Schild's
Ladder
by by Greg Egan
A book review by Mark L. Olson
Eos, 2002, $25.95, 340 pp
This one blew me away!
I've always liked Greg Egan's work, especially when he does one of his harder SF stories like Disapora. He is perhaps the greatest hard SF writer writing today. This one is remarkable, though, even for Egan.
Schild's Ladder is set in a future he Egan has used before, where humanity is spread out over thousands of planets in an STL universe. Modern mankind's minds run on processors which occupy the brain cavity (if they choose to be embodied – many choose to live in AI worlds) and people are enormously long-lived, especially since they can transmit their mental state to a backup. The ability to transmit a mental state also allows for form of light-speed teleportation. You send your mind off on a radio beam and at the receiving end, it's put back into a body.
The world is odd in that it is not a post-Singularity world. Strong AI happened, but nothing much changes. People – in spite of now being infinitely malleable in both body and mind – have chosen not to change much from ur-humanity, society isn't even that different. Odd, and rather implausible, I think.
Quite early in the story, some scientists working on really basic Planck-level physics accidentally destroy the universe. There were being very careful, but these things happen. The vacuum starts collapsing into a new state and this new state expands away from the site of the experiment at half the speed of light.
When people can transmit their minds at lightspeed, there's plenty of time to get away, so there is no significant loss of life, but the loss of thousands of planets is terrible and Earth itself (home to a tiny fraction of humanity, but revered for its antiquities) is only a few hundred years from being doomed as the front where space, time, matter, and energy are all being dissolved into strangeness sweeps toward it.
Some scientists have built a ship, the Rindler which has been carefully maneuvered to be just a mile in front of the edge of the collapsing vacuum, moving at the same half-lightspeed. To people on the Rindler, the edge of the collapsing space seems like a stationary glowing wall which they can study. Gadgets to study the vacuum front can be as close as a few feet from it.
But factions break out among the scientists as among mankind as a whole: the Yielders think that the new phenomenon is good for mankind, since it forces people out of their age-old rut (think of the kinds of ruts societies could get into when nearly everyone is thousands of years old and have lived in the same house for a thousand years), while the Preservationists want to stop the process and preserve the planets and their traditional cultures.
Some major discoveries are made, the main one being that the advancing front isn't simply a collapse of the vacuum to a new, more stable state but a collapse of the laws of physics as we know them into a stew of multiple chaotic laws all mixed together and superimposed by quantum mechanics. (This is all fairly plausible – while it's serious handwaving, it's very well-disciplined handwaving and could even turn out to be true, though neither I nor Egan would bet on it. Incidentally, some people may be put off by the extensive description of quantum mechanics and quantum physics that Egan employs. Just skim over it. He's playing fair and if you follow where he leads, you'll get enough of the gist to follow him to the wonderfully bizarre places he takes you.)
The factionalism becomes so extreme that the major scientific instruments are duplicated so that each group can pursue its own researches. The Yielders are attempting to study the collapse, while the Preservationists are attempting to build a countermeasure ("Planck worms") which will freeze its advance or even reverse the process.
At the climactic end of the story, a few characters manage to penetrate the barrier by indirectly constructing computing equipment on the other side and transmitting their minds (which run on computers on this side, anyway) onto them. The final chunk of the book is the exploration of the utterly alien – but terribly beautiful – world of quantum-chaotic physics.
As if this wasn't enough, in parallel with all this Egan returns to one of his favorite themes: the nature of identity, self and consciousness. Are these near-immortals really nearly immortal? When they transmit themselves, turning off the copy on their origin planet and turning on the copy at the destination, does a single person travel or does one person die and someone who merely thinks they're the same person appears elsewhere? When people back themselves up – which the people in this world do all the time – and then are re-created from a backup after an accident, are they the same person with a couple days' memory loss or did someone really die? Etc. Egan quite clearly comes down on the side of memory being all there is: a copy of you is you if you think you're you. (This is obviously a deeply-held believe of his, but I still find it extremely hard to accept.)
He also takes a good look at the problem of identity in a near-immortal. If you have an active adult life measured in tens of thousands of years (and it may be much longer – few people have died in Egan's sense anywhere since the development of these technologies 20,000 years previously) are you still the same person after ten thousand years of small changes or have you turned into a complete stranger? We face the same problem, of course, but on a much smaller scale.
