David Langford: Graffiti in the Library of Babel

"There seems to be no difference at all between the message of maximum content (or maximum ambiguity) and the message of zero content (noise)."

-- John Sladek, "The Communicants"

As it turned out, they had no sense of drama. They failed to descend in shiny flying discs, or even to fill some little-used frequency with a tantalizing stutter of sequenced primes. No: they came with spray cans and spirit pens, scrawling their grubby little tags across our heritage.

Or as an apologetic TotLib intern first broke the news: "Sir, someone's done something nasty all over Jane Austen."

# # #

The Total Library project is named in homage to Kurd Lasswitz's thought experiment "Die Universal Bibliothek," which inspired a famous story by Jorge Luis Borges. Another influence is the "World Brain" concept proposed by H. G. Wells. Assembling the totality of world literature and knowledge should allow a rich degree of cross-referencing and interdisciplinary…

Ceri Evans looked up from the brochure. Even in this white office that smelt of top management, she could never resist a straight line: "Why, congratulations, Professor. I think you may have invented the Internet!"

"Doctor, not Professor, and I do not use the title," said Ngombi with well-simulated patience. "Call me Joseph. The essential point of TotLib is that we are isolated from the net. No trolls, no hackers, none of what that Manson book called sleazo inputs. Controlled rather than chaotic cross-referencing."

"But still you seem to have these taggers?"

"Congratulations, Doctor Evans! I think you may have just deduced the contents of my original email to you."

"All right. All square." Ceri held up one thin hand in mock surrender. "We'll leave the posh titles for the medics. Now tell me: Why is this a problem in what I do, which is a far-out region of information theory, rather than plain data security?"

"Believe me, data security we know about. Hackers and student pranksters have been rather exhaustively ruled out. As it has been said, 'Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.'"

"'Holmes, this is marvellous,'" said Ceri dutifully.

"'Meretricious,' said he." Joseph grinned. "We are a literary team here."

Ceri felt a sudden contrarian urge not to be literary. "Maybe we should cut to the chase. There's only one logical reason to call me in. You suspect the Library is under attack through the kind of acausal channel I've discussed in my more speculative papers? A concept, I should remind you, that got me an IgNobel Prize and a long denunciation in The Skeptic because everyone knows it's utter lunacy. Every Einstein-worshipping physicist, at least."

A shrug. "'Once you eliminate the impossible…' And I'm not a physicist. Come and see." He was so very large and very black. Ceri found herself wondering whether his white-on-white decor was deliberate contrast.

# # #

The taggers had spattered their marks across the digital texts of TotLib: short bursts of characters that made no particular sense but clearly belonged to the same family, like some ideogram repeated with slight variations along the shopping mall, through the car park and across the sides of subway carriages. Along Jane Austen, through Shakespeare and underground to deface Jack Kerouac and the Beats. After half an hour of on-screen examples Ceri felt the familiar eye glaze of overdosing on conceptual art.

"The tags," she said cautiously, "never appear within words?" This is a test. Do not be afraid of the obvious.

"We decided all by ourselves to call them tags." The faint smile indicated that Joseph was still in a mood for point-scoring.

"Okay. I see." She didn't, but in a moment it came. "Not just graffiti but mark-up, like HTML or XML tags. Emphasis marks. You think they're not so much defacing the texts as going through them with a highlighter. Boldface on, It is a truth universally acknowledged, boldface off."

"Congratulations! It took our people several days to reach that point."

Ceri drummed her fingers irritably against the TotLib workstation. "The point seems to be that it's already been reached. So why me?"

"I saw a need for someone who can deal with the implications. If this tagging is coming in through your acausal channels -- and we truly cannot trace any conventional route -- and if that New Scientist piece on you was not too impossibly dumbed down…"

"Oh Duw oh God. It was, but never mind."

"…the origin of the transmission would necessarily be something in the close vicinity of a supermassive black hole?"

"Well. That assumes the channel source is in our universe in the first place. The IgNobel presenter was very funny about Dimension X and the Phantom Zone." Another memory that clung and stuck, a mental itch she couldn't stop scratching.

"So many times it has been said, 'They laughed at Galileo.'"

"And sometimes it's also been said that they laughed at nitrous oxide."

Again Joseph smiled hugely. "Would you care for lunch?"

"Let me have another look first. Let me plod my slow way to some other plateau your staff reached last week. Boldface on, instruments of darkness, boldface off. Did that make you think of my black hole? Masters of the universe. God's quarantine regulations. These things need to be grouped or sequenced -- no, both."

