Information on the nature of light may be found under the following headings:
The intensity of the aurora borealis (or northern lights) corresponds to the sun spot activity with a retardation of two days. Those beauty spots of the sun are gigantic eruptions that send out a flow of charged particles of high energy content and high speed that reach the earth. The magnetic field of the earth directs this flow to the poles and the aurora borealis lights up as soon as the particle flow reaches the outermost layer of the earth’s atmosphere The invisible magnetic field of the earth also pulls in solar winds that brighten the long polar nights with their colourful lights.
The light proves that the universe started out quite suddenly billions of years ago. All matter that we know of is derived from this one event that brought energy and the natural laws into being. The Big Bang created the smallest components of the universe, the elementary particles, as well as the forces that join them together to form everything from galaxies to people.A hundredth second after the Big Bang, the universe had generated the incredible temperature of a hundred billion degrees above absolute zero. Compared to this, our sun’s core is just a faint glow. At that point, there was an immense number of photons that carried an enormous amount of energy. Part of this light was transformed into matter, because at this extreme temperature the colliding of photons converted them into elementary particles containing mass. The newly formed universe was a thick soup of matter and radiation. It expanded inexorably, like an exploding ball, while its density and temperature decreased.
Radiation, light and a soup of electrons – this was the basic substance of the universe when space and time were born. During the course of ten thousand million years, this atomic dust clumped together to form planets, stars and galaxies. And on one of those planets life forms developed that began to explore the history of the universe.At the beginning there was a world of light. Today, physical science can trace back into time for more than ten billion years, and the history of the universe turns out to be a history of light. Light is the language of creation.
When a candle is lighted, the flame moves down the wick, melts the wax in the middle of the candle tip, and the air rising up around the candle cools the edges and causes a raised border to remain. Thus, a bowl is created that is ideally formed to prevent the molten contents from flowing down.
The fluid wax climbs up the wick due to the same forces that make the sap in a tree or a plant ascend. But instead of nourishing leaves and flowers, the molten wax evaporates in the dark, blue-black inner region of the flame that is closest to the wick, mixes with air and nourishes the flame. If this was all, however, a candle would give only little light.The bright yellow cone that spreads its uniform glow is due to tiny pieces of burning coal, pieces that settle down in the form of soot if the wick gets too long and the wax cannot burn completely any more.
An altogether ordinary substance creates light! The substance purges itself in the act that creates the light. In the flame, coarse matter is purified to light. A candle radiates approximately 4 x 1044 light quantums per second.
Characteristics of light
Is there light in the darkness? Is the night empty and dead or does it offer more than meets the eye?
If everything material is removed and the rest is cooled down to absolute zero, there is still the vacuum that glows in a very special light. Even if all matter and all light is removed from space, an infinite amount of energy remains. So darkness may contain a much richer abundance, may be more complex and more structured than we may have thought. Even in the darkest shadow we will find hidden light once we start searching for it.
If the universe collapses, the long wavelengths, the radio and micro waves and the infrared waves, would be lost first. No words and pictures would be transmitted any more by radio and TV. Along with the infrared waves the warmth of the sun light on our skin would vanish, the fibre optic net would become useless and all reproduced music would turn silent.Next the marginal regions of our vision would blur and vanish, first in the red range, then orange and yellow. The many-hued colours of the flowers, the sea and the heaven would vanish into the dark. Only black and white would remain as long as the remaining light of the visible spectrum would be able to convey this monochromatic world.
Then, the ultraviolet wavelengths would vanish as well. The sun light could no longer cause cancer and x-rays could no longer harm us, nor could we make use of them any more. As soon as the wavelengths shorter than that disappeared as well, we would not have to fear nuclear radiation any more. But then, we would not be able to live any longer in a cosmos darkened like that!
When light meets darkness, colour unfolds. Thus, colours are the product of the strongest polarity that our universe provides. In the words of Goethe: “Colours are the actions and sufferings of light in its interplay with darkness.”
