* * * *
After they'd finished the snack—which turned out to be oatmeal cookies her mom had gotten from the Mennonites—Caitlin and Dr. Kuroda returned to the basement. Caitlin had switched her eyePod to simplex mode for the break, but now had it back in duplex and was looking again at webspace.
"Okay,” said Kuroda, settling into his chair, “we've got a background to the Web made up of cellular automata—but what exactly are the cells? I mean, even if they're just single bits, they still have to come from somewhere."
"Slack storage space?” suggested Caitlin. Hard drives store data in clusters of a fixed size, she knew; the new computer her dad had bought yesterday probably had an NTFS-formatted drive, meaning it used clusters of four kilobytes, and if a file contained only three kilobytes of data, the fourth kilobyte—over eight thousand bits—was left unused.
"No, I don't think so,” said Kuroda. “Nothing can read or write to that space; even if there was some way for Web protocols to access slack space on servers, you wouldn't see bits flipping rapidly. No, this must be something out there—something in the data pipes.” He paused. “Still, there's nothing I can think of in the Internet's TCP/IP or OSI model that could produce cellular automata. I wonder where they're coming from?"
"Lost packets,” Caitlin said suddenly, sitting up straighter.
Kuroda sounded both intrigued and impressed. “Could be."
At any moment, Caitlin knew, hundreds of millions of people are using the Internet. While doing so, their computers send out clusters of bits called data packets—the basic unit of communication on the Web. Each packet contains the address of its intended destination, which might, for instance, be the server hosting a webpage. But traffic on the Web almost never goes directly from point A to point B. Instead, it bounces around on multi-legged journeys, passing through routers, repeaters, and switches, each of which tries to direct the packet closer to its intended destination.
Sometimes the routing gets awfully complex, especially when packets are rejected by the place they were sent to. That can happen when two or more packets arrive at the same time: one is chosen at random to be accepted and the others are sent back out to try their luck again later. But some packets never get accepted by their intended destinations because the address they've been sent to is invalid, or the target site is down or too busy, and so they end up being lost.
"Lost packets,” repeated Kuroda, as if trying the notion on for size. Caitlin imagined he was shaking his head. “But lost packets just expire."
And indeed they mostly do, she knew: each packet has a “hop counter” coded into it, and that counter is reduced by one every time the packet passes through a router or other device. To keep lost packets from clogging up the Web infrastructure, when a router receives a packet whose hop counter has reached zero, it erases the packet.
"Lost packets are supposed to expire,” Caitlin corrected, “but what if the packet is corrupted so that it no longer has a hop counter, or that counter doesn't decrement properly? I imagine some portion of packets get corrupted like that, by faulty routers or bad wiring or buggy software, and, with trillions of them going out each day, even if only a very tiny proportion ended up with broken hop counters, that would still leave huge numbers kicking around forever, right? Especially if their intended destination simply doesn't exist, either because the address has been corrupted along with the hop counter, or the server has gone offline."
"You know a lot about networks,” Kuroda said, sounding impressed.
"Hey, who do you think set up the one in this house?"
"I'd assume your father..."
"Oh, he's good at networking now,” she said. “I taught him. But really, he's a theoretical physicist. He can barely operate the microwave."
Kuroda's chair squeaked. “Ah."
She felt herself getting excited; she was on to something—she knew it! “Anyway, there are probably always some ... some ghost packets that persist long after they should have died. And think about that thing that happened in China recently: a huge, huge portion of the Web was cut off because of those power failures, or whatever. Hundreds of trillions of packets intended for China suddenly had no way to get to their destinations. Even if only a tiny fraction of those got suitably corrupted, it would still mean a huge increase in the number of ghost packets."
"'Ghost packets,’ eh?” Kuroda had brought a cup of coffee downstairs with him, and she heard it clatter; he must have just taken a sip. “Perhaps. Maybe a bug in some operating system or common router has been generating them for years under certain circumstances, for all we know—a benign bug that doesn't inconvenience users might never have been noticed."
