As we have seen, imagination can conjure habitable planets, life thereon, and even intelligent life, along with a variety of explanations about why ET is not returning our calls.
Many people assume that if you doubt the existence of extraterrestrials, you must have a hidden religious reason. Continuing lack of evidence is sufficient reason for doubting Bigfoot, these critics agree, but not ET.
Some astronomers do discuss the possibility that apart from Earth intelligent life is very rare. After an analysis of the 500 planets discovered to date showed that all were hostile to life, Harvard astrophysicist Howard Smith has gone on record (2011) as affirming that “we are alone in the universe.” Princeton scientists have also announced that there is no reason to assume life on other planets. And Marcelo Gleiser dismisses “evolution” as a counterargument because “Contrary to what many believe, evolution doesn’t lead to complex life forms: evolution leads to well-adapted life forms.” Complexity may or may not promote survival.
One way of insulating such doubts from intemperate attack is to find a quirky but barely permissible reading of Darwin. In 2011 Geoff Marcy, successful planet-hunter, told Space.com,
If I had to bet — and this is now beyond science — I would say that intelligent, technological critters are rare in the Milky Way galaxy. The evidence mounts. We Homo sapiens didn’t arise until some quirk of environment on the East African savannah — so quirky that the hominid paleontologists still can’t tell us why the australopithecines somehow evolved big brains and had dexterity that could play piano concertos, and things that make no real honest sense in terms of Darwinian evolution.
As long as Marcy is willing to assert that he is “beyond science” when he doubts, and shores it up by invoking Darwin, he is allowed his doubts. But Darwinism is typically far more use to the pro-alien side because it parallels the Copernican Principle: As Earth is just a mediocre planet, so humans are just an evolved species. Surely there are countless others. The Perimeter Institute’s Adrian Kent explicitly invokes Darwinian theory to account for the aliens’ absence: Natural selection, he argues, favors quiet aliens, due to competition on a cosmic scale for natural resources.
Similarly, Smith dubs his pessimistic view the “misanthropic principle,” a play on the “Anthropic Principle,” meaning that because we are probably alone, we must solve our own problems. As long as he puts it that way, he is mostly safe from charges of being “anti-science.”
At New Scientist (2011), Lee Billings utters the question: “Two decades of searching have failed to turn up another planetary system like ours. Should we be worried?” The magazine editorialized an answer pronto:
The fact that there are few plausible Earth lookalikes among the 1200-plus candidate planets identified by Kepler is not hard to explain away. Such small lumps of rock are more elusive than bigger gassy bodies, and once they have been glimpsed it will take time to verify their existence. More perplexing is the apparent lack of any other solar systems that have the familiar qualities of our own, which we believe to have given rise to life.
More often we are just told that we lack imagination, we have searched too narrowly: Moonless planets have been unfairly dismissed and sunless ones could maybe ferry life around the galaxy. Some argue that hardy Earth life forms could have made it to one of Jupiter’s moons and survived there. Jupiter’s moon Europa looks promising to many. NASA has talked of a “flying-saucer-shaped space boat” to Saturn’s moon Titan, some day. And the excitable word about another Saturn moon is, “Enceladus Now Looks Wet, So It May Be ALIVE!”
Exoplanets orbiting red dwarfs at a distance, it is said, may counterintuitively support life. So might exoplanets’ moons. Every month, we hear of a planet or moon capable of supporting hype.
More exotically, some seek life around failed or dying stars. If that doesn’t work, dark matter could make planets habitable (though we don’t yet know what dark matter is). And, should the laws of physics vary from place to place, life elsewhere might follow different laws. In that case, should the physics term “constant” be changed to “local variant”?
Lastly, encountering hard, doubting hearts, alien life proponents resort to moralizing: An editorial preaches “Uniqueness seems rather too presumptuous a claim for one small planet in an undistinguished corner of a vast cosmos.” Our vaunted respect for evidence is a mere cloak for pride and presumption!
But, as we shall see, the Copernican Principle is capable of far greater feats than marshaling penny ante defenses against doubt. Provided, that is, we take one giant step further beyond evidence: Our entire universe is not alone.
Image: E.T. the Extra-Terrestrial/Wikipedia.