A bit of enlightenment.
There is more to light than just the physical sense. Light means life! Without it, no trees, no animals, no flowers… it is fundamentally the source of life and as we believe to know, the sun is the cause…. the light the matter!
Throughout the history of humanity the matter of light has occupied the brightest philosophers’ and scientists’ brains of each stage of cultural and scientific development. Light has been the source of wondering, fantasizing, questioning and most paramount the subject of worship. Light as the source of life on earth was existential for all living organism surrounding us and in a wider sense feeding our stomachs and not least our fantasies. Existential circumstances often fertilize myths when knowledge and common logic become deficient. Light and its sources like the sun, yes even the electric bulb, have been eliciting an imagery of marvellous and dramatic stories, which fostered cultic and deep religious beliefs. From the prehistoric period up until today the light and life-giving sun became a central object in cultures and religious cults around the globe. Being it the Egyptians’ sun god Ra who travelled across the sky during the day from east to west in his solar barge Atet. Returning during the night through the underworld to be ready to start a new day for the Egyptians by creating spectacular sunrises over the eastern desert and equal spectacular mythic and romantic sun sets at dawn over the dunes of Sahara.
The history of human’s perception of light shows that the line between science, myths and religion wasn’t as straight a line as the beam of the light itself.
The Greek philosopher Pythagoras (c. 500 BC) proposed that sight is caused by visual rays emanating from the eye and striking objects, whereas Empedocles (c. 490 – c. 430 BC) postulated that the light came both from the eye and the sun.
Taking reference from higher powers he believed that Aphrodite made the human eye out of the four elements fire, air, earth and water and that she lit the fire in the eyes, which then shone out from the eyes making sight possible. Eventually a lighting fire in human eyes might have had other reasons than ordinary physical circumstances, of which Aphrodite eventually… as the goddess of Love, Beauty, pleasure and procreation… might have known better than Empedocles. But if it had been a physical matter it would have had an extraordinary practical function for the humans by making us seeing during the night just as well as during the day. Empedocles recapitulation on the inner light of the eye made it clear that goddesses and earthen common sense might have its obstacles, so he went for a compromise. Aphrodite’s lighting fire in our eyes was comprised with light from the outside. A wise solution that kept the light of fire in the eyes of lovers and the scientific insight on light take its detours through history. As Empedocles commented: “We see only a part, but fancy that we have grasped the whole”.
The fact is that all we “see” is light! The things around us we only see because it passively reflects light into our eyes in consummate shapes and splendid colours. Since Empedocles, fellow scientists and philosophers were thrown back and forth between a number of hypotheses, theories, postulates, and visionary fantasies on light and questions such as: Are light particles? As Isaac Newton proclaimed in his treatise “Optics” 1704.
Are light waves transmitted at infinite speed through a pervasive elastic medium? As postulated in La Dioptrique (1637), by the French philosopher - mathematician René Descartes in which he described light as a pressure wave.
Is light electromagnetic waves? The answer came in an 1864 lecture before the Royal Society of London, “A Dynamical Theory of the Electro-Magnetic Field,” Maxwell asserted: We have strong reason to conclude that light itself—including radiant heat and other radiation, if any—is an electromagnetic disturbance in the form of waves propagated through the electro-magnetic field according to electro- magnetic laws.
Maxwell’s achievement ranks as one of the greatest advances of physics!
Or is light a so-called quantum? In 1900, the German physicist Max Planck succeeded in calculating a so called blackbody spectrum (Blackbody radiation refers to the spectrum of light emitted by any heated object; a common example is the heating element of a toaster and the filament of a light bulb.) that matched experimental results by proposing that the elementary oscillators at the surface of any object could emit and absorb electromagnetic radiation only in discrete packets, with the energy of a packet being directly proportional to the frequency of the radiation, simply expressed E = hf. The constant of proportionality, h, which Planck determined by comparing his theoretical results with the existing experimental data, is now called Planck’s constant. Planck did not offer a physical basis for his proposal; it was largely a mathematical construct needed to match the calculated blackbody spectrum to the observed spectrum.
But in 1905 Albert Einstein gave a groundbreaking physical interpretation of Planck’s mathematics when he proposed that electromagnetic radiation itself is granular, consisting of quanta, each with an energy hf. He based his conclusion on thermodynamic arguments applied to a radiation field that obeys Planck’s radiation law. The American chemist Gilbert N. Lewis later coined the term photon, which is now applied to the energy quantum of light.
