Alternate View Column AV-64
Keywords: communication bandwidth internet communicarion WorldWideWeb
Published in the March-1994 issue of Analog Science Fiction & Fact Magazine;
This column was written and submitted 9/12/93 and is copyrighted ©1993 by John G. Cramer.
All rights reserved. No part may be reproduced in any form without
the explicit permission of the author.
Technological revolutions are often visible well before they arrive. We knew, for example, that transistors and computers were going to become important long before they had any actual impact on society. But other revolutions can sneak up on you. Without my noticing various minicomputers were linked over commercial telephone lines and satellite links to form a computer network, and one day, without even asking for it I was able to send E-Mail from my VAX to other computers across the continent and the world. A bit later digital scanning and telephone modem technology matured, and suddenly fax machines were everywhere.
Well, it's happened again. About 6 months ago I discovered the WorldWideWeb (WWW) hypertext system for Internet, a system that allows access to distant computers with almost magical ease. As of about a week ago (8/93) the UNIX workstation in my office became a "server" on WWW. I'll explain in more detail later, but essentially it puts me in the electronic publishing business. I can place illustrated reports, formatted papers with figures, drawings, maps, technical manuals, slides from my recent vacation, pictures of my children, my latest short story, ... in files on my computer, and instantly they become accessible to anyone on the planet with suitable hardware, network connections, and software. I can access similar electronic documents elsewhere, fetching beautiful astronomical pictures of Supernova 1987A or the Ring Nebula from NASA Goddard, taking a tour of a special exhibit of medieval documents from the Vatican Museum courtesy of the Smithsonian, examining weather maps, satellite pictures, and even viewing movies of changing Pacific weather patterns supplied by a server in Australia, or fetching a software manual from CERN in Switzerland.
What happened? Well, the Internet happened, and clever network specialists and programmers have now devised remarkably effective and painless ways of using the Internet and the bandwidth behind it to work electronic miracles. To explain what has been going on in this area, let me use a question-and-answer format.
Q: What is bandwidth?
A: "Bandwidth" in its narrow engineering definition is the permissible frequency change that can be made in a selected "carrier frequency" in order to transmit information. For instance, an FM station that is broadcasting at 100.5 MHz (million cycles per second) is permitted to vary that central frequency up or down by about 100 kHz (thousand cycles per second) to send its music and speech. The stations are carefully spaced over the FM band so that the bandwidth of one station does not overlap that of stations on neighboring frequencies.
The more general meaning of bandwidth, as it is now entering our everyday speech, is the rate at which information can be transmitted over a given medium (telephone cables, cable TV, microwave relays, fiber optics, satellite links, etc.) In general the permissible bandwidth, for both regulatory and technical reasons, is about 0.1% to 1% of the carrier frequency. This means that the available bandwidth grows with the carrier frequency. Thus the higher the frequency, the greater the volume of information that can be transmitted. Similarly, if there are several transmission paths, more information can be sent and so the effective bandwidth is increased. Below I include references to a couple of recent articles by George Guilder that discuss the virtues of new-found bandwidth.
Q: Why is there a bandwidth revolution?
A: We think of microelectronics as dropping rapidly in price. But, as a scarce commodity, bandwidth is dropping in price even faster. There are several reasons for this. First, the transmission media are becoming faster. The twisted pairs of copper wires in telephone lines are being replaced by coaxial cables and fiber optic cables capable of operating at far higher carrier frequencies. The electronic circuits that process the information at each end are also speeding up. A second reason is that, because of the availability of very inexpensive fast computing, the transferred information can be "compressed" at the transmitter and "decompressed" at the receiver, thereby requiring a factor of 2 to 10 less bandwidth for a given rate of information transfer. The third reason for the increasing availability of bandwidth is the networking of computers by high-speed land-based lines and satellite links.
Q: How can networking computers create bandwidth?
A: Each computer in the net is linked to several other computers, producing a multiplicity of possible paths between any pair of computers in the net. Information at the transmitting computer site is broken up into "packets", each with its own addressing and "checksum" consistency information. These packets are passed to other computers to which the originator is linked, and these in turn compute a best path for each packet and pass it on to the next computer in the net. The computer at the receiving end reassembles the packets, verifies the checksums to detect transmission errors, requests retransmission of packets when errors are detected , and acknowledges receipt of the information. To the user this breakup, reassembly, checking, and handshaking is invisible. But while the requirement for bandwidth increases roughly as the number of computers in the net, the number of possible transmission paths and thus the available bandwidth grows geometrically as the number of computers in the net increases. Thus, networked computers are not so much consumers as generators of bandwidth.
And the network is growing. Four years ago, only 7% of the personal computers in this country were linked in a network. Today, two thirds of them are networked, with many local area networks also linked to the Internet system.
Q: Where did the Internet come from?
A: In the mid-1960's the Defense Advanced Research Projects Agency (DARPA) was funding many high-tech projects that required large and expensive mainframe computers. Someone in the agency, noting the vast sums of money being spent on computer hardware that stood idle part of the time, had the bright idea that if these computers could be linked, i.e., tied together in a network, the available computing resources could be shared more efficiently and the overall cost per compute cycle could be reduced (or at least kept within tolerable limits). And so DARPA funded the development of the hardware, protocols, and software necessary to link these mainframes, and DARPA Net was born.
