The key to making it all work is the concept of layers. The top layer is the application that you’re using at the moment—a word processing application like Microsoft Word, say. The word processing application talks to your operating system, like Vista, a lower layer that handles requests to do things like save a file. In turn, the operating system talks to the hardware, such as your central processing unit, which has the responsibility for actually storing the file. And each one of those layers is composed of many sublayers. “It’s layer upon layer upon layer.…To me, the most marvelous thing about it is that all this stuff is transparent,” says Warren Harrison, a professor of computer science at Portland State University in Oregon. What Harrison means by “transparent” is that each layer makes the messy details of what it’s doing invisible to higher levels. This approach means that your word processor can just say “save this file” without worrying about the low-level details of how to organize the bits on your computer’s hard disk. Transparency also “gives us division of labor. So I can specialize in writing network software, and I don’t have to worry about knowing how to write a good user interface. Or, conversely, I can specialize in writing user interfaces and I don’t have to worry about network software,” Harrison says.
This principle of transparency extends to the Internet. Whenever I check the online weather report or my Facebook profile, the request passes from computer to computer until it reaches its destination. Yet as I sit at my computer, all these computers hide their presence as best they can, so it looks as if I have a direct computer-to-computer connection with the Web site of my choice.
1 p.m. Lunchtime. I go out to grab something at a gyro stand down the street. I’m surrounded by buildings that are rather on the short side for Manhattan, rising only 10 or 11 stories. North of 33rd Street and at Manhattan’s southern tip, buildings that are over 40 stories high are common, giving the city’s skyline a saddlebacked appearance, as building heights drop sharply between the two clusters of towers. Another quirk of geology is to blame. The city’s bedrock, formed through a cataclysmic series of tectonic collisions 550 million years ago, rises close to, or even pushes through, the surface in some parts of the city, creating the perfect foundation for very tall buildings. In other parts—such as near 14th Street, where I am standing, waiting for my lunch—the bedrock is covered by up to several hundred feet of dirt and gravel. This looser material can’t support as much weight as the bedrock, resulting in more squat buildings.
The Microbial Manifest
Lunch in hand, I return to the office. The rest of the day is spent in meetings and working at my computer. Six o’clock rolls around and I descend again into the subway. The train is usually pretty crowded, so I often have to stand and hold on to a metal railing for the trip. It’s when the railing is still warm and slightly greasy from an earlier passenger’s hand that my thoughts turn to the subway’s microbial population. Vincent LaBombardi, director of microbiology at Mount Sinai Hospital in New York City, is reassuring, though: “Most organisms that you find are not pathogenic; they’re typical environmental bugs that you would not be terribly surprised to find, like corynebacterium species and bacillus species.” LaBombardi does note that also to be found is “the cold virus and other types of the adenovirus and whatnot—but that is no different from anyplace else.”
Just to make sure, I swabbed a subway car handrail and had it checked for two bugs that are often in the news lately, E. coli and staph bacteria, as well as for a general measure of bacterial activity, known as the standard plate count, or SPC. The E. coli and staph test came back negative, and the rail’s SPC count of 480 compared favorably with the SPC of 200,000 that was obtained from a swab taken at a water fountain in a park near DISCOVER’s offices.
On the less reassuring side, LaBombardi says that in New York City tropical diseases are common: “We have a lot of people who travel, and they bring back souvenirs. So we see malaria; we see many parasitic infections.” But his big worry is drug-resistant bacteria. New York has “more strains that are resistant to antibiotics” than do other parts of the United States. For “some of these bugs [such as enterococcus] we have no drugs left,” he says. “They’re totally resistant to everything now.” Hand-sanitizing gels do not get rid of spores such as those belonging to Clostridium difficile, “a big pathogen” that can cause diarrhea and inflammation of the colon. But old-fashioned hygiene makes a good defense—LaBombardi recommends simply washing hands regularly with soap and water.
Once home, therefore, I make sure to wash my hands before fixing dinner. My wife, Annie, and I settle down to watch a DVD. DVDs—like CDs before them and the Blu-ray discs that will eventually replace them—are a form of optical media. Beneath the plastic surface of the DVD, tiny pits and level spots called lands are arranged in a spiral with a 0.74-micron pitch about the size of an average bacterium. These tiny pits and lands encode digital zeros and ones. The DVD player spins the disc, and as it rotates, the spiral is scanned by a laser beam, which acts much like the needle in an old record player. The laser light used in DVD players operates at a wavelength of 650 nanometers (nm), which means it has a visible red color. Blu-ray discs squeeze more information onto the same size disc as a DVD—up to 50 gigabytes on a typical disc, compared with about 8 gigabytes for many movie DVDs—by using a data spiral with a pitch of just 0.32 micron and a 405-nm laser beam. Although 405 nm corresponds to a violet color, it is referred to as blue—hence the name of the format.
The Arthropod Army
Soon enough it’s midnight and time for my eight hours of shut-eye. I climb into bed, not thinking of the extensive colony of tiny arthropods lurking in my pillow and mattress. These arthropods are dust mites, and unless you’ve taken exceptional measures, they’re in your pillow and mattress too. Dust mites “need places to hide, and they like places with higher humidity,” says Jason Rasgon, an assistant professor of microbiology at the Johns Hopkins Bloomberg School of Public Health. “They’ll definitely be in mattresses and pillows; they’ll be in the carpets. They can be pretty much everywhere.” Dust mites feed on organic detritus: “Household dust is made up of dirt and shed skin cells, and they like that kind of stuff,” Rasgon says. Male dust mites live for about a month. The females live about twice that and lay about 30 eggs in their lifetime. Both sexes are less than 420 microns long and look like specks of dirt to the naked eye. There can be as many as 19,000 dust mites in three-hundredths of an ounce of dust (but a few hundred is more likely).
Dust mites are a subject of increasing health concern because they can be highly allergenic. According to Rasgon, people can react not only to the mites themselves but also to their exoskeletons, which are shed as the mites molt during their life cycles. And then there’s frass, which, Rasgon helpfully explains, is “mite poop.” Dust mite allergens can trigger serious asthma attacks and other allergic reactions. Some severe sufferers have to cover their mattresses and pillows with impermeable material.
For me, though, it’s head down and off into the realm of sleep. Exactly what happens inside our skulls when we are dreaming is still an area of active debate, but my nighttime visions are anything but invisible to me as I slumber, resting and gathering my forces for another day.
For more information please read The Invisible Things That Give a Hometown Its Flavor.