Terry Pratchett - Night Watch

“And the beer bottle?”

For the first time since Vimes had met him, the monk frowned.

“Y'know, some bugger always tosses one over the wall on his way back from the pub on Friday nights. If it wasn't forbidden to do that kind of thing, he'd feel the flat of my hand and no mistake.”

“It's not part of the higher organization?”

“Possibly. Who cares? That sort of thing gets on my thungas , it really does,” said Sweeper. He sat back with his hands on his knees. Serenity flowed once more. “Well now, Mister Vimes…you know the universe is made up of very small items?”

“Huh?”

“We've got to work up to things gradually, Mister Vimes. You're a bright man. I can't keep telling you everything is done by magic.”

“Am I really here too? In the city? I mean, a younger me?”

“Of course. Why not? Where was I? Oh, yes. Made up of very small items, and—”

“This is not a good time to be in the Watch. I remember! 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 once when he'd been stabbed and would've bled to death if Sergeant Angua hadn't caught up with him, and how, 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 Abbot 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 Twenty-fifth 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 could happen without breaking any physical laws, it must happen. But it hasn't. And yet the ‘many universes’ 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 Abbot's very excited about this. He nearly swallowed his rusk. 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. But look, I remember Keel and, yes, he did have a scar and an eye-patch 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 three,” said Sweeper.

“Well, three's trickier, of course, but—”

“You're the policeman. You guess the name of the third man, Mister Vimes.”

Vimes hardly had to think. The answer erupted from the depths of darkest suspicion. “Carcer?”

“He soon settled in, yes.”

“The bastard was in the next cell! He even told me he'd grabbed some money.”

“And you're both stuck here, Mister Vimes. This isn't your past any more. Not exactly. It's a past. And up there is a future. It might be your future. But it might not be. You want to go home now, leaving Carcer here and the real John Keel dead? But there'll be no home to go to, if you could do that. Because young Sam Vimes wouldn't get a swift course in basic policing from a decent man if you did. He'll learn it from people like Sergeant Knock and Corporal Quirke and Lance-Corporal Colon. And that might not be the worst of it, by a long way.”

Vimes shut his eyes. He remembered how wet behind the ears he'd been. And Fred…well, Fred Colon hadn't been too bad, under the half-hearted timorousness and lack of imagination, but Quirke had been an evil little sod in his way and as for Knock, well, Knock had been Fred's teacher and the pupil wasn't a patch on the master. What had Sam Vimes learned from Keel? To stay alert, to think for himself, to keep a place in his head free from the Quirkes and Knocks of the world, and not to hesitate about fighting dirty today if that was what it took to fight again tomorrow.

He'd often thought he'd have been dead long ago if it wasn't for—

He looked up sharply at the monk.

“Can't tell you that, Mister Vimes,” said Lu-Tze. “Nothing's certain, 'cos of quantum.”

“But, look, I know my future happened, because I was there!”

“No. What we've got here, friend, is quantum interference. Mean anything? No. Well…let me put it this way. There's one past, and one future. But there are two presents. One where you and your evil friend turned up, and one where you didn't. We can keep these two presents going side by side for a few days. It takes a lot of run time, but we can do it. And then they'll snap back together. The future that happens depends on you. We want the future where Vimes is a good copper. Not the other one.”