Night Watch

There’s the curfew. And that was only the start!”
    “Small items, Mister Vimes,” said Sweeper sharply. “You need to know this.”
    “Oh, all right . How small?”
    “Very, very small. So tiny that they have some very strange ways indeed.”
    Vimes sighed. “And I ask you: what ways are these, yeah?”
    “I’m glad you asked that question. For one thing, they can be in many places at once. Try to think, Mister Vimes.”
    Vimes tried to concentrate on what was probably the Discarded Fish-And-Chip Wrapper of Infinity. Oddly enough, with so many horrible thoughts crowding his head, it was almost a relief to put them on one side in order to consider this. The brain did things like that. He remembered how once, when he’d been stabbed and would’ve bled to death if Sergeant Angua hadn’t caught up with him, as he lay there, he’d found himself taking a very intense interest in the pattern of the carpet. The senses say: we’ve only got a few minutes, let’s record everything, in every detail…
    “That can’t be right,” he said. “If this seat is made up of lots of tiny things that can be in lots of places at once, why is it standing still?”
    “Give the man a small cigar!” said Sweeper jubilantly. “That’s the big problem, Mister Vimes. And the answer, our Abbott tells us, is that it is in lots of places at once. Ah, here’s the tea. And in order for it to be in lots of places at once, the multiverse is made up of a vast number of alternative universes. An oodleplex of oodleplexes. That’s like the biggest number anyone can think of, ever. Just so’s it can accommodate all the quantum. Am I going too fast for you?”
    “Oh, that ,” said Vimes. “I know about that . Like, you make a decision in this universe and you made a different decision in another one. I heard the wizards talking about that at a posh reception once. They were…arguing about the Glorious 25th of May.”
    “And what were they saying?”
    “Oh, all the old stuff…that it would have turned out different if the rebels had properly guarded the gates and the bridges, that you can’t break a siege by a frontal attack. But they were saying that, in a way, everything happens somewhere…”
    “And you believed them?”
    “It sounds like complete thungas. But sometimes you can’t help wondering: what would have happened if I’d done something different—”
    “Like when you killed your wife?”
    Sweeper was impressed at Vimes’s lack of reaction.
    “This is a test, right?”
    “You’re a quick study, Mister Vimes.”
    “But in some other universe, believe me, I hauled off and punched you one.”
    Again, Sweeper smiled the annoying little smile that suggested he didn’t believe him.
    “You haven’t killed your wife,” he said. “Anywhere. There is nowhere, however huge the multiverse is, where Sam Vimes as he is now has murdered Lady Sybil. But the theory is quite clear. It says that if anything can happen without breaking any physical laws, it must happen. But it hasn’t. And yet the ‘multiverse’ theory works. Without it, no one would ever be able to make a decision at all.”
    “So?”
    “So what people do matters!” said Sweeper. “People invent other laws. What they do is important! The Abbott’s very excited about this. He nearly swallowed his biscuit. It means the multiverse isn’t infinite, and people’s choices are far more vital than they think. They can , by what they do, change the universe.”
    Sweeper gave Vimes a long look.
    “Mister Vimes, you’re thinking: I’m back in time, and damn me, I’m probably going to end up being the sergeant that teaches me all I know, right?”
    “I’ve been wondering. The Watch would offer any gutter trash a job in those days, because of the curfew and all the spying,” said Vimes. “But look, I remember Keel, and yes, he did have a scar and an eyepatch, but I’m sure as hell that he wasn’t me.”
    “Right. The universe doesn’t work like that. You were indeed taken under the wing of one John Keel, a watchman from Pseudopolis who came to Ankh-Morpork because the pay was better. He was a real person. He was not you. But do you remember if he ever mentioned to you that he was attacked by two men not long after he got off the coach?”
    “Hell, yes,” said Vimes. “The muggers. He got this—he got his scar that way. A good old Ankh-Morpork welcome. But he was a tough man. Took ’em both down, no problem.”
    “This time, there were