Egan is a devout and proselytizing atheist, and he seems to have had particular difficulty dealing with C. S. Lewis – hardly surprising, since Lewis addressed a lot of his writing specifically challenge people like Egan. Like his excellent, but flawed, story "Oracle", Schild's Ladder is something of an answer to Lewis and, like "Oracle", is a failed answer.
Lewis, particularly in his superb That Hideous Strength took on the worship of science and change and, in particular, the idea that mankind might remake itself into its own image. Lewis felt that the odds were somewhere between high and certain that if Mankind could remake itself, it would botch the job and create a literal hell on Earth.
The N.I.C.E. in That Hideous Strength is nominally aimed to develop the techniques which will allow man to be immortal and to entirely control his own destiny, though reflecting Lewis' opinion of the enterprise, is actually a front for a demonic power hoping to corrupt all of humanity.
Since Egan buys N.I.C.E.'s ostensible program lock, stock, and barrel – most of his fiction shows its working-out – it's hardly surprising that he vigorously objects to Lewis. To be sure, Egan's people are, well, nicer than the people of N.I.C.E. who are an amalgam of British communists, British fascists, and irritating college officials. The terrible destruction which was visited on N.I.C.E. in That Hideous Strength was just. While Egan's characters are people you'd like to have as friends. (I doubt that any of them would still be very nice after even a thousand years of life in Egan's world. I find Lewis much more persuasive than Egan, primarily because all Egan does is write a story where everyone is nice, while Lewis writes a story showing how people can degrade each other.)
One of the criticisms leveled against That Hideous Strength is that N.I.C.E.'s science is a caricature of real science. (The people, however, are all too real. I've met people who are like each of the villains, though, happily for me, not as far gone.) This is true, but it mostly reflects Lewis' background in English literature. Lewis could have written just the same story using the beginnings of Egan's much more plausible technologies.
"Oracle" is Egan's direct reply to THS: A thinly-disguised Lewis in a thinly-disguised Oxford finds himself in a situation paralleling That Hideous Strength, though in Egan's story they are beings who claim to be time travelers rather than angels. Egan tries to show that the Lewis-character must necessarily be a fool to follow the script of That Hideous Strength, thus invalidating the book.
He fails, utterly, because he has to provide the Lewis-character with something to parallel the angels of THS. But time-travelers? Frankly, in the real universe, I think angels are a rather more likely explanation for seemingly impossible events than time travelers! The physics we know tells us that time travel, while theoretically possibly possible, is so utterly unlikely that a rationalist and a skeptic – which Egan demands us to be – must reject that as an explanation of the facts in the story. Angels, which are merely outside our personal experience (and, further, are well-attested to in history) are a far more rational explanation!
(Technically, the problems are that time travel seems to require energies so large that they couldn't be used in the vicinity of the Solar System without dire consequences, and additionally, we cannot imagine any way to actually build a time machine. Finally all of the plausible time machines only allow travel during the lifetime of the machine. They cannot take you back before the machine started operating.)
I can't say that I expect to encounter either, but from a purely rational point of view, the objections to angels are fewer. Egan the rationalist could only attack Lewis the irrationalist (or so Egan thinks, at least) by abandoning his own rational principles.
Likewise in Shild's Ladder (in one of the less-satisfying parts) Egan takes a bit of a back-handed swipe at Lewis by introducing characters who have spent the last 20,000 years traveling in cold sleep. They're religious fanatics of some unspecified, but anti-Eganist, cult who left 23rd century Earth because they hated its nascent Eganism and have spent the last 20,000 years turning up now and then, seeing that mankind is still corrupt, and running off again. Silly – and not even tragic.
The problem is that unlike in "Oracle" where he took a first-rate shot at answering Lewis, here all he does is take a cheap shot.
These minor problems notwithstanding, this is a truly wonderful piece of hard SF. It's full of sensa wonder and brilliant speculations, all strongly grounded in the best of today's science. Previously, I thought that Diaspora was Egan's best: this topped it.
Highly recommended! (And it will come as no surprise to any of you that this will surely be on my Hugo list.)
See my other review of books by Greg Egan: Shild's Ladder, Quarantine
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