It is no surprise that I spent a lot of time as a kid thinking about life on other planets. I am of the “Star Wars” generation after all—age 5 when the first film came out; 8 years old when “The Empire Strikes Back” hit the theaters; 11 with “Return of the Jedi.” Now, with “Star Wars: The Force Awakens” bringing my childhood heroes back to the big screen, my thoughts again return to contemplating the possibility of life in galaxies far, far away…
Through most of the 20th century, scientists theorized that our Milky Way galaxy was swarming with life—not just simple organisms but whole civilizations as advanced or more advanced than our own—on planets orbiting distant stars. While both these extra-solar planets (or exoplanets) and the civilizations upon them were theoretical at the time, it seemed inevitable that we would discover them in short order. After all, our Earth is just an insignificant speck tucked away in a corner of a vast galaxy of roughly 300 billion stars. Yet today, while astronomers have proved the existence of more than 2,000 exoplanets, our Milky Way remains remarkably and frustratingly silent.
The silence pulls at our collective imaginations. Our species craves interaction; our literature is defined by encounters. We have always sought companionship to fill the quiet. For ages we have looked at the vastness of the night sky and wondered: Can we really be alone? The sheer number of stars seems to confirm the mathematical likelihood that there are other intelligent beings out there. And yet, we hear nothing. No one has answered our calls, except in fiction.
Popular science fiction has often reflected the prevailing scientific theories about intelligent life on other planets. In the 1960s and ’70s, when the idea of widespread extraterrestrial intelligence was prevalent, television shows like “Star Trek” and “Doctor Who” and films like “2001: A Space Odyssey” and “Close Encounters of the Third Kind” were fictional versions of our greatest hopes in the search for extraterrestrial intelligence.
‘Where is everybody?’
More recently, however, the reimagined “Battlestar Galactica” series on television and the Christopher Nolan film “Interstellar” display a lonelier universe that is more in keeping with the concerns embodied in what is known as “Fermi’s paradox.” In 1950 the Nobel Prize winning physicist Enrico Fermi was discussing the possibility of alien life with a number of fellow scientists, all of whom believed it must be plentiful. After the conversation drifted to other subjects, Dr. Fermi reportedly blurted out: “Where is everybody?” The “everybody” in question was extraterrestrial civilization. The physicist posited that if there were so many alien civilizations in the galaxy, there should be evidence of them all around. So why had we not yet encountered them, either by their visiting Earth or through some sort of broadcast picked up by our radio telescopes?
The Milky Way is around 10 billion years old. An advanced alien civilization, using ships that travel at even a fraction of the speed of light, could easily spread from its native solar system to numerous planets orbiting distant stars in just 10 million years—a sliver of time compared to the age of the galaxy. So the night sky should be abundant with evidence that we are not alone. Yet there has been no such evidence—not in 1950 and not today.
Fermi’s paradox has led many people to conclude that the silent stars can mean only one of two things: Either we are indeed alone in the galaxy or there is some “great filter” that prevents most extraterrestrial life forms from either reaching sentience or our level of technological achievement.
Maybe the idea that we are unique in this universe is a comfort to some; for me, it’s an unsettling concept. Worse still is the possibility that a great filter like natural disasters, war, famine, disease or environmental degradation has prevented another civilization from reaching the stars—or will prevent us from doing it.
Fermi’s paradox is fascinating, but too many people who cite it assume that we have already somehow amassed enough evidence to conclude we are either alone or in a whole lot of trouble. But is that the case? We have been studying the stars with radio telescopes for less than a century and discovering exoplanets for just the last 20 years. There is a lot of real estate left in the sky to explore.
What we can say at this point is that intelligence like our own is looking to be a very precious commodity. And that means we, the plain old human race, are quite literally extraordinary. It means that we have already survived a number of great filters in our recorded history, and very likely in our prehistory, to stand here now, not only existing but contemplating our place and purpose in the universe. It also gives me hope that we will use the intelligence given to us to overcome the considerable filters still before us—not only the natural disasters and diseases, but also our own tendencies toward self-destruction and abuse—and to one day go out among the stars.
It is easy to knock the human race for our failings. We have got an awful lot of them. Just pick your deadly sin: wrath, greed, sloth, pride, lust, envy, gluttony. Our history provides more than enough ammo to think that our species will eventually succumb to any or all them. But it is hard not to marvel at the fact that a race as flawed as ours has survived all these thousands of years and continues to survive even as it struggles, however fitfully, with its own demons.
The answer to Fermi’s paradox may one day be revealed. We may be alone because no other sentient life has ever developed. We may be alone because no other civilizations had a chance to develop to the point that they could make contact. But this latter possibility does not predict our future. Past, in this context, is not prologue because our civilization and an alien one may not be analogous.
What we do know is that all manmade constructs end. Civilization as we know it may one day end, but that does not mean that humanity itself has to end along with it. Our history proves that we are as creative and as adaptable as we are destructive and brutal, and that we have used these more positive talents to literally reshape the face of this planet. We have flourished as a race because we can accept change as needed. Maybe a change of planets is a large leap. But is it any larger than the one made to the first fire-cooked meal or to the first harvest? Or to the acknowledgment that every person is your brother or sister? Each change has in common the leaving behind of one life and the taking up of another.
If all that is true, we really better make sure we stick around. That means, in the short term, assuring that we take care of and defend this planet and all of the very precious living cargo upon it. In the long term, it means preparing our race to live on planets and in environments far different from the warm and comforting nest of our Mother Earth. For humanity to survive—for the one known sentient species in the galaxy to continue—we must become a spacefaring people. The stars need not be silent forever.