Science of Discworld III

with zero momentum is not moving at that instant, and so will not go anywhere, whereas one in the same position with non-zero momentum – which appears identical – is moving, even though instantaneously it stays in the same place.
    Got that?
    Anyway, we were talking about Thief of Time , and thanks to Xeno we’ve not yet got past see here . The main point is that Discworld time is malleable, so the laws of narrative imperative sometimes need a little help to make sure that the narrative does what the imperative says it should.
    Tick .
    Lady Myria LeJean is an Auditor of reality, who has temporarily assumed human form. Discworld is relentlessly animistic; virtually everything is conscious on some level, including basic physics. The Auditors police the laws of nature; they would very likely fine you for exceeding the speed of light. They normally take the form of small grey robes with a cowl – and nothing inside. They are the ultimate bureaucrats. LeJean points out to Jeremy that the perfect clock must be able to measure Xeno’s smallest unit of time. ‘It must exist, mustn’t it? Consider the present. It must have a length, because one end of it is connected to the past and the other is connected to thefuture, and if it didn’t have a length then the present couldn’t exist at all. There would be no time for it to be the present in.’
    Her views correspond rather closely to current theories of the psychology of the perception of time. Our brains perceive an ‘instant’ as an extended, though brief, period of time. This is analogous to the way discrete rods and cones in the retina seem to perceive individual points, but actually sample a small region of space. The brain accepts coarse-grained inputs and smooths them out.
    LeJean is explaining Xeno to Jeremy because she has a hidden agenda: if Jeremy succeeds in making the perfect clock, then time will stop. This will make the Auditors’ task as clerks of the universe much simpler, because humans are always moving things around, which makes it difficult to keep track of their locations in time and space.
    Tick .
    Near the Discworld Hub, in a high, green valley, lies the monastery of Oi Dong, where live the fighting monks of the order of Wen, otherwise known as History Monks. They have taken upon themselves the task of ensuring that the right history happens in the right order. The monks know what is right because they guard the History Books, which are not records of what did happen, but instructions for what should.
    A youngster named Ludd, a foundling brought up by the Thieves’ Guild, where he was an exceptionally talented student, has been recruited to the ranks of the History Monks and given the name Lobsang. The monks’ main technological aids are procrastinators, huge spinning machines that store and move time. With a procrastinator, you can borrow time and pay it back later. Lobsang wouldn’t dream of living on borrowed time, though – but if it wasn’t nailed down, he would almost certainly steal it. He can steal anything, and usually does. And, thanks to the procrastinators, time is not nailed down.
    If you haven’t got the joke by now, take another look at the title.
    LeJean’s plan works; Jeremy builds his clock.
    Ti —
    Time stops, which is what the Auditors wanted. Not only on Discworld: temporal stasis expands across the universe at the speed of light. Soon, everything will stop. The History Monks are powerless, for they, too, have stopped. Only Susan Sto Helit, Death’s granddaughter, can get time started again. And Ronnie Soak, who used to be Kaos, the Fifth Horseman of the Apocralypse, but left because of artistic disputes before they became famous … Fortunately, the Auditors like obeying rules, and DO NOT FEED THE ELEPHANT really perplexes them when there is no elephant to feed. Fatally, they also have a love–hate relationship with chocolate. They are living on stolen time.
    A procrastinator is a sort of time machine, but it moves time itself, instead of moving people through time. Moreover, it’s fact, not fiction, as is all of Discworld to those who live there. On Roundworld, the first fictional time machine, as opposed to dreams or narrative timeslip, seems to have been invented by Edward Mitchell, an editor for the New York Sun newspaper. In 1881 he published an anonymous story, ‘The Clock That Went Backward’, in his paper. The most celebrated time-travel gadget appears in Herbert George Wells’s novel The Time