The blue of the sky and the sea come about through the incident light transferring its energy to the molecules of air and water. In fact all the colours of the world and every change in hue is caused by matter selectively reflecting and absorbing, diffracting and scattering light.
There is a direct correlation between light of a certain wavelength and the observable colour. The light of the sun or of artificial sources of light generally comprises a mixture of various wavelengths. We can see up to ten million different hues of colour.
We have to get rid of the obsolete notion that we are equipped with invariable eyes like a video camera and a static computer brain that enabled us to develop something we call consciousness. The colourful world of perception is unfolding in a far more complex interplay of inner and outer light.
Colour is a sense perception that is caused in our consciousness through light. Colours are the “precious waves, that ripple brightly the wake of light”.
Everything is relative. There is no absolute space, no absolute stillness, no identifiable place of origin of the universe. There is no faster speed than the speed of light. Space and time are inextricably intertwined and light is the bridge between them.
Close to the speed of light a continuously accelerating rocket will gain not in speed, but in mass. Thus, mass turns out to be an extremely concentrated manifestation of energy. In other words: mass is nothing but frozen light.
Each kind of wave, whether it is a wave in the sea, a wave of sound in the air or the light, has a frequency that determines its temporal character. Frequency is best understood through the following mental experiment: imagine standing on the shore of a quiet lake, throwing a stone into the water and watching the crest of a wave spreading in a circle from the point of immersion. Now you throw in stone after stone in regular intervals, e.g. one second, all landing in the same place so that a series of concentric crests and troughs is created. Someone who watches from far away and does not know what you are doing will still be able to come to the conclusion that the force that causes the waves is acting once per second, for with this rate or frequency the waves are arriving. If you throw the stones faster, the observer will count more crests per second. This is the frequency of the wave.
Two eyes looked down onto the old Egyptian world: the two eyes of Horus, the sun and the moon. There was no more significant symbol in that culture than the eye of the sun god Ra. His eye, the sun, represented life itself. For the men and women of that culture, standing in the light of day always meant that the eye of their god was looking down upon them. The power of seeing, the ability to brighten the world, was a universal power that was projected onto the largest scale: it became the brightness of day. God looking down was light. Light meant that God was looking.
Medieval society prepared for darkness each night as though preparing a ship for an upcoming storm. At sundown people retired into their houses and barred all doors and windows. In darkness the fear of preternatural forces and human malice awakened. If after dark someone was met out in the open without a light whose glow made him recognisable, this betrayed that he was up to some mischief.
When Galilei pointed his telescope to heaven, he intruded with his prosaic and scientific mind into formerly sacrosanct spaces. Looking heavenward, he saw not angels and perfection, but craters and mountains where the moon’s mirroring surface had been expected. Even the sun, the pure source of divine light, was found blemished by sun spots. Perfection was gone. From this time onwards, the universe was not illuminated by god or gods anymore.
The analytical scrutiny of Leonardo da Vinci, Dürer and Galilei had reached the spheres of heaven. The purity of heaven had turned into common stone. Where could one now expect perfection?
Earth and her many creatures had always been deemed corrupt – now the entire universe shared the fate of mankind: imperfection. From now on a deep chasm separated the material from the mathematical world, reality from the ideal – and man from his creator.
Ptolemy chose the earth as his point of reference when looking into the universe, but Copernicus transferred human consciousness from its traditional home on earth to the sun. The earth was no longer the central point around which the universe turned.
From now on earth was moving around the sun. And even the sun was recognised as an insignificant star in the Milky Way – which is only one galaxy among many others. Thus, there was no material centre of creation any more, all places were equal. Einstein went even further: now there isn’t even a place of rest any more – everywhere everything is in motion. Copernicus rendered place relative, Einstein rendered movement relative.
Together, they freed human consciousness. One by one the framework of science, religion and society was removed. Now humanity stands lost and alone in an unlimited universe. Alien and homeless, each one of us has to become his own centre, has to endure the emptiness without a fixed reference point, has to find stability in himself. In this flood of new ideas, with the loss of all reference points in space and time there remained only one “truth” that proved independent of all outer frameworks – the speed of light.
