Phascinating Phacts about Photons (well, light)
My gambol into alliteration ends with that dreadful series of fricatives, which I found too tempting to resist.
When a scientist talks about photons, he means light. Photons are the massless particles that move between something you see and your eyes, so that your eyes can send messages to your brain, allowing you to have the sense of sight. Photons are the part of the whole process of sight that is outside your body. It's a sophisticated process and the photons part no less so than the things that happen inside your head.
Photons have no mass, yet they are particles. That, alone, is counterintuitive. The mystery doesn't end there. Photons have been around since shortly after the Big Bang. We don't know about their goings on until about 500,000 years after the Big Bang because before that they weren't visible. Did they exist and were held in by unimaginably huge gravity, greater than any black hole? Unknown. We do know that photons only floated freely after that initial period.
That's why astronomers and cosmologists say they can't see back to the dawn of existence as we know it, as photons--if they existed--couldn't escape during that first half million years. Without photons coming to meet our eyes, we can't see.
Photons, being light, travel at the speed of light (186,282.4 miles per hour, 298.051.84 kilometres per hour). No surprise there. But did they, if they existed right after the Big Bang, travel at faster than the speed of light, as other known particles did during that mysterious early period of our universe? Unknown. Travelling faster than the speed of light flies in the face of Einstein's proof that nothing can travel faster than light. Or is it just particles without mass that can do that? Unknown, likely, still strange. Lots of speculation, no evidence to date.
Photons travelling through space don't actually travel at the speed of light. They travel a bit slower, possibly because they must travel through dark energy or dark matter. Oh, don't go there, it's too messy to think about. Photons only travel at the speed of light in a vacuum.
Photons also originate deep in the core of our sun. The early universe photons still hang around, causing "snow" on the screen of a badly tuned television screen and static on a radio that is not tuned to a station. Collectively they form what science calls the cosmic microwave background.
Unlike the exotic neutrinos that stop or slow for almost nothing (thousands can pass through your body every second while doing no damage), photons actually slow down when travelling through something less dense than space. In diamonds they tend to bounce around back and forth among the carbon atoms before finding their way out. This lends diamonds their sparkle. Photons travel through diamonds at a pondering 77,500 miles per second (124,000 kilometres per second).
Eyeglasses and contacts enable people to have their vision corrected because light bends when it moves from air to glass or plastic. Thus the lenses focus light the eyeballs cannot.
The ancient Greek philosopher Plato thought that our eyes shoot out rays of light so we can see. I suspect that story may have been twisted over the years because someone of Plato's brilliance would realize that we couldn't see unless those rays bounced back to our eyes. Good story, but likely a perverted folk tale.
However, our bodies do glow beyond what pregnant women are said to give off when a new baby is expected. Especially from our lips and cheeks, we glow from bioluminescence, like all living things. We glow most in the afternoon. The glow may have something to do with chemical reactions in molecular fragments called free radicals.
In the deep ocean, below 1500 feet, at least 90 percent of the animals have the option of glowing through bioluminescence. Some do it to attract mates, others to find prey or other food.
Second World War aviators were known to find darkened ships by the bioluminescence of their wakes. Apollo 13 astronaut Jim Lovell, as a pilot back in 1954, found his way back to his own aircraft carrier using this method.
Europe will ban incandescent light bulbs by 2012 because they are inefficient. They convert only 10 percent of the power they use into light. The rest becomes heat, which apparently European legislators find unwanted. Their replacements, compact fluorescent bulbs (CFB), are much more efficient in terms of creating light. But they remain controversial in situations where they are closer than 18 inches (45 cm) to a person's head--such as on a bedside table--because they give off a small amount of radiation.
When LED bulbs become more commercially viable they will likely take over dominance in the market because they give off no radiation and are even more efficient than CFBs. And they last a very long time.
A 100-watt incandescent bulb in an Easy-Bake oven can raise the temperature inside to 325 degrees Fahrenheit, enough to bake a cake. Maybe European legislators don't eat Easy-Bake cakes either.
Though light lacks mass, as a form of particle it can push when it strikes something. Late in 2010 the Planetary Society will launch Lightsail-1, a space vehicle designed to use photon power to push it along. Theory says that while photons push and nothing else pushes back (we don't know yet about dark energy and dark matter), a ship could reach interplanetary speed in two years. Stopping without power when such a ship reaches another planet or even back at earth could be a problem.
Our moon is moving farther away from earth at the rate of 1.5 inches (3.3 cm) per year. We know that because scientists continue to bounce light off mirrors left on the moon back in the Apollo days.
In the electromagnetic spectrum that stretches from radio to gamma waves, visible light makes up less than one ten-billionth of the spectrum. Goldfish can see infrared, which we can't. Bees, birds and lizards can see ultraviolet, which is just beyond the other end of the spectrum we can see.
The word "photography" was coined by astronomer John Herschel, who discovered infrared. "Photography" means "writing with light."
At the equinoxes, vernal and autumnal (they occur simultaneously, depending on whether you live north of south of the equator) everyone on the planet has equal numbers of minutes of daylight and darkness in a 24 hour period.
The aurora borealis (the northern version) and aurora australis (southern) light up the night sky when solar wind particles excite atoms in the upper atmosphere. Oxygen shines as green while nitrogen glows blue and red. Now you can watch with awe and amazement and actually know what you are seeing in the night sky.
To the Inuit (living in northern Canada and Greenland--their enemies the Algonquians called them Eskimos, "eaters of raw flesh" but that name is no longer used) believe that the aurora borealis is the spirits of their dead ancestors hovering to keep them safe. At least that's the myth. In the developed world, myths are thought to be fantasies believed by simple people. In fact, true myths are life lessons told in story form, surrounded by fictitious stories to make them more memorable to young people who hear them.
People in the developed world pay little attention to myths and don't find time to teach life lessons to their children. Look around you to see the results. Myths have a valid purpose, but it's not to perpetuate fantastic stories. Now you too can see the light.
Bill Allin is the author of Turning It Around: Causes and Cures for Today's Epidemic Social Problems, an easy to read book parents and teachers can use to teach life lessons to their children.
Learn more about the book and the worldwide TIA project at http://billallin.com