George O. Smith is a radio engineer; radio is his field of technology. As such, his predictions tend to be based on the extrapolation of a single line of activity. But it may be that all his predictions may come to nothing due to a development in an entirely separate field of technical progress. It might be, for instance, that Dr. Rhine's work on extra-sensory perception developed into a science, that equipment was developed capable of recording, receiving, amplifying and broadcasting whatever strange energy form is involved--and that telepathy completely displaced radio engineering. The atomic pile is the only form of nuclear energy machine we have available; because war-time engineering was operating under forced draft, and war-time basic science was in abeyance, we have no basic science from which to predict more advanced forms of energy-harnessing devices. But it is quite conceivable that, long before we reach Mars and Venus to establish colonies, we will achieve the ultimate in energy-harnesses for atomic energy--a small, sealed box with two projecting terminals from which unlimited electric power can be drawn directly. Also, any extrapolation whatsoever is, necessarily, based on the implied, but unstated proposition, "If things go on as they have been...." The proposition is, right now, open to serious question. For one thing, whenever science becomes engineering, it meets legislation made by men. Now the laws of Nature are predictable, understandable, and absolute. They don't depend on the viewpoint of the individual, or the social theory popular at the time, or the Majority Leader's severe chronic indigestion. The patent law very definitely does. At the moment, as a matter of fact, an extrapolation of the trend of patent law suggests that half the Venus Equilateral series will be rendered plotless; there won't be any patents. The science-fiction writer is, therefore, faced with a simply stated problem: Taking off from the solid ground of known laboratory science, sighting along the back-track of past experience, he launches into the future. But he may come down in a never-will-be future, because somebody harnessed telepathy, and threw civilization off on an entirely unexpected track. Or because the Supreme Court, currently invalidating 24 out of every 25 patents brought before it, has eliminated the institution of patents. Or because a new social theory has decided that no scientific advance should be permitted for a period of 250 years while a great program of meditation and navel-inspection instead of Naval inspection is pushed forward. Nevertheless, science-fiction can be not only fun, but an extremely valuable experience. If a friend steps out of a dimly lighted doorway it may provoke a "Yipe!" of momentary fear, or a casual "Hi," dependent entirely on whether or not you expected to meet him there.