Ursula Le Guin - The Compass Rose

“Come on, fella,” I coaxed him. “Come, come on, that’s a boy, good doggie!” I opened a can of pork and beans for him at once, for he looked half starved. He ate voraciously, gulping and lapping. When it was gone he said “Wow!” several times. I was just about to scratch him behind the ears when he stiffened, his hackles bristling, and growled deep in his throat. He had noticed the cat

The cat had noticed him some time before, without interest, and was now sitting on a copy of The Well-Tempered Clavier washing sardine oil off its whiskers.

“Wow!” the dog, whom I had thought of calling Rover, barked. “Wow! Do you know what that is? That’s Schrodinger’s cat!”

“No it’s not, not any more; it’s my cat,” I said, unreasonably offended.

“Oh, well, Schrodinger’s dead, of course, but it’s his cat. I’ve seen hundreds of pictures of it. Erwin Schrodinger, the great physicist, you know. Oh, wow! To think of finding it here!”

The cat looked coldly at him for a moment, and began to wash its left shoulder with negligent energy. An almost religious expression had come into Rover’s face. “It was meant,” he said in a low, impressive tone. “Yah. It was meant. It can’t be a mere coincidence. It’s too improbable. Me, with the box; you, with the cat; to meet—here—now.” He looked up at me, his eyes shining with happy fervor. “Isn’t it wonderful?” he said. “I’ll get the box set up right away.” And he started to tear open his huge knapsack.

While the cat washed its front paws, Rover unpacked. While the cat washed its tail and belly, regions hard to reach gracefully, Rover put together what he had unpacked, a complex task. When he and the cat finished their operations simultaneously and looked at me, I was impressed. They had come out even, to the very second. Indeed it seemed that something more than chance was involved. I hoped it was not myself.

“What’s that?” I asked, pointing to a protuberance on the outside of the box. I did not ask what the box was as it was quite clearly a box.

“The gun,” Rover said with excited pride.

“The gun?”

“To shoot the cat.”

“To shoot the cat?”

“Or to not shoot the cat. Depending on the photon.”

“The photon?”

“Yah! It’s Schrodinger’s great Gedankenexperiment You see, there’s a little emitter here. At Zero Time, five seconds after the lid of the box is closed, it will emit one photon. The photon will strike a half-silvered mirror. The quantum mechanical probability of the photon passing through the mirror is exactly one half, isn’t it? So! If the photon passes through, the trigger will be activated and the gun will fire. If the photon is deflected, the trigger will not be activated and the gun will not fire. Now, you put the cat in. The cat is in the box. You close the lid. You go away! You stay away! What happens?” Rover’s eyes were bright.

“The cat gets hungry?”

“The cat gets shot—or not shot,” he said, seizing my arm, though not, fortunately, in his teeth. “But the gun is silent, perfectly silent. The box is soundproof. There is no way to know whether or not the cat has been shot, until you lift the lid of the box. There is no way! Do you see how central this is to the whole of quantum theory? Before Zero Time the whole system, on the quantum level or on our level, is nice and simple. But after Zero Time the whole system can be represented only by a linear combination of two waves. We cannot predict the behavior of the photon, and thus, once it has behaved, we cannot predict the state of the system it has determined. We cannot predict it! God plays dice with the world! So it is beautifully demonstrated that if you desire certainty, any certainty, you must create it yourself!”

“How?”

“By lifting the lid of the box, of course,” Rover said, looking at me with sudden disappointment, perhaps a touch of suspicion, like a Baptist who finds he has been talking church matters not to another Baptist as he thought, but a Methodist, or even, God forbid, an Episcopalian. “To find out whether the cat is dead or not.”

“Do you mean,” I said carefully, “that until you lift the lid of the box, the cat has neither been shot nor not been shot?”

“Yah!” Rover said, radiant with relief, welcoming me back to the fold. “Or maybe, you know, both.”

“But why does opening the box and looking reduce the system back to one probability, either live cat or dead cat? Why don’t we get included in the system when we lift the lid of the box?”

There was a pause. “How?” Rover barked, distrustfully.

“Well, we would involve ourselves in the system, you see, the superposition of two waves. There’s no reason why it should only exist inside an open box, is there? So when we came to look, there we would be, you and I, both looking at a live cat, and both looking at a dead cat. You see?”

A dark cloud lowered on Rover’s eyes and brow. He barked twice in a subdued, harsh voice, and walked away. With his back turned to me he said in a firm, sad tone, “You must not complicate the issue. It is complicated enough.”

“Are you sure?”

He nodded. Turning, he spoke pleadingly. “Listen. It’s all we have—the box. Truly it is. The box. And the cat. And they’re here. The box, the cat, at last. Put the cat in the box. Will you? Will you let me put the cat in the box?”

“No,” I said, shocked.

“Please. Please. Just for a minute. Just for half a minute! Please let me put the cat in the box!”

“Why?”

“I can’t stand this terrible uncertainty,” he said, and burst into tears. I stood some while indecisive. Though I felt sorry for the poor son of a bitch, I was about to tell him, gently, No; when a curious thing happened. The cat walked over to the box, sniffed around it, lifted his tail and sprayed a corner to mark his territory, and then lightly, with that marvellous fluid ease, leapt into it. His yellow tail just flicked the edge of the lid as he jumped, and it closed, falling into place with a soft, decisive click.

“The cat is in the box,” I said.

“The cat is in the box,” Rover repeated in a whisper, falling to his knees. “Oh, wow. Oh, wow. Oh, wow.”

There was silence then: deep silence. We both gazed, I afoot, Rover kneeling, at the box. No sound. Nothing happened. Nothing would happen. Nothing would ever happen, until we lifted the lid of the box.

“Like Pandora,” I said in a weak whisper. I could not quite recall Pandora’s legend. She had let all the plagues and evils out of the box, of course, but there had been something else, too. After all the devils were let loose, something quite different, quite unexpected, had been left. What had it been? Hope? A dead cat? I could not remember.

Impatience welled up in me. I turned on Rover, glaring. He returned the look with expressive brown eyes. You can’t tell me dogs haven’t got souls.

“Just exactly what are you trying to prove?” I demanded.

“That the cat will be dead, or not dead,” he murmured submissively. “Certainty. All I want is certainty. To know for sure that God does play dice with the world.”

I looked at him for a while with fascinated incredulity. “Whether he does, or doesn’t,” I said, “do you think he’s going to leave you a note about it in the box?” I went to the box, and with a rather dramatic gesture, flung the lid back. Rover staggered up from his knees, gasping, to look. The cat was, of course, not there.

Rover neither barked, nor fainted, nor cursed, nor wept. He really took it very well.

“Where is the cat?” he asked at last

“Where is the box?”

“Here.”

“Where’s here?”