This is an interesting new take on the Fermi Paradox. Like all paradoxes, there shouldn't really be any contradiction actually occurring - it just points to a gap in our knowledge and/or assumptions.
I hadn't realised it before but the Bayesian and anthropic approaches aren't dissimilar. Starting from what we know to be true now, we can infer something about the processes that led to this point. A universe actually containing life (or bookshelves or cabbages or dust or whatever) must be suitable for making and sustaining life. However, this does not guarantee that life will be abundant. So, a universe only containing a little bit of life, but without that life standing much chance of detecting anything else, must be suitable for only generating a little bit of life and/or sustaining it for a short while.
I was particularly interested in three things from this analysis (I'm somewhat pressed for time, so I read the blog post but only skimmed the paper) :
1) Life could be abundant in some galaxies, but not necessarily throughout the Universe. They infer a distribution of civilisations where the median is 1 civilisation [per galaxy ?], the mean 27 million, and 21% of all galaxies are completely empty. So there could still be plenty of life out there, just not that much in our own part of it.
My question on that front would be : what's special about our region ? What physical processes are at work to cause this widely varying distribution ? I would imagine that the probability of life occurring should be evaluated on a world-by-world basis, not galaxy by galaxy. Oh, sure, there will be some large-scale influence, but probably not very much. I rather suspect we're back to Great Filters, which the authors want to avoid.
The authors aren't astronomers so it's fine that they just raise the statistical argument, but it would be oh so much more interesting with a physical justification. Without this, it's not really clear if they're solved the paradox after all. If the statistics says one thing and the physics another, then the paradox remains.
2) The paradox is essentially solved by simply admitting that we're suitably rare. Our assumption is that life is abundant but there is as yet, they say, sufficient uncertainty in our understanding of the processes needed for life to form for that assumption to be questionable. So, given that clearly no Galactic Empire has yet arisen, they re-evaluate the probability of life occurring in light of this. There's no paradox if we're just alone.
Again though, the paradox would return if it could be shown with a more science-based (rather than statistical) approach that there should be every reason to expect an abundance of life.
3) : Modern genetics required >1/5 of the age of the universe to evolve intelligence. A genetic system like the one that preceded ours might both be stable over a google cell divisions and evolve more slowly by a factor of 10, and run out the clock. Hence some genetic systems may be incapable of ever evolving intelligence.
I don't know if its fair to say "required" in that first sentence. Maybe it's correct. Maybe intelligence evolved as soon as the genetic code allowed it, and previously no animals were actually capable of a human-like intelligence. Anyone of the species that evolves it first is unavoidably going to find the situation very strange (and therefore, during that special period soon after achieving higher reasoning, should avoid making any Carterian inferences about the lifespan of intelligence, since they're at a special point in history). On the other hand, it seems at least equally plausible to me that intelligence is a freak accident that could have arisen at almost any point since the emergence of complex organisms. That's very much my non-geneticist, non-neuroscientist speaking, mind you.
https://www.universetoday.com/139467/new-model-predicts-that-were-probably-the-only-advanced-civilization-in-the-observable-universe/
http://aleph.se/andart2/space/seti/dissolving-the-fermi-paradox/
Waaaiiiiitt.... so basically they resolve the paradox by saying "We're just unlikely"? Um... okay. That's not really new ground. Their justification seems to be "We must be unlikely because we don't see anyone else". Perhaps you can explain why this is an oversimplification of their argument?
ReplyDeleteFurther reading of the blog article seems to be "Well, we aren't saying that we're necessarily unlikely, it's just that there seems to be a lot of uncertainty in the parameters of the Drake Equation; we need more data".
ReplyDeleteNo shit.
Let's take an arbitrary cube containing a hundred stars, keep expanding the cube until you do encompass a hundred stars. Our star happens to be in a fairly empty region of this galaxy. Life as we understand it wouldn't fare particularly well anywhere closer to the galactic core: it's pretty hot in there.
ReplyDeleteOur star also has a great cleanup utility, Jupiter, to hoover up stray asteroids which would otherwise routinely create extinction events.
The Drake Equation is just a combination of just such factors: when Frank Drake created it, it was more to demonstrate the scale of the numbers involved, that the odds were somewhat better than nil. It's an interesting enumeration of factors but by no means a complete enumeration.
The SETI crowd is just annoying. We've got intelligent life in the cetaceans and the great apes, lots more life to consider as well. We can't hardly stick a microphone in the water without hearing them - well, I take that back, with our noise pollution, the cetaceans can barely hear each other.
Where are the aliens? This species is so hateful and stupid it puts children in cages. Forget the search for intelligent life elsewhere, I'd argue there isn't any for the aliens to find. And those poor monkeys on the ISS, that collection of beer cans on orbit, can't even feed themselves. Garbage manufacturers, that's what we are. If there is intelligent life in the universe, it should surely put us in quarantine, as if we were some malevolent pestilence.
Chris Greene Yes and no. See their last paragraph. I think the attempt to quantify the probabilities by considering the end result is novel, especially the notion that the frequency of civilisations is strongly variable. I also found it useful to explicitly state the underlying assumptions and methodology here, e.g. finding nothing either means you must be doing the wrong search, or tells you something about what you're searching for. Perhaps this should be obvious, but it wasn't to me. I found it useful to have phrased in this way.
ReplyDelete