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!

Advertisements

~ by Planetologist on October 25, 2008.

6 Responses to “A solution to Fermi’s Paradox?”

  1. I’ve always been sort of skeptical of the whole “blow ourselves up” scenario. Yes, we could do enough damage to wipe out civilization, but probably not the species. All that matters is survival. Twelve thousand years after a nuclear war – a period equal to the time since the last ice age – no one will remember anything from our age, but the urge to survive and advance will still be there in humans. Another civilization will come, and another, until we break out to space.

    Humans are like opossums, or lystrosaurus… we’re generalists and we’re highly adaptable. Forget technology, we’re capable of being anything from pure predators to pure vegetarians, even parasites (on milk cows). We can weather a lot, just based on our biology and our behavioral flexibility. Sure, some species might wipe themselves out, but why believe they do so as a matter of course? We haven’t, yet. N isn’t even 1, on the list of known self-destroying sentient species.

    For better or worse, I think humans are a lot more capable of biological survival on a ravaged Earth than we tend to assume.

  2. Another solution to the Fermi Paradox is that technical civilizations may not stay technical for more than a millennium or two. Sir Martin Rees explains some of the threats that face technical civilizations in “Our Final Hour”. I suspect that he is being a bit too pessimistic, but the threats that he describes are very real, and there are more risks that he does not go into. It may be that a planet only has a very limited window of opportunity when its life can go galactic.

    On the bright side, the GRB extinction hypothesis has a serious flaw. Current thinking is that GRBs occur primarily in environments with low concentrations of heavy elements (anything heavier than helium) relative to the Solar abundance. The Milky Way has a fairly high abundance of heavy elements relative the average for the host galaxies of gamma-ray bursts, so GRBs may be relatively rare in the Milky Way. Another factor working if favour of life is that GRBs beam their radiation into fairly narrow cones, which are randomly distributed relative to the Galactic north pole. Since the Milky Way is a fairly thin disc (at least for the stars that are likely to have life-bearing planets) the odds are that most GRBs will be beamed out of the Galactic Plane, where they will have the least chance of zapping a life-bearing planet.

  3. As I see it, Fermi’s Paradox is a result of virtual reality.
    Any spacefaring civilization must develop computers. With computers you create simulations. Then virtual reality. In a very short time you will find yourself spending most of your time exploring your infinite number of virtual universes, rather than the real one.
    That, and the virtual sex, will put an end to any spacefaring.

  4. Oh, I agree. I like to think we’ll manage it. I have to think that. Heck, maybe we’ll get to help some other struggling civilization in the future.

    I read way too much SF.

  5. That’s not a bad way to look at it…. but I still want the Galactics to show up and take charge. Our species definitely needs some house-training.

  6. Robbed, eh? Maybe not. At least it means that humanity won’t be a Johnny-come-lately; we’re well positioned to be one of the first galactic civilizations. Assuming the model is right. And assuming we make it that far.

    At least that’s my science fiction view of it.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

 
%d bloggers like this: