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PAGE 1 Fun educational hands-‐on workshops exploring basic principles of light science through the eyes of the 11th century scientist Ibn Al-‐Haytham. http://www.IbnAlhaytham.com PAGE 2 PAGE 3 Contents The International Year of Light 2015 (IYL 2015) Ibn Al-‐Haytham Global Campaign 1001 Inventions and The World of Ibn Al-‐Haytham Who Was Ibn Al-‐Haytham Themes and Learning Objectives Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 12 Page 16 Page 20 Page 23 Ibn al-‐Haytham’s Spinning Light Disc Workshop Ibn al-‐Haytham's Optical Illusions Demonstration Page 27 Page 29 Educational Workshops and Demonstrations Ibn Al-‐Haytham’s Camera Obscura Workshop Ibn al-‐Haytham's Eye Dissection Demonstration Ibn al-‐Haytham's 3D Glasses Workshop Ibn al-‐Haytham's I-‐Scura Model Building Activity Ibn al-‐Haytham’s Kaleidoscope Activity PAGE 4 The International Year of Light 2015 (IYL 2015) The United Nations General Assembly 68th Session proclaimed 2015 as the International Year of Light and Light-‐based Technologies (IYL2015). In proclaiming an International Year focusing on the topic of light science and its applications, the United Nations has recognised the importance of raising global awareness of how light-‐based technologies promote sustainable development and provide solutions to global challenges in energy, education, agriculture and health. The International Year of Light is a cross-‐disciplinary educational and outreach project, which includes coordinated activities on national, regional and international levels. Activities will be planned so that people of all ages and all backgrounds from all countries enjoy and appreciate the central role of light in science and culture, and as a cross-‐cutting scientific discipline that can advance sustainable development. This International Year brings together hundreds of stakeholders including UNESCO, scientific societies and unions, educational and research institutions, technology platforms, non-‐profit organizations and private sector partners to promote and celebrate the significance of light and its applications during 2015. ‘1001 Inventions and the World of Ibn Al-‐Haytham’ global campaign in partnership with the King Abdul Aziz Center for World Culture is an official partner of UNESCO and the International Year of Light. http://www.Light2015.org PAGE 5 Ibn Al-‐Haytham Global Campaign ‘1001 Inventions and the World of Ibn Al-‐Haytham’ is a high-‐profile international educational campaign and transmedia initiative, celebrating the 11th century scientist Ibn Al-‐Haytham, promoting light science and its applications for humanity. Launched in January 2015, the year-‐long campaign is delivered in partnership with UNESCO and the United Nations ‘2015 International Year of Light and Light-‐ based Technologies’ (IYL) that includes celebrating the 1,000 year anniversary of Ibn Al-‐Haytham’s optics work. The campaign aims to engage 25 million people around the world, inspire a future generation of scientists, promote social cohesion and cross-‐cultural understanding. It aims to use experiential learning to revive children’s natural motivation to learn and to leverage their intrinsic curiosity and imagination. Created by UK-‐based 1001 Inventions and the King Abdulaziz Center for World Culture in association with UNESCO and the International Year of Light. The campaign is partnering with many other organisations around the world to roll out to countries in 2015 and beyond. http://www.IbnAlhaytham.com PAGE 6 1001 Inventions and the World of Ibn Al-‐Haytham Who first proved how we see? How do scientists uncover mysteries of our world? What is Experimental Science? Why is it so important today and for our future? Who pioneered it? What can we learn from him? The fascinating true story of a brave young scientist from 10th century Arabia, who embarked upon a quest to uncover ancient mysteries that would change our world forever! 1001 Inventions brings you this new, first of its kind experience exploring Ibn Al-‐Haytham’s inspirational story, and introducing the birth of Light Science and Experimental Science in a simple yet engaging & spectacular and fun way. Aiming to inspire inquisitiveness and curiosity by celebrating the life of one of the most important Scientists from the creative Golden Age of Muslim Civilisation. PAGE 7 Who was Ibn Al-‐Haytham? “If learning the truth is the scientist’s goal… then he must make himself the enemy of all that he reads.” Ibn Al-‐Haytham Al-‐Hassan Ibn Al-‐Haytham (Latinised as Alhazen), born 965 Basra, died 1040 Cairo. Ibn Al-‐Haytham was a brilliant physicist who discovered and made major contributions to the scientific method, understanding how we see, and how light travels. Described by physicists as "father of modern optics”, “a master of light”. He spent much of his life in Egypt, including a decade under house arrest, where he published his most celebrated work, Kitab al-‐Manazir (The