65 years ago, in 1950, while having lunch with colleagues Edward Teller and Herbert York, Nobel physicist Enrico Fermi suddenly blurted out, “Where is everybody?” His question is now known as Fermi’s paradox.
Fermi’s line of reasoning was the following: (a) Most likely there are numerous (maybe millions) of other technological civilizations in the Milky Way galaxy alone; (b) if a society is less advanced than us by even a few decades, they would not be technological, so any other technological civilization is, almost certainly, many thousands or millions of years more advanced; (d) within a million years or so (an eye-blink in cosmic time) after becoming technological, a society could have explored or even colonized most of the Milky Way; (e) so why don’t we see evidence of the existence of even a single extraterrestrial civilization?
Clearly the question of whether other civilizations exist is one of the most important questions of modern science. And a discovery of such life, say by analysis of microwave data, would certainly rank as among the most significant and far-reaching of all scientific developments. For one thing, it would lend credence to the suggestion by some eminent scientists, such as Freeman Dyson, that the universe is primed for intelligent life.
But after 50 years of searching, the bottom line is that nothing has been found. If there are indeed numerous technological civilizations in the Milky Way, why have we not been able to detect any signals or other evidence of their existence? Why are they making it so hard for us to find them? In Fermi’s parlance, “Where are they?” . . .