The TotLib interface was easy enough to use. Ceri backtracked, paused, went forward again through lexical chaos. "The structure of those tags…there's a flavour of inversion symmetry…suppose ON has a group identifier wrapped around a sequence number, and OFF is sequence around group? Or the other way around, of course. That would sort your grab bag of quotes into chunks and give the chunks an internal order. Oh bugger, I'm biting my nails again. Sorry. Have we caught up with your clever staff yet?" She hadn't meant to get hooked on the dizzy rush of problem-solving. But, she thought, be glad it still comes.

The big man seemed perceptibly less smug. "My clever staff will catch up with you…maybe next week. Ceri -- if I may -- I am impressed. It is most definitely time for lunch."

# # #

The meal was inoffensive and the wine better, if only by about ten per cent, than you'd expect from an institution in a secure vault under a dour Swiss alp. As her host explained: "The Scientologists are working to preserve their founder's teachings for all eternity, and our sponsors feel there should be an alternative view."

At first Ceri had felt obscurely prickly about Dr Joseph Ngombi, and she tried now to be a little friendlier: mustn't let him think a good Welsh girl like herself had a streak of racism. Part of her mind was elsewhere, though (structured tags, that kaleidoscope of quoted fragments), and her vague attempts at friendly signals led to some carefully placed mentions of his dear wife and children. Earlier that day she'd thought she was looking good, with a new dark-red hair rinse; now she wondered whether Joseph saw her as a dyed and predatory hag. What were the chances of making sense of graffiti from some distant, supermassive black hole when communications went astray across the width of a restaurant table?

"No thanks," she said, protecting her wineglass from the waiter's menacing pass. "I'll need a clear head." Or maybe just an empty one. The trouble with an open mind, the saying went, is that people come along and put things in it.

# # #

Ceri liked the idea of TotLib staff handling the boring rote-work, but didn't want to get too far away from that tagged text. Layers of abstraction are great in software but tend to blur the focus of real-world problems. They compromised on a multi-view workstation: defaced ebooks here, grouped and sequenced tags there, and the clear light of understanding in the window that for a long time stayed dismally blank.

Clearing away the relentless tag repetition through multiple editions, critical cites and anthologies of quotations, there were just 125 tagged phrases in all. "Five to the third power," Ceri muttered. "The science fiction writers would say straight away that our friends must count to base five, meaning they have five limbs or five tentacles or…" She stared moodily at the significant number of jointed manipulators on her left hand. "Or not."

Joseph spread out a hand that proved to be missing one finger. "Just an old accident, but I would seem to be ruled out. Perhaps, though, that is merely my cunning."

The first of the eleven sequences, or maybe the last ("Has it never occurred to you that the ancient Romans counted backwards?" Ceri quoted), ran a gamut of fuzzily resonating phrases from "It is a truth universally acknowledged" through Hazlitt's "How often have I put off writing a letter" to E. M. Forster's "Only connect…"

"Translation: It would be sort of dimly nice to maybe talk in some kind of indistinct fashion, probably." Ceri glared at the screen. "Right, I'm going to lecture now. To be that vague and at the same time stick to a theme, the taggers must understand English. Not just literal meaning but metaphors and nuances and stuff. Otherwise 'No man is an island' wouldn't be in there."

"So they could choose to communicate in clear?" suggested Joseph.

"That's it. They could spell out an absolutely unambiguous message, one word or one letter at a time. I can't imagine a good reason for doing it this way, but I have a suspicious enough mind to think of a bad one. The taggers know all about us but they don't want to let slip a single data point concerning themselves. So they feed our own phrases back to us. We aren't to be allowed the tiniest clue to their thinking from style or diction or word order. Does that seem sinister to you?"

Joseph sighed. "It was so much easier when aliens said 'Take me to your leader.'"

"Or 'Klaatu barada nikto.' Don't let me distract myself. Here's the 'instruments of darkness' cluster, with the Tao Te Ching quotes, Zen koans and that mystic cobblers from Four Quartets that would cost them a packet in permission fees if the Eliot estate got wind of it. The general flavour of all this seems to be that they're using an acausal comms route that bypasses the Usual Channels. 'The way that can be spoken of / Is not the constant way.' Which would be most interesting to know if it hadn't been the assumption we started with."

An intern came in with plastic cups of coffee, which made for a few seconds' natural break. Ceri burnt a finger and swore under her breath in Welsh.

"Gesundheit. What about those quarantine regulations?"

