I glimpsed the bulk of an outboard atomic rigging behind him, strapped to the back of the wheelchair. He fingered a knob on the arm of the chair and the two exhaust ducts behind the wheel-housings flamed for a moment, and the chair began to roll.
Obediently, we started walking. You don't argue with a blaster, even if the man pointing it is in a wheelchair.
"What's going on, Ron?" Val asked in a low voice as we walked. Behind us the wheelchair hissed steadily.
"I don't quite know, Val. I've never seen this guy before, and I thought I knew everyone at the Dome."
"Quiet up there!" our captor called, and we stopped talking. We trudged along together, with him following behind; I could hear the crunch-crunch of the wheelchair as its wheels chewed into the sand. I wondered where we were going, and why. I wondered why we had ever left Earth.
The answer to that came to me quick enough: we had to. Earth needed radioactives, and the only way to get them was to get out and look. The great atomic wars of the late 20th Century had used up much of the supply, but the amount used to blow up half the great cities of the world hardly compared with the amount we needed to put them back together again.
In three centuries the shattered world had been completely rebuilt. The wreckage of New York and Shanghai and London and all the other ruined cities had been hidden by a shining new world of gleaming towers and flying roadways. We had profited by our grandparents' mistakes. They had used their atomics to make bombs. We used ours for fuel.
It was an atomic world. Everything: power drills, printing presses, typewriters, can openers, ocean liners, powered by the inexhaustible energy of the dividing atom.
But though the energy is inexhaustible, the supply of nuclei isn't. After three centuries of heavy consumption, the supply failed. The mighty machine that was Earth's industry had started to slow down.