Entry 1287, on 2011-04-14 at 13:42:48 (Rating 1, Science)
As I write this blog entry I am flying at over 10,000 meters on my way to Brisbane for an iPhone/iPad programming workshop. The flight to Australia is only 3 to 4 hours but it's a good opportunity to catch up on some reading. Of course I am reading an ebook on my iPad, specifically a book about astronomers' failure to find extraterrestrial intelligence called "the Eerie Silence". Yes, this is the same book I blogged about a while ago - I read several books simultaneously and have only just got back to this one.
Currently the book is discussing the famous Drake Equation. This is an idea more than a formal equation which can be used to estimate how many intelligent civilisations there might be in our galaxy. Unfortunately many of the factors in the equation are rather poorly known (actually, let's be honest: they aren't known at all) so the final number can vary from 1 (us) to hundreds of millions.
So there is a lot of conjecture involved in estimating how common intelligence actually is. But there is also some real empirical evidence. We have been deliberately looking for intelligent life for many years now and there are also ways that observations intended for other purposes might reveal intelligent life's existence.
But that evidence is famously absent. The universe is eerily silent (hence the name of the book). Why?
There seem to be several possibilities. First, we might be looking for the wrong thing. Most attempts at detecting extra-terrestrial intelligence (ETI) concentrate on detecting radio transmissions. But strong, undirected radio is a poor technology for most purposes and is declining even now on Earth. We now use more optical fibres, directional radio beams, and shorter range radio cells. So the period that our technological civilisation would be detectable by its radio signals is quite small.
But it's reasonable to think that other anomalies would become apparent where an advanced technology is present. Yet we don't see them, or at least we don't recognize them. It's possible that as a technology becomes very advanced it might not even be recognisable as technology. As science fiction author Arthur C Clarke said: any sufficiently advanced technology is indistinguishable from magic.
But if the number of planets with intelligence is towards the high end of the estimate we might expect, just by luck, to detect something which we recognise. Yet we don't, so again I ask, why not?
There seem to be two good possible reasons: the "lucky Earth" and the "doom soon" scenarios.
The first states that the Earth has been extremely lucky. First life arose quite quickly, then it evolved without becoming totally extinct and passed through several difficult transitions (the appearance of photosynthesis, multicellular life, etc), then advanced intelligence arose (by that we mean intelligence capable of producing a technology which can communicate with ETI on other planets). Maybe all of this happening within the window of opportunity which the life of a typical star creates is unlikely. Maybe we really are here just through luck. Maybe there is no other ETI in the whole observable universe just because no other planet has been lucky enough.
That's an intriguing thought in itself. Being the only intelligent life is even more surprising than actually finding ETI.
But what about the second idea: doom soon? This posits the theory that intelligence does arise fairly commonly but it doesn't last for long. There could be many reasons why a technological civilization might disappear: environmental destruction, conflict, various global natural disasters, or just social and political instability. If intelligent life doesn't last long then it might have arisen many times but we just haven't been looking at the right time. In the almost 14 billion year age of the universe we have only been looking for about 50 years. That's just 0.0000004% of the universe's age.
So both of these theories are a mixture of good and bad. The lucky Earth means we will probably survive as a species a lot longer (perhaps indefinitely in some form) but we will probably never find any other intelligence in the whole universe. But the doom soon theory suggests we might meet an unfortunate end in the relatively near future, but on the other hand there could be many other intelligent civilizations we could meet before then.
There really is no way to pick between these (and other ideas as well) until we get some real empirical evidence. The radio-based SETI program has failed - at least it has failed to find positive evidence which is an important finding in itself - but what other options are there?
The current most relevant program is the Kepler mission. I have discussed this in the past. It is an extremely interesting and precise mission which has detected many planets orbiting other stars. Because of the way it works Kepler has mainly found very big planets orbiting their stars in very short periods but as time passes it should return data on a wider range of planets.
That mission is designed to find planets, not intelligent life, but it might be able to detect some of those interesting anomalies I mentioned earlier. Just finding one other example of life (preferably intelligent life) would give us so much more data. Currently we are trying to make probability-based predictions based on a sample size of one. It might be more honest not to even try!
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