Extraterrestrial Civilizations - Isaac Asimov [127]
* If a photonic drive were possible, the rate of time passage to people experiencing the drive would be zero. All trips, even to the very edge of the Universe, would seem to take place in an instant. That is why, fast as time dilatation makes astronauts think they are going, they can never beat a ray of light. It may take them only 60 years to reach the Andromeda Galaxy, but when they get there they will find that a light ray would have reached the Andromeda Galaxy efore they did.
* It is easy to speculate that those UFOs that are not hoaxes or mistakes (assuming there are any that don’t fall into one category or the other) are probes, rather than actual extraterrestrial spaceships piloted by living organisms. That is not inconceivable, but, on the other hand, there is no reasonable evidence in favor of this notion. Not yet For that matter, it might well be that the probes have outlived their particular civilization and are sending back messages uselessly.
*Lyman Spitzer suggested such generations-long voyages in 1951, and the science fiction writer Robert A. Heinlein wrote a novelette called “Universe” on this theme in 1941
* It is conceivable that particular free-worlds might be isolationist, fearful or suspicious of other free-worlds, and might choose to veer away from the approach of another. Surely this would not happen often, however. I have better hopes of the curiosity of intelligent creatures
* Those with a more romantic imagination might even suggest that there was an intact planet in the orbit between those of Mars and Jupiter; that a free-world dismantled it in order to build numerous space settlements over a long period of time; and that the asteroid belt is the remnant they left behind.
CHAPTER 13
Messages
SENDING
We have concluded, then, that there may well be over 500,000 civilizations in the Galaxy, but that the only way any of them are likely to emerge from their planetary systems is by interstellar probes or in the form of free-worlds.
There is nothing compelling about either emergence. The vast majority of civilizations, conceivably all of them, may simply remain in their own planetary systems. Any interstellar probes that are sent out may be devices not designed to land on habitable planets but to confine themselves to observations and reports from space. Any free-worlds that may come our way might be more interested in material and energy with which to maintain themselves than in involvement with a sedentary civilization.
In this way, we can rationalize the apparent paradox that while the Galaxy may be rich in civilizations we remain unaware of them.
But what ought we to do in that case?
The simplest answer and the one that involves the least trouble is to do nothing at all. If extraterrestrial civilizations can’t or won’t reach us, we could just go about our own business. Certainly we have enough troubles of our own to occupy us.
The second possibility is to send out some sort of message in order to make contact. Even if an extraterrestrial civilization can’t reach us, or we them, we can perhaps establish communication across space; even if it is only the message: “We are here. Are you there?”
This is such a normal impulse that back in the nineteenth century, when people were still speculating concerning life on other worlds in the Solar system and almost taking it for granted that there would be civilizations even on the Moon, there were suggestions for methods of communication.
The German mathematician Karl Friedrich Gauss (1777–1855) once suggested that lanes of forest be planted on the steppes of central Asia in the form of a gigantic right triangle with squares on each side. Within the triangle and squares, grain would be planted to darken the shapes with a uniform color. A civilization on the Moon or Mars, for instance, closely studying the surface of the Earth, might see this clear display of the Pythagorean