Book of Optics). Ibn Al-‐Haytham made significant advancements in optics, mathematics and astronomy, and has laid down the foundations of the present day scientific method. Ibn Al-‐Haytham’s work on optics is credited with contributing a new emphasis on carefully designed experiment to test theories and hypotheses. Artist representation of Ibn al-‐Haytham Ibn Al-‐Haytham is credited with explaining the nature of light and vision, using what is now commonly referred to as a Camera Obscura. Ibn Al-‐Haytham wrote as many as 200 books, although only 55 have survived. Translations of his work are known to have influenced many Renaissance thinkers, such as Roger Bacon, Christian Huygens, and René Descartes. He was known in the West as “Alhazen”, and the crater Alhazen on the Moon is named in his honour, as is the asteroid 59239 Alhazen. PAGE 8 Themes and Learning Objectives 1001 Inventions and the World of Ibn Al-‐Haytham inter-‐links themes of science, art, culture, nature, education, technology and sustainability. Based on the story of Ibn Al-‐Haytham, the inspirational young scientist who 1,000 ago laid the foundations for modern optics and, using what we call a camera obscura, explained how our eyes work. Light science is a tremendous subject to motivate education and is vital for existing and future advances in medicine, energy, communication, astronomy, architecture, archaeology, art and culture. Introducing origins of light science in a simple and fun way, this engaging show presents physics, optics, light, vision, illusions, lens and the birth of scientific methodology that underpins modern science. The science of the past is linked to contemporary issues such as renewable energy and how light and light technologies offer solutions to many challenges and can positively impact people’s lives. Learning Objectives ü Promote light science and its applications to humanity through Ibn Al-‐Haytham’s discoveries ü Encourage inquisitiveness and curiosity in the world ü Spark interest to study Science, Technology, Engineering and Math (STEM) disciplines ü Engage under-‐represented groups and promote social cohesion and intercultural dialogue ü Inspire young people to pursue careers in science and strive towards building a brighter future ü Nurture youth with the principals, attitude and methodology of pioneers like Ibn Al-‐Haytham ü Provide an exciting learning experience that would further instill pride in science heritage PAGE 9 Educational Workshops and Demonstrations Ibn al-‐Haytham’s Camera Obscura Workshop (ages 10 – 15) Ibn al-‐Haytham is credited with explaining the nature of light and vision, through using a dark room he called “Albeit Almuzlim”, which has the Latin translation as the “camera obscura”; the device that forms the basis of photography. His experiments inside a dark room explained that light travels in straight lines. When light rays reflect off a bright subject, they pass through a small hole and do not scatter, but instead they cross and reform as an upside down image on a surface parallel to the hole. Materials Required: A wooden or cardboard build-‐it-‐yourself flat-‐pack camera obscura kit. Learning Objectives: • Ibn al-‐Haytham’s discovery led to the invention of the camera obscura, which led to today’s modern day cameras • Learn to build your own camera obscura • Test the theory that the smaller the hole, the clearer the picture PAGE 10 • • Understand how light rays travel in straight lines, are used in the processing of images Use light rays to create a photographic image Instructions: 1. Stick the plastic lens to the front plate using sticky tape. The front plate is the one with the smaller hole. 2. Assemble the outer box using sticky tape if needed to hold it together. Remember to slot the front plate in as you stick the outer box together. 3. Stick the screen to the viewing plate. The viewing plate has a large round hole in it. 4. Assemble the inner box using sticky tape to hold it together. Remember to slot the viewing plate in as you stick the inner plate together. 5. Carefully slot the inner box inside the outer box. Make sure the viewing screen is towards the front of the camera obscura. What Happens? Now your camera obscura is made and ready to use. Point it towards a brightly lit area and look through the viewing screen from the back. Now carefully slide the inner box backwards and forwards to get a clearer focus of the image you are looking at. PAGE 11 Ibn al-‐Haytham's Eye Dissection Demonstration – (ages 18+) We see the world because light gets into our eyes. Our eye uses that light to make an image of the world inside our eyes—just as a camera uses light to make a photograph. In this fascinating workshop we will dissect a cow’s eye to demonstrate how every layer of an eye works. A cow eye is very similar to a human eye and this demonstration offers a deep understanding about sight and how the eye works through this step-‐by-‐step process of the craft and skill of dissecting a cow eyeball. Materials Required: • Cow Eye • White Tunic • Scissors • Scalpel • Dissecting Tray • Rubber Gloves • Goggles • Cleaning Materials • Anti-‐bacterial Hand Wash Learning Objectives: • Understand the anatomy and physiology of the cow’s eye • The functions of each layer and the structure of the cow’s eye • Observe the similarities and differences between a cow’s eye and a human eye • Understand how vision works PAGE 12 1. 