Black, White and Red
I’ve been walking the beach here on Marco Island for two weeks
and I must say those walks have been the least colorful and least
interesting in all the years I’ve been coming here. I haven’t seen
a single conch shell, sand dollar, jellyfish, scallop shell of any
significant size, dolphin or even any dead fish even though
there’s reportedly a hint of red tide in the area. Also, not a single
sea urchin, subject of last week’s column.
There was some color, or lack of it, associated with one of our
stocksandnews.com crew. I must join the ranks of the many who
have congratulated our Lamb creator and award-winning
cartoonist Harry Trumbore on his 55th birthday last week. More
impressive than reaching this milestone was his winning of his
black belt in karate the night before his birthday. This required
him to fight seven individuals, most of them much younger. The
fights are no holds barred with punching, kicking, etc. Aside
from the black belt, Harry is also garnered a black eye in one of
those fights! At 55, his parents are relieved that he survived the
Our editor, Brian Trumbore, reports that Harry’s eye is a
relatively mild degree of blackness. An object is black when it
absorbs most or all of the light that hits it. Both blackness and
whiteness are the subjects of two very different recent scientific
investigations. Chunlei Guo of the University of Rochester and
his research team have been working on blackness. Specifically,
they’ve found a way to make almost any metal black – no black
paint involved. An article on their work in the November 26,
2006 Toronto Star is reprinted on the university’s Web site.
What Guo and his team did was to focus extremely short pulses
of an intense laser beam on tiny spots on the surface of various
metals. By extremely short, I mean a few quadrillionths of a
second! By tiny spot, think the size of the spot to be about the
area of the point of a needle.
It’s hard to believe but the article says that the ultrashort laser
burst unleashes as much power as the entire power grid of North
America onto the tiny spot. This is somewhat akin to what we
did as kids when we took a magnifying glass and focused the
sun’s rays on a small spot on a piece of paper or wood and made
it burn. The ultrashort bursts of laser power on such tiny spots
results in the formation of nanosize pits, globs, and strands of
metal that increase the surface area tremendously. When the
laser pulses are scanned over a sizeable area, the irregularities in
the surface make it difficult for light to get back out once it hits
the surface. Virtually no light is reflected. Almost all of it gets
absorbed and the surface is pitch black.
Why should anyone care about making black surfaces? If you’re
in the game of detecting light, say in astronomy, a black surface
will capture those photons very efficiently. A silicon solar cell
captures photons to make electricity. Guo and his team have also
made silicon black. Silicon is pretty good at capturing photons
as it is but the black silicon might improve the efficiency of solar
cells by about 30 percent. Black trim on cars could be another
possible application. The laser-pulsed surface should be more
resistant to scratches or other wear and tear than a painted
surface. Another possible application is in fuel cells, which
depend heavily on platinum or other catalysts for their operation.
Catalysts are more effective the higher the surface area, which is
enhanced by the laser pulsing.
Admittedly, the laser process used by the Rochester team is not
yet ready for prime time. To blacken an area on the surface of a
piece of metal the size of a fingernail may take over half an hour
and the researchers are studying how to speed up the process.
Don’t try this at home – these short pulses of laser light can burn
through your skin if it gets in the way!
Blackness is the absence of reflected light; whiteness is the
opposite, when light of all colors is scattered and reflected. The
January 19 issue of Science contains an article by Pete Vukusic,
Benny Hallam and Joe Noyes of Exeter University and Imerys
Minerals Ltd. in the UK titled “Brilliant Whiteness in Ultrathin
Beetle Scales”. I hadn’t realized that really striking whiteness is
relatively uncommon in animals. The article reports an
uncommonly white whiteness in the Cyphochilus spp. beetle.
The article in Science seems to expect the reader to know what a
Cyphochilus spp. beetle is. I had to turn to an article on the BBC
Web site sent down here by Brian Trumbore to find it’s a “finger
tip sized” beetle that lives in Southeast Asia. The beetle is
brighter and whiter than milk or the average human tooth,
measuring 60 on a whiteness scale in which human milk teeth
rank about 40. What surprises the scientists is that the beetle has
scales that are only 5 microns thick; a human hair is typically
around 50 microns or so. The scales are also in a haphazard
random arrangement that scatters and reflects light of all colors.
Why is the beetle so white? Speculation is that it evolved to be
so white as a camouflage ploy to avoid predators since it lives in
an environment of white fungi. In the world of color, it’s
possible to make white just as bright and white as the beetle but
it takes materials around a hundred times thicker than the beetle
scale to accomplish the whiteness. There’s the possibility that
whiter plastics or paints could result from these studies on the
Asian beetle. Maybe someone will marry the black metals with
the white plastics to create unique black-white contrasts in
products that people will want to buy.
I’m posting this column on Valentine’s Day and, appropriately,
Brian Trumbore also sent me an article by Natalie Angier in the
February 6 New York Times titled “How Do We See Red?
Count the Ways”. Angier points out that red is the premier
signaling color in the natural world and not just on Valentine’s
Day. Take the attraction of the redness of a ripe apple or the
avoidance of a red poisonous ladybug by a female bird that, on
the other hand, will be attracted by a male’s scarlet feathers. Red
is a color of passion and danger and apparently the first color we
learn to identify as babies.
The light-sensing cone cells in our retinas are the cells that
provide us with color information. We and our great ape cousins
are supplied with more red- and yellow-sensing cone cells than
cells sensitive to bluish light. Reds and yellows are the colors
most prevalent in fruit and the speculation is that we evolved to
better detect the ripeness and condition of desirable fruits by
concentrating on the reds and yellows. Natalie jokes in her
article that she has 40 (red) lipsticks she never wears compared
to only three blue eye shadows. She also cites research by
Russell Hill and colleagues at the University of Durham in the
UK. They found that in Olympic sports such as boxing and tae
kwan do, where red or blue shorts are randomly assigned to the
combatants, the red-shorted competitors won more often than
expected from chance. The reasons for this finding are not
Speaking of red, I misspoke when I described my walks as
colorless. The beach has been consistently covered with what I
had thought to be unusually large amounts of seaweed.
However, a news item on the local TV news dealt with a problem
that apparently extends over a wide area of Southwest Florida
apparently. It’s not reddish brown seaweed. It’s red algae. So,
color my walks red. Happy Valentine’s Day!
Allen F. Bortrum