Today, lasers are the most impressive manifestation of artificial light. Their focused light contains enough energy to cut through metal and is precise enough to transmit information. Lasers in their various forms supply the most intensive and versatile light ever produced by man.
A commercially available laser pointer emits approximately 1016 photons per second – about as many as there are grains of sand on a beach. Together, they form a forceful beam, with each single photon containing only a small amount of energy.
How is it possible to concentrate light in a tiny point of such enormous potency?
How can it be that light contains so much energy that it can even cut through steel and diamonds? The reason for this is hidden in the amazing characteristics of photons: since they do not possess any mass, enormous quantities of them can be concentrated in a small space.
Light by itself
Scientists have constructed a box in which the light that is projected into it does not touch any objects or walls. A projector sends bright light into this box while its inside can be watched through an opening. Inside the box exists only pure light. The question is: what does light look like all by itself?
Nothing can be seen but the blackness of empty space. Complete darkness. This is because we can see only objects, but not the light by itself. Without any objects to reflect the light there is only darkness to be seen. Light itself is invisible.
Therefore, in the sunlit emptiness of space only the dark reaches of the universe can be seen, studded with the pinpoints of light of myriad stars. The sunlight is ubiquitously present, but only darkness can be seen since the light is not reflected by anything.
Along with the knowledge about light came the skill to use it for more purposes than just illuminating the night. Light that has been sent through lenses can bring far-away objects closer, even the barren surface of the moon. Light also provides access to the teeming life under the microscope. Concentrated or portioned, light may be used for technical purposes.
Broken down into impulses it carries information in the form of language, pictures or data. Imprisoned in tubes it travels around half the world. Due to lightwave cables a phone call to Japan seems like a local call nowadays. A tiny infrared laser in a compact disc player turns frozen music into a stream of living sounds. When light forms words, pictures and numbers on a computer screen, it facilitates fast information transfer. In medicine it opens up new possibilities of diagnosis and healing. Light enables photosynthesis and keeps up life.
Origin of light
Light has its origin in atomic processes of matter: excitation, release of energy in the form of light (photons) or warmth, return to the basic state.
In every source of light it is basically this process that creates the glow. The actual source of light, the atom, has a size of only about 1/10 nanometer, i.e. 0.0000000001 m. Even the smallest part of matter consists of an incredible number of atoms, in which this process is continually repeated, so that an enormous flood of photons is released. Photons are released through energetic transitions of electrons in atoms. Light is pure energy.
Photons, the smallest particles of light, are dot-like, without volume and mass. They are immaterial. Most elementary particles decay, but photons remain forever. Light is the truly intangible, perfect particle. Even the faintest light is composed of billions and billions of photons that are radiated each second. While sunbathing, quadrillions of photons hit each square centimetre of skin every second.
Each photon of this cascade is like a grain of sand on a beach. If the sand is studied with a microscope, the grains can be distinguished and counted. But when the sand runs through your fingers the single grains lose their granularity in this fluid stream, just as the photons lose their granularity in a flood of light.
If white light is sent through a prism, its different wavelengths are diffracted by the prism’s boundary, with the short wavelengths diffracted more than the long wavelengths. Thus, white light is dispersed according to its different wavelengths and various colours appear. This was first described by Isaac Newton in 1704. In a rainbow the small droplets of water act as prisms, diffracting the rays of the sun and revealing the spectrum of sun light. The same phenomenon causes the colourful brilliance of a cut and polished diamond or a shiny dew drop.
Everything that surrounds us can be perceived through reflection. Reflection always occurs at the interface between two media. Whenever light moves through a medium and comes upon a different one, some photons advance into the new material while others bounce off from the boundary layer like a tennis ball that hits the ground rebounds into the air. Thus, our view of an object is formed by photons that are emitted from the sun, are refracted by this object and then enter our eyes.
If we see an image on the water, the light has been reflected twice: the photons have been reflected from the object onto the surface of the water, and from this boundary between air and water into our eyes.
