'And then you open the box . . .'
Ian sipped his coffee, oblivious to the horrid lumps of spoiled milk. 'And in one universe you get the dead cat. But in the other, the radioactive source didn't go off. Remember there was only a fifty/fifty chance of it happening? This is the branch of the multiverse in which it didn't. The cat's still alive.'
Moira sensed that Ian was nearing the crux of his revelation. 'All right,' she allowed.
'Now this is the clever bit. What happens next is that we take the same cat - give it a nice saucer of milk and a bit of Whiskas, of course - and put it back in the box. And run the experiment again. Same thing happens: the cat isn't dead. What do you conclude?'
'You conclude that you could be in deep shit with the RSPCA, if they ever find out what you've been doing.'
'And apart from that?'
'I don't know. That you're in the branch in which the decay didn't happen, again?'
'Yes,' Ian said. 'But think about what that means: you've now switched onto the no-decay branch twice. Carry out the experiment again: same thing. Another time, and another time after that. You keep doing it, and every time you can't kill the bloody cat.'
Moira raised a finger. 'Only because you keep specifying that the cat must be alive. But if I did that experiment - say I tossed a coin, instead of going to all that trouble with Geiger counters and stuff - it wouldn't work like that, would it? I might not kill the cat straight away, but after two or three goes I'm pretty sure I would.'
'But the point is, whenever you did kill the cat, there'd always be a counterpart of you - another Moira - that didn't.'
'After one or two goes, maybe. But if I kept on not killing the cat, I'd begin to think it was a bit unusual: that something was wrong with the experiment. That's not how it works, Ian. You can't keep coming up heads. Sooner or later you always hit tails. Look, I've got a pound coin in my pocket here, I can prove--'
'No,' Ian said, correcting her gently. 'Sooner or later one of you hits tails. But the other one comes up heads. And that's how it keeps happening. No matter how improbable it seems, there'll always be one counterpart of you that finds it impossible to kill the cat, no matter how many times they try.'
'But that's absurd.'
'No, just very unlikely. Which doesn't mean that that particular counterpart doesn't exist: just that your chances of being it are very small. It's like being the queen. Someone has to be the queen, even if any one person's chances are tiny. Have you ever wondered how Her Maj feels, when she wakes up? Fuck me, she must think. I'm the queen. I'm the sodding queen!'
'I'm sure she's got used to it by now.'
'But the point still applies: logically, there'll always be one counterpart who keeps ending up in the universe in which the cat doesn't die. They might feel odd about it - they might look back at all the experiments they've run and feel a bit strange that they've been chosen as the one who never gets to kill the cat. But if they take the Many Worlds theory seriously, they'll have to conclude that someone had to end up never killing the cat. And when they finally do kill the cat, they'll know that someone else - another counterpart of them - has just failed to kill it again. And that's how it goes on.'
'For ever?'
'For ever and ever.'
They sat in silence for several moments, Moira once again wondering about the phone and the gun. If Ian had disconnected the phone, how difficult would it be to make it work again? If it was just a question of popping the connection back into the wall socket . . . she imagined herself fumbling it in, somehow managing to dial the police before Ian ripped the phone out of her hands . . . but no. That wouldn't work: Ian was an inveterate tinkerer. He'd have opened the phone and removed something. And even if he hadn't, even if she did magically get through to a warm human being, how long would it take them to get here?
And the gun: still no joy. She thought about shoving the table towards Ian, levering it up from her side so that it came crashing down on his knees, but unless she did it very quickly Ian would have time to move aside. The one thing she didn't want to do was make him any angrier without getting the gun off him.
'So that's it, is it?' she asked. 'Your big revelation? In some remote twig of the infinitely branching universe, there'll always be a cat you can't kill?'
For the first time Ian showed a flash of irritation. 'There's more to it than that. Much more. Frankly, Moira, I was hoping you'd have seen it for yourself by now.'
'Seen what?'
'The bigger picture. The cat in the box represents the outcome of just one quantum process: the tick of a Geiger counter. Now imagine if there were a million Geiger counters in the box, each pointed at their own piece of radioactive material. It only takes one tick to kill the cat. The overwhelming likelihood is that at least one Geiger counter will register an event.'
Moira chose her words carefully. 'Then I suppose the cat dies.'
'Nearly all the time, yes,' Ian said. 'But there'll still be a branch in which it doesn't. There'll still be one experiment in which none of those million counters register an event. Just because it's weird doesn't mean it won't happen, in some extreme branch of the multiverse.'
'All right,' Moira said. 'If I follow you, then you've collapsed one chain of events into a single massively unlikely outcome. How does that change things?'
'It changes things because there's no limit to how far I can take that process. Everything that ever happens is a series of quantum events. Every process in every cell in your body - every chemical reaction - it all boils down to quantum probabilities in the end. And no matter how complex the macroscopic event, there'll always be a finite probability of it not happening.'
