The question of whether extra-terrestrial civilizations exist has long since been the debate of scientists, and the premise of science fiction. In a galaxy of billions of planets, we might find extraordinary that, if such life exists, we have not yet met it.
In the early 1950s, Nobel physicist Enrico Fermi pointed to an apparent paradox. He considered that our galaxy, the Milky Way, is home to some 200 billion stars, and that there are most probably (as we now know with greater certainty) several hundred billion planets orbiting them. So why have we not yet been visited by at least one extra-terrestrial civilization?
Even if life exists on only a tiny fraction of those billions of planets, the shear size of our galaxy (about 100,000 light years across) means that a civilization like ours, which should soon be able to explore surrounding solar systems at an appreciable fraction of the speed of light, could possibly investigate a significant part of our galactic star system in less than a million years. This time frame is only about 1/10,000th of the age of our galaxy, which dates back some 13 billion years, or of the Universe, which is approximately 14 billion years old. It would therefore have been highly likely for our planet to be visited by several hundred different extra-terrestrial species.
So where are they?
Image: The Fermi Paradox
More recently, science has offered answers to Fermi’s paradox. It all boils down to resources. Based on a modest 2% annual growth rate in the consumption of resources, Earth’s supplies should have run out in a few hundred years.
The argument goes that civilization acceleration is the real paradox, in that as a civilization grows, it rapidly accelerates towards its own doom by consuming resources at a greater and greater pace. The further a species advances, the closer it comes to self-destruction, or at the very least reaching a place where it can no longer survive. If you throw the endless cycles of violence that we see in most species, but most obviously our own, into this mix, it points to an inevitable destruction, long before we make that jump to interstellar.
We see these same principles at play in the theories of Charles Darwin, where resources become a key factor in evolution. Our planet’s history is littered with species destroying themselves though over consumption. There is no way of knowing which of our defunct ancestors might have evolved into great civilizations if not for their extinction. However, we do know we are exceptional, and our progress has been remarkably rapid. In about fifty thousand years, we have moved from caves to reach for the stars, but are we still on that inevitable collision course? At what point do we over-stretch ourselves? Have we peaked, and are already on the decline?
What is certain, is that life does exist out there. What is far less certain, as Fermi’s paradox suggests, is that civilizations are capable of escaping the resource traps that limit them to their near space. Perhaps some do, but the chances are so infinitely small that none have yet wandered our way. Perhaps, humankind will make it, and avoid the trap that threatens our future.
What do you think?
The future depicted in Hadrian’s Gate is one in which we are still masters of those resources, and have reached to the stars. Life has been found on many worlds, but no species to rival our own. However, the threat of alien civilizations still preoccupies the human race, and provided the historical catalyst for the formation of the Union. Despite peace, we find a military obsessed with growth and power, determined to dominate a united galaxy, ready for the threats hiding among more distant stars.