As the capacity of optical fibers climbs, so does the economic damage caused when the cable is severed. FLAG makes its money by selling capacity to long-distance carriers, who turn around and resell it to end users at rates that are increasingly determined by what the market will bear. If FLAG gets chopped, no calls get through. The carriers' phone calls get routed to FLAG's competitors (other cables or satellites), and FLAG loses the revenue represented by those calls until the cable is repaired. The amount of revenue it loses is a function of how many calls the cable is physically capable of carrying, how close to capacity the cable is running, and what prices the market will bear for calls on the broken cable segment. In other words, a break between Dubai and Bombay might cost FLAG more in revenue loss than a break between Korea and Japan if calls between Dubai and Bombay cost more.

The rule of thumb for calculating revenue loss works like this: for every penny per minute that the long distance market will bear on a particular route, the loss of revenue, should FLAG be severed on that route, is about $3,000 a minute. So if calls on that route are a dime a minute, the damage is $30,000 a minute, and if calls are a dollar a minute, the damage is almost a third of a million dollars for every minute the cable is down. Upcoming advances in fiber bandwidth may push this figure, for some cables, past the million-dollar-a-minute mark.

Clearly, submarine cable repair is a good business to be in. Cable repair ships are standing by in ports all over the world, on 24-hour call, waiting for a break to happen somewhere in their neighborhood. They are called agreement ships. Sometimes, when nothing else is going on, they will go out and pull up old abandoned cables. The stated reason for this is that the old cables present a hazard to other ships. However, if you do so much as raise an eyebrow at this explanation, any cable man will be happy to tell you the real reason: whenever a fisherman snags his net on anything - a rock, a wreck, or even a figment of his imagination - he will go out and sue whatever company happens to have a cable in that general vicinity. The cable companies are waiting eagerly for the day when a fisherman goes into court claiming to have snagged his nets on a cable, only to be informed that the cable was pulled up by an agreement ship years before.

In which the Hacker Tourist delights in Cairo, the Mother of the World. Alexandria, the former Hacker Headquarters of the planet.

The lighthouse, the libraries, and other haunts of ancient nerds and geeks. Profound significanceof intersections. Travels on the Desert Road. Libya's contact with the outside world rudely severed - then restored! Engineer Musalamand his planetary information nexus. The vitally important concept of Slack

31° 12.841' N, 29° 53.169' ESite of the Pharos lighthouse, Alexandria, Egypt

Having stood on the beach of Miura watching those miserable-but-plucky Japanese surfers, the hacker tourist had reached FLAG's easternmost extreme, and there was nothing to do except turn around and head west. Next stop: Egypt.

No visit to Egypt is complete without a stop in Cairo, but that city, the pinnacle of every normal tourist's traveling career, is strangely empty from a hacker tourist point of view. Its prime attraction, of course, is the pyramids. We visited them at five in the morning during a long and ultimately futile wait for the Egyptian military to give us permission to rendezvous with FLAG's cable-laying ship in the Gulf of Suez. To the hacker, the most interesting thing about the Pyramids is their business plan, which is the simplest and most effective ever devised:

(1) Put a rock on top of another rock.

(2) Repeat (1) until gawkers arrive.

(3) Separate them from their valuables by all conceivable means.

By contrast, normal tourist guidebooks have nothing good to say about Alexandria; it's as if the writers got so tired of marveling at Cairo and Upper Egypt that they had to vent their spleen somewhere. Though a town was here in ancient times, Alexandria per se was founded in 332 BC by Alexander the Great, which makes it a brand-new city by Egyptian standards. There is almost no really old stuff in Alexandria at all, but the mere memory of the landmarks that were here in its heyday suffice to make it much more important than Cairo from the weirdly distorted viewpoint of the hacker tourist. These landmarks are, or were, the lighthouse and the libraries.

The lighthouse was built on the nearby island of Pharos. Neither the building nor even the island exists any more. Pharos was eventually joined to the mainland by a causeway, which fattened out into a peninsula and became a minuscule bump on the scalp of Africa. The lighthouse was an immense structure, at some 120 meters the tallest building in the world for many centuries, and contained as many as 300 rooms. Somewhere in its upper stories a fire burned all night long, and its light was reflected out across the Mediterranean by some kind of rotating mirror or prism. This was a fine bit of ancient hacking in and of itself, but according to legend, the optics also had magnifying properties, so that observers peering through it during the daytime could see ships too distant to be perceived by the naked eye.

According to legend, this feature made Alexandria immune to naval assault as long as the lighthouse remained standing. According to another yarn, a Byzantine emperor spread a rumor that the treasure of Alexander the Great had been hidden within the lighthouse's foundation, and the unbelievably fatuous local caliph tore up the works looking for it, putting Pharos out of commission and leading to a military defeat by the Byzantine Empire.

Some combination or other of gullible caliphs, poor maintenance, and earthquakes eventually did fell the lighthouse. Evidently it toppled right into the Mediterranean. The bottom of the sea directly before its foundations is still littered with priceless artifacts, which are being catalogued and hauled out by French archaeologists using differential GPS to plot their findings. They work in the shadow of a nondescript fortress built on the site by a later sultan, Qait Bey, who pragmatically used a few chunks of lighthouse granite to beef up the walls - just another splinter under the fingernails of the historical preservation crowd.

You can go to the fortress of Qait Bey now and stare out over the ocean and get much the same view that the builders of the lighthouse enjoyed. They must have been able to see all kinds of weirdness coming over the horizon from Europe and western Asia. The Mediterranean may look small on a world map, but from Pharos its horizon seems just as infinite as the Pacific seen from Miura. Back then, knowing how much of the human world was around the Mediterranean, the horizon must have seemed that much more vast, threatening, and exciting to the Alexandrians.

Building the lighthouse with its magic lens was a way of enhancing the city's natural capability for looking to the north, which made it into a world capital for many centuries. It's when a society plunders its ability to look over the horizon and into the future in order to get short-term gain - sometimes illusory gain - that it begins a long slide nearly impossible to reverse.

The collapse of the lighthouse must have been astonishing, like watching the World Trade Center fall over. But it took only a few seconds, and if you were looking the other way when it happened, you might have missed it entirely - you'd see nothing but blue breakers rolling in from the Mediterranean, hiding a field of ruins, quickly forgotten.

31° 11.738' N, 29° 54.108' EIntersection of El Horreya and El Nabi Daniel, Alexandria, Egypt

Alexandria is most famous for having been the site of the ancient library. This was actually two or more different libraries. The first one dates back to the city's early Ptolemaic rulers, who were Macedonians, not Egyptians. It was modeled after the Lyceum of Aristotle, who, between other gigs, tutored Alexander the Great. Back in the days when people moved to information, instead of vice versa, this library attracted most of the most famous smart people in the world: the ultimate hacker, Archimedes; the father of geometry, Euclid; Eratosthenes, who was the first person to calculate the circumference of the earth, by looking at the way the sun shone down wells at Alexandria and Aswøan. He also ran the library for a while and took the job seriously enough that when he started to go blind in his old age, he starved himself to death. In any event, this library was burned out by the Romans when they were adding Egypt to their empire. Or maybe it wasn't. It's inherently difficult to get reliable information about an event that consisted of the destruction of all recorded information.