Lifestyle Column: 10 Neat Things

This week: 10 neat things about light.

1. Not all light comes from the sun. There are several kinds of light or luminescence, not all from the sun or even from other kinds of burning or heating (incandescence or thermoluminescence). There is also cold body luminescence such as bioluminescence or chemiluminescence, resulting from chemical interaction and manifested by animals, plants or bacteria. (See list below for other types of luminescence.)

2. Sunshine on a pinhead. Most natural light comes from the sun and is reflected off other bodies, including the moon at night. Since light always moves in a straight line, when it hits an object, it either bounces (reflected), is absorbed or is refracted. When it passes through a material such as water or glass, the photons are slowed and bent or redirected (refracted). Surfaces such as concrete or wood or your hair scatter the light in all directions. Mirrors, however, reflect the light in exactly the way they receive it which is why you can see your image. A leaf absorbs light, combining it with carbon dioxide and water to create sugars as food and giving off oxygen as a bi-product. And the pinhead? Light is made up of very tiny particles called photons. These are so tiny that on a sunny day, 1,000 billion photons fall on the head of a pin in a single second.

3. Didn't Edison invent the electric light bulb? While it is true that no good ideas exist in a vacuum, Englishman Sir Joseph Swan invented the first incandescent light bulb and demonstrated it publicly in December, 1878. Hiram Maxim, an American who emigrated to the United Kingdom, is said to have copied the process, producing his own version in New York, but manipulation of patent laws gave Thomas Edison the manufacturing rights. Later, Swan and Edison collaborated on improvements and, in 1883, the Edison and Swan United Electric Light Company was established.

4. Night light according to Pi. In the movie, the Life of Pi, we are treated to an exaggerated demonstration of bioluminescence when the nighttime ocean lights up with millions of glowing sea creatures. Fact is, though, that most bioluminescence occurs in the oceans among plankton, jelly fish and even on the tips of the two feeding arms of the Giant squid, which can emit a very strong light. While sunlight penetrates only 80 metres beneath the surface of the sea, the lower levels are illuminated by many of its denizens, 90 per cent of which are said to be somewhat bioluminescent.

5. Other bioluminescence.  In certain parts of Canada, it is the habit of young children to capture fireflies in a jar to light up their special corner of the night. Also called lightning bugs and glowworms (when still in the larval stage), fireflies emit short bursts of yellow, green or pale red light apparently to attract a mate. It is said that the 16th century Italian painter, Michaelangelo Caravaggio, used dried fireflies to create a photosensitive surface for his paintings in a primitive type of photography. His use of glowing light opposed to dark created an extraordinarily beautiful chiaroscuro effect.

6. I hope that I shall never see, a glowing street light that is a tree. But we might. Scientists in Taiwan are experimenting with gold nanoparticles injected into leaves of the aquatic Bacopa caroliniana to produce a plant that emits a reddish glow. The ultimate goal is to transfer this or other biotechnology to boulevard trees to reduce power consumption and pollution. When chlorophyll is exposed to violet light with a wave length of 400 nanometers, as from the gold nanoparticles, the normally green substance glows red. At Cambridge, British scientists have tried a mixture of firefly proteins and sea bacteria to create a luminous effect. They imagine a house that could be lit at night by glowing algae feeding on household bio-waste. (They don't say how you would turn out the lights, though.)

7. What light through yonder forest breaks...? The gills of the orange jack o'lantern mushroom, Omphalotus olearius, glow blue-green in the dark. Resembling chanterelles to the uninitiated, they are poisonous and will cause nausea, vomiting and diarrhea if eaten.

8. The sun is something to sneeze at! You may be one of the 25 per cent of people who sneeze when exposed to sunlight. Called a photic sneeze, it is caused by a confused signal along the trigeminal nerve, which is responsible for most sensation in the face. The nerve tricks the brain into "thinking" that the signal it is receiving is from the nose instead of the eye, triggering a sneeze to expel the light.

9. Remember the prism. Every fourth grader used to be able to tell you that sunlight sent through a prism at a certain angle would separate the colours of light as it is refracted by the glass. This is because the light changes speed as it travels from air though a medium such as glass and is refracted at different speeds. The light breaks down in the following order: red, orange, yellow, green, blue, indigo and violet. The same thing happens when sunlight travels at a certain angle through water vapour in the atmosphere to create a rainbow.

10. Faster than a speeding bullet. Light, as we were taught by Albert Einstein, has been believed to be the fastest moving thing in the universe, travelling at an approximate speed of 300,000 km per second. However, scientists are now saying, "Hold on. This may not be entirely true." They believe that neutrinos may be slightly faster (slightly being a comparative term since we are dealing with billionths of nanoseconds here). If they are right, this knowledge could open the door to time travel . . .

Note: Light sources
Crystalluminescence from the heating of crystals; electroluminescence from an electric current; mechanoluminescence from mechanical action on a solid; photoluminescence, moving electrons by absorbing photons; radioluminescence resulting from the exposure of some material to ionizing radiation (old watch dials); sonoluminescence from the flash of light that occurs when bubbles in certain liquids are imploded by exciting the liquid with sound; and finally, cathodoluminescence which happens when a beam hits a luminescent material.

Copyright© Pegasus Publications, Inc.

Dorothy Dobbie is the author of 10 Neat Things, published by Pegasus Publications and is a new contributor to KBR.