“It’s an interesting theory,” said Arnold, “but I don’t see how you could ever prove it.” They had come to the steepest part of the hill and for a moment Webb was too breathless to reply.
“I’m not trying to,” he said when he had gained his second wind. “I’m only exploring its consequences.”
“Such as?”
“Well, let’s be perfectly logical and see where it gets us. Our only assumption, remember, is that the universe is infinite.”
“Right. Personally I don’t see what else it can be.”
“Very well. That means there must be an infinite number of stars and planets. Therefore, by the laws of chance, every possible event must occur not merely once but an infinite number of times. Correct?”
“I suppose so.”
“Then there must be an infinite number of worlds exactly like Earth, each with an Arnold and Webb on it, walking up this hill exactly as we are doing now, saying these same words.”
“That’s pretty hard to swallow.”
“I know it’s a staggering thought – but so is infinity. The thing that interests me, though, is the idea of all those other Earths that aren’t exactly the same as this one. The Earths where Hitler won the War and the Swastika flies over Buckingham Palace – the Earths where Columbus never discovered America – the Earths where the Roman Empire has lasted to this day. In fact the Earths where all the great If’s of history had different answers.”
“Going right back to the beginning, I suppose, to the one in which the apeman who would have been the daddy of us all, broke his neck before he could have any children?”
“That’s the idea. But let’s stick to the worlds we know – the worlds containing us climbing this hill on this spring afternoon. Think of all our reflections on those millions of other planets. Some of them are exactly the same but every possible variation that doesn’t violate the laws of logic must also exist.
“We could – we must – be wearing every conceivable sort of clothes – and no clothes at all. The Sun’s shining here but on countless billions of those other Earth’s it’s not. On many it’s winter or summer here instead of spring. But let’s consider more fundamental changes too.
“We intend to walk up this hill and down the other side. Yet think of all the things that might possibly happen to us in the next few minutes. However improbably they may be, as long as they are possible, then somewhere they’ve got to happen.”
“I see,” said Arnold slowly, absorbing the idea with obvious reluctance. An expression of mild discomfort crossed his features. “Then somewhere, I suppose, you will fall dead with heart failure when you’ve taken your next step.”
“Not in this world.” Webb laughed. “I’ve already refused it. Perhaps you’re going to be the unlucky one. “
“Or perhaps,” said Arnold, “I’ll get fed up with the whole conversation, pull out a gun and shoot you.”
“Quite possibly,” admitted Webb, “except that I’m pretty sure you, on this Earth, haven’t got one. Don’t forget, though, that in millions of those alternative worlds I’ll beat you on the draw.”
The path was now winding up a wooded slope, the trees thick on either side. The air was fresh and sweet. It was very quiet as though all Nature’s energies were concentrated, with silent intentness, on rebuilding the world after the ruin of winter.
“I wonder,” continued Webb, “how improbably a thing can get before it becomes impossible. We’ve mentioned some unlikely events but they’re not completely fantastic. Here we are in an English country lane, walking along a path we know perfectly well.
“Yet in some universe those – what shall I call them? – twins of ours will walk around that corner and meet anything, absolutely anything, that imagination can conceive. For as I said at the beginning, if the cosmos is infinite, then all possibilities must arise.”
“So it’s possible,” said Arnold, with a laugh that was not quite as light as he had intended, “that we might walk into a tiger or something equally unpleasant.”
“Of course,” replied Webb cheerfully, warming to his subject. “If it’s possible, then it’s got to happen to someone, somewhere in the universe. So why not to us?”
Arnold gave a snort of disgust. “This is getting quite futile,” he protested. “Let’s talk about something sensible. If we don’t meet a tiger round this corner I’ll regard your theory as refuted and change the subject.”
“Don’t be silly,” said Webb gleefully. “That won’t refute anything. There’s no way you can–“
They were the last words he ever spoke. On an infinite number of Earths an infinite number of Webbs and Arnolds met tigers friendly, hostile or indifferent. But this was not one of those Earths – it lay far closer to the point where improbability urged on the impossible.
Yet of course it was not totally inconceivable that during the night the rain-sodden hillside had caved inward to reveal an ominous cleft leading down into the subterranean world. As for what had laboriously climbed up that cleft, drawn towards the unknown light of day – well, it was really no more unlikely than the giant squid, the boa-constrictor or the feral lizards of the Jurassic jungle. It had strained the laws of zoological probability but not to the breaking-point.
Webb had spoken the truth. In an infinite cosmos everything must happen somewhere – including their singularly bad luck. For it was hungry – very hungry – and a tiger or a man would have been a small yet acceptable morsel to any one of its half dozen gaping mouths.
The theory of multiple worlds, with which Mr Clarke has toyed so effectively and terrifyingly in the just-finished story above, is one of the most fascinating in the entire realm of speculative thought upon which science fiction is based. It goes by many names – among them parallel worlds, parallel time-tracks and even the broomstick theorem of space-time. The whole idea is based on a more-or-less reasonable supposition that everything that happens in our world and universe could or can happen in several ways – and does so in an infinity of ever-branching cosmoses. Hence the unpleasant hungry “tiger” in Mr Clarkes hillside becomes quite unpleasantly reasonable. And while the whole idea of multiple worlds may seem absurdly and abstractively impractical to literal minds it might be well to remember that the A and H-bombs were mere metaphysical speculations until not so many years ago. Practical-minded folk would be wise to stay on guard. (Original postscript to the story from Fantastic Universe.)
Arthur C. Clarke (1917-2008) was considered one of the “Big Three” writers of twentieth century science fiction, alongside Isaac Asimov and Robert A. Heinlein. His short story, “The Other Tiger”, was first published in 1953 in the June-July issue of Fantastic Universe.
Cyborg Ink 