2. The white part is the sclera the outer covering of the eyeball. The blue is the cornea, which starts as a clear colour but becomes cloudy after death. Cut away the fat and muscle. Without moving our heads, we can look up, look down and look all around. Six muscles attached to our eyeball move our eye so that we can look in different directions. But cows and sheep have only four muscles that control their eyes. They can look up, down, left, and right, but they can’t roll their eyes like we can. 3. Use a scalpel to make an incision in the cornea. Cut until the clear liquid under the cornea is released. That clear liquid is the aqueous humor. It’s made of mostly of water and keeps the shape of the cornea. If we could reach up and feel around our eyes, we would feel the bone of our skull. There’s fat surrounding our eyeballs to keep it from bumping up against the bone and getting bruised. 4. Use the scalpel to make an incision through the sclera in the middle of the eye. 5. 6. Use your scissors to cut around the middle of the eye, cutting the eye in half. You’ll end up with two halves. On the front half will be the cornea. In this eye dissection, we cut away all the fat and muscle so that we can see the eyeball. A clear tough surface called the cornea covers the front of our eye and protects our eye. If we make a cut in the cornea, a clear fluid oozes out. That’s the aqueous humour, which is made of protein and water. The aqueous humour helps give the eye its shape. The next step is to pull out the iris. The iris is between the cornea and the lens. It may be stuck to the cornea PAGE 13 7. 8. 9. 10. or it may have stayed with the back of the eye. Find the iris and pull it out. It should come out in one piece. You can see that there’s a hole in the center of the iris. That’s the pupil, the hole that lets light into the eye. The iris contracts or expands to change the size of the pupil. In dim light, the pupil opens wide to let light in. In bright light, the pupil shuts down to block light out. Now you want to remove the lens. It’s a clear lump about the size and shape of a squashed marble. If you look at your eye in a mirror, you will see a colored circle with a black spot in the middle. The colored circle is the iris. The black spot in the middle of the iris is the pupil, a hole through the iris that lets light into the eye. In dim light, the pupil opens wide, letting lots of light in. Here is the back half of the eye. With the cornea and the iris out of the way, you can see the lens. It looks grey in this photo, but it’s really clear. The clear goo around the lens is the vitreous humour. The eyeball stays round because it’s filled with this clear gooey substance. Put the lens down on a newspaper and look through it at the words on the page. What do you see? Everything on the other side looks upside down and backward. You can use the lens to make an image, a picture of the world. That’s what the lens does in your eye. It makes a picture of the world on your retina. Now take a look at the rest of the eye. If the vitreous humor is still in the eyeball, empty it out. On the inside of the back half of the eyeball, you can see some blood vessels that are part of a thin fleshy film. That film is the retina. The retina is made of cells that can detect light. The eye’s lens uses the light that comes into the eye to make an image, a picture made of light. That image lands on the retina. The cells of the retina react to the light that falls on them and send messages to the brain. PAGE 14 11. 12. 12. Use your finger to push the retina around. The retina is attached to the back of the eye at just one spot. That’s the place where nerves from all the cells in the retina come together. All these nerves go out the back of the eye, forming the optic nerve, the bundle of nerves that carries messages from the eye to the brain. The brain uses information from the retina to make a mental picture of the world. The spot where the retina is attached to the back of the eye is called the blind spot. Because there are no light-‐sensitive cells at that spot, you can’t see anything that lands in that place on the retina. Under the retina, the back of the eye is covered with shiny, blue-‐green stuff. This is the tapetum. It reflects light from the back of the eye. Have you ever seen a cat’s eyes shining in the headlights of a car? Cats, like cows, have a tapetum. A cat’s eye seems to glow because the cat’s tapetum is reflecting light. If you shine a light at a cow at night, the cow’s eyes will shine with a blue-‐green