The Captain was in control again. "Gravity nullifier? Big deal. That's standard technology; got one in the ship. No bounty there, I'm afraid."

Disappointed, we turned away; but Ballantine trotted after Bayliss. "Captain, the ship's nullifier consumes gigawatts. Its central generator fills a room! This thing must work on completely new principles--"

The Captain turned on him. "Ballantine, get off my back, will you? All I care about is the schedule I've got to meet." She looked at something approaching over Ballantine's shoulder, and she smiled faintly as she continued: "If you can prise that thing out of the wreck in the next twelve hours, fine. Otherwise don't bother me." Her smile widened.

Ballantine opened his mouth to complain further -- but never got the chance. A massive arm closed around his waist and lifted him, wriggling, into the air.

The Captain just kept on grinning.

"Come on, Ballantine!" Krupp roared, carrying him to the wreck. "Let's see whether this thing of yours really works." And he flicked the switch over and held Ballantine with two hands over the gravity disc. The other men watched expectantly. "Go for it, Krupp!" Ballantine just hung there like a limp doll.

With one mighty boost, Krupp hurled the little scientist straight up.

Now Krupp is a big man. Under normal gravity he could have launched Ballantine's weight through -- what? A couple of yards?

Under one percent of gee, Ballantine soared up two hundred yards. He took about thirty seconds to drift back down; he had to tumble like a clumsy snowflake into a circle of laughing faces.

He stumbled away, brushing past me. His eyes were bright, like ice.

After ten hours we'd just about finished. Most of the men were in their cabins, cleaning up. I stood on the ship's ramp, peering up at the eclipse of one egg-shaped star by another.

Ballantine emerged from the ship and stood with me, gazing out in silence. After a while I decided to be sociable. Lethe, we were all a long way from home. "Did you get your nullifier free from the wreck?"

He shook his head angrily. "What a waste. And it works on a completely new principle."

"Really?" I asked, already regretting opening my mouth.

"Did you know that gravity is actually made up of three forces?" he lectured. "There's the positive force Newton discovered -- and two extra, short-range forces called the Yukawa terms. Yukawa was a twentieth-century scientist.

"One Yukawa is positive and the other is negative, so they cancel each other out. Overall, two positives and a negative leave you with one positive, you see..."

His voice got higher, sharp with bitterness. I began to wonder how I could get away. "What the Xeelee artifact does is to nullify the Yukawas. The control switch has two settings. The first neutralizes the positive Yukawa, so that leaves the negative and just one positive -- nothing, to within one percent.