"Aliens, if an when we find them, could be so alien, so different from humanity as to undermine the meaning of any exchange we might have, or even make such exchange impossible." --Henry Gee
There is a widespread belief that alien beings have traveled to Earth from some other planet and are doing reproductive experiments on a chosen few. Despite the incredible nature of this belief and a lack of credible supportive evidence, a cult has grown up around it. According to a Gallup poll done at the end of the twentieth century, about one-third of Americans believe aliens have visited us, an increase of 5% over the previous decade.
According to the tenets of this cult, aliens crashed at Roswell, New Mexico, in 1947. The U.S. Government recovered the alien craft and its occupants, and has been secretly meeting with aliens ever since in a place known as area 51. The rise in UFO sightings is due to the increase in alien activity on Earth. The aliens are abducting people in larger numbers, are leaving other signs of their presence in the form of so-called crop circles, are involved in cattle mutilation, and occasionally provide revelations such as the Urantia Book to selected prophets. The support for these beliefs about aliens and UFOs consists mostly of speculation, fantasy, fraud, and unjustified inferences from questionable evidence and testimony. UFO devotees are also convinced that there is a government and mass media conspiracy to cover up the alien activities, making it difficult for them to prove that the aliens have landed.
It is probable that there is life elsewhere in the universe and that some of that life is intelligent. There is a high mathematical probability that among the trillions of stars in the billions of galaxies there are millions of planets in age and proximity to a star analogous to our Sun. The chances seem very good that on some of those planets life has evolved. It is even highly probable that natural selection governs that evolution (Dawkins). However, it is not inevitable that the results of that evolution would yield intelligence, much less intelligence equal or superior to ours. It is possible that we are unique (Pinker 1997: 150 ff.).
We should not forget, however, that the closest star (besides our Sun) is so far away from Earth that travel between the two would take more than a human lifetime. The fact that it takes our Sun about 200 million years to revolve once around the Milky Way gives one a glimpse of the perspective we have to take of interstellar travel. We are 500 light-seconds from the sun. The next nearest star to Earth's sun (Alpha Centauri) is about 4 light-years away. That might sound close, but it is actually something like 24 trillion miles away. Even traveling at one million miles an hour, it would take more than 2,500 years to get there. To get there in twenty-five years would require traveling at more than 100 million miles an hour for the entire trip.* Our fastest spacecraft, Voyager, travels at about 40,000 miles an hour and would take 70,000 years to get to Alpha Centauri.
Despite the probability of life on other planets and the possibility that some of that life may be very intelligent, any signal from any planet in the universe broadcast in any direction is unlikely to be in the path of another inhabited planet. It would be folly to explore space for intelligent life without knowing exactly where to go. Yet, waiting for a signal might require a wait longer than any life on any planet might last. Finally, if we do get a signal, the waves carrying that signal left hundreds or thousands of years earlier and by the time we tracked its source down, the sending planet may no longer be...