He shifted in his chair, then: “Or maybe they aren't immortal packets at all. Maybe this is just the normal ebb and flow of lost packets that will expire, and while they're bouncing around trying in vain to reach their destination their time-to-live counters do decrement normally, but it's the switch from odd to even counts with each handoff that causes them to flip from black to white in your perception. You'd still get as many as 256 permutations out of each doomed packet—that's the maximum number of hops that can be coded for, because packets use an eight-bit field to store that value. But that's still a goodly number of iterations for a cellular-automata rule."
He paused, then blew out air noisily; Caitlin could almost hear him shrug. “But this is way out of my area,” he continued. “I'm an information theorist, not a network theorist, and—"
She laughed.
"What?” said Kuroda.
"Sorry. Do you ever watch The Simpsons?"
"No, not really. But my daughter does."
"The time Homer ended up becoming an astronaut? These two newscasters are talking about the crew of a space mission. The first guy says, ‘They're a colorful bunch. They've been dubbed “The Three Musketeers,” heh heh heh.’ And the other guy—it's Tom Brokaw—says, ‘And we laugh legitimately: there's a mathematician, a different kind of mathematician, and a statistician.’”
Kuroda chuckled then said, “Well, actually, there are three types of mathematicians: those who can count, and those who can't."
Caitlin smiled.
"But, seriously, Miss Caitlin, if you go into a career in maths or engineering, you will have to choose a specialty."
She kept her voice deadpan. “I'm going to focus on the number 8,623,721—I bet nobody's taken that one yet."
Kuroda made his wheezy chuckle again. “Still, I think we need to talk to a specialist. Let's see, in Israel it's ... hey, it's only 8:00 p.m. She might be around."
"Who? Anna?"
"Exactly: Anna Bloom, the network cartographer. I'll IM her to see if she's online. Does this new computer have a webcam?"
"I suspect my dad didn't think I'd have much use for one,” she said gently.
"Well, he—ah! He's more of an optimist than you think, Miss Caitlin. There's one right here, sitting on top of the tower.” He used the keyboard for a few moments, then: “Yup, she's at home and online. Let me get a webcam call going..."
"Konnichi wa, Masayuki-san!" said the same voice Caitlin had heard on the speakerphone the night she'd seen the Web for the first time. But the woman immediately switched to English, presumably when she saw that he was with a Westerner. “Hey, who's the sweet young thing?"
Dr. Kuroda sounded slightly embarrassed. “This is Miss Caitlin.” Of course, Anna hadn't seen her when they'd spoken before.
Anna sounded surprised. “Where are you?"
"Canada."
"Oooh! Is it snowing?"
"Not yet,” said Kuroda. “It's still September, after all."
"Hi, Caitlin,” Anna said.
"Hello, Professor Bloom."
"You can call me Anna. So, what can I do for you?"
Kuroda recounted what they'd dreamed up so far: legions of ghost packets floating in the background of the Web, somehow self-organizing into cellular automata. Then: “So, what do you think?"
"It's a nove
l idea,” Anna said slowly.
"Could it work?” asked Caitlin.
"I ... suppose. It's a classic Darwinian scenario, isn't it? Mutant packets that are better able to survive bouncing around endlessly. But the Web is expanding fast, with new servers added each day, so a slowly growing population of these ghost packets might never overwhelm its capacity—or, at least, it clearly hasn't yet."
"And the Web has no white blood cells tracking down useless stuff,” said Caitlin. “Right? They would just persist, bouncing around."
"I guess,” said Anna. “And—just blue-skying here—but the checksum on the packet could determine if you're seeing it as black or white; even-number checksums could be black and odd-number ones white, or whatever. If the hop counter changes with each hop, but never goes to zero, the checksum would change, too, and so you'd get a flipping effect."
