As humanity continues to make heady progress in space exploration, the question of whether life exists elsewhere in the universe is naturally becoming more pertinent. Of course, by life, we generally mean organisms as sentient and advanced as us, if not more so — not that the existence of other lifeforms as simple as bacteria would not still be amazing.
The debate about extraterrestrial lifeforms is hardly a new one, even if it does have great significance now that we are making great inroads in observing an ever-expanding proportion of the universe. Perhaps one of the most famous participants in the discussion is Nobel Prize-winning Italian physicist Enrico Fermi, who in the 1950s conceived of the Fermi Paradox: If the universe was teeming with intelligent, technological civilizations, where are they?
More to the point, even if we grant that said life has simply not reached Earth yet, why have we not seen evidence of their colonization or arrival elsewhere in the universe? NPR explores the matter further:
The most important thing to understand about Fermi’s paradox is that you don’t need faster-than-light travel, a warp-drive or other exotic technology to take it seriously. Even if a technological civilization built ships that reached only a fraction of light speed, we might still expect all the stars (and the planets) to be “colonized.”
For example, let’s imagine that just one high-tech alien species emerges and starts sending ships out at one-hundredth of the speed of light. With that technology, they’d cross the typical distance between stars in “just” a few centuries to a millennia. If, once they got to a new solar system, they began using its resources to build more ships, then we can imagine how a wave of colonization begins propagating across the galaxy.
But how long does it take this colonization wave to spread?
Remarkably, it would only take a fraction of our galaxy’s lifetime before all the stars are inhabited. Depending on what you assume, the propagating wave of colonization could make it from one end of our Milky Way to the other in just 10 million years. While that might seem very long to you, it’s really just a blink of the eye to the 10-billion-year-old Milky Way (in other words, the colonization wave crosses in 0.001 the age of the galaxy). That means if an alien civilization began at some random moment in the Milky Way’s history, odds are it has had time to colonize the entire galaxy.
In other words, even if the galaxy, let alone the whole universe, is conceivably too big for even an advanced species to explore or propagate, it is not necessarily so big as to preclude any kind of mark left by an intelligent, space-faring race.
Granted, there is no shortage of explanations and counterarguments to this paradox: that the aliens have not reached space-faring capabilities, that for one reason or another they have chosen not to travel beyond their world, etc. But the article goes on to suggest a more unsettling conclusion worth at least considering: maybe we truly are alone out there, at least within our Milky Way galaxy (anything farther than that would be unfathomably unreachable and visa versa).
On the one hand, it’s possible that no other species has ever reached our state of development. Our galaxy with its 300 billion stars — meaning 300 billion chances for self-consciousness — has never awakened anywhere else. We would be the only ones looking into the night sky and asking questions. How impossibly lonely that would be.
On the other hand, it’s also possible that other species have made it to where we stand today. But no one has made it much farther. Say that like a “great filter,” something like war or environmental collapse keeps anyone, anywhere, from reaching beyond our stage of technological development. If that’s true then we, like all who have come before us, are doomed.
Personally, I still like to hold out hope that intelligent life does exist “out there”, or at the very least once did (there is no reason to believe that such a species did not destroy itself or otherwise go extinct from some sort of natural catastrophe). The probability of some sort of organism existing elsewhere in our galaxy seems high, but whether it (or they) is intelligent is apparently still an open question.
What are your thoughts?