Objects that appear coloured reflect only light of a certain wavelength. A blue pigment, for example, absorbs all light waves outside the blue range. Only light of the blue range, between 450 and 500 nm, is reflected by the surface of the pigment. This phenomenon is called reflection. If the light is scattered in all directions, the reflection is diffuse. If the surface is extremely smooth, like a mirror, all light is reflected uniformly, with the angle of incidence equalling the angle of reflection. This is called specular reflection.
In 1910 two surgeons reported the successful operation of an eight year old boy who had been blind from birth. Afterwards, they were eager to know whether the child would now be able to see. But light and functioning eyes alone were not enough to bestow him with sight. Even though the light could now enter through the clear pupils of the boy, no corresponding image was formed in his brain. Sight began as an empty and terrifying form of seeing. Daylight beckoned but the light of consciousness did not answer in the anxiously gaping eyes of the child. The light of nature and the light of consciousness have to connect in the eye in order to bring about sight. Isolated, each of these lights remains mysterious and dark.Sight is the most complex of our senses. The combination of eye and brain is characterised by an enormous flexibility under constantly changing visual conditions and highlights our amazing ability to shape patterns out of the torrent of information communicated via light waves. A camera only reproduces the images the lens transmits, while the brain and the eye combined work like an autofocus camera with automatic colour correction that even searches for its motif all by itself.
Touch, taste, smell, hearing – each of our senses has its special characteristics, but none of them traverses space with the ease of a glance. Sound can only be perceived if the source is not too far away, touch has a range that is determined by the length of our arms, and smell and taste depend on direct contact with the molecules.
Sight makes enormous demands on our brain. It has to monitor a quarter of a billion sensors, co-ordinate the data from two eyes, move the eyes synchronously and combine all this to form a real-time image of the world. If we express this achievement in the language of computers we may gain a clearer understanding of this achievement: 40 billion bytes are needed to convey the information of a single colour slide. So while the images of a movie run past our eyes, in each second the memory store of several computers is filed away in our brain. Sight also requires a process of cognition that resides on a higher dimension than the mere vision of the eyes. Consciousness does not happen in a central place of our brain, but is composed of a series of events that occur at different places and different time points everywhere in the neuronal network. This concept clashes with the deep-rooted notion that the self, situated behind our forehead, is the captain of our being and has everything under control. There is no doubt that visual perception is a decentralised process.
By turning on a TV set or a computer we cause electromagnetic waves to radiate from each pixel glowing on the screen with a speed of approximately one billion kilometres per hour. Swiftly an impressive series of events unfolds. The eyes of the viewer turn to the glowing pixel point. Six flat muscles effortlessly move each eyeball (weighing around seven grams) in its sockets lined with adipose tissue and bring it into position. Behind blinking eye lashes, the pupils are open and the arriving electromagnetic waves enter. They are slowed down slightly when crossing the cornea and the aqueous humour to the aperture of the pupil. Possibly the person closes the eyes slightly in order to avoid the brightness, but human reflexes operate on a time scale of thousandths of seconds which is way too slow for these fast intruders. Thus, they penetrate the pupil without meeting any resistance, are focussed further by the lens and are directed through the vitreous humour onto the retina which is connected to the brain via the optic nerve. But light is more than what we can see. All light waves can be differentiated by their frequency. In our universe there exist approximately forty different octaves of light, and only one of them is visible to us.
If we could see light waves beyond the visible spectrum from 400 to 750 nm, we would perceive an infrared universe. All objects that are warmer than their surroundings would assume their own visual existence after dark. Our bodies, a stone that has been exposed to the sun, the running motor of a car or an air plane – all these objects would be visible. The sun would still be overwhelmingly bright, since it emits just as much infrared light as visible light.
