In this highly readable standalone novel, Ken MacLeod continues to bring his own quirky socio-political perspective to hard SF.
Initially, the world which must be learned is an immense, human-built habitat-cum-starship known as a sunliner (referring to its axial thread of illumination, like Gene Wolfe's Long Sun). The learner is a young member of the latest ship generation, reared to colonize the destination system. Cutely named Atomic Discourse Gale, she publishes a weblog-equivalent called Learning the World and at an early age discovers – is encouraged to discover – that although the sunliner is nearing the end of a mere 400-year journey, it is four thousand years old.
The traditional SF problem of lost knowledge and continuity doesn't arise here, since human lifespans are indefinitely extended and the ship generation feels almost overburdened with elder mentors. Constantine the Oldest Man, who named the starship four millennia ago, is still present and active.
The second world to be learned is Ground, one of the planets at journey's end, which closely resembles Earth. Its batlike inhabitants are grappling with electromagnetic communications, and are good enough astronomers to note the oddity of an approaching "comet" whose path implies deceleration. Of course the notion of alien contact is bizarre, unthinkable, the stuff of old batwives' tales and batpulp magazines ...
Aboard the sunliner this concept is even harder to swallow, owing to many thousands of years of hope and invariable disappointment. Humanity knows from experience that there are no aliens. Odd signals from Ground must clearly be misinterpretations of periodic lightning in long-lived storm systems. Or something.
MacLeod's gentle comedy of misunderstanding and misinterpretation takes off from here. The fact of out-of-system arrivals cannot be long concealed, especially when the human-launched probe automatically proceeds to rewire Ground dung beetles ("shittles") as literal bugs, whose transmissions soon alert the natives by interfering with phone systems. A Groundling attempt at reciprocal communication through the shittles triggers ancient, forgotten layers of probe software, producing a recorded message which though not disastrous is a seriously inept First Contact.
For all their sense of cultural superiority as long-time cave dwellers (living within asteroids and space habitats rather than on horrible old planets), the human elders start to panic at the shock of the new, and to tinker dangerously with shipboard civil liberties. Those "alien space bats" are engaging when seen through other Grounder eyes, but to outsiders come across as uncuddly, unhygienic, and committed to the practice of slavery. Should they follow the pattern of our own history, it is nervously argued, they must shortly plunge into cycles of war, arms races and gigantic atrocities. When Earth's twentieth century is gently explained to one younger human, he pukes uncontrollably.
Meanwhile, Atomic and her contemporaries are frustrated by delays to their promised destiny of filling this system with the Earth-biosphere habitats which, to the puzzlement of Ground astronomers, are increasingly giving the stars in "our" quarter of the sky a tinge of green. Old man Constantine arranges a compromise which provides a jolting sense of the sunliner's scale. The youngsters are turned loose on an internal playground tens of thousands of cubic kilometres in size, littered with millions of tons of asteroid material from the previous port of call, all this casually hauled along at 0.01c by the ship's resistless "cosmogonic engine". There is more to this gambit than meets the eye.
Besides rebellious youth and worriedly over-controlling elders, a third sunliner faction is the crew itself, mostly committed to travelling forever like contented Flying Dutchmen. Since aliens have always been assumed not to exist, the crew feels unconstrained by any prime directive and launches an ingenious scheme to decipher the Grounder language by "non-intrusive" means which nevertheless create a profound transformation. The law of unintended consequences strikes again.
It's all great fun, full of neat touches like the conceit of living in caves being the apex of civilization, or the internal economics of the sunliner (including a buoyant market in solar-system-exploitation futures), and such defining SF moments as a character's first, surprised encounter with airborne plant seeds: "Genetic machinery was falling out of the sky." There are witty suggestions of parallel mental evolution, or of inevitable convergence, as Ground's institutions echo human ones – even to the extent of a Fortean data dump, the Anomaly Room, where clues to the activity of the alien space monkeys may be gleaned.
Whether it's parallel plot evolution, intentional homage, or my own imagination, Learning the World resonates interestingly with Vernor Vinge's notable first contact novel A Deepness in the Sky. Both feature aliens (spiders; bats) on the cusp between 19th- and 20th-century scientific comprehension, who are charmingly human (perhaps almost too human) from one viewpoint, unprepossessing monsters from another. Starfaring human visitors have vastly superior technology but also deep divisions that lead to conflict. The discovery of television plays a vital part below, while antique, accreted layers of computation and protocol are important above. In each novel a very old founding father plays a devious game involving the release of booby-trapped suggestions and data.
But this is to digress. Back in the present work, there are well-timed climactic surprises for both batfolk and humans. The latters' sense of smug maturity is quietly but firmly punctured. Actual events seem understated and lightweight by comparison with the foreshadowed possibilities of this first-contact scenario, but the finale is amply satisfying.
Almost as an afterthought – though preparations have been laid in a passage of bravura technobabble – MacLeod offers a bizarre cosmological answer to the Fermi Paradox which has exercised more than one character. If the universe is so conducive to life, and the statistics require countless Earthlike planets to exist, then just where is everybody else? A single contact with Ground makes the question more rather than less pointed: the counter-argument that life on Earth was a uniquely freakish one-off is deflated when it emerges that the lightning has struck again, even to the extent of similar DNA, in our own galactic neighbourhood. All is resolved in the final pages of Learning the World, which left at least one reader murmuring, "Oh, not so damned shaggy ..."