what secrets lie behind these walls. discover new adventures in 360 degree. and explore fascinating world heritage sites. w. world heritage 360 get in here now. you're watching tomorrow today the science show on t w. this week it's about something that lets us see the world around us but which itself is intangible life. will be talking about light in everyday life in industry and in medicine. we'll be looking at life particles that overcomes space and time. alike based internet.

and the effects of city lights on nature. but let's start at the beginning with how we see light. when light enters our eye it hits the retina. and is received by photo receptor cells the so-called rod cells respond to light and dark the cones are responsible for color vision but we only see the light that actually enter his our eyes if you are in zambia wanted to know more. light travel. during a thunderstorm or you see the lightning straight away but we hear the thunder. that's because sound waves move slowly or as light travels super fast. 300000

kilometers per 2nd. it maintains that speed in space where there's a vacuum and it moves only slightly slower through the earth's atmosphere but other media slow it down for example water in which it travels at a mere 225000 kilometers a 2nd. light travels like ripples spreading on the surface of a liquid in all directions simultaneously. and in straight lines which is why we talk of light rays sometimes it's even possible for us to see the. light that does not strike our retinas remains invisible we only see light inside view for example when it scattered off particles of dust or droplets of water and into our eyes. on a rough surface light rays scatter in all directions in shallow water this produces

wavy abstract patterns. when this light hits a smooth as glass surface it changes direction through refraction and is separated into different colors. like continues to move until it meets an obstacle in the case of dark clouds it simply swallowed up. and thanks to help are dying star in special theory of relativity we know that nothing can travel at or beyond the speed of light. what is light exactly for one thing it's electromagnetic radiation us only a small section of it is visible to us between violet's and great old wavelengths between 380 and 715 enemy c. . objects illuminated by that light a visible to us we don't actually see the objects themselves. but the radiation

that they reflect there's much more to life than meets the eye. it brightens things up everywhere light is omnipresent but what kind of weird matter is light isn't even matter at all or is it pure energy light only seems familiar to us might particle for photons open the doors to a truly strange world scientists used to believe that mind comprised tiny balls of being around through space them light was regarded as a wave but today we know that depending on the experiment light can be either one or the other. wave light is a particle it depends on how we observe it in the sense its both both at the same time and that's truly bizarre. light may indeed seem like a far fetched notion but it exists we literally see it constantly but if you take

a closer look at it it practically vanishes not least if you try to wait a photon. you know that yes this really is kind of strange at 1st glance. also. so i'm now sitting on this chair and i have a certain mass if i had some scales it would be my rest mass. that also applies to the elementary particles that were made up of. but by the photon it's different it actually has no rest mass at all. so a photon both exists and does not exist at the same time photons are never at rest according to physicists they're constantly in motion what's more at the speed of light which is where the next strange phenomenon minds at 1st glance the speed of light seems bewilderingly fast. 1.3 seconds to the moon or one second to circle the

earth 7 times. but looking further afield there's no longer sound so awesome. light needs an hour and a half to go all the way to saturn the farthest planet that can be seen with the naked eye and getting to the nearest star takes 4 years. and to the andromeda galaxy and out of this world 4 and a half 1000000 years. 300000 kilometers per 2nd that's not just any speed nothing moves faster absolutely nothing and never the light from a car is headlamps while not move any faster if the car is also moving it doesn't need to. be very light always moves at the speed of light i can't add to it but the consequence of this if you think about it for half an hour is that time does not always pass at the same speed the currents does it side and the mug life never get

. thanks to albert einstein who needed a bit more than half an hour we now know that space and time become distorted when we move the faster we go the stronger the distortion and at 300000 kilometers per 2nd photons move very fast the distortion is so extreme at that speed that from the photons perspective time stands still and space start expanding to go any faster when the point less. the photons perspective. the universe. no longer expounds i'm everywhere in the universe at the same time unfortunately we can't put ourselves in the photon's perspective that would be fantastic if we could join it and also have that perspective everybody that has a mass needs infinite amounts of energy to reach the speed of light. all of which when the consequence of us

a photon would be very exotic it would have no space and no time one kind of site. it's no wonder that light inspires contemplation. my approach to life as such is down to earth enough but the fact that light remains a secret on a level that is not the mystical nor romantic. notions well that is a factor for me. during a quiet all month when i am relaxed. of course i think about how what i do every day can be incorporated into fundamental equations the fundamental laws of nature i'm calling playing them like sean because the thing is that so that poor. might evoke some of the most profound mysteries in our world not just at the altar of the various religions but also in the illuminating minds of physicists.