light because the light reflects from the tapetum. Look at the other side of the back of the eye. Find the optic nerve to see the separate fibres that make up the optic nerve. Pinch the nerve with a pair of scissors or your fingers. If you squeeze the optic nerve, you may get some white goo. That is myelin, the fatty layer that surrounds each fibre of the nerve. What Happens? The cow eye is fully dissected and every layer and component has been identified and explained. You now understand how your eye makes an image of the world. Knowing a little bit about lenses also helps, as the clear glass (or plastic) in a magnifying glass is a lens, like the lens that’s inside your eye. You can watch the video and follow the instructions here -‐ http://www.exploratorium.edu/learning_studio/cow_eye/step01.html PAGE 15 Ibn al-‐Haytham 3D Glasses Workshop – (ages 7 – 12) In order to see things in 3D each eye must see a slightly different picture. This is done in the real world by your eyes being spaced apart so each eye has its own slightly different view. The brain then puts the two pictures together to form one 3D image that has depth to it. The mode of 3D we are most familiar with are the paper glasses with red and blue lenses. The technology behind 3D, also known as stereoscopic movies is actually very simple. They simply recreate the way humans see normally. Since our eyes are about two inches apart, they see the same picture from slightly different angles. Our brain then correlates these two images in order to gauge distance. This is called binocular vision and binoculars mimic this process by presenting each eye with a slightly different image. A stereoscopic motion or still image in which the right component of a composite image usually red in colour, is superposed on the left component in a contrasting colour like blue, it will produce a three-‐dimensional effect when viewed through spectacles with the same colour filters. Materials Required: • • • • • The 3D glasses templates below printed out on thick card to the size required 2 small sheets of cellophane, red and blue Glue Scissors Clear Sticky Tape PAGE 16 Learning Objectives: • To understand how polarizer lenses in 3-‐D movie glasses work • Teach the basics of 3D design principles • Demonstrate the 3D components, Height Width and Depth Instructions: 1. Print out and glue, or tape this template on to a heavier piece of card. Then cut out the three templates below. Remember to cut out the eye-‐holes. PAGE 17 2. Once you have the three pieces cut out, glue, or tape pieces of red and blue cellophane on to the inside of the glasses. Be careful not to get the glue on the viewing area of the cellophane. PAGE 18 3. 4. Finally, glue on the side panels to complete your own cool 3-‐D glasses. Fold the end panels to complete your glasses and try them out on. What Happens? Once your glasses are fully constructed, wear them and try them out. Visit any website that has anaglyphic 3D images online and view in awe the 3D pictures using your own home-‐made glasses. You can also purchase a range of magazines dedicated to this topic from any good newsagent. PAGE 19 Ibn al-‐Haytham I-‐Scura Model Building Activity -‐ (ages 12 – 16) Materials Required: • White Plastic Flip-‐Top Waste Bin Lid • Black Plastic Waste Bin • White Shower Curtain • 3 Dioptre Lens • Gaffer Tape • Scissors PAGE 20 Learning Objectives: • Ibn al-‐Haytham’s discovery led to the invention of the camera obscura, which led to today’s modern day cameras • Learn to build your own I-‐Scura which is a giant version of a camera obscura which you can put on your head • Test the theory that the smaller the hole, the clearer the picture • Understand how light rays travel in straight lines, are used in the processing of images • Use light rays to create a photographic image Instructions: 1. Black out the inside of a laundry basket and a flip top litterbin with gaffer tape 2. Find a lens that has a focal length of the height of the bin lid. One option is to use a lens from a 4+ dioptre pair of reading glasses 3. Buy a cheap, thin white dust sheet 4. Gaffer tape the whole lot together 5. Put on somebody's head PAGE 21 What Happens? Your home-‐made I-‐scura is now ready to us. Place it on your head and create stunning inverted images inside the I-‐scura by looking at brightly lit places and objects indoors and outdoors. PAGE 22 Ibn al-‐Haytham Kaleidoscope Activity – (ages 8 – 12) The word kaleidoscope comes from Greek words meaning "beautiful form to see." At the most basic level, a kaleidoscope is made of two or more mirrors or reflective surfaces positioned at an angle to each other, usually forming a V-‐shape or a triangle. A tube or case, often looking like a spyglass, is the body surrounding the mirror assembly. A collection of objects is positioned at one end of the mirrors, and there's an eyehole at the other end. What you see when you look through that eyehole will never be exactly the same twice! While the container