ending for his border war with mexico trump wants five point seven billion dollars added to the budget for the war and says he will not sign off on any spending legislation. search and rescue teams in indonesia are looking for hundreds of missing people following saturday's deadly tsunami a tarantula rains are hampering their efforts the death toll has now risen to four hundred twenty nine with a further one thousand four hundred people injured. and at least six people including three suicide bombers have been killed in an attack on the foreign on the foreign ministry in the libyan capital tripoli they detonated a car bomb before opening fire on the ministry itself two of the attackers managed to get into the building it's not yet clear who was behind the attack those are the top stories stay with us science in a golden age is coming up next why. the marshall islands holds a toxic legacy from years of u.s. military nuclear testing. as the sea levels rise investigates the threats this fall

. on al jazeera. the nature of light has intrigued scientists throughout the ages today it's used in all sorts of applications from lasers and communication to particle accelerators we're living in a science and technology boom period but the roots of our understanding of optics and light can be traced back to a period between the ninth and fourteenth centuries that's when a revolution in science took place in the islamic world a golden age of science. a british professor of theoretical physics but born in baghdad all been looking at the states of the off topic patients of optics and tracing back their roots to those pioneers in the islamic world who revolutionized the new understanding of light during the golden age.

this is sesame in jordan it's a synchrotron a giant particle accelerator that's going to produce high energy light for groundbreaking experiments now sesame stands for synchrotron light. and applications in the middle east the lights allow us to study the structure of matter with incredible detail to learn more about for example how cancer grows in

living cells or to analyze cracks in concrete to see why bridges fail for pollution in the soil this facility is a pioneering collaboration that's bringing together scientists from around the middle east the neighboring countries to carry out fundamental research that transcends political and cultural differences in a way that hasn't been seen in this part of the world since the golden eight thousand years ago. the ruling of the medieval islamic world together around the globe scientific knowledge. among their achievements they revolutionized the way we think about vision and paving the way from modern understanding of life . isn't yet fully operational but today i've been given exclusive access.

to see how. by using very fast moving electrons. this is the mystery this is the which increases in energy. right and where the electrons produced in the schools ok. so this is where it. hold begins this is the latest film which produces electrons an excellent it's been uphill specific you know just so that they can be injected into the blister effect they look for are produced from this source which is a victim gun and they're isolated by the other source which we call the megatron is the same device in the microwaves at home but with larger power and when they close up it's integrated we can't threaten them with a cluster like it do that with the singleton and it's in the booster ring that they are accelerating to round in a circle faster and faster yet to get more in of just so their speed will be almost

the speed of light and then they are injected into the storage of it where we accumulate that and it's all been there all the talk produced the same performance and that's when you can use the lights exactly for those of us to do the experiment yes so there are several stages to sesame first the electrons are produced in the microphone which accelerates them around. when they're fast enough they get injected into the bush to read with their accent or a city even faster and finally as they approach the speed of light itself there fades into the storage room as the electrons are around using powerful magnets they lose energy in the form of light this is the synchrotron light we should be used for all sorts of experiments. even without the synchrotron lights some experiments are already underway at sesame. is

a scientist who's using infrared light which is invisible to the human eye to see the effects of drugs on skin she's using a special infrared microscope which allows her to determine the chemical composition of samples of skin. i can see here on your computer screen here what the microscope yet of course can see this is the surface of our sample that we are studying it is a skin cell ben if you click and you want you want you can get the infrared the stick around for this boy when you add a drug or treat your sambit in a new way these peaks will be different so you can study what is the effect of your drug on this by studying the changes on your infrared spectrum will routes research currently uses its own infrared light source but once the synchrotron is up and running she'll be able to do her research one of the experimental stations that will be built around the storage ring and she'll use the

synchrotron light when we have the beam line which is from the synchrotron we will have a lot which is very bright so our sample can be started with a very high resolution and so our result will be bitters. the experiments that would be carried out here at sesame will all rely on a precise mathematical understanding of light and it was the scholars of the medieval islamic world as they sought to mathematicians science who first laid the foundations of our understanding of light. isaac newton studied here in cambridge in the seventeenth century and is regarded by many as the father of optics but there's another father of optics who goes back much earlier and who is often overlooked his name was no haitham born in the tenth

century he's probably my favorite scholar of the golden age because like me he's a physicist. born in basra it know haitham excelled at optics math astronomy and much more as a young man the prodigious of no haitham travel to cairo. the story goes that he was invited to egypt after he promised the ruling kailash there he could stop the nile from flooding by building a dam. however he soon realized that this task was technically impossible and so he feigned madness to escape the caleb's anger and was instead thrown into an assignment there he still to have written much of his important work key tarbell my novel the book of optics which was hugely influential the centuries. met it had died is an iraqi engineer at cambridge university together we're going

to recreate one of the mill haitham as most famous experiments the camera obscura pharmaceutical you thought very very nice what's the view like. we have installed ok i think that clock how be perfect. all we need to do is block out the windows and get the screen in place. the camera obscura is essentially a giant pinhole camera the size of a room so that we can stand inside it although the idea of the camera obscura was known about previously it no hey thumbs accounts is the earliest to mathematically explain how it works he used it as proof that light travels in a straight line ok i just know i need to make a hole so if you get the screen. i'll turn the lights out we'll see if we can all be at our.

