A solution to Fermi’s Paradox?
In the latest issue of Origins of Life and Evolution of Biospheres, two scientists at the Astronomical Observatory of Belgrade, Milan M. Ćirković and Branislav Vukotić, have proposed a solution to Fermi’s Paradox.
For those with insufficient geek cred, Fermi’s Paradox asks the question, “Where is everybody?”… where are all the aliens? The argument follows from two premises: 1) that life in the universe is commonplace, and 2) that even limited by the speed of light, the time it would take a civilization to populate the entire galaxy is very short compared with the age of the Earth. If the premises are true, there has been far more time available to build Galactic civilizations… so why aren’t we already colonized? If the premises are true, the conclusion is obvious; when we first learned to build telescopes and look up, we should have seen a sky filled with alien constructs, or at least filled with the distant signals of alien technology. But we don’t.
This new study makes a convincing case that the premises supporting Fermi’s Paradox are wrong. As argued by the authors, life may indeed be commonplace, but there may not have been as much evolutionary time for everybody as we thought. On Earth, the evolution of life has been interrupted many times by mass extinctions; catastrophic events on a global scale that physically destroy enough biomass and destabilize the biosphere so profoundly that a majority of the extant species of life are snuffed out, in a very brief period. One of Earth’s mass extinctions, at the end of the Ordovician Period about 444 million years ago, might have been triggered by a gamma ray burst in our galactic neighborhood. These bursts, called GRBs, are thought to be caused when supermassive stars end their lives and become black holes. The brilliant shower of hideously energetic photons released by a single GRB can sterilize most of a galaxy.
Ćirković and Vukotić argue that GRBs act like a galactic brake, slowing the evolutionary progression of planets by resetting their evolutionary progress… in most cases reducing their biospheres to only the simplest, most rugged survivor species, such as bacteria. Every time a GRB goes off in our galaxy, most of the life-bearing plaents in our galaxy have to re-evolve complex life. Over an astronomical timescale, the general success of evolving biospheres in a galaxy will depend on how often GRBs occur… not including all the other, more local ways any particular planet can be randomly abused, such as asteroid impacts or solar flares.
According to the authors’ model, the rate of GRBs limits how quickly Galactic civilizations can evolve, though at some point enough of them will evolve to learn how to shield themselves from GRBs and other sources of cosmic death, and will move out to permeate the galaxy. This would happen very quickly on an astronomical scale, in no more than about 100 million years or so. By comparison, the dinosaurs died out only 65 million years ago. One hundred million years is not very long ago, geologically.
The solution to the paradox lies in what would follow from the authors’ proposals: that any galaxy is going to have a youth when no life can exist (not enough elements to build planets with), a long dragging middle age as life evolves throughout the galaxy, but keeps getting smacked down by GRBs…. and then a sudden burst of activity, as the first wave of mature civilizations learn how to survive and propagate among the stars. After a brief transition time… a critical, seminal epoch… the galaxy will be filled with intelligence.
We have the sour luck to live just before the Galactic Phase Transition… the galaxy-wide shift from scattered animals to ruling Galactics. By definition we don’t live in our galaxy’s lifeless youth, and obviously we don’t live in a busy galaxy of tentacled masters, so by elimination we have to be somewhere in between, on the slow, tortuous stair that leads to the grand prize.
I hate this model. It might be true, but I still hate it. As a geologist I am used to thinking in geologic units of time. According to the new model, the transitionary phase from the appearance of the first intelligences in our galaxy until Galactic civilization commences is probably on the order of 100 million years, give a take a few hundred million. That’s nothing.
For four billion years Earth limps along, hosting only bacteria, and then after all that time, in 500 million years our world goes from Algaeland to Humanland? Why couldn’t stromatolites have just wasted a few more eons? Maybe we could have spent more time in Trilobiteland, or something?
Only a hundred million years, and then we could have gone straight from fire to the League of Peoples?
Dammit! I was robbed!