"On the other hand, on the basis of what has been proved so far, it remains possible that there may exist (and even be empirically discoverable) a theorem-proving machine which in fact is equivalent to mathematical intuition ..."

"What's he talking about?" Sta-Hi demanded.

Cobb had stopped to watch the hollow of the great master. He still remembered the years he had spent brooding over the passage which was being recited. Humans can't build a robot as smart as themselves. But, logically speaking, it is possible for such robots to exist.

How? Cobb had asked himself throughout the 1970's, How can we bring into existence the robots which we can't design? In 1980 he had the bare bones of an answer. One of his colleagues had written the paper up for Speculations in Science and Technology. "Towards Robot Consciousness," he'd called it. The idea had all been there. Let the robots evolve. But fleshing the idea out to an actual...

"Let's go," Sta-Hi urged, tugging Cobb through G6-del's talking hollow.

Beyond, two frightened lizards scampered down the hallway. A leathery-winged creature came zooming up the hall towards them, and darted its scissoring beak at the lizards. One of the little beasts escaped with a quick back-flip, but the other was carried off over Cobb and Sta-Hi's heads, dripping pale blood.

"Survival of the Fittest," an announcer's mellow voice intoned. "One of the two great forces driving the engine of evolution."

In speeded-up motion, the little lizard laid a clutch of eggs, the eggs hatched, and new lizards grew and whisked around. The predator returned, the survivors laid eggs... over and over the cycle repeated. Each time the lizards were more agile, and with stronger rear legs. In a few minutes' time they were hopping about like loathsome little kangaroos, fork-tongued and yellow-eyed.

It was Cobb who had to urge them past this exhibit. Sta-Hi wanted to stick around and see what the lizards would come up with next.

Stepping out of the prehistoric scene, they found themselves on a carnival midway. Rifles cracked and pinball machines chimed, people laughed and shrieked, and under it all was the visceral throb of heavy machinery. The floor seemed to be covered with sawdust now; and grinning, insubstantial bumpkins ambled past. A boy and girl leaned against a cotton-candy stand, feeding each other bits of popcorn with shiny fingers. He had a prominent Adam's apple and a bumpy nose. A sine-wave profile. She wore a high, blonde pony-tail fastened by a mini-blinker. The only jarring note was a hard rain of tiny purplish lights... which seemed to pass right through everything in the scene. At first Cobb took it for static.

To their right was a huge marquee with lurid paintings of distorted human forms. The inevitable barker... checked suit, bowler, cigar-butt... leaned down at them, holding out his thin cane for attention.

"See the Freaks, Feel the Geeks!" His loud, hoarse voice was like a crowd screaming. "Pinheads! The Dog-Boy! Pencil-Necks! The Human Lima Bean! Half-Man-Half-..." Slowly the carnival noises damped down, and were replaced by the rich, round tones of the voice-over.

"Mutation. " The voice was resonant, lip-smackingly conclusive. "The second key to the evolutionary process."

The zippy little dots of purple light grew brighter. They passed right through everyone on the midway... especially those two lovers, french-kissing now, hips touching.

"The human reproductive cells are subjected to a continual barrage of ionizing radiation," the voice said earnestly. "We call these the cosmic rays."

The carnival noises faded back in now. And each of the fast little lights made a sound like a slide-whistle when it passed. The two kissing lovers began slowly to grow larger, crowding out the rest of the scene. Soon an image of the swain's bulging crotch filled the hallway. The cloth ripped loose and a single huge testicle enveloped Cobb and Sta-Hi, standing there mesmerized.

Hazy red light, the heavy, insistent sound of a heartbeat. Every so often a cosmic ray whistled through. An impression of pipes-a 3-D maze of plumbing which grew and blurred around them. Gradually the blur became grainy, and the grains grew. They were looking at cells now, reproductive cells. The nucleus of one of them waxed to hover in front of Cobb and Sta-Hi.

With a sudden, crab-like movement the nuclear material split into striped writhing sausages. The chromosomes. But now a cosmic ray cut one of the chromosomes in half! The two halves joined up again, but with one piece reversed!

"Geek gene," a hillbilly muttered somewhere in the nearly infinite fairground. And then the pictures went out. They were in a down-sloping stone hallway.

"Selection and Mutation," Cobb said as they walked on. "That was my big idea, Sta-Hi. To make the robots evolve. They were designed to build copies of themselves, but they had to fight over the parts. Natural selection. And I found a way of jiggering their programs with cosmic rays. Mutation. But to predict..."

Just ahead, a door branched off to the right. "This is your meet," Sta-Hi said, consulting his map. "The Cobb Anderson Room."

Chapter Thirteen

Looking in, our two heroes could see nothing but darkness, and a dimly glowing red polygon. They stepped through the door and the exhibit came on.

"We cannot build an intelligent robot," a voice stated firmly. "But we can cause one to evolve." A hollow of the young Cobb Anderson walked past banks of computers to meet the visitors.

"This is where I grew the first bopper programs," the recorded voice continued. The hollow smiled confidently, engagingly. "No one can write a bopper program... they're too complicated. So instead I set thousands of simple AI programs loose in there," he gestured familiarly at the computers. "There were lots of ... fitness tests, with the weaker programs getting wiped. And every so often all the surviving programs were randomly changed... mutated. I even provided for a sort of... sexual reproduction, where two programs could merge. After fifteen years, I..."

Cobb felt a terrible sickness at the gulf of time separating him from the dynamic young man he had once been. The heedless onward rush of events, of age and death ... he couldn't stand to look at his old self. Sick at heart, he stepped back out of the room, pulling Sta-Hi with him. The display winked out. Again the room was dark, save for a glow of red light near the opposite wall.

"Ralph?" Cobb called, his voice trembling a bit. "It's me."

Ralph Numbers came clattering across the room. His red flicker-cladding glowed with swirls of complex emotion. "It's good to see you, Doctor Anderson." Trying to do the right thing, Ralph held out a manipulator, as if to shake hands.

Sobbing openly now, Cobb threw his arms around the bopper's unyielding body-box and rocked him to and fro. "I've gotten old, Ralph. And you're... you're still the same."

"Not really, Dr. Anderson. I've been rebuilt thirty-seven times. And I have exchanged various subprograms with others."

"That's right," Cobb said, laughing and crying at the same time. "Call me Cobb, Ralph. And this is Sta-Hi."

"That sounds like a bopper name," Ralph remarked. "I do my part," Sta-Hi replied. "Didn't they used to sell little Ralph Numbers dolls? I had one till I was six... till the bopper revolt in 2001. We were in the car when my parents heard it on the radio, and they threw my Ralphie out the window."

"Of course," Cobb said. "An anarchist revolutionary is a bad example for a growing boy. But in your case, Sta-Hi, I'd say the damage had already been done."

Ralph found their voices a bit blurred and hard to follow. Quickly he programmed himself a filter circuit to clean up their signals. There was a question he'd always wanted to ask his designer.