as long as defective hard drives are replaced. in order to keep the ever increasing amounts of data under control researchers are developing smaller and smaller storage devices in the future synthetic d.n.a. could replace conventional data carriers. these artificially generated genetic strands would have more than a 1000000 times the capacity of modern hard drives. on the reconstruction of neanderthal d.n.a. has shown the d.n.a. molecules are still legible after thousands of years. another method of storing data in courts is 5 d. technology uses nano lasers to write information into 5 dimensional fused courts of mind boggling speed. these glass does the size of coins can store up to 360 terabytes. and they last a very long time to turn 18800000000 years. whether or not there's someone in 13800000000. you can read the data was another question. $0.59 a binds the $59.00 with $21.00 zeros that is a lot of data and it's the amount estimated to have been created captured and consumed by the end of 2020. in the next 4 years the amount is forecast to almost triple. in order to preserve the information it has to be constantly copied and uploaded onto new data carriers plus anyone can get in on the act of producing more and more data. for example it's estimated that in 2020 over a trillion digital photos were taken. data that is meant to capture memory as. we asked our viewers what data would you save forever and how. your rights your wedding day the moment of birth and anything to do with love so how romantic. sense here is a little more pragmatic we should preserve our knowledge of metalworking as well as plants and seeds on a floppy disk in order to ensure food security in the future. mohamed recommends internal rather than external storage writing i want to store everything in my brain we tend to lose the ability to remember things as we age hopefully in the near future we'll be able to upload data to our brain finally randy rides he's most interested in saving images thousands of family photos and videos from birth to wedding to grandchildren in his case 50 years or 28 terabytes in total thanks for getting in touch. and. snapshots can only capture so much of a person but these days it's possible to bring old photographs back to life. all of a sudden subjects can move their hands or blink. uncanny even if it doesn't look quite natural. that. lets you know you scientist marie curie is among those who have been given this kind of treatment in her case there's no doubt that this video isn't authentic with people who are still alive telling real from fake can be more challenging. these days all it takes is one photograph to create a fake video in no time at all that's pretty impressive. with the help of artificial intelligence researches can now bring any photo to life in under 3 minutes manipulating the image remotely. these examples took just a few minutes to put together and they show what this technology is already capable of. 'd to raj ebrahimi is team of specialists chiefly working on ways to automatically identify deep fakes like. these detectors will be crucial in the future. also the fake detectors are not going to be perfect but they will be able to detect the majority of the deep fake content that is going to be distributed and in many cases this is good and what is important that the solutions have to be done in such a way that they can reinvent themselves and evolve as the technology for the fakes evolve. the fakes are also an issue in business it's becoming increasingly important to track down fake images in cases of insurance fraud for example. image analysts are researching ways to spot the markers of a phony image. intelligent image recognition software is fed countless fake images and videos and learns how to recognize anomalies. soon as clear markers are detected a red box indicates that something has been manipulated. if you look at the pic technology 6 months ago a lot of the video was very very easy to detect they were distorted you could immediately see there's something wrong with if you look at them today they are at the verge of becoming very believable it's becoming more and more difficult to detect whether a video is fake or not. it's a matter of 3 to 9 months before 99 percent of people when they watch fake video they wouldn't know that it is fake a bleak prospect or fact checkers fortunately fact checking company many common. doesn't yet encounter deep thanks every day but without new detection tools expert is pessimistic. my hope for the future is that as more deep faith technology emerges the people tracking the fakes will have better tools to recognize the fixes eg. because so much misinformation is spread so fast on social media users will have to raise their game using the fact checkers golden rules. i'm functionally timid as i firstly does oneself i have to know myself in the media i consume that's very important but if you fall for something from a media source that you trust deeply then it becomes difficult next just to see who's writing where something comes from so you need to master search engines clearly i need to know how search engines work and be able to do comparative searches on top of that of course is the search for images so-called reverse image search finally speed up the rate of information consumption and if something sounds overdramatic then maybe it's better to ask people who know about us. as a windows system and our skin but that alone is not enough more education is also needed. and of course we want something to happen in the schools now comes the big but always shouting that schools need to do something we're saying that there's so much fake news on facebook this is a problem young people are not on facebook. it's a $35.00 to $55.00 generation and now we've identified the core of the problems and we're not doing enough educational outreach to adults. ok let's give it a go what do you make of this video and it was lightning striking a train track well it's a fake pay close attention to the trajectory of the flash it should really leave some burn marks in its wake but there's not a trace also the camera operator is way too calm and steady. but there's also a clue in the title of the video here cd computer generated images clearly faked. some also branded this video with a woman doing a reading in the middle of the military take over in myanmar. so what do you reckon or is it real or fake. this shadow seems to suggest it's a fake they seem very truncated bangs if you look more closely you'll see that there are steps behind her this supposed to be located at the royal lotus roundabout in myanmar comparing the image to that in the video reveals the markings on the ground the street the flower pots are identical in the video the silver posts must have been installed since the google image was recorded in 2018 or so the location appears plausible and the shadows of the downs and those of the cars match up. the lighting is the same so this video is no fake. the problem is red white and maybe you. do you have a science question you'd like us to answer. send it in as a video text over israel if we featured on the show who did it little surprise from us as a thank you come on you just ask. and for more exciting stories check out our website or find us on twitter. that's all for now thanks for joining us on tomorrow today. will be back next week with more fascinating stories from the world of science and technology until then by. slightly. everything seems possible here. 19 as you. might think is where the peaceful revolution begat. today it's a creative and driving the truck last. post just right on a plate tricked into the city's past and fresh chickens. coming up on t.w. . your life when it's no longer for a bit. to career when you're finally allowed to pursue it. it's your opinion when you can finally say it. is freedom more important than homeland. we need artists in exile living in berlin. barks. 20. and 30 minutes on d w. and you hear me now years yes we can hear you and how last year's german chancellor will bring you back or as you've never heard her before surprised yourself with what is possible who is magical really what moves her i'm part of who talks to people who follows her along the way admirers and critics alike how is the world's most powerful woman shaping hard liquor joining us from echols last august. i was issued when i arrived here i slept with 6 people in a room. it was hard i was free. i even got white hairs that. learning the german language helped me a lot this gets me a little bunch maybe too in trouble let's say you want to know their story in my son's birth fighting and reliable information for migrants. by 2015 more than half the world will be living with limited water resources we haven't had to think about our war all the worry about. i think that era is over this is the crisis of our time it's a financial product like any other financial could live in a competitive world is just cold it's cold it's been cold water used to be seen but the world is changing the most important moments you get is called the fisa. laws of water sitting for commodity starts march 22nd on d w. this is d w news and these are our top stories chancellor angela merkel's conservative party has been handed a blow by voters in 2 german states elections in the southwestern state of brandon virgin birth the green party looks set to stay and paula so too the social democrats and neighboring rhineland pluck to name the c.d.u. lost ground in both states the polls were seen as a dress rehearsal for germany's federal election later this year. in germany.