[For part one of the story, click the “time detective” tag]
So I should probably explain what it actually is that I do, shouldn’t I? I’m a private detective, but I started out as a physics student. I was planning on a relatively dull career in academia, as a matter of fact – I was interested in doing some work in gravitational physics, which was hardly a cutting-edge whizz-bang area, and the Brian Cox career path had yet to be invented. My plan was to finish my Master’s, get a doctorate, then settle into a life of producing three or four papers a year which nobody would read.
But I made two big mistakes. The first was putting a chemistry module down as one of my optional modules, because I didn’t like the look of electronic engineering. The other was actually paying attention.
A chance remark in an organic chemistry lecture about an unusual property of thiotimoline caused me to think about what would happen to the shape of the molecule in a Gauss-Riemann geometry. I put that together with a couple of other things – which I’m not going to mention here, obviously – and suddenly found I had worked out a way to travel through time. And not one of those “build two black holes ten thousand light years apart and rotate one of them” jobs. This required practically nothing – you probably have most of the equipment to build a small time machine yourself, though you could probably only go back a week or so on a domestic power supply without blowing a fuse.
I posted something on USENET, not saying exactly what I’d done – I didn’t want to pre-empt publication and risk that Nobel prize – but posting a couple of the calculations in a different context, as a gedankenexperiment, just to make sure I hadn’t done anything incredibly stupid.
Two hours later, a man I didn’t know, in an immaculately-tailored suit, one that fit so well that the gun he had in his pocket was extremely conspicuous, showed up at the door of my room in Halls and asked me to take a walk.
As we walked through Sackville Park, he explained the situation to me.
“You’re not the first to figure it out, you know. Feynman knew the trick, and Von Neumann. Godel probably did as well, though by the end he didn’t know much of anything. We get about one undergrad every three or four years figuring it out now.”
“So why haven’t I heard of it before?”
“Oh for God’s sake, man, I thought you were meant to be clever. It’s too dangerous ever to be made public.”
“Dangerous? But I’ve proved that changing history and paradoxes are both impossible. This would only work in a universe with a single consistent history.”
“Exactly. Think about what that means, for a moment, man. Say you want my PIN number. You say you’ll try 1111, and if it works, write it down on a piece of paper and send it back to yourself five minutes earlier. If it doesn’t, you write 1112 and send it back to yourself.” He sat down on a bench. “The only consistent history where that works is the one where you instantly get a piece of paper with my PIN on it. All cryptography becomes useless. All national secrets are instantly open to anyone. The whole fabric of civilisation comes under threat.”
“So, what, you want me to stop investigating this stuff?”
“Not at all. We know that you can’t get the truly curious to ever stop experimenting. You want to build a time machine for your own personal use, we can’t stop you – the components are too easy to get hold of. What we want you to do is to sign the Official Secrets Act – you never tell anyone else how to do it, and any attempt to misuse the technology gets you convicted of high treason. Also, you quit university, today. We don’t want you slipping bits of these ideas out, even by accident.”
“Yes. Drop out. Find another job. Whatever you want – the government will pay you thirty thousand a year to keep your mouth shut, anyway, and you can carry on your research in your own time, so long as you pass all your work on to the government. That’s the deal, take it or leave it.”
“You offer that to everyone who figures this out?”
“Yes, it’s our standard offer.”
“And has anyone ever turned you down?”
“Oh, one or two, one or two…” he stood up,“I’ll be round tomorrow with your copy of the Official Secrets Act.”
As he went, he patted the statue that he’d been sitting next to on the bench. The statue of Alan Turing.
I did as he asked.
So now, I work as a private detective. Not because I need the money as such, but just to give me something to do with my brain now that physics isn’t an option. Not that most of my cases require much of a brain. But a few require a little investigation, and that’s where I have the edge over my competitors. With my personal-sized time machine I can only go back in time a week or so, and I have to be careful not to give myself too much information about the future (the government keep a very close eye on trans-temporal communication – any sudden lottery wins and I’d be the richest man in the graveyard), but it does mean that if someone says their husband came home late last Wednesday, for example, I can go back and follow him and see where he went.
Those are the neat cases, of course. This one was worse. This time someone was dead, and it was my fault, somehow. And I was going to have to go back and meet this man, knowing he was going to die, and knowing there was nothing I could possibly do to stop it.
It’s days like that that make me wish I’d gone for electronic engineering after all.