last point credible it almost looks like a painting doesn't it doesn't always doesn't look real and you know all we've done is block out the light from the room and then allow it to come through this small hole that is the clocktower you can see such detail just from across the across to even see the. yeah they're not in focus because you could make them in focus if you made the hole smaller right but of course they're less likely to get it so we wouldn't be so bright whereas now you see all these do you know the vivid colors and it's so simple that we're going to hate them would have set up an experiment like this in a darkened room such a simple thing to create without any lenses or all modern equipment you know a thousand years ago for him to have explained how this image is created through through the hole i must make you proud as an as an iraqi who comes from just down

the road from them was born that is exactly what i was. from an area very close to one of them was born so it makes me proud. i don't hate them as explanation of the camera obscura helped us understand how vision works the i is itself a camera obscura the same principles apply to modern photography after all that's where the word camera comes from. i'm going to stumble to the museum of the history of science and technology. saying that kool-aid has been studying no papers work including his explanation for why the camera obscura makes an image that's upside down. he's well regarded as as the first scientist to correctly explain the camera obscura talk me through how

this works if you press the button there. this is the primary light source and this is the object lighted by dislike the light has to go into the box it through a dispy hope you see here and if you look at from here. you will see that the this. is it is upside down. yes because the the light from the top passes in the hole. and they cross over because light takes the shortest way and it travels in straight lines and this was something that he was able to show improve the fact that light travels in straight lines was known before him but he heard the first time proved it mathematically. it will hate them skitz album a novel is often cited alongside newton's principia

mathematica as one of the greatest textbooks of physics ever written latin translations of it influence such men as division chief galileo descartes among others such as his fame today he is commemorated on the back of an iraqi ten thousand d.n.r. banknote he's probably most famous for being the man who explained how vision works . until then the excepted view had been that of the ancient greeks men like plato in euclid who argued that the way we see objects is by shining light out of our eyes on today. it will hate him knew of this view from arabic translations of greek texts but he challenged it arguing instead correctly that the way we see is by light entering our eyes from outside either reflecting off objects or directly from numinous

bodies like candles or the sun. what was most impressive about them is that he combined theory and experiments so not only would he devise careful experiments to demonstrate particular ideas like light travelling. straight line he also put mathematical flesh to these ideas he math i'm a times whole fields of science. professor stephen sweeney is a colleague of mine at the university of sorry he works at the cutting edge of laser physics today in the medieval world there's one stall in particular that i'm passionate about it no hate them and he wrote a book of optics a thousand years ago in which he was doing all those sorts of things that you sociate with with experiments with light today so reflection and refraction of light even down to designing experiments with camera obscura is to prove that

like travels in straight lines but those aspects of understanding the properties of the key to modern science technology actually but perhaps the idea that light travels in a straight line is one of the most important ones and it's one that we really now make use of in technology and science and actually we've got a nice example of that here that i can show you today just based on research we're doing right now we're going to be using a laser and we need to wear these just to protect our eyes for the experiment. ok so what we've got now is there's a beam of light and a visible beam of light traveling a nice straight line from this laser down to this detector the other end now if i put this card in the way you can see that there's a nice spot nice red spot when i take that away the lights traveling through and it's hitting this piece of material here that's got a photovoltaic cell to heard about solar cells for flecked and sunlight this is a particular type of photovoltaic cell for collecting laser light and it's actually

then driving this little motors that's just little fancy five like that again it stops if i pull that away you can see the fan starts again ok so it's another way of transmitting energy essentially so not using electricity but using light itself is the medium and what sort of applications might this device this set up one of the key projects that we're interested in at the moment is transmitting energy from space because in the infrared we can actually get straight through the atmosphere without losing energy we used a system like this in space we could transmit solar power twenty four hours a day anywhere on the planet that we needed this has huge implications the world over in terms of producing power we wouldn't need pylons and power lines yet power could be delivered to remote areas or disaster zones and this technology also has implications for the internet we obviously use the internet for data transmission but use infrared light actually but if we also put in some so high powered

components that we can also deliver the energies we can actually deliver the power signal for the internet as well and this this light you see infrared so if i put my hand there i don't see it i can sort of i imagining i can feel what you're probably imagining it because i don't although it's infrared light it's not quite far enough into the infrared to be measured as heat the reason we use infrared light is purely because it's a better way of transmitting that light through the atmosphere and actually more than ninety nine percent of the energy can transfer through the air now in the real application that we would. this fall we've actually been even further in fred's laser and that would allow us to not have to wear these safety goggles so it's what we call the nice safe way flow. sort of wondering what it will hate them would think of doing experiments with candles and pinhole cameras. but he wouldn't even be able to imagine a world a thousand years later i think it's a long way for exactly the same principles but he was thinking about.

