These geologic advantages—a terrific natural harbor and an easy transportation route into the interior—allowed an active trading outpost to be established on Manhattan Island by 1625. Over the next four centuries, this blossomed into the international financial and cultural powerhouse that is New York City today—one that still draws people from all over the world to settle here.
Magnetic Attraction
There’s a lot of worry about what we might be breathing while commuting, so I borrowed an air sampling pump to find out.
It’s only a few minutes’ walk up the hill to the subway, and I descend the steps and enter the realm of magnetism. Magnetism is what gets 5.4 million passengers around New York City’s subway system every day, starting with the MetroCard I swipe at the turnstile to enter the system. My MetroCard has a stripe made from a slurry of barium ferrite particles painted onto the card. The stripe encodes a couple hundred bytes of data in magnetized patterns. The data are read by the subway turnstile, which decides whether I have paid for the trip. The turnstile also keeps a record of the card’s unique identification number and the time and date the card was used, regularly uploading this information to the New York City Transit Authority’s central computers. (The local police have found this inconspicuous record-keeping handy in implicating or exonerating suspects in criminal cases and have even used it to trace notorious fugitives such as Peter Braunstein, who sexually assaulted a woman after pretending to be a fireman checking for smoke damage in her building, according to newspaper accounts.)
But where magnetism really reigns supreme is in the motors that drive the subway trains. The New York City subway system supplies power to its trains via a third rail charged with about 625 volts of direct electric current (DC). A device called an inverter turns this into alternating current (AC), which is fed to the motors underneath each car. Inside the motor, the AC electricity flows through coils that surround the rotating core of the motor. The alternating current creates a constantly changing magnetic field and, through some clever engineering, magnetizes the core of the motor as well. Magnetic attraction pulls the rotor toward one coil and then to the next. The changing magnetic field ensures that the rotor will never come to rest, and its strength—thousands of times more powerful than a typical refrigerator magnet—provides the necessary push to keep the train moving.
Iron Lungs
Driven by its motors, my train rumbles into the station, clattering along the tracks. It’s about a 35-minute commute to my stop at 14th Street and Sixth Avenue in Manhattan, and from there a five-minute walk to DISCOVER’s offices. There’s often a lot of worry in New York City about what we might be breathing into our lungs while we’re commuting and otherwise out and about. As is common around the country, New York State’s Department of Environmental Conservation routinely monitors the levels of ozone, carbon monoxide, sulfur dioxide, nitrogen oxides, and particulates in the air. Together these measurements give a pretty good snapshot of the health of the air, known as the Air Quality Index (AQI). Anyone can get a real-time report on the AQI in his or her area by visiting airnow.gov. But I was interested in finding out what else I might be breathing, so I borrowed an air sampling pump from Jennifer Richmond-Bryant, an assistant professor of environmental and occupational health sciences at Hunter College in New York City.
Fortunately for me, I’m in no danger of metal poisoning—nearly all the elements we tested for, including lead, arsenic, and chromium, weren’t present at detectable levels. But two were detectable—iron and calcium. The iron comes from my time in the subway, generated from “wear and tear on the wheels and on the tracks,” which produces tiny iron particles in the air, Richmond-Bryant explains. The calcium comes from aboveground: There is “a decent amount of calcium in concrete,” she says. The concrete gets ground up “when people drive over it or when construction is going on,” and small amounts of it are released into the air. But New Yorkers needn’t worry—iron and calcium are not considered hazardous air pollutants by the EPA.
Radio Free New York
As I stroll along 14th Street to work, I’m also wandering through an invisible electromagnetic bedlam. Indeed, if I could see radio waves, the top of the Empire State Building 20 blocks north of me would be lit like a kaleidoscopic flare, illuminating the entire city. The Empire State Building is host to an array of antennas that are taking advantage of the building’s 1,454-foot height—to the top of its lightning rod—to broadcast a bevy of radio and television stations.
But it’s not just radio and TV signals that are in the air. Cell phones, Wi-Fi-enabled laptops, walkie-talkies, and more are all adding to the bedlam. To prevent transmissions from interfering with each other, the Federal Communications Commission and the National Telecommunications and Information Administration tightly regulate the use of every radio frequency on the electromagnetic spectrum. With a device known as a spectrum analyzer, it’s possible to visualize just how the spectrum is being used. I borrowed one that could detect signals from 100 kilohertz (kHz), just below the frequency of long-wave radio stations, up to 3 gigahertz (GHz), somewhat above the 2.4 GHz portion of the spectrum used by Wi-Fi connections (see “Radio Ways,” below). If you have a Wi-Fi-enabled computer, you can create your own poor-man’s version of a spectrum analyzer. You’ll need a piece of software like Kismet or KisMAC, which you can find free online. This software taps into your Wi-Fi card’s radio and displays all the signals from nearby Wi-Fi base stations, along with the frequency, or channel, that they are broadcasting on. This can come in handy if you’ve noticed a slowdown in your wireless connection speed—it might be that neighbors have set up a new Wi-Fi base station that is using the same channel as yours, resulting in interference. If you spot an unused channel with Kismet or KisMAC, you might want to adjust your base station so that you are connecting without interference.
It’s not just radio and TV signals. Cell phones, Wi-Fi laptops, walkie-talkies, and more are adding to the bedlam.
Software Shock
Once I finally reach DISCOVER’s office, around 10 a.m., the first thing I do (after fixing myself a cup of tea) is fire up my computer and check my e-mail accounts. The difference between a computer that is useful and one that is an expensive paperweight is, of course, software. A piece of software is essentially a list of instructions that tell a computer what to do. And these days, computers, along with their software, are everywhere.
If you’ve ever struggled to understand how a piece of software works, you are not alone. In fact, simply checking for new e-mail triggers a cascade of activity so complex that no human being could ever completely understand all of it. Subsystem interacts with subsystem as electrons surge and flow through microchips that operate according to the dictates of semiconductor physics. How is it, then, that every time you log on to the Internet, there’s a cool new Web site that seems to work just fine, despite not being programmed by a crack squad of Nobel laureates?