"I thought of something similar,” Kuroda said, “although the checksum didn't occur to me."
"And,” Caitlin said to Dr. Kuroda, “you said cellular automata rules can arise naturally, right? Like with that snail that uses them to paint its shell? So maybe all of this just spontaneously emerged."
"Maybe indeed,” said Kuroda, sounding intrigued.
"I think I smell a paper,” said Anna.
"You want to be a mathematician when you grow up, right, Miss Caitlin?” asked Kuroda.
I am a mathematician, she thought. But what she said was, “Yes."
"How'd you like to get the jump on the competition and coauthor your first paper with Professor Bloom and me? ‘Spontaneous Generation of Cellular Automata in the Infrastructure of the World Wide Web.’”
Caitlin was grinning from ear to ear. “Sweet!"
* * * *
Chapter 28
"Well, there's no doubt now, is there?” said Shoshana, shifting her gaze from the painting to Dr. Marcuse and then back again. “That's me again, all right."
They were in the main room of the bungalow, watching the live video feed as Hobo painted away in the gazebo. Four LCD monitors were lined up on a workbench, one for each of the cameras; it reminded Shoshana of the security guard's station in her apartment building's lobby.
Marcuse nodded his great lump of a head. “Now, if he'd just paint something other than you.” A pause. “Note that he's doing your same profile again: you looking off to the right. If he'd done it the other way, that might have torpedoed my thought about it reflecting brain lateralization."
"Well,” said Shoshana, “it is my good side."
He actually smiled, then: “Okay. Let's put your video-editing skills to work."
Shoshana had a not-so-secret hobby: vidding. She took clips of TV shows she'd snagged from BitTorrent sites and cut them to fit popular songs, making humorous or poignant little music videos that she shared with like-minded vidders on the Web. Her fandoms included the TV medical drama House, which had a lot of slashy subtext that was great for mixing to love songs, and the latest incarnation of Doctor Who. Marcuse had caught her working on these once or twice over lunch, using the fancy Mac the Institute had had donated to it.
"When Hobo's done,” continued Marcuse, “take the footage from all four cameras and splice together a version that shows the whole thing as it happened. Real Hollywood-style, okay? Shot of Hobo, shot of canvas over Hobo's shoulder, close-up on canvas, back to Hobo, like that. I'll write up a voice-over commentary to go with it."
"Sure,” Shoshana said, looking forward to the assignment. Timbaland has nothing on me.
"Good, good.” Marcuse rubbed his big hands together. “After this hits YouTube, the only cutting room our Hobo is going to be involved with is your edit suite."
* * * *
"What we really could use,” Kuroda said, down in the basement, “is an expert on self-organizing systems."
"And there's never one around when you need one!” Caitlin declared in mock seriousness. “But my dad's a physicist. He must know something about them.” In fact, he knew something about just about everything, in her experience—at least in theoretical areas. “I'll go get him."
Caitlin headed upstairs. She took a detour, going all the way up to her bedroom first. It really was chilly in the basement, so she grabbed her PI sweatshirt, which her mom had thoughtfully run through the dryer after last night's storm.
She found her dad in his den, which was a little room near the back of the house. It was easy enough tracking him down: he had a three-disc CD player in there, which seemed perpetually loaded with the same discs: Supertramp, Queen, and The Eagles. “Hotel California” was playing as she stepped through the open doorway. He was typing on his keyboard; he had an ancient, heavy IBM one that clicked loudly. She rapped her knuckles gently on the door jamb, in case he was too absorbed in his work to notice her arrival, and said, “Can you help Dr. Kuroda and me?"
She heard his chair pushing back against the carpet, which she took as a “yes."
Once they got downstairs, Caitlin let her dad have the chair she'd been sitting in, and she leaned against the worktable; through the small window, she could hear a few of the neighborhood kids playing street hockey. Anna Bloom was still hooked up via webcam from the Technion in Israel.