'Give me an example.'
'Life itself,' Ian said. He seemed to have calmed down a little now. 'Think about it, Moira. Think about your body: every cell in it working to sustain the ongoing momentum of living. Molecules being shuffled around, crossing membranes, interacting with other molecules . . . all of it riding on quantum processes. The avalanche is unstoppable. But there's still a tiny probability - cosmically rare, I admit - that every single one of those processes will suddenly swerve in the wrong direction for the continuation of life. It'd be like a room full of clocks suddenly stopping ticking. Unlikely, but - given a multiverse of possibilities - it could and must happen, somewhere.'
'What if . . .' Moira said, groping for an objection. As long as she could keep Ian engaged, he seemed unlikely to do anything regrettable. 'What if the multiverse isn't big enough to contain all those possibilities? What if some events are just too rare for consideration?'
'It doesn't have to be that extreme, of course. Not every quantum process has to go wrong. Just some of them. Enough to kill you.'
'Still pretty unlikely.'
'But vastly more likely, if you take that view.'
'Now you're frightening me.'
'Then consider the more benign alternative. You're very old, lying in your deathbed after a long and happy life. You're about to die of natural causes.'
'All right,' Moira allowed.
'But what does that mean, exactly? What is death if it isn't just a series of chemical processes coming to an end?'
'Pretty bleak way of looking at it.'
'On the contrary,' Ian told her. 'Think of those chemical processes grinding to a halt. Underlying them, of course, are yet more quantum interactions. That's all anything is. And if it's possible to think of those processes coming to a halt, then it's also possible to consider them being minutely prolonged.'
'So one of me gets another minute of life?'
'More than that, Moira. One of you gets immortality. One of you never ever dies. Death is a chemical threshold. There'll always be one of you that can't quite cross it. Some flicker of life keeps sustaining you. You'll be slipping into ever remoter branches of the multiverse with each breath, but from your point of view - what does it matter? You don't perceive all those earlier versions of yourself dying away. You just feel yourself persisting.'
'That doesn't
sound like any kind of immortality I'd choose for myself,' Moira said. 'To me it sounds more like a kind of hell. Always drawing the last breath, but never, ever quite getting there. I think I'd rather throw myself under a bus than face the prospect of that.'
Ian smiled again. 'You're forgetting that no outcome is disallowed, no matter how improbable. An engine drops off a passing plane and smashes the bus to pieces. A hole opens in the road and swallows it. The bus just spontaneously disintegrates: every single weld failing catastrophically at the same moment. A freak whirlwind lifts you out of harm's way.'
'That sounds more like a miracle.'
'That's exactly what it would look like. You'd know, though: you'd realise that all that had happened is that you found the nearest non-fatal branch.'
Moira could see where this was heading. 'A gun, then,' she said, speaking the words with a kind of dull inevitability. 'I'll put a gun to my head and pull the trigger.'
'Won't work either. It will misfire. Consistently so, until you point it away from your head, or at an angle that won't prove fatal.'
'But what about the people watching me do it? Most of them will see me blow my head off. Not much immortality as far as they're concerned. They're not going to believe, are they?'
'Not until they try it for themselves.'
'We all have to put a gun against our heads, is that it? Squeeze the trigger, and if we survive - if the gun misfires - then we conclude that we're immortal?'
Ian leaned forwards. She could see the alloy gleam of the gun, the tip of the handle jutting from his pocket. So near - so tempting to try and grab it. But the very thought of trying made her feel sick with fear.
'Look back on your own life,' he said. 'Was there never a time when you came through something - an accident, or a frightening moment - and thought you were lucky not to have been killed?'
Moira shook her head, but not with complete conviction. 'I can't think of anything specific.'
'Why did you give up parachuting, Moira?'
'I didn't give it up,' she said. 'I just lost interest. I was never mad on it to begin with. There was just this bloke I happened to fancy at the time - you remember Mick, don't you?'
'I remember Mick. But I also remember why you stopped jumping. It was the day you snagged your ripcord on the door handle, walking through the canteen doorway. Unfortunately the chute didn't open. It hadn't been packed properly. And if you hadn't snagged it on the doorway, you'd never have found out until you were already falling.'
'I'd have had the reserve chute.'
'But when they examined your reserve chute, they also found that it hadn't been packed properly. Mick's ex-girlfriend still showed up at the club now and then, didn't she? No one was going to swear that it wouldn't have opened, and no one was going to swear that Mick's ex might have had something to do with it. But that was the last time anyone saw you at the club. I know, Moira. I was sorry to see you go.'
'We kept in touch.'
'There was a bit of a gap before we hooked up again. Face it: it spooked you. You kept thinking back to that door handle, and wondering what would have happened if you hadn't nipped back into the canteen for those cigarettes.'
