Extraterrestrial Civilizations - Isaac Asimov [97]
This continues without limit. Human beings now have at their disposal a series of weapons deadlier than they have ever had, and they still strive for a further intensification of deadliness.
We can conclude that it is impossible for any species to be intelligent without coming to understand the meaning of competition, to foresee the dangers of losing out in competition, to develop an indefinite number of material things and immaterial abstractions over which to compete, and to develop weapons of increasing power that will help them compete.
Consequently, when the time comes where the weapons the intelligent species develops are so powerful and destructive that they outstrip the capacity of the species to recover and rebuild—the civilization automatically comes to an end.
Homo sapiens has, it would seem, run the full gamut and now faces a situation whereby a full-scale thermonuclear war could end civilization—perhaps forever.
Even if we avoid a thermonuclear war, the other concomitants of a developing technology that has been allowed to expand without sufficiently intelligent and thoughtful guidance could do us in. An endlessly expanding population combined with dwindling reserves of energy and material resources would inevitably bring about a period of increasing starvation, which might lead to the desperation of thermonuclear war.
The pollution of the environment may diminish the viability of the Earth—by poisoning it with radioactive wastes from our nuclear power plants, or with chemical wastes from our factories and automobiles, or with something as unremarkable as the carbon dioxide from our burning coal and oil (which may induce a runaway greenhouse effect).
Or civilization may just break down in internal violence without the thermonuclear horror, as the constraints of civilization simply fall apart under the strains of increasing populations and the decline in living standards. We see this already in the rising tide of terrorism.
Well, then, suppose that that is how it always is on any world. A civilization arrives, technological advance accelerates until it reaches the nuclear bomb level, and then civilization dies with a bang, or possibly with a whimper.
Let us further take ourselves as average and say that on every habitable planet with a total potential life-bearing duration of 12 billion years, an intelligent species comes into being after 4,600,000,000 years, and in the course of 600,000 years builds a civilization slowly and ends it quickly—ruining the planet, in the process, to the point where no further civilization can arise upon it.
Since 600,000 is 1/20,000 of 12 billion, we can divide the 650 million habitable planets in our Galaxy by 20,000 and find that only 32,500 of them would be in that 600,000-year period in which a species the intellectual equivalent of Homo sapiens is expanding in power.
Judging by the length of time human beings have spent at different stages in their development and taking that as the average, we could suppose that 540 habitable planets bear an intelligent species that, at least in the more advanced parts of the planet, are practicing agriculture and living in cities.
In 270 planets in our Galaxy, intelligent species have developed writing; in 20 planets modern science has developed; in 10 the equivalent of the industrial revolution has taken place; and in 2 nuclear energy has been developed, and those 2 civilizations are, of course, near extinction.
Since our 600,000 years of humanity occur near the middle of the Sun’s lifetime, and since we are taking the human experience as average, then all but 1/20,000 of the habitable planets fall outside that period, half earlier and half later. That means that on about 325 million such planets no intelligent species