"Even if there are lost packets persisting on the infrastructure of the Web,” her dad said, after Kuroda had briefed him, “why would Caitlin see them? Why would they be represented at all in the feed she's getting from Jagster?"
Kuroda shifted noisily in his chair. “That's a good question. I hadn't—"
"It's because of the special method Jagster uses to get its data,” Anna said.
"Sorry?” said Kuroda, and “What?” said Caitlin.
Anna's voice sounded tinny over the computer's speakers. “Well, remember, Jagster was created as an alternative to the Google approach. PageRank, the standard Google method, looks for how many other pages link to a page, right? But that isn't necessarily the best measure of how frequently a page is accessed. If you're looking for info on a hot rock star, like, say, Lee Amodeo..."
"She's awesome!” said Caitlin.
"So my granddaughter tells me,” said Anna. “Anyway, if you're interested in Lee Amodeo, how do you find her website? You could go to Google and put ‘Lee Amodeo’ in as the search term, right? And Google will serve up as number one whichever page about her has the most links to it from other pages. But the best Lee Amodeo page isn't necessarily the one people link to the most, it's the page they go to the most. If people always go directly to her page by correctly guessing that the URL is leeamodeo.com—"
"Which it is," Caitlin said.
"—then that might be the most popular Lee Amodeo site even if no one links to it, and Google wouldn't know it. And, in fact, if you upload a document to the Internet but don't link it to any Web page, but you send a link to it to people via email, again, Google—and other search engines—won't know it's there, even if ten thousand people access the document through the email links."
"Okay,” her dad said. Caitlin doubted Anna knew how privileged she was to get an acknowledgment at all.
Anna went on. “So, besides just traditional spidering, Jagster monitors raw Web traffic going through major trunks, looking at the actual stream of data moving through the routers, and that would include lost packets."
"Isn't that sort of like wiretapping?” Caitlin asked.
"Well, yes, exactly,” said Anna. “But Jagster is the good guy here. See, in 2005, a whistle blower named Mark Klein outed the fact that AT&T has special equipment at its central office in San Francisco—and, indeed, at several of its other facilities—that allows the NSA to tap into raw Internet traffic."
Caitlin knew the NSA was the National Security Agency in the US. She nodded.
"It's a tricky technical problem,” continued Anna. “You can monitor what's going on in copper wire without interfering with the signal, because the magnetic fields leak out. But more and more of the Web is carried by fiber optics, and those don't leak. If you want to monitor the traffic, you actually h
ave to put in a splitter, diverting part of the signal, which reduces the signal's strength. And that, among other things, was what they were—and are—doing at AT&T, apparently. It's called vacuum-cleaner surveillance: they just suck up everything that's going down the pipe."
"And that's where Jagster gets its data?” Caitlin asked. “From AT&T?"
"No, no,” said Anna. “There's a class-action suit about all this, initiated by the Electronic Frontier Foundation: Hepting versus AT&T.” She paused, perhaps trying to remember—or maybe she was googling at her end. “AT&T is a for-profit corporation, but an awful lot of Internet traffic goes through universities—always has, right back to the early days. And a bunch of universities decided to tap their trunks, just to show what sort of data could be mined, so they could file amicus briefs in Hepting; they wanted to show that the government could access all sorts of private stuff this way—things they should need a warrant to get. The university consortium put scrambling routines in up front, so that certain data strings—email addresses, credit-card numbers, and the like—are always munged before the feed is made public, but otherwise, they've basically done what AT&T did under government instructions, in order to demonstrate, despite the government's claims to the contrary, just how invasive this sort of monitoring can be."
"Cool,” said Caitlin.
"Jagster decided to use that same data-stream,” continued Anna, “because it lets it rank pages based on how many times they're actually accessed, rather than just how many times they're linked to. And since your eyePod is being fed a raw Jagster dump of everything, you're seeing the orphaned packets."
Analog SFF, January-February 2009 Page 21
