Richards turned back to the rest of the group. "This chart shows what we've been able to learn about the power unit. Which isn't much. There's no input to it. No batteries, no solar cells, nothing. There's a fuel tank—at least, we think it's a fuel tank—that's sunk inside a cryogenic magnetic coil."
Elaine spoke up. "You told us that last time. Have you been able to get into the tank?"
Richards shook his head. "Not unless we break up the coil, which we don't dare try. It would probably mean destroying the power unit and stopping all the machinery. And we can't do that until we're certain of what the machinery's doing."
"We all know that," said Dr. Kulaki, a wiry Polynesian who headed the electronics group.
"Yes. Well, we did make a very elegant experiment," Richards continued, "a variation of Cavendish's experiment to obtain the gravitational constant, in the Eighteenth Century...."
"Spare the history," Dr. Kurtzman said, half-smiling.
"Okay, okay," Richards said. "We determined the mass of the fuel tank, and therefore of the fuel in it. The tank contains a degenerate gas...."
"What?"
"A degenerate gas," Richards repeated. "The stuff must weigh several tons per spoonful."