'We'll never know,' Moira said.
'We can guess, though. The vast majority of you died, or were maimed. Some small minority of you survived. Some of you just decided not to jump that day. Some of you went back into the canteen and had the good fortune to snag that handle. Some of you did jump anyway, and even though the equipment was sabotaged you still came safely down to Earth. Some of you don't even know how lucky you are.'
'All right,' Moira said. 'So sometimes we come through the odd scrape, when things could have been much worse. But that doesn't--'
'It works on a planetary level, too,' Ian said.
'I'm sorry?'
'Have you ever realised how many times we've come this close to World War Three? The number of times when the button's almost been pushed? Not just during international flare-ups, but all the other times: when someone mistakes the moon for a salvo of incoming ICBMs; when a flock of geese or a meteor shower almost trigger Armageddon? It's terrifying, Moira! It keeps happening, over and over again! We've no right to have made it this far! It's already a fucking miracle that we made it out of the twentieth century, and yet it keeps on happening. Forget putting a gun to your head; just check your history. We've already proven it works. We're already on an extremely unlikely branch of the multiverse, whether we like it or not.'
'But we're not immortal,' Moira said. 'The people around us keep dying. Doesn't that prove--'
'Of course they keep dying. From your perspective. But from their own perspective? Nobody you ever knew has ever died. They just see everyone else dying around them.'
'Then that's our fate, is it? To live for ever, but to have everyone we ever loved die, slipping away from us like passing traffic?'
'That's why I have to know,' Ian said. 'I never said it was good news. Frankly, I'm hoping I blow my brains out. But if I keep pulling this trigger, and the pin keeps failing to fall on the loaded chamber . . . then I'll know.'
'And then?'
'Then I've got a problem. Then we've all got a problem.'
Ian removed the gun from his pocket. He spun the chamber: it made a pleasant, well-oiled whirring sound. He pushed the chamber back into the body of the gun and held the weapon to the side of his head. It looked stupid and toylike, unreal amongst the pizza boxes and Ben Elton novels and the smiling pterodactyl. It's now or never, Moira thought. She lurched forwards, grasping for the gun across the kitchen table. Her sweater caught on her coffee cup, sending it spilling across the science magazines. Ian jerked back, keeping the barrel tight against his temple.
'Don't . . .' she said.
Ian pulled the trigger. The hammer clicked down on empty space.
'Once,' he said. Then - hardly removing the gun from his head - he spun the chamber again. He pulled the trigger.
'Twice.'
He spun the chamber again. Moira pushed back from the table, her sweater sodden with coffee. She stood up, but felt frozen with terror. 'Please Ian . . .'
Ian had backed himself against the pile of computer boxes. 'Don't come any closer, Moira.'
'Or what, Ian? Or you'll kill yourself?'
He pulled the trigger again. 'Three times.'
'Ian, please.'
The whirr of the chamber, the click of the trigger. 'Four times. What do you think are the odds of that, Moira? I think rather a lot of me must have already died.'
'Ian, no.'
He spun the chamber again, let the hammer fall. 'Five times. Getting a bit spooky now, don't you think? We'll do it up to ten. Then I'll make us another cuppa.'
He spun the chamber, pulled the trigger.
By the time the police and ambulance had arrived, Moira had finished all the other cigarettes in the packet. She waited in the living room until she saw the blue lights of the emergency vehicles, spectrally beautiful in the early morning snowscape. It was still dark. When they knocked, she could barely bring herself to walk through the kitchen to open the door.
The policeman looked at Ian, swore softly. Behind him, the paramedic slowed his approach perceptibly. She had told them on the phone that Ian was dead, that there could be no doubt about it, but they had rushed here all the same. She was grateful for that: all she wanted to do was get as far away from Ian's cottage as possible.
As far away from Ian.
The policeman took her into the living room. He was about forty-five, with a beer belly and mutton-chop sideboards: she imagined him playing in a country and western band on weekends.
'Can you talk, love?'
'I told you what happened on the phone.' She smoked, having cadged another cigarette from one of the police.
'It wasn't me. I just need to know roughly what happened: we can deal with a proper statement later.'
Moira looked back through the door into the kitchen. She could just see the back of Ian's chair, with
Ian's left shoulder poking into view. She could hear soft, attentive voices. It was easy to imagine that Ian was being spoken to as well.
'Ian called me,' she said. 'We were old friends. He sounded a bit funny, so I decided it was worth driving over.'
'Bit funny in what way?'
'He kept talking about not killing himself.'
'Not killing himself?'
'I wasn't going to split hairs. I knew something was up. I just wish I'd called someone else first, so that I didn't come here on my own.'
'If it's any consolation, I doubt that we'd have got here any sooner. Not on a night like this.' He nodded back towards the paramedics in the other room. 'Those lads are on a double shift as it is.'