The Long Earth

when we return through this world, or when another craft passes this way in the future.’
    Among the creatures by the lake below were some kind of rhino, giant beasts with oddly slender legs. They clustered at the water’s edge, shoving each other aside as they tried to get a drink.
    Lobsang said, ‘You’ll find binoculars and cameras throughout the observation deck. Those animals look something like an elasmotherium, perhaps. Or a much-evolved descendant.’
    ‘That means nothing to me, Lobsang.’
    ‘Of course not. You want a species of your own? Name them if you like; I’m recording everything we see, hear, say and do, and will lodge the claims when we get home.’
    Joshua sat back. ‘Let’s go on. We’re wasting time.’
    ‘Time? We’ve all the time in the worlds. However—’
    The stepping began again, and the rhino-like herd disappeared. Joshua felt the ride now as a gentle jolting, like a car with good suspension travelling over a rutted road.
    He figured they were now crossing an Earth every couple of seconds, over forty thousand new worlds a day, if they kept this up around the clock (which they wouldn’t). Joshua was impressed, but he wasn’t about to say so. Landscapes swept beneath the prow of the ship, only their broadest features possible for him to discern, whole worlds passing to the beat of his own pulse. Animal herds and lone beasts were no sooner glimpsed than they were gone, whisked into the unreality of stepwise otherness. Even the tree clumps shifted in shape and size from world to world, shift, shift, shift. And there were flickers – plunges into brief darkness, occasional flares of light, washes of odd colours across the landscape. Exceptional worlds of some kind, pulled from his sight before they could be comprehended. Otherwise there was only the chain of worlds, Earth after Earth smoothed to uniformity by the ship’s motion.
    ‘Joshua, do you ever wonder where you are?’
    ‘I know where I am. I’m here.’
    ‘Yes, but where is
here
? Every few seconds you enter a different stepwise world. So
where
is this world in relation to the Datum? And the next, and the next? How can there be room for them all?’
    Actually Joshua had wondered about that. It was impossible to be a stepper without asking such questions. ‘I know Willis Linsay left a note: “The next world is the thickness of a thought away.”’
    ‘Unfortunately that was about the only comprehensible thing he did write down. Apart from that we’re floundering. So where is
this
world, this particular Earth? It’s in exactly the same space and time as Datum Earth. It’s like another mode of vibration of a single guitar string. The only difference is that now we can visit it; we couldn’t even detect it before. That’s pretty much the best answer transEarth’s tame physicists can supply.’
    ‘Is all this science stuff in Linsay’s notes?’
    ‘We don’t know. He seems to have invented his own mathematics. We have Warwick University working on that. But he also compressed everything he wrote into a fantastically arcane code. IBM won’t even quote on untangling
that
. Also his handwriting’s appalling.’
    He kept talking, but Joshua managed to tune him out. It was a skill, he suspected, he was going to have to develop.
    Music filled the deck, the cold notes of a harpsichord.
    ‘Would you mind shutting that off?’
    ‘It’s Bach,’ Lobsang said. ‘A fugue. A clichéd choice for an entity of mathematics such as myself, I know.’
    ‘I prefer silence.’
    ‘Of course you do.’ The music died. ‘It will not offend you if I continue to listen, in my head, as it were?’
    ‘Do what you like.’ Joshua stared at the latest landscape blankly.
    And the next, and the next.
    He rolled off his couch and tried out the deck’s can. It was a chemical toilet with a narrow bay for a shower, inside a plastic-walled compartment. Joshua wondered if Lobsang had eyes in here too. Well, of course he did.
    Thus the day wore away. At last it grew dark on all the Earths, the myriad suns sinking to their respective horizons.
    ‘Do I have to go up to my stateroom to sleep?’
    ‘Your couch will fold out. Pull the lever to your right. There are blankets and pillows in the trunk.’
    Joshua tried it out. The couch was like a first-class airliner seat. ‘Wake me if anything interesting happens.’
    ‘It’s all interesting, Joshua. Sleep now.’
    As he settled under a comfortingly heavy throw, Joshua listened to the