today we understand the physics of how light behaves but back in the hey can stay this wasn't a total obvious his book changed everything and he's regarded by many as being the father of modern optics in fact i'll go further than that and say he was the greatest physicist in the two thousand year span between archimedes and isaac newton. so many cities around the world today spectacularly by light it seems the applications of optics are reverie where you have a look at this beautiful fountain behind me it looks as though the colored beams of light are bending round following the path of the water however that's an optical illusion lights in fact a shining up from the base of the fountain and then reflecting off the water

droplets into our eyes like always travels in straight lines however there is a way that light can be made to bend. if i shine this laser pen through this glass of water if you look carefully you can see the beam of light. as it enters the glass in the water this is something that every physicist knows snell's law refraction. but it was known many centuries earlier let me show you this rather remarkable diagram it's from a text that was discovered only twenty years ago partly in tehran and partly in damascus it's by a little known scholar by the name of it been sad and it describes snell's more reflection beautifully let me explain this line represents the boundary

between air and water if a beam of light enters the water at an angle it will refract bends towards the vertical this angle is larger than this one or draw a circle around it the ancient greeks understood that this angle of incidence the angle that the beam enters through the air is larger than the angle of refraction in the water but they knew that the ratio of the two angles remains constant if you double this angle that angle doubles the way they described it was in terms of the ratio of these two parts of the circles perimeter that was wrong or even sell understood was that it was in fact the ratio of two straight lines he said that this chord divided by this chord is always a constant number this is the correct way we understand it today now europeans

argue about whether it was snell or descartes who should be given credit for the more refraction in fact it was discovered by even seven six hundred fifteen years earlier so really it should be known as it been so hands nor a fraction. and another little known scholar from the golden age fascinates me is a man called it been who in the eleventh century came up with one of the earliest estimates of the heights of the atmosphere there he worked out that after the sun sets the last remaining daylight's comes from light reflected off the upper edges of the atmosphere he figured out that this would take place when the sun was nineteen degrees below the horizon.

imagine that i'm standing on the surface of the earth at this point a. the sun has gone nineteen degrees below the horizon above me as the atmosphere and i can see the last light of the day reflected from the top of the atmosphere that. we can draw this triangle to the center of the earth that. knowing the size of the earth calculated by the astronomers of baghdad in the ninth century they've been marked was able to use geometry to work out that the atmosphere was about eighty kilometers high that's not bad for almost a thousand years ago. throughout the golden age. and many other scholars wrote detailed texts on optics but none were so comprehensive and influential as if no haitham ski tarbell menarche. at the same money

a library in istanbul professor. shows me an ancient copy of it no hate them as great work. other than the book of optics. of course this isn't in the original copy this was written in the mid fifties century. mohammad who founded the ultimate empire is written for his library. third me what's amazing is that we all around the world we talk about newton as being the father of optics and yet here we are a thousand years ago seven hundred years before newton and his away diagram this is there's a there's a convex lens and there's a focal point and there's all the brain lines and power lines in the angles of

refraction here it is a thousand years ago. optics are all around us from the glasses of contact lenses you wear to the screen you're watching me on right now to the particles of light produced in the synchrotron everything we know about top six today is built upon the work of scholars like insect had been was and the father of modern optics if no hate who first opened our eyes to the science of life. next time i'll be taking a look at modern day astronomy in that case and i'm exploring the contribution made to these fields by the scientists of the golden age that's where his genius comes in because this diagram it's also coupled simplified

a lot of that complicated math we see the role they played in the evolution of astronomy we still have had to develop an area of mathematics called spherical geometry which was exceptionally advanced four thousand years ago and we reveal how scholars from the from the world consolidated and refined the astronomy of the early civilizations and came up with ideas that have influenced the stormy white through to the present day copernicus only used this day to these medieval astronomers from the golden age. colleague must much the same is now being held in pretrial detention for two years what is his crime. why hasn't he been tried yet why hasn't justice been applied in this case is he detained because he said journalists as journalism become

a crime have moles become a tool to silence voices of truth we will continue i news coverage with professionalism and impartiality our work will remain credible and accurate but journalism is not a crime incarcerating journalists is not acceptable we demand the immediate release of our colleague mahmoud to say and all journalists detained in a gyptian jails free mahmoud's and all his colleagues we stand for press freedom. a policy imposed decades ago. that she would selectively goods and boards changing demographics across asia with far reaching consequences are creating a pool of socially disadvantaged young men so you have the system where people at every level will be get being given money money to agree to star as

a ship or money to get other people to be the star of social out there examines the politics of population control. al-jazeera. where ever you are. too often on the streets of india. are victims but a new force is at play. female police officers are combative sexual assault and domestic abuse. but changing society is a challenge and so is life behind the badge for india's lady called.

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