* * * * * The earthmen blinked their eyes. They were in the ship, unharmed. They stood at their posts in the same position as before. And about them the black of far space and the shining points of the star-studded Milky Way. Kendall gazed into the lens of the rear port, beckoned to the others. The red planet was already a small, crimson disk behind them, passing into oblivion as they accelerated onward, outward. Broster laughed. "It's all clear now. Why the space-chart seemingly did not function, why our weapons were useless." "And why we were not killed, and why their beams could be seen in space," added Seaward. "Because they weren't in space; they were in air. In the air of another universe." "It was all an illusion," explained Seaward. "The ships, the planet, everything. That is why none of these things registered on the space chart; there were no gravity waves emanating from them because they were not there." Broster leaned back in his chair. "We've all known that there are many universes beside ours, separated from us by the fourth-dimensional space-time sheet. That was demonstrated by Marilus centuries ago. Laboratory experiments have produced images of other planets. All this was just such an image. "The space-time envelope must have been a little warped at this point. Enough so as to let part of the waves emanating from the atoms of that section to pass through to our universe--and permit waves emanating from the atoms of our universe to pass through to them. We were able to see the red rays of their spectrum, nothing else. They saw us as a violet ship. But that was all." "Then," put in Kendall, "that's why they seemed to be shooting rays at us." "Right. We appeared to them, in their world, as suddenly as they appeared to us in space; it was a double mirage. At one end of the warp, they and their planet suddenly appear in what the instruments show to be empty space; at the other end, we appear out of nowhere, a strange ship headed for their planet. And, it must have seemed to them, that we went right through their planet, too. That planet of theirs, by the way, must be a tremendous one. Many times the mass and density of Jupiter. It's probably what causes the space-warp." "What!" exclaimed Kendall. "You mean that thing's a permanent institution in space?" "Certainly." "Then let's go back and have a good look." "Check," agreed Broster. "We'll give their fleet and their planet the jitters again," laughed Seaward as he prepared the plates for special photos.