Tommy and Pete looked at each other, and Tommy's hands were shaking. "I think," he said, "we'd better find Charlie Karns right now." * * * * * Math Section was like a tomb. The machines were silent. In the office at the end of the room they found an unshaven Charlie gulping a cup of coffee with a very smug-looking Grdznth. The coffee pot was floating gently about six feet above the desk. So were the Grdznth and Charlie. "Charlie!" Tommy howled. "We've been trying to get you for hours! The operator--" "I know, I know." Charlie waved a hand disjointedly. "I told her to go away. I told the rest of the crew to go away, too." "Then you cracked the differential?" Charlie tipped an imaginary hat toward the Grdznth. "Spike cracked it," he said. "Spike is a sort of Grdznth genius." He tossed the coffee cup over his shoulder and it ricochetted in graceful slow motion against the far wall. "Now why don't you go away, too?" Tommy turned purple. "We've got five months," he said hoarsely. "Do you hear me? If they aren't going to have their babies in five months, we're dead men." Charlie chuckled. "Five months, he says. We figured the babies to come in about three months--right, Spike? Not that it'll make much difference to us." Charlie sank slowly down to the desk. He wasn't laughing any more. "We're never going to see any Grdznth babies. It's going to be a little too cold for that. The energy factor," he mumbled. "Nobody thought of that except in passing. Should have, though, long ago. Two completely independent universes, obviously two energy systems. Incompatible. We were dealing with mass, space and dimension--but the energy differential was the important one." "What about the energy?" "We're loaded with it. Super-charged. Packed to the breaking point and way beyond." Charlie scribbled frantically on the desk pad. "Look, it took energy for them to come through--immense quantities of energy. Every one that came through upset the balance, distorted our whole energy pattern. And they knew from the start that the differential was all on their side--a million of them unbalances four billion of us. All they needed to overload us completely was time for enough crossings." "And we gave it to them." Pete sat down slowly, his face green. "Like a rubber ball with a dent in the side. Push in one side, the other side pops out. And we're the other side. When?" "Any day now. Maybe any minute." Charlie spread his hands helplessly. "Oh, it won't be bad at all. Spike here was telling me. Mean temperature in only 39 below zero, lots of good clean snow, thousands of nice jagged mountain peaks. A lovely place, really. Just a little too cold for Grdznth. They thought Earth was much nicer." "For them," whispered Tommy. "For them," Charlie said. Transcriber's Note: