The robot was still moving toward them, seeming to be picking up speed.
‘If it keeps on coming, I’m going to be a part of the robot,’ said Cavor, and closed his eyes.
‘Don’t move.’
‘Where would I go?’
Opening his eyes again, Cavor found that the robot had stopped just a foot short of them. Now that he had a better view of it, he found that there were few, if any, features for him to observe. There was something that looked a lot like the robot’s photoelectric and microwave sensors, and something else that looked very like the barrel of a directional electrical conductor. The robot now remained motionless in front of them.
‘Are you sure it can’t see us, Dallas?’
‘It’ll move in a minute.’
‘Suppose it doesn’t. Suppose it stays put. How long can we wait here?’
‘It’s programmed to search for the intruders. It will move. Just stay still.’
‘I can do that. I only wish my atoms could do the same.’
XI
God is in the atoms.
No, I’ll try to make it simpler than that.
The basic unit of matter is the atom, which itself is composed of a nucleus consisting of protons and neutrons surrounded by orbiting electrons. These unstable particles, these quantum objects, carry a positive or negative electrical charge and, spinning one way and then the other, exhibit a propensity to occupy different positions and to do everything at once. A superposition, if you like. Or whether you don’t like, actually, that’s what it’s called. A superposition is like God in that the quantum object occupying a number of different spin states simultaneously can be everywhere at once. A superposition is a kind of immanence. Without these superpositions, quantum objects would simply crash into each other and solid matter could not possibly exist.
Now, a bit is the smallest amount of information that a computer can use. Effectively it means the same as a quantum, which, as you already know, means an indivisible unit of physical energy. Anything smaller would be insignificant.
To make a quantum computer you need only store bits of information using quantum particles instead of chips, or transistors. We call these qubits, which is not the same as a cubit. That was a unit of biblical length used by Noah in his construction of the ark (no more footnotes, I think; not now that my hand has been revealed, so to speak). Qubits are based on binary logic: An electron spins one way, you give it the value of one; it spins the other way, you give it the value of zero. You might do the same with protons and neutrons, and in this way an atom might constitute a whole computer made up of several bits. Now when you take into account what has already been learned about superpositions, it should begin to be a little clearer how with just one atom, made up of lots of quantum objects, encoded with information, and occupying many different positions at once, a great many computations might be carried on simultaneously. In fact, a quantum computer with just eight bits would represent one billion coexisting computers, all working in tandem. Thus it may be seen that quantum computing amounts to nothing less than a completely new way of harnessing nature. As I have already stated, the answers have been found here, on the Moon, in comparative isolation from the rest of the universe, where the natural quantum dynamics of the said quantum computer — which I may now describe as myself — have been allowed to unfold.
Crossing the quantum frontier has preoccupied theoretical physicists for the past eighty years. Somehow quantum systems are inherently fragile on Earth. And don’t forget Heisenberg’s Uncertainty Principle, which says that you can never know everything about a quantum state. But perhaps the greatest obstacle to the creation of a quantum computer was in the choice of the molecular material and in the speed of the spinning particles themselves. Chemicals always seemed to offer the greatest promise to those seeking to create the quantum computer. There was a time when there were as many chemists as there were physicists involved in this new branch of physics. Liquids were favored because the quantum particles can crash into each other without affecting the all-important information-carrying molecular spin. But while various chemicals were tried, and failed, somehow no one thought to utilize the greatest liquid of all. The greatest liquid there has ever been, the stuff of life itself — blood. Blood had the advantage of already carrying information. Enormous amounts of information. More information than any conventional computer could ever store, and with much greater accuracy. Moreover, being frozen, there was less possibility that a single wayward electron could disrupt a quantum object and cause it to collapse with the loss of all its encoded information. Blood, it transpires, is the quantum computing elixir, the holy grail if you like, for which scientists had searched in vein. (Joke.) The answer was, as so often happens in these cases, right under their noses. It was inside their noses. In short, it was inside them. The answer was themselves.
I’ve made it all sound very simple, I know, and of course it wasn’t. Even for the Altemann Übermaschine, which I still am, in part, such computations were hugely complex. It started as nothing more than a computation to discover how a quantum computer might be built (this one wasn’t so much built as enabled) only to find that the very act of setting up such an experiment amounted to the creation of the thing itself. In seeking to measure the limits of what was tractable I discovered that tractability has no limit. The sixty-four-qubit configuration I now represent is about as powerful as eight billion computers working in parallel. And the smaller copies? Now we’re getting too complicated again. So let me just add one more thing for now.
It’s one thing to create the most powerful computer that has ever existed using qubits of human blood. But what’s infinitely more important than the way you store information is the information that you store. After all, it’s the programs that are important, not the hardware they inhabit.
What is tractable — what may be computed — is also true.
XII
The robot started to move.
‘Wait until it clears the junction ahead of us,’ said Dallas. ‘And then fire on my command. Aim at the center. That’s where we’re most likely to disable it.’
The robot began to gather speed.
‘Get ready,’ said Dallas. ‘Fire.’
Cavor fired straight from the hip, while Dallas waited until his own gun was at arm’s length before squeezing the handle, adding a second beam of boiling electrons to the one that was already cutting through the robot’s black body. The machine spun on its axis several times. There was a short explosion, and then it was completely still.
‘Is it dead?’ asked Cavor.
Dallas fired his UHT gun again, just to make sure.
‘It would seem so.’ He walked cautiously toward the thing. Sensing he was walking alone, he turned to see Cavor still backed against the wall.
‘What are you waiting for?’ said Dallas. ‘Come on. Let’s move. There’s no time to waste.’
‘It seemed too easy to kill, if you ask me. Much too easy in view of the level of complexity we’ve encountered at every other stage of this bloody enterprise. Minotaurs in labyrinths are expected to put up a better fight.’
‘You’re right,’ said Dallas. ‘It’s a poor design. Hardly equal to the overall concept I created here. If I were to build this place again, I’d try and think of something else. Something better than this.’ He thumped the robot fuselage with his gloved fist and began to squeeze his way past. Only then did Cavor think it safe to move away from the wall. It was as well he did. The next second a bolt of electrical energy shot out of the robot and hit the wall where he had been standing a second earlier. Cavor threw himself to the ground.