"Put it this way. You draw a graph, an' you cross two lines. The block at the upper right intersection o' them two lines is the is universe. The one we live in. Ain't that right?"
Biggs nodded. "That's a simple way of graphing existence, yes. The horizontal line would represent existence in space, the vertical line existence in time. At any given moment, a man's position in space and time is coördinated in the positive sector. But—"
He stopped abruptly, looking at Hank with startled eyes.
"But you don't mean, Hank, we're in the bottom sector of the graph!"
Hank sighed. "'Fraid that's 'zackly what I do mean, Lanse. It's no wonder nuthin' looked natcheral to you. We done bust plumb out o' space an' time as we ordinarily know it. We're in the imaginary sector o' space-time! The coördinate of where we are now ain't even positive numbers. They're all based on a negative factor—the square root o' minus one!"
CHAPTER IV
Danger Ahead
I looked at Bert Donovan and he looked at me. Judging by the faces of our two screwball intellectuals, there was something smelly on the Saturn. But it was all a deep and dark mystery to me.
I said, "Hank, for old times' sake, would you brush that off again lightly for me? In words of one syllable, what has the little letter i got to do with space flight, gray skies and time-travel?"