Aliens, so popular in books, film and TV. Sometimes friendly, as in E.T. the Extraterrestrial, and sometimes not so much, as Independence Day. I certainly remember Michael Rennie as Klatu in The Day the Earth Stood Still telling the people of Earth to behave themselves. And Invaders from Mars still gives me the creeps. Recent additions to the genre include the excellent Contact and Arrival (both, interestingly, with female protagonists). I can’t think of an example of a “first contact” story where humanity’s first encounter with aliens from space doesn’t completely turn the world on its head.
In America, there’s also a whole set of conspiracy theories around aliens, with one of the most popular being that Area 51 in Nevada hides alien bodies, or maybe even captive aliens, recovered from the crash of an alien spacecraft near Roswell, New Mexico in 1947. A Pew Research survey conducted last year indicated that roughly 65% of Americans believe that extraterrestrials exist, and approximately 51% say that UFO sightings reported by members of the U.S. military represent visits from intelligent aliens. Whoa!
Is it likely there actually are aliens out there in space? It depends on your choice of four possible assumptions about intelligent life elsewhere in the Universe: 1) life is common, and intelligence is common, 2) life is common, and intelligence is rare, 3) life is rare, and intelligence is common, and finally 4) life is rare, and intelligence is rare. The problem is that we only have one data point, Earth, to help in choosing which assumption is correct. That means there are arguments about how to make intelligent statements about the probability of alien life. Researchers at the University of Nottingham in England made headlines in June of 2020, when they calculated that there should be at least 36 intelligent civilizations in our galaxy capable of communicating with us. Of course, other researchers immediately thought they were “way off base.”
As far as we know, the speed of light is the limiting speed of travel in our universe, and that means it takes a long time to communicate with, or visit, another planet. Coupled with the fact that the universe is a very big place, and we only became noticeable to other beings in the universe (by virtue of radio transmissions) relatively recently, it’s not so far-fetched that we haven’t seen or heard anything from other intelligent life forms. On the other hand, the Milky Way has lots of stars like our sun, and thus lots of planets like our Earth. Some are older than Earth, and some of those planets might have evolved intelligent life long enough ago that they could have already traveled across the galaxy, even limited by the speed of light. So, where is everybody?
Which brings us to the Fermi Paradox (named for groundbreaking nuclear physicist Enrico Fermi). Simply stated, it’s “the conflict between the lack of clear, obvious evidence for extraterrestrial life and various high estimates for their existence.” If there are lots of alien species, why hasn’t one of them paid us a visit? Of course, the joke is that there is no intelligent life on earth.
There are many hypotheses as to why no one has dropped by. A popular one is that intelligent life tends to destroy itself before it can leave its own star system. Given the warming of the Earth’s atmosphere, and how little is being done to avoid it, or the possibility of global thermonuclear war unleashed by an unhinged autocrat—it’s certainly plausible.
My earlier joke might also be true: aliens who have seen us don’t consider us intelligent, or to be worth communicating with. Or perhaps other species don’t expand and colonize as relentlessly as humans do. Perhaps they just decided to stay home and read a good book.
Or, for whatever reason, Earth is deliberately avoided. Humiliating, but certainly possible.
There’s one more thought. Aliens have realized that it’s safer not to tout the fact that they exist. If the galaxy contains other species that would be happy to exterminate you for unspecified reasons (I nominate religion, based on my understanding of human history), then it’s better to just keep quiet. This is the “dark forest” hypothesis, outlined by Chinese science-fiction author Liu Cixin in his 2008 novel of the same name, part of a trilogy of novels that relate to Earth’s first encounter with aliens from Alpha Centauri, the nearest star to Earth in our galaxy.
It would be nice to have benevolent aliens come to earth and help us solve our problems. Even a scold like Klatu (“Your choice is simple: join us and live in peace, or pursue your present course and face obliteration”) might affect things positively, inspiring a new spirit of international cooperation. Here’s to hoping we don’t live in a dark forest.
