Robert Silverberg a signé un article dans Analog intitulé The Search For Other Earths.
Il est à lire ici
Voici le début.
“To consider the Earth the only populated world in infinite space,” the Greek philosopher Metrodoros the Epicurean wrote about 300 BC, “is as absurd as to assert that in an entire field sown with millet only one grain will grow.”
I believe that too, although the only evidence I have for its truth is the same as Metrodoros’: simple common sense. He knew of five planets aside from our own—Mercury, Venus, Mars, Saturn, and Jupiter —and perhaps he thought they were inhabited, but also he could see that the sky was full of stars. He didn’t have any telescopes to show him the existence of worlds of other stars, and neither do I. But the universe is infinitely large, as Metrodoros understood two and a half millennia ago, and that which is infinite contains an infinite amount of everything. It is a place in which not merely uncountable numbers of suns exist, but uncountable numbers of galaxies. To me it seems unlikely, to say the least, that in all that literally unthinkable multitude of galaxies there is only one planet, one little dinky world, on which living beings can be found.
For many centuries the concept of a multiplicity of worlds was dangerous heresy in Christian Europe. A literal interpretation of the Bible had produced the belief that God had created the world—flat, floating on water—in six days, and had placed the sun in the sky to provide light, and in that same week had created man and woman and various subordinate creatures to populate it. Earth was unique and at the center of the universe. There was nothing in Scripture about other worlds or other forms of life; therefore, such things did not exist.
The work of the sixteenth-century Polish mathematician Nicolaus Copernicus began the process of undermining the concept of a geocentric cosmos. Copernicus showed that the Earth and its sister planets must move in orbit around the sun, rather than the sun going around us, as it appeared to do; but he mistakenly thought the orbits were circular, and it remained for the German astronomer Johannes Kepler, building on the work of a Dane, Tycho Brahe, to show that the planetary orbits were in fact elliptical. With the mathematical foundations now in place, the modern view of the universe began quickly to emerge. I suppose there are still some believers in the pre-Copernican theory of the universe, but very few, I suspect, are readers of this magazine; the rest of us have no difficulty with the notion that Earth travels around the sun and is just a speck in a vast universe full of stars and—very likely—a host of other planets more or less like our own.