"I think that's the most interesting one," Ceri said cautiously. "C. S. Lewis and 'God's quarantine regulations' -- the old boy was talking about interplanetary or interstellar distances saving pure races from contamination by horrible fallen us. Then there's a handful of guarded borders and dangerous frontiers from early Auden. 'The empyrean is a void abyss': that's The City of Dreadful Night, I actually read it once. Lucretius on breaking through 'the fiery walls of the world' to explore the boundless universe. There's a pun in there, I'm sure. Firewalls. Something blocks or prevents communication across deep space. Who? 'Masters of the universe.' Maybe for our own good, but who knows? In a nutshell: SETI was a waste of time. Don't let the coffee get cold."

Joseph sipped. "That seems something of a stretch."

"Well, right now I'm just talking, not publishing. And while I'm still just talking, I wonder whether we can try to talk back."

"Presumably you keep one of those acausal widgets in your handbag? Next to the black hole, no doubt."

"Of course not. Much simpler. The taggers are in tune with a particular medium -- the Total Library -- and they're messaging us by modulating it. We can modulate too, without any help from astounding super-science."

She hadn't seen Joseph wince before. For an instant his face was terrifying. "Ask a librarian to deface his own collection? You will be suggesting I ignore the SILENCE signs next."

"Just turn a blind eye and leave it to my criminal mind. When I was a girl in the valleys I worked out eight ways to nick books from the public library." And never did, and lay awake all night with a guilty conscience the one time she'd accidentally lost one, but let's not go there just now.

"While I am still in shock, whatever do you plan to say? That it is indeed vaguely nice to share a warm fuzzy lack of communication?"

"I rather thought of asking them for goodies. We haven't talked yet about the taggers' gift-exchange thread. As You Like It: 'gifts may henceforth be bestowed equally,' and half a dozen more in that general ballpark. They can't be asking. They're already the Entities Who Have Everything -- they've nicked all our books from the public library. Our architecture and our playing cards, our mythological terrors, our algebra and fire…" She waited half a beat.

"Borges. When you talk to a librarian about how he should turn a blind eye, Borges has to be in the offing."

"I never could resist a good digression, boyo. Summary: all we can exchange with the taggers is information. They're waffling about gifts. There's no further information we can give them. So they must be offering something to us in exchange."

"Mmmm. A proof of Fermat's Last Theorem would be traditional, but that one is now far past its sell-by date. I suppose the mathematicians would like to know about the other thing, what is it? The Riemann hypothesis."

"Oh, diawl. Dry as dust. And how'd we express that horror as a set of artful quotations? What I thought of asking for was a global warming fix -- some kind of clean power source with no greenhouse emissions. Cheap fusion. Zero-point energy. I don't believe what I've read about either, but maybe it's like that physicist's lucky horseshoe: it works even if you don't believe in it. And where's the harm in trying?"

"I admit to curiosity. Especially about how you plan to put across concepts like zero-point energy."

More coffee came, and then more still, while Ceri wrestled with search engines and the dictionary of quotations. "'Expecting something for nothing is the most popular form of hope.' Who's Arnold Glasgow? Anyway, he said it. And I must insist on having a line from the sainted sot of Swansea: 'Rage, rage against the dying of the light.' Then there's Blake, of course, with 'Energy is eternal delight!'"

The eventual result, they both agreed, was a monstrous hodgepodge and thus perfectly in keeping with the taggers' own approach. A pained but not quite protesting IT intern called Chaz rattled off a script that would spraygun the Total Library with Ceri's message. Joseph made a particular point of being absent in the director's toilet at the time of the fateful mouse-click. Despite all the TotLib apparatus of backups and recovery points, the instincts of a librarian died hard.

# # #

An hour passed. At the terminal, the now deeply bored Chaz ran his hundredth data scan. Anticlimax had settled on the white room like the leaden aftermath of a drinking binge. It had been a thinking binge, Ceri told herself blearily, but sometimes the hangover seemed much the same.

"You will be wishing to rest in your hotel," Joseph suggested.

"I suppose so. We don't even know whether the taggers operate on our timescale. They might live and think many times faster or slower. We don't know how long it takes them to prepare their tag payload. We don't know whether I did it right…" A general sense of running down. Sleep would be good.

"Sir," said Chaz, "something happened again. Mostly in the physics texts. Hundreds of new tags."

Ceri licked her lips. "Physics." Excitement seemed possible once more.