But the star chart would have to be redrawn since in the infrared range each planet, each star and every galaxy would look different from what it looks now. If the range of our sight would comprise wave lengths below 400 nm, the world would be dark even after sunrise. The night sky, however, would be brightened by some incredibly intense cosmic light sources. In the presence of X-rays, we would be able to see through materials like metal, plastic and human flesh. Ultraviolet light would also reveal hidden attributes of our living world, as, e.g., the patterns on flowers that attract the attention of bees since they can perceive wave lengths in the range down to 300 nm.
Once light was believed to be infinitely fast. During the 17th century it became possible for the first time to measure the speed of light, even if only approximately. It became clear that light does indeed move very fast, but with a finite velocity. Thus, light turned into a probe that reaches far back into time. The light that comes to us from far away may be used to look into a figurative “time tunnel”. The distance of one light year – light travels almost ten trillions of kilometres in one year – represents a journey into the past. When watching a star that is one thousand light years away we perceive it in the state it was in one thousand years ago. Therefore, light also is the fastest way to convey a message.
In 1983 the history of measuring the speed of light that dated back for 380 years was ended once and for all when the speed of light in space (through a vacuum) was determined at 299 792 458 m/sec according to the most exact measurements available back then.
If you accompany a moving object and move at the same speed, the object seems to stand still. But this does not apply to light: If you move beside a light beam at the speed of light, it does not stand still. Light cannot stand still! Nothing moves faster than light, therefore light cannot be caught up with. You cannot even get any closer! Light has no place, but it has a speed, and we are always 299 792 458 m/s away from it.
What would the world look like if we moved at the speed of light?
What would we see if we had a light body? Space and time would be changed in surprising ways. The distances we travel would diminish and a hundred years would shrink to a mere instant. Would light move without time lag from one place to the other, we would perceive only the present moment everywhere in the universe.
Situated in the centre of the solar system, the sun was formed about 4.6 billion years ago through the collapse of a cloud of gas, probably triggered by the shock waves of one or more supernovae. With a radius of 1.4 million kilometres (earth: 13.000 km) it is the giant of our solar system and boasts 330.000 times the weight of our planet. Its centre is characterised by enormous pressure and heat (about 15.000.000 °C). The surface is relatively cool, with a temperature of 6000 °C. Inside the sun, 700 mio t of hydrogen nuclei fuse into helium each second. This process is the sun’s motor and produces the energy that is emitted by radiation. The thermal radiation that reaches the earth is equivalent to about 175 billion megawatt.The sun’s light reaches us from a distance that would take a jumbo jet 22 years to cross. It takes 8 minutes to reach the earth, and we are lucky: if the sun was any closer to us, our water would evaporate, if it was further away, we would freeze.
In a billion years’ time the mean temperature on earth will exceed the critical temperature of 30 °C, after another billion years it will reach 100 °C. Our galaxy, the Milky Way, comprises approximately 200 million stars. The light takes 100.000 years to travel from one end of it to the other. There are probably 100 billion galaxies in our universe.
When scientists explored the nature of matter and of atoms, they discovered more and more that matter is not as material and real as they had thought – rather it is composed of agglomerations of energy. They had to acknowledge that the electron – and thus all matter – apparently possesses the characteristics of consciousness. Faced with these discoveries Albert Einstein is recorded to have said: “It looks more and more like the whole universe is nothing but a single fantastic thought!”Thoughts are able to travel into the past or the future or to the most remote objects of the universe with a speed faster than light, without any loss of time.Everything is thought or electric light energy! Ultimately, all things are thought, residing on different levels of energy. In this view, matter is nothing but thought congealed into form. This means that spirit defines matter.
If a wave comes up to us in the sea there is a moment when we are afraid it will pull us along and crash us onto the shore. As soon as it is gone we notice that the water around us has not travelled to the shore along with the wave, but has only risen and subsided again. No water has flown by, it only moved up and down. So what has actually happened? What is this wave? It is a shape, a pulsation, a behaviour pattern of water.
Could light also be a shape, a pulsation? Nothing moves – apart from the form and shape of the light? Light would thus not be a substance, but a shape!Today it seems likely that light is a wave when crossing empty space but turns into a myriad of particles when it encounters solid matter.