As DARPA Net grew and evolved, its users came to realize that sharing compute cycles was not really as important as some of the other capabilities that had become available. By carefully and rather tediously specifying a route through the maze of linked computers, information in the forms of programs, data files, and even personal messages could be routed electronically through DARPA Net from one computer to another. E-Mail was born, and soon after the drudgery of path finding was assumed by the computers themselves.
In 1983 DARPA Net went civilian, and the Internet was created, adopting in the process the new TCP/IP networking standard to facilitate information transfer. Internet has been growing explosively ever since. In 1981 some 281 computers, most in the USA, were linked by DARPA Net . In 1992 more than 1.1 million computers all over the world with 4.7 million users were linked by Internet. The increase in Internet linked computers is between 15% and 30% per month. If this growth rate were to persist to the end of this decade, the entire population of the planet would be linked by Internet by about 2001.
Q: Who pays for Internet?
A: At my laboratory all the costs for Internet and the associated communications lines are paid by the University of Washington. I'm not sure what the fees are, but it they are small enough that I have not heard complaints from our administration. Businesses link to Internet the same way, by leasing lines and paying hookup fees. The costs of high-bandwidth connections are high enough that few private individuals can afford Internet hookups except by voice telephone modem to a commercial or university nodes. However, this may change. The telephone companies, cable TV suppliers, and cellular telephone networks all have plans for delivering high-bandwidth links to your doorstep in the next few years.
Q: What can you do on Internet?
A: In my experience there are five capabilities provided by Internet that are very useful. The "Telnet" protocol allows remote log-in access to any Internet-linked computer (if you have an account), perhaps logging into a computer on the other side of the planet as if it were in the next room. The "FTP" file transfer protocol allows high-speed sending and fetching of files to and from remote computers, often accessing files even when you do not have an account on the system. Because of the bandwidth available on Internet, an FTP file transfer takes only about 1% of the time that would be required to transfer the same file by 2400 baud modem over voice telephone lines with standard "kermit" protocol. Internet E-mail allows the sending of messages (and also data or program files) to any user on any Internet-linked system, provided you know that user's E-mail address (e.g., email@example.com). Internet News is another feature of the Internet system, with hundreds of "interest groups" within which participants swap opinions and information about the subject of interest, be it "sci.phys" or "alt.sex.kinky". Be warned, however, that reading Internet News can become a full-time activity, since an active interest group can generate hundreds of new messages each day. (Cramer's Corollary of Sturgeon's Law is that on most of Internet News, 99% of everything is crap.) Finally, the Internet system offers extremely powerful UNIX oriented multi-media transfer protocols like WorldWideWeb (and also the older protocols Gopher and WAIS, which will not be discussed here).
Q: What is WorldWideWeb?
A: WorldWideWeb is a distributed hypertext system that accesses information on Internet-linked computer servers all over the planet, welding these resources into a unified navigation and information access system that can present to the user formatted text, data, sound, high-quality graphics, and digital movies. The system was conceived by Tim Berners-Lee at the CERN Laboratory in Geneva, Switzerland. It was originally invented as a method of sharing data, reports, and information among groups participating in the same CERN-based particle physics experiments. But WWW has far outgrown its particle physics roots, to the extent that today only a small fraction of the information on WWW is concerned with particle physics.
What is it like? Imagine something resembling a full-color HyperCard stack operating on a Macintosh, except that the "cards" of the stack are actually files stored on a thousand computers all over the world and the computer platform used is a powerful UNIX workstation with high-resolution color graphics, good quality sound, and an Internet connection. The WWW "card" that appears on my X-terminal screen is formatted text in a very readable type font (new century schoolbook), punctuated with mnemonic icons and postage-stamp-size graphics, all in a scrollable X-window field. Across the top of the window are fields providing the title of the card and its network address. Here and there in the text are icons, words, and phrases shown in blue or red. These are "anchors", active spots that, with a click of the mouse, can change the display by replacing the present card (actually a text file written using the HTML hypertext formatting language) with another card. The new card could reside in the same directory of the same computer or it could be fetched from another computer anywhere on Internet where a WWW server is operating.
The "home" card for the WWW system at my laboratory provides 29 different anchors to information, resources, graphics, and other WWW sites. The network address of our system at the University of Washington Nuclear Physics Laboratory in Seattle is: "http://www.npl.washington.edu/home.html". You are invited to try it, particularly if you have a system on Internet that can run X-Mosaic, an excellent WWW "browser" developed at the University of Illinois National Center for Supercomputer Applications (net address: "ftp.ncsa.uiuc.edu", X-Mosaic available by anonymous FTP.).
We are in the midst of a revolution that is changing the way we communicate and
organize our work and our leisure. The end result of this revolution is
nowhere in sight. It may come to resemble "cyberspace", but in its present form
it is very different. In the next few years the computer in your home, your
workplace, and your briefcase will be linked at high bandwidth to Internet and
WWW (or their successors). And the world will be a very different place.
Bandwidth and Networks:
George Guilder, "Wireless New World", Forbes ASAP Technology Supplement , (March 29, 1993), and "Telecosm: The Issaquah Miracle", Forbes ASAP Technology Supplement , (June 7, 1993).
SF Novels by John Cramer: my two hard SF novels, Twistor and Einstein's Bridge, are newly released as eBooks by Book View Cafe and are available at : http://bookviewcafe.com/bookstore/?s=Cramer .
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