The scientific study of light in history doesn’t stop with Max Plank, Einstein, Bohr or an infinite number of other scientists and thus all these essential questions ended up in one, for a layman very surprising answer; considering that we are educated to expect only concise definite explanations with the purpose of coming as close to the factual truth as possible from scientists . But never the less, modern theory of quantum mechanics explains light as both a particle and a wave, and on the other side as a phenomenon, which is neither a particle, nor a wave. The frustrating message from the scientists is that they see light as something that eventually can be explained with a metaphor for particles and sometimes a metaphor for waves in water. But their final conclusion is that light is something that cannot be fully imagined!
Once again it is demonstrating that light is a primary and constant component of our physical world that should change our view on the world and the entire universe and with the enlightening help of Nikolaus Kopernikus (1473 -1543) Johannes Kepler (1571 -1630) and Galileo Galilei (1564 – 1642) including a couple of very rudimentary telescopes they both replaced earth with the sun as the centre of the world order. Something other scientists before them knew but didn’t dare to tell. Earth was, to the annoyance of the Catholic Church, no longer the centre of the world and even Galilei wasn’t the inventor but the warm defender of the new world order of a seemingly levitating planetary system and an eternal universe as we understand it today. Galileo was by the Catholic inquisition deemed to house arrest for the rest of his life.
Since light still can’t be fully imagined it eventually fosters a new mystifying and poetic perception, we continue to consider and question, like way back in Empedocles time if the metaphor of Empedocles and Aphrodite’s collaboration about how the glow of light enters into the eyes is less trustful and intelligible than the apparent metaphors of quantum mechanics or isn’t it just making light even more fascinating and mysterious or are we simply just waiting for yet another genius breakthrough in understanding light or was it simply it?
In the middle of the scientific revolution turning all what was known as common sense down, the English poet, John Donne, expressed in the year 1611 his comprehensible human frustration over the scientist and philosophers view on the phenomenon light, when he wrote these ironical lines.
(The) new Philosophy calls all in doubt,
The Element of fire is quite put out;
The Sun is lost, and the earth, and no man's wit
Can well direct him where to look for it.
This situation might not have changed since then! There is in the myths and in science more to light than just the physical sense…light is a wonder that shapes our life whether the source is the sun or it is an electric light bulb…we need light and we need good light whatever that is at a given time in history or in the moment we switch it on to enlighten our life at dawn!
To know what good light is we even as laymen need to be curious and critical to find a bit of enlightenment and start understand light in a wider context of physical, scientific and historical sense.
Human’s innovative and creative occupations with light is of course closely related to creating lamps and so to say find a replacement for the disappeared sun to lightening homes from dusk till dawn. The development of light sources from oil lamps over candles made from beeswax 3000 years ago by Egyptians; to petroleum and gas lamps is not an abrupt ending when the invention of the electric light in 1802 was invented by Humphry Davy.
It should take nearly 7 decades and 20 inventors before a reasonable and long living incandescent light bulb was switched on in Thomas Alava Edison’s lab in 1879. Carbonized bamboo as filament allowing for a lifetime of 1200 hours was patented by Edison and as a result the electrical light bulb became commercialised in 1880. It was an electrifyingincredible development in artificial lighting sources and none the less casting its bright light on the new world that became the result of this invention.
When the newer development of Fluorescent light tubes took its beginning in the 1930ies, due to energy shortage, it sparked a new and for the quality of the light unfortunate development. The “tube” or “strip light” was saving energy and lasted longer than incandescent light, which only converted 10% of the energy into useful light; the rest would evaporate as heat. In the 1950ies and 1960iess Fluorescent light tubes probably took over the lighting from incandescent bulbs in all kind of places from industries to offices and even domestic housings from Hong Kong living rooms to San Francisco kitchens. In Hong Kong the “tubes” competed with aggressive mosquitoes in buzzing noise from the electronic ballast turning life into a cooling blue. In San Francisco kitchens the bluish light painted T-bone steaks brown before they ended up with grilled Alcatraz stripes forth and back. Our visual world was jailed in blue flickering buzzing cool light!
It was another energy shortage -- the 1973 oil crisis -- that caused lighting engineers to develop a fluorescent bulb that could be used in residential applications. They were named Compact Fluorescent Light; CFLs. Since the 1990s, the improvement of CFL’s performance and efficiency resulted in 75 percent less energy than incandescent light bulbs used and could show a 10 times longer lifetime. If the world was saved for its lack of energy is doubtful but in an economic excess and hallucinating excitement most industrial countries around the world banned incandescent light bulbs and send natural light lovers in despair over the insensible flickering light of these clumsy spiralled “power savers”.
