"Well, change 'miles' to 'parsecs' and you've got the picture of deep-space speeds and operations," Kinnison informed her. "Our speed varies, of course, with the density of matter in space; but on the average--say one atom of substance per ten cubic centimeters in space--we tour at about sixty parsecs an hour, and full blast is about ninety. And our ultra-wave communicators, working below the level of the ether, in the subether--" "Whatever that is," she interrupted. "That's as good a description or definition of it as any," he grinned at her. "We don't know what even the ether is, or whether or not it exists as an objective reality; to say nothing of what we so nonchalantly call the subether. We do not understand gravity, although we can make it to order. No scientist yet has been able to say how it is propagated, or even whether or not it is propagated. No one has been able to devise any kind of an apparatus or meter or method by which its nature, period, or velocity can be determined. Neither do we know anything about time or space. In fact, fundamentally, we don't really _know_ much of anything at all," he concluded. "Says you. But that makes me feel better, anyway," she confided, snuggling a little closer. "Go on about the communicators." "Ultra-waves are faster than ordinary radio waves, which of course travel through the ether with the velocity of light, in just about the same ratio as that of the speed of our ships to the speed of slow automobiles--that is, the ratio of a parsec to a mile. Roughly nineteen billion to one. Range, of course, is proportional to the square of the speed." "Nineteen billion!" she exclaimed. "And you just said that nobody could understand even a million!" "That's the point exactly," he went on, undisturbed. "You don't have to understand or to visualize it. All you have to do is to remember that deep-space vessels and communicators can cover distance in parsecs at practically the same rate that Tellurian automobiles can cover miles. So, when some space-flea talks to you about parsecs, just think of miles in terms of an automobile and a radio and you won't be far off." "I never heard it explained that way before--it does make it ever so much simpler. Will you sign this, please?" "Just one more point." The music had ceased and he was signing her card, preparatory to escorting her back to her place. "Like your supposedly tight-beam Luna-Tellus hookups, our long range, equally tight-beam communicators are very sensitive to interference, either natural or artificial. So, while under perfect conditions we can communicate clear across the Galaxy, there are times--particularly when the pirates are scrambling the channels--that we can't drive a beam from here to Alpha Centauri. Thanks a lot for the dance." * * * * *