pretty strange stuff linus photons have actually been used to teleport information thanks to a phenomenon called quantum entanglement 2 particles such as photons can be correlated in such a way that they always do as the other does no matter how far away they are from each other. like faraway clocks that somehow synchronize. einstein 1st described this effect as spooky action at a distance the entangled photons can exchange data almost instantaneously but in fact it's possible to transmit data at high speeds with normal light sources using a life i intellect. when the lights go on here not only does the room brighten but data is being transmitted

these researchers at the found the half institute in berlin are working on wireless data communication using lice it's a technology known as life i short for like the delicacy the visible light transmitters are l.e.d. lamps. l.e.d.s. are the main light source for this technology other light sources would be far too slow to be useful. really rapidly sensors on the receiver device capture the signal. if a signal transmission is very high thanks to the fact that life i usually light is a very broad spectrum. wireless from our ceiling lights it's super fast but could it be a problem for our vision. the question is does it flicker the whole time. and we can see that here the

modulation is very very high far higher than the eye can detect. him and come. the small green lamps flickering here are just playful design elements the device was newly developed by the berlin scientists and the green lights tell the user that its operating the prerequisite for this optical wireless system to function is that there must be visual contact between transmitter and receiver if the light source is interrupted the signal is lost the data transmission rate drops to 0. and 4th is an advantage of this optical data connection is that it can be easily confined to a room all i need to do is close the blind and i am completely isolated from the outside world. and all my data stay in the room when they're being transmitted. that is a definitive advantage compared to a radio which you can easily be picked up from the outside.

the system doesn't allow the data transmission to be disrupted from my side the life internet was tested in a pilot project in collaboration with a car maker the technology is packed into this box. other life i devices were set up at fixed points in such a way that there was always at least one visual contact despite the constant motion of the robot the data transmission remained stable a big success for the project. in my view this technology will 1st be applied in an industrial field. that's for an objective need to exist we have to show that we can fulfill certain specifications with this technology and at the same time that we have a professional area where it can and will find an application. via.

data transmission by life could move into daily life. such as in museums or in public transport situations where there are many users at once or where wife i transmission is faulty but 1st a number of problems have to be solved. and if you move around in a room or you go from that room to another you have to have a system there that can guarantee an interrupted data transmission. we already have those kinds of solutions in the radio frequency area we have to adapt those solutions to optics. only then will we have a fully functioning system in this system how the researchers hope to master those problems within 3 years bringing life i out of its nice position and into their life. there's nothing

like twinkling lights to get you into the festive spirit. but human made lighting at nice is bad for the environment light pollution is a growing problem across the planet some of the artificial light that shines into the atmosphere is reflected back creating a dome of diffuse like known as sky glow it can have devastating consequences for creatures who survival depends on the darkness. in germany there are many places where it gets truly dark at night one of them is lake stateliness brandenburg ideal conditions for a unique experiment it's 3 o'clock in the morning this is when water fleets tend to come to the surface of the lake to feed an alkie biologist is waiting for them. the light from the head torches would disturb the experiment so they switch them off and infrared light is allowed. ok and his team are exploring the effects of sky

glow on water. they've positioned l.e.d. lights in circles in a number of test basins they simulate various degrees of light pollution. and. this is explained it's extremely hard to develop a test model which allows you to observe the effects of sky glow on an ecosystem what we have here is a very very diffuse light but it still affects vast swathes of the landscape at night. areas across germany europe all over the world are affected by sky glow in. the sky go into the top. 24 test basins make up a floating laboratory the researchers will be trying to identify the extent that sky glow affects the underwater world the life processes of marine organisms are determined by the intensity of light the researchers take water samples from the

test cylinders illuminated to varying degrees samples are taken from various depths and at different times of night and day every type of marine organism from bacteria to algae to fish is of interest the fish as the light allows the fish to see better as they feed and so all plankton. the water fleas that were researching normally come to the surface at night to feed because they know the fish can't see anything . they're safe to feed on our. parts they use the light to adjust their depth. in the daytime they head to the bottom of the lake to avoid the fish so light sends them a message that it's twilight sort of permanent twilight and they need to stay in the depths. we're looking at with our water samples whether they're consequently feeding on less out in bacteria and whether this development is perhaps triggering other processes. time for the research is to get some sleep. but

they said there alarms for 3 hours later. just before daybreak they're up and heading off to fetch more samples from the lake. and their name is to document the marine organisms daily cycles. last night its way today the illuminated basins are clearly visible against the non illuminated control basin the research is eager to find out of the algae in the basins exposed to sky glow have significantly multiplied because the water fleas stayed away from the surface of the water. ponds hogan and his team then set about examining their water samples in the lab. they use a piece of equipment that saves them hours of laborious work with a microscope it's called a flow cam it automatically scans the sample revealing star shaped rock algae and blue green algae. everything is counted measured and documented.