With LEDs an entire new chapter in lighting sources was undertaken with a quantum leap in energy saving and life performance as well as quality of emitting light when a certain Mr. Nakamura presented blue light from a diode. A new chapter in domestic lighting was written. The performance of light from diodes was bringing the rainbow of colors from the incandescent light bulb back to life. Although expensive and not reaching the highest values of so-called colour-rendering index, in short CLI, LEDs became the state-of-the-art in lighting. With a minimum of 25000 hours lifetime before it loose 30% of its efficiency LEDs still prove an eminent power saving efficiency far beyond CFLs. But still the LED doesn’t provide the perfect rainbow of the sun, the candle and Edison’s incandescent light bulb from 1880.
LEDs should not become the end of story and it is not the end of perfect light because it isn’t perfect. So what is the perfect light of tomorrow?
Researchers at the Vanderbilt University accidently discovered in 2005 that so called Quantum Dots can emit white light and can be used as a lighting source. Recalling Einstein’s idea that electromagnetic radiation itself is granular, consisting of quanta, it might eventually not be an accident with quantum dots? Asking what a quantum dot is, we have to secure a scientifically correct explanation and in this case we have to trust that Wikipedia has got it right. Because this accident of discovery is hard to comprehend and boil down to a popular simple understanding and goodwill is surely needed. Because not being a scientists and obsessed with nanotechnology, the reading after all leave you with the understanding that candles, incandescent bulbs, fluorescent tubes, CFL spiralling horrors and LED in comparison to tomorrow's lighting sources will make the past innovations obsolete. Although light strange enough stays the same in the world of nanotechnology and quantum dots the way of creating light and how to make use of it has ironically taken yet another mega jump, be it for the good and exiting of it or for the bad of new technology wonders turned into horrors…lamps will no longer hang from the sealing in a Newtonian gravity but hover somewhere in space? It will make designer lamps nostalgic candles and deep history.
But what about the Quantum dots (QD)? They are very small semiconductor particles, only several nanometres in size, so small that their optical and electronic properties differ from those of larger particles. Many types of quantum dot will emit light of specific frequencies if electricity or light is applied to them, and these frequencies can be precisely tuned by changing the dots' size, shape and material, making it possible to be implemented in many applications.
Quantum dots can also be understood as artificial atoms, a term that emphasizes that a quantum dot is a single object with bound so-called, discrete electronic states, as is the case with naturally occurring atoms or molecules. QD’s optoelectronic (the application of electronic devices and systems that source, detect and control light) properties change as a function of both size and shape. Larger QDs (radius of 5–6 nm, for example) emit longer wavelengths resulting in emission colours such as orange or red. Smaller QDs (radius of 2–3 nm, for example) emit shorter wavelengths resulting in colours like blue and green, although the specific colours and sizes vary depending on the exact composition of the QD.
Potential applications include transistors, solar cells, LEDs, diode lasers and quantum computing, medical imaging and might it become light bulbs once again, to mention just a few options which sooner or later will enter our homes as lighting source. Be aware that quantum dots already are lighting your TV screen. Additionally, their small size allows for QDs to be suspended in a solution, which leads to possible uses in inkjet printing and it might even be possible to spray the source of light onto objects yes entire rooms. Light and communication everywhere in our physical surroundings and objects are tomorrows answer of getting the sunlight and Ra’s solar barge Atet sailing into the night and yet another attempt from Aphrodite to light the fires in the eyes of the beholder… with best regards from Empedocles… end of story?
If historians can be trusted the Inuits already 2000 years ago knew how to protect their eyes from granular dots of light with a speed of 299 792 458 m/s and the eight minutes it takes light to travel to a snow covered Alaska to be reflected into the eyes of an Inuit it is no wonder that you by carving two thin slides in a peace of qisuk (wood) need to protect yourself. How we with the future light sources and its application know to protect ourselves without burning our retinas but allow for a bit of mythical dark shadows in the corners of our homely nests is a big question which shouldn’t be in the hands of goodwill engineers and naïve admiration of technologic evolution.
Light has an enlightening as well as a blinding property and as our eyes passively register and see our surroundings it is the brain that hallucinating decides for too much and too little of it.