holding the objects is usually as large as, or larger than the kaleidoscope tube, only the portion of the objects that fall within the space of the triangle within the object holder is reflected. Materials Required: • A cardboard kitchen roll tube • Mirror Board • Small colourful transparent objects (e.g. beads, sweet wrappers, etc) • Three transparent plastic discs • Scissors • Glue stick and sticky tape Learning Objectives: • • • • Understand the principles of light and how a kaleidoscope works Learn how geometry, symmetry and angles combine to form beautiful patterns Find out if adding more mirrors to a kaleidoscope increases the number of reflections you see How does the kaleidoscope image change when you change the number of coloured beads (or other objects) PAGE 23 Instructions: 1. Begin by cutting your mirror card into three strips. The strips need to be 4.3 cm wide and 21cm long. Once cut, sellotape the three sides together to form a triangular prism. Make sure the shiniest sides face inwards. Push into kitchen roll tube so that the prism is flush at one end. 2. Cut two discs of plastic (I cut them from some old food containers). The circles need to have a diameter of 5.3 cm. One disc needs to be totally transparent whilst the other needs to be frosted. If you haven’t got frosted plastic to hand then simply glue a piece of greaseproof paper onto a transparent disc. Put the transparent disc inside the tube so that it rests at the end of the prism. Tape into place. 3. Pour your beads into the end of the tube. Don’t over fill as the beads need to be able to move around. 4. Place the frosted plastic disc onto the end and secure in place with tape. PAGE 24 5. Turn the kaleidescope over. At this end you need to tape a disc of cardboard (5.3 cm diameter) with a peephole cut into the centre. Glue a disc of black paper to the cardboard disc just to make it look a bit smarter. PAGE 25 6. Decorate the outer tube in any way you fancy to personalise the design. What Happens? Your home-‐made kaleidoscope is now ready to use. Look through it and you will see the sunlight bounces off the coloured beads and plastic and is reflected in the mirror boards to create beautiful patterns, which you can see when you look inside. Experiment further using more mirrors and different types of objects to create amazing patterns. PAGE 26 Ibn al-‐Haytham Spinning Light Disc Workshop -‐ (ages 5 – 8) Ordinary light consists of the seven rainbow colours, red, orange, yellow, green, blue, indigo, violet. In this activity children learn that not only can white light be broken up into the rainbow colours, but also that the rainbow colours can be brought together to produce white light. They also learn about persistence of vision (when things move fast enough the eye cannot distinguish between them and they merge). Materials Required: • • • • • Thick White Card Paint or Felt Pens– red, orange, yellow, green, blue, indigo and violet Scissors Pencil Circular lid to draw around Learning Objectives: • • • • Understand the principles of colour mixing and light Investigate the splitting and mixing of light Learn that not only can white light be broken up into the rainbow colours, but also that the rainbow colours can be brought together to produce white light Learn about persistence of vision (i.e. that if things move fast enough the eye cannot distinguish between them and they merge) PAGE 27 Instructions: 1. 2. 3. 4. 5. 6. 7. 8. Draw a circle using the lid onto the white card Cut out the circle Draw seven equal segments from the centre of the circle to the edge of the circle Colour in each segment in each of the seven colours Make two holes in the centre of the circle about 1cm apart Use 1m long string and push it through the two holes and tie a knot Put a finger through the end of each loop and flip the disc over the string several times until the string is well twisted Pull your hands apart and let the string go slack, the disc should now spin What Happens? When the disc spins around at very high speed your eyes see the different shades but they get mixed up in your brain. So your brain sees a mixture of all seven colours, which is white. PAGE 28 Ibn al-‐Haytham Optical Illusions Demonstration – (ages 10 – 18) DOWNLOAD RESOURCES AND MOVIE HERE: http://www.ibnalhaytham.com/discover/education-‐resources/ For most optical illusions, it is the brain that is being tricked and not the eye. The eye only sees visual information, the brain interprets what this information is. For this demonstration you will need a laptop attached to a large monitor and a range of digital optical illusions similar to the ones shown below. There are many good sites out there like -‐ http://www.michaelbach.de/ot/ Optical illusions give us an insight into how the brain processes visual information. There are many optical illusions that scientists still can’t explain. We see the illusion in front of us as the light rays enter our eyes. But it's not really our eyes that