"Please, please do not expect miracles," Joseph said repressively. "Remember that their peculiar mode of conversation doesn't permit them to tell us anything we don't already know."

"But looking in the right order at chunks of what we know could so easily reveal something we don't. We may just need the hint. It's happened so many times in the history of science."

The internal numbering of the latest tags confirmed that their makers didn't count backwards and that the sequence containing "It is a truth universally acknowledged" was #1.

Just one quote-cluster from the new batch steered clear of the physics department. "That has to be the descriptor, the label on the tin. Let's see. From a Shakespeare sonnet, 'no such matter.' They Do It with Mirrors -- that's an Agatha Christie title. Macbeth and 'where men may read strange matters.' Another title: Prometheus Unbound. 'Turning and turning in the widening gyre.'" Ceri scanned onward. "Joseph, I have a bad feeling about this."

"Strange matter? All I know of it is the name."

"No, I think it's antimatter. Mirror matter. The perfect nuclear fuel with one hundred per cent conversion efficiency."

"In fact, something we already knew. We make the stuff, do we not, at CERN and places of that kind?"

Ceri shook her head. "That's tiny, tiny amounts. The production rate is, oh, billions of years per gram. What I'm terribly afraid we've been given, what a physicist will see when she puts those textbooks and papers together, is some space-rotation trick that flips matter into antimatter. Unlimited quantities." She called up figures. "Here. Total energy release of forty-something megatons when a single kilo meets normal matter and annihilates. No fiddly fission triggers, no critical mass to assemble: it just does it. You wouldn't need a huge amount to burn the whole biosphere clean."

"Ah. I don't suppose our friends' interesting cascade of phrases on the theme of gifts included any mention of Greeks?"

"Not even Danes," said Ceri at random. "Quote search, quote search, and here it is. Timeo Danaos et dona ferentes. I know it's Greeks really, but I always used to read it as 'beware of Danes bearing gifts.'"

"That," said Joseph solemnly, "was known as the Danelaw."

Ceri giggled, although it was a noise she didn't like making. She'd been talking too fast and nervously, maybe faster than the speed of logic. Good to have the brakes applied. "Thank you," she said.

"So. They like to gift others with dangerous toys. Perhaps out of malice -- the afrit who smilingly grants your wish, knowing that it will destroy you. Perhaps only in a spirit of healthy experiment to see what we will do. By the way, what will we do?"

"I suppose we have a sort of duty…" Out of the corner of her eye Ceri saw her notes window change. She hadn't touched the keyboard or mouse. Just before the flatscreen went black and flickered into a reboot sequence, she saw the coloured tags where no tags had been before. In her own notes. Surrounding the copied words "quarantine regulations."

Chaz wandered in and helpfully announced that the invulnerable TotLib systems were having their first ever unscheduled downtime.

When the Library came back up, it wasn't only Ceri's transcripts that had vanished in a puff of electrons. To Joseph's loudly expressed relief there had been a general clean-up, a thorough scrubbing of the library's defaced stacks from Jane Austen through to Zola. No tags anywhere.

"Iesu Grist. Call me a superstitious peasant if you like," Ceri murmured, "but I think the Masters of the Universe just stepped in."

# # #

Over a late supper in the Gasthof Schmidt, Ceri and Joseph managed to work themselves partway down from unnerving conceptual heights. A bottle of Riesling helped, and soon after the second arrived Joseph bashfully admitted that his wife and children were mythical. "The truth is that I often find myself curiously scared of attractive women." Communications were always a bugger, but sometimes contact could be made even across those fearful spaces. They celebrated with a brief though intense fling in the few days before duty called and Ceri boarded a Eurostar train for the first leg home to Oxford, the solitary flat, and her incommunicable researches at the Mathematical Institute.

Half a year later, in place of his regular reassurance that the Library stayed graffiti-free, Joseph sent an email whose header read: "What goes around, comes around." From the included links, Ceri gathered that the Human Genome Project was in a tizzy. What was thought to be an unidentified retrovirus had been tampering with the introns, the huge dead-code segments of our genome that seem to do nothing at all. The paired intrusions, suitably translated from the genetic alphabet, had an all too familiar structure. No one, as yet, had christened them "tags."

Ceri thought: So they found another channel and something else to modulate. Too much to hope that it might be another and nicer They. And does anyone get more than one deus-ex bailout? Staring at her own thin hand again, this time with deep distaste: tags. In there, tags. She wondered what question the biochemists would want to ask, how they might contrive to encode it, and what the afrit's poisoned answer would be.