"Okay, give," said Fuller.
Arcot grinned and lit up his own pipe, joining Wade in an attempt to fill the room with impenetrable fog.
"All right," Arcot began, "we needed two things: a tremendous source of power and a way to store it.
"For the first, ordinary atomic energy wouldn't do. It's not controllable enough and uranium isn't something we could carry by the ton. So I began working with high-density currents.
"At the temperature of liquid helium, near absolute zero, lead becomes a nearly perfect conductor. Back in nineteen twenty, physicists had succeeded in making a current flow for four hours in a closed circuit. It was just a ring of lead, but the resistance was so low that the current kept on flowing. They even managed to get six hundred amperes through a piece of lead wire no bigger than a pencil lead.
"I don't know why they didn't go on from there, but they didn't. Possibly it was because they didn't have the insulation necessary to keep down the corona effect; in a high-density current, the electrons tend to push each other sideways out of the wire.
"At any rate, I tried it, using lux metal as an insulator around the wire."
"Hold it!" Fuller interrupted. "What, may I ask, is lux metal?"
"That was Wade's idea," Arcot grinned. "You remember those two substances we found in the Nigran ships during the war?"
"Sure," said Fuller. "One was transparent and the other was a perfect reflector. You said they were made of light—photons so greatly condensed that they were held together by their gravitational fields."