are being tricked by what we are seeing. Nearly a thousand years ago, Ibn al-‐Haytham realised that our brains have to be involved in vision too. It's the brain that is processing the images and making sense of what we are seeing. So when these optical illusions trick us, it's actually our brain, not our eyes, that are being fooled. Now, we often say that 'seeing is believing'. But the optical illusions we have here will make you question your own senses. Materials Required: • • Laptop, Monitor A collection of digital optical illusion images (these can be sourced on many optical websites like -‐ http://www.archimedes-‐ lab.org/Gallery/new_optical_illusions.html and http://www.optics4kids.org/home/content/illusions/ ) Learning Objectives: • • • • Discovering more about optical perception, and about perception as a concept Exploring the relationship between attention and perception Understand the concept of visual deception due to the arrangement of images, effect of colours, impact of light source and other variable Learn how the brain and the perceptual system function PAGE 29 Description of Illusions Rotating Dots • In this optical illusion, a series of dots rotate about a central ball. • Both sets of dots are rotating anti-‐clockwise. • Ask the visitors to focus their attention on one set of dots. • Now, ask them to now switch their attention to the other set of dots. • What direction does each set of dots rotate? • Focusing on one set of rotating dots will make the other set of dots appear to rotate in the opposite direction. Breathing Square • Watch the image on the screen, ask the visitors to describe what they see. • The blue object seems to expand and contract. • As more of the blue object is revealed, it becomes apparent that it is a rotating square. • The blue square will appear to expand and contract again as it is covered up. Motion Silence • Show the visitors that the dots on the screen are all changing colour. • Now ask them to concentrate on the white dot in the middle of the screen. PAGE 30 • What do they notice when the dots begin to move? • As the dots more, they seem to stop changing colour so rapidly. • If the visitors switch their focus from the white dot in the centre and follow the colour dots as they rotate, they will see that the dots are still changing colour as they move. Stepping Feet • In this illusion, visitors watch a blue and white square travel across a screen of black and white lines. • What do the visitors notice about the movement of these objects? • The blue and white squares appear to step one after the other. • When the lines are removed, it can be seen that both the white and blue squares are actually travelling together side by side. • When the lines are replaced, the stepping motion becomes apparent again. Motion After Effect • Ask the visitors to watch the spiral for a couple of minutes. • Get them to concentrate on the centre of the spiral without looking around. • Then instruct them to look away from the screen at any object. • The object they look at will appear to expand outwards for a few seconds. • Repeat the illusion, suggesting that they look at a friends’ face when they look away from the spiral. • The effect they are experiencing is called a motion after effect. PAGE 31 Moving Circles • Ask the visitors to slowly scan the image on the screen. • As they look around the screen, some of the circles will appear to rotate. • Reassure the visitors that there is no animation on this page, just a static image. • Ask the visitors to stare at the image in one place, the movement will stop. Circle and Square • Ask the visitors to tell you which circle is the largest. • Most will suggest that the circle in the square is the largest. • Both circles are actually the same size. • The circle in the square appears to be larger because we compare it to the size of the square it is in. Ebbinghaus Illusion • Ask the visitors to tell you which circle is the largest. • Most will suggest that the circle surrounded by smaller circles is the largest. • Both circles are actually the same size. • Regardless of relative size, if the surrounding circles are closer to the central circle, the central circle appears larger and if the surrounding circles are far away, the central circle appears smaller. • This illusion is similar to the Circle and Square Illusion. • The illusion was discovered by the German psychologist Hermann Ebbinghaus (1850–1909). PAGE 32 Kanizsa Triangle • Ask the visitors to describe what they can see. • The central triangle (without border lines) appears to be brighter than the background. • However, both the background and triangle are the same colour and brightness. • In reality, the triangle doesn’t even exist, but our brain forms edges of the shape based on the cut-‐out circles and the bordered triangle. • Point out to the visitors that this triangle looks closer to the viewer than the other objects on the screen. Jagged Edge • Ask the visitors to watch the image