How fast can you read this? How fast will your computer keyboard accept the characters you type? How fast does water flow out of your kitchen faucet? The answers depend on bandwidth. Simply put, bandwidth is a measurement of how much, how quickly. The speed at which your brain absorbs words (words per minute), your computer accepts keystrokes (characters per second), or your faucet squirts water (gallons per minute) can be described in terms of bandwidth.
The rate at which computers can send and receive information is expressed in bandwidth, too, as bits per second. Surveys tell us that most readers connect to Slate with 28.8 modems, which, under optimal conditions, deliver a bandwidth of 28,800 bits of data per second. What’s a bit? A bit is the smallest unit of data, either a zero or a one. For example, eight bits represent a single letter in the alphabet: The eight-letter word “alphabet” contains 64 bits.
The average Slate article–and I just happen to have one right here, “Booker Snooker“–contains about 800,000 bits of text, images, and formatting information. It takes about 30 seconds to download via a 28.8 modem. (Let’s do the math: Eight hundred thousand bits divided by 28,800 bits per second equals 27.8 seconds.)
Software developers like me lust for more bandwidth, and so do civilians like you who only use computers. We all want Slate and ESPN Sportszone and Amazon.com to download faster to our computers. Bandwidth! Bandwidth! Bandwidth! the masses cry. But ever since mankind first took serious notice of bandwidth–ever since the invention of Morse code, that is–there hasn’t been enough of it. An average telegrapher can communicate at 20 to 40 words per minute. That’s about 16 to 32 bits per second. If your computer operated at Morse code’s bandwidth, it would take between a half-day and a full day to download a page from Slate.
The bandwidth bottleneck bugs me because we’ve seen dramatic increases in performance on almost every other computer front. A 1985 processor (386) ran at 12 MHz. A 1997 Pentium II processor runs at 300 MHz–about 20 times faster. Over that same time, the storage capacity of the average computer has grown by a factor of 250. But usable bandwidth for the home user has increased only about threefold.
Have the bandwidth guys been taking long lunches, or what? Actually, they’ve been doing a great job–it’s the rotten telephone companies that have been lollygagging. Everybody has heard about Moore’s Law, named after an Intel founder, which holds that the power of CPUs doubles every 18 months. There’s a corresponding bandwidth law, named after its discoverer, right-wing techno-utopian George Gilder, which states that bandwidth triples every 12 months. And it has been tripling every 12 months for the last decade or so.
T he phone companies haven’t piped this wonderful bandwidth into most homes yet because they’re fairly happy with the quaint technology of copper wire they’ve installed over the last century. Copper-wire telephone connections have enough bandwidth to transmit voices, but not enough for gluttons like me. Click for an explanation of “Shannon’s Limit,” which tells you why the bandwidth of conventional telephone connections will never exceed 56,000 bits per second.
If you’re lucky, your friendly neighborhood telephone monopoly provides ISDN service in your town. ISDN stands for “integrated services digital network,” and the technology moves data to computers at 128,000 bits per second. That’s five times faster than a regular modem, which means you can download the average Slate page in about six seconds. The service isn’t cheap. In Seattle, the phone company charges about $100 for ISDN installation and about $65 a month for flat-rate access. The ISDN modem itself will set you back about $200. ISDN is the most popular alternative to conventional modems: Slate’s Washington, D.C., offices connect to the Web and the Redmond mothership through ISDN.
T he best bandwidth is free bandwidth. For most people, that means a T1 connection at work or school. (In New York City, some Net-savvy landlords are outfitting apartment buildings with T1 service. I wish those landlords would buy my building in Seattle.) Like ISDN, T1 breaks the 56,000-bits-per-second barrier by going 100-percent digital, that is, by transmitting ones and zeros instead of the up-and-down waves of an analog signal. For a more detailed explanation of how ISDN, T1, and other ultrafast technologies work, click.
T1 transmits data at 1.5 million bits per second, delivering Slate articles in about half a second. Of course, your mileage may vary depending on how many users are connected to your T1 line, how busy the Internet or Slate’s Web site might be at the moment, and how clogged your local-area network might be. You can only move so much data through the pipe at a time.
But you want faster. Some phone companies are offering test trials of a new technology, ADSL, or “asymmetric digital subscription line.” Right now, ADSL is ridiculously expensive–more than $1,000 for the modem alone. But it’s also ridiculously fast. Connection speeds are around 8 million bits per second from the Internet to you and about 800,000 bits per second from you to the Internet. It would take only one-tenth of one second to download a Slate article via ADSL.
If ISDN or ADSL haven’t come to your block and you want to punish the phone companies for their intransigence, try the DirecPC satellite service from Hughes Electronics. The first question you should ask yourself is, “Are you man enough for DirecPC’s 400,000-bits-per-second bandwidth?” The company’s Web site sets down these specific restrictions, among others: You must have 1) an “[u]nobstructed line of site to the South from your home [or] office” and 2) “[n]o tolerance for waiting.” DirecPC beams the Internet from Hughes’ satellites to personal dishes and then into users’ computers. Please allow two seconds for Slate pages to download. DirecPC is a bad choice for those who want to transmit data, because it uplinks on conventional phone lines at a paltry 28,800 bits per second. Another bandwidth initiative, Broadcast PC, will exploit the unused bandwidth in broadcast television signals to beam content. This one-way connection will offer speeds up to 150,000 bits per second.
The bandwidth to end all bandwidth comes to you from another despicable monopoly, your local cable guy. The cleverly named Silicon Valley start up @Home promises 30 million bits per second of bandwidth through cable-TV lines. Theoretically, @Home can deliver a Slate page in 0.0266 seconds. The company has forged alliances with several cable companies such as Comcast (full disclosure: Microsoft recently invested $1 billion in Comcast) and Cox to provide service. Analysts say cable-modem service will be ubiquitous by the turn of the century.
Sounds like nirvana, right? The big gotcha is that 30 million bits per second is faster than the Internet connects to itself. Many Web sites connect to the Internet through T1 lines, which, you recall, have a bandwidth of 1.5 million bits per second. Because your Internet connection is no faster than your slowest link, you won’t see a Web page in 0.0266 seconds unless it is stored on the @Home computer. Slate throws a fire hose at this problem and connects to the Internet through a DS3 line, which has a bandwidth of 45 million bits per second.
If Gilder’s Law is correct, bandwidth will soon be cheaper than air. But will the bandwidth explosion be undermined by Shuman’s Law? Shuman’s Law holds that you can count on talented twentysomething software developers (like Shuman) to write big, stinking pieces of software that will swallow all your expanding computer resources–your processor, your hard disk, your memory, and your bandwidth–resulting in no net performance gains. Already, talented twentysomething software developers are laying plans to choke the cable-enhanced Internet with full-motion video (one feature-length movie contains almost 17 gigabytes of data, or 136 billion bits), virtual-reality games, assorted business applications, XXX live smut, and Webzines about politics and culture.
Actually, I think that the young software developers will be swamped by a bandwidth tsunami and that we’re entering the “age of experience” on the Web predicted by Peter Cochrane, top research geek at BT Networks and Systems. Soon, the Web will transmit what Cochrane calls “full expertise.” If a picture is worth 1,000 words, he writes, and a moving picture is worth 1,000,000 words, then an “interactive pictographic world” of a supercharged Web is worth 1,000,000,000 words. Bandwidth permitting, anything that can be done in meatspace will be doable in virtual space. I just hope that by the time I’m scheduled for remote double-bypass surgery, the Web no longer transmits “404 Site Not Found” errors.