these are the algae types that water fleas and coppa pods feed on if they dare venture to the lake surface. but the more light there is the less brave they feel. is sky glow is still a relatively unknown quantity yes our 1st observations indicate that there is something going on even as a result of it. the slightly changing light conditions so we have to assume it affects large areas. the signs are that light pollution adversely affects the food chain of lakes and therefore contributes to more frequent algal bloom in france her correctly swedish colleagues against nice go are about to do their last water analysis of the day. not in a lab this time but in the actual tanks they're going to install an underwater microscope camera. once it's

underwater the device takes a nonstop series of photographs these allow the researches to establish the depth of the organisms and where they're headed the camera can the fleas as tiny as 1200th of a millimeter. can see the exact location and movement of these marine organisms they immediately react to changes in light bright sunlight makes them head down to the bottom of the lake. they return to the surface when it's dark the findings are clear the. bodies of water and their inhabitants are evidently adversely affected by light pollution. if they're working up of the data confirms their hypotheses. and his colleagues will have identified a worldwide problem now the experiment is over the water flees in lake the he can go back to business as usual today with the sun goes down we'll have peace and

quiet again. islamists behind the scenes television is all about light without it our cameras would record this. the images you see other result of captured light. to get a good shot you need to make sure your settings are right if your cameras out of focus there's no selvage in the image. but in your way of capturing lights to change that. what's happening here could revolutionize film and t.v. production research is from the computer science department of germany's island university the testing out a brand new way of capturing video using light field cameras they not only measure the intensity of the light emanating from

a scene but also the direction in which the individual rays are traveling this is the light field. you closer to for the a few additional photography reproducers a point in a scene long to a point on the film or the sensor. in a light field photography you tray of light is mapped to the point that's being reflected from you know so for every point in a scene various rays are reflected in different directions which are captured and analyzed and the physics behind it is nothing new but right now the system is only used for stills it's allows you to adjust the focus of any point on the image after it's been taken if this works for moving images to make you completely change filmmaking. as whitefield video cameras would allow you to do all kinds of things and post your pictures the depth of field angle and camera position retrospectively could come off you could even add tracking shots things you'd normally need on the original material but what else you could do them after or. this is tim uses

$64.00 individual cameras and therefore send $64.00 times as much image data 17 gigabytes per 2nd need to be stored in real time not only can you count kill at the position of every point of lights you can also count kill light the direction of the light rays. it's already works in the lab. now they want to test it on to more real life conditions at the animation institute and not fix bugs that planning to film a cellist playing in a studio and capture her movements using light field equipment. and deputy zoom by using light field cameras we hope that we'll be able to shift the focus around the space in a way that's not possible with real physical lenses. nuclear that us is so this is an ocean this is a great example of what's so new and innovative about this technology and their

guns and taken wilkie's. preparations are underway for the 1st flight field video shoot in europe they need to break up the cameras and connect fast lengths of cables and prepare the stage for. star. the scientists and animation specialists will test whether it's possible to capture this new form of video and transfer the enormous amounts of data at the same time. refuses to come out using 64 cameras gives us 64 different perspectives. in addition to the color and light properties of each point you can also calculate the distance this has huge advantages for post production you can add the extra factor after the fact and who knows what. the light field video shoot his prefer to success the team has managed to create a 3 d. model of the cellist the recordings have captured the amount of light reflecting in

all different directions from every point in the scene. and this means they can calculate the exact position of each of those points. they've also managed to successfully capture her movements using the spatial data they can replicate the cellist from different angles and even have her play polyphonic length. or physical used for eventually a light field technology might work like a kind of scanner system he wouldn't have actual cameras anymore so all the camera work would take place and post. that. we're trying to bring this technology into film production for the 1st time that's what's so special and what it does is but it won't be possible until we have the necessary equipment to handle data on the scale of these kinds of productions because people do so in the hope that. the

research is demonstrates how the focus can be shifted around the scene. it starts close upon the bow and gradually moves across the various figures. light field video really does work and in the future it could be possible to capture all of these perspectives and achieve these post-production effects with just one single camera. if problem is read write are great but only if you. do have a science question that you've always wanted answered we're happy to help out and send it to us as a video text over a smell if we answer it on the show one send you a little surprise as a thank you can i just ask. you'll find as i do w dot com slash science or drop us a line at d w underscore site tech on facebook

d w dot science. that wraps up today's show next time we take a look at hyperloop a technique that could transport people and goods at over 1000 kilometers an hour is this the future of transport join us next time to find out by.

250 years of look like beethoven a major anniversary. our host look at travels to vienna he lived here for over 3 decades and wrote his masterpiece this man discovers crops that finding the history . of a lot of questions that need answering following the footsteps of the great before . coming up on t.w. . explorer.

naturalist. renaissance man. bugs under-funded a multitude. to mark is 250th birthday. we talk with a 100 voters historian the offer. on the road extra. 30 minutes on d w. was the speech of his life perhaps his best and certainly his most difficult the speech by calling tristen on just summer 19th 1989. shortly after the fall of the of the chancellor addresses the people of east

germany. the middest tense the crowd clamors for german unity journalist peter allen boyd was at the scene. 30 years later he looks back on the time. interested. in storage december 19th d w. a there i believe it and this is climate change that. happiness increased book. the book for you. to get smarter birth free to go where you go. with. the.

christian. god. this is deja news these are our top stories marathon un climate talks in madrid have ended in disappointment with a wanted down deal delegates from 200 countries passed ambitious climate protection targets but failed to agree on regulating carbon emissions trading activists say what's been agreed will have little impact i know. and lebanon thousands rallied outside parliament in the capital beirut to protest over a security crackdown.