on the screen. • What do they notice? • The rotating red image appears to jolt forwards and the stationary blue image appears to jolt backwards. • Only the rotating red image is moving. Herman Grid • Ask the visitors to look around the black and white grid. • What do they notice at the junction of the white lines? • They may see a small grey circle. • The grey circle is not there. • Ask them to stare at a particular junction of white lines. PAGE 33 • What happens to the grey image? It should fade away. • This illusion was published by Ludimar Hermann in 1870. Penrose Triangle • Ask visitors to study the image of the triangle. • Could this shape really exist? Why not? • This type of illusion is often referred to as an ‘impossible object’. • This illusion was popularised by mathematician Roger Penrose in the 1950s. Impossible Cube • Ask the visitors to study the image of the cube. • Could this shape really exist? Why not? • This type of illusion is often referred to as an ‘impossible object’. Face and Vase • Ask the visitors to describe what they see? • Can they see two faces looking at each other? Or, can they see a white vase shape? PAGE 34 Hidden Bird • Ask the visitors to watch the bird as it flies over the image, can they see it? • When the bird stops, how easy it is to work out where it is? Are there any other birds on the screen? • It’s easy to see the camouflaged birds when they are moving, compared to when they are stationary. • Is it easier to find the birds when you repeat the experiment, why is this? Perceived Brightness • Ask the visitors to study the image on the screen. • Which part of the image is the brightest? • The visitors will perceive that the centre looks brightest, but the level of illumination is the same across the whole screen. • Not only does our brain think the centre of the screen is the brightest, but our eyes also react to this perceived brightness also, with the iris become smaller to protect us from the “bright light”. Contrasting Colours • Watch the two sets of lines move from one side of the screen to the other. • Ask the visitors to describe their colour. • One set appears to be slightly orange, the other set slightly darker. • As the two sets of images pass each other, it will become obvious that both sets of lines are just red. • As the images move away from each other, they will return to their perceived colours. PAGE 35 Disappearing Spots • Ask the visitors to look around the screen and describe what they can see. • Now get them to stare at the black dot in the middle. • What happens to the colours around the screen? • The colours should slowly fade away and disappear. • If the visitors blink or look away from the screen and back again, the colours will return. Revolving Circles • Ask the visitors to stare at the black dot in the centre of the screen. • Now get the visitors to move the heads backwards and forward (towards and away from the screen). • What happens to the two circles? • As you move your head towards the screen, the inner circle spins anticlockwise, the other circle spins clockwise. • The circles spin in the opposite direction as you move your head away from the screen. Lilac Chaser • Ask the visitors to watch the objects on the screen, what do they see? • Now get them to concentrate on the black dot in the centre of the screen. • With a steady gaze, they may see a blue/green dot rotating around the central black dot. • With a really steady gaze, the purple dots will disappear completely, leaving only the rotating blue/green dot. • However, there are only purple dots on the screen, the blue/green dot is not part of the animation, but is an after image. PAGE 36 What Happens? A presentation of optical illusions like these will work in any environment with audiences of all ages but should be viewed in full resolution and on a big screen to have the desired effect. Try out some of these illusions and many others with an audience to discover just how tricky it can be for your brain to accurately interpret the images from your eyes. Below are samples of amazing street art optical illusions, which take this concept of visual perception to the next level. PAGE 37 Useful Resources Official Ibn Al-‐Haytham Website -‐ http://www.ibnalhaytham.com/ Resources: http://www.ibnalhaytham.com/discover/education-‐resources/ 1001 Inventions and the World of Ibn Al-‐Haytham launch at UNESCO -‐ http://www.1001inventions.com/unesco Ibn Al-‐Haytham launch at the China Science Festival -‐ http://www.1001inventions.com/china_science_festival 1001 Inventions Official Website -‐ http://www.1001inventions.com/ 1001 Inventions Social Media: https://www.facebook.com/1001inventions https://www.youtube.com/user/1001Inventions https://instagram.com/1001inventions/ https://twitter.com/1001inventions 1001 Inventions Educational Books, Games and Products http://inv.ecgroup.net/c-‐9-‐all-‐products.aspx PAGE 38 D I S C O V E R I N G T H E P A S T I N S P I R I N G A B E T T E R F U T U R E PAGE 39
