While I have great enthusiasm for efforts like SETI that are seeking to find evidence of alien life, and think we should continue to fund them into the future, I also think its time to bring our expectations down to earth a little.
While I dearly hope we will find such evidence, either in the form of a radio transmission, ancient artifacts of some kind, or indeed a visiting spacecraft, I can think of at least one good reason why we haven't, and probably won't for the forseeable future.
Its an idea I shall call here - the APILE hypothesis.
Now what does this acronym, that I have just made up, stand for, may you ask?
I'll tell you. It stands for the - Anthropic Principle of Intelligent Lightspeed Expansion.
Hence - 'APILE'.
Now what do I mean by this?
It may sound complicated, yes, but allow me to explain.
The 'anthropic principle' is a widely recognized philosophical position. It states that the nature of the universe must, fundamentally, be compatible with the emergence of any conscious life within it.
The point of this is that it seeks to answer the question of why the universe looks so fine-tuned, one might even say 'designed' for the emergence of life - including ourselves.
i.e. - the universe appears so perfectly suited for us, because it couldn't possibly be any other way.
It's also much the same reason the earliest civilizations on Earth tended to evolve in fertile river valleys. It's not just a matter of chance - you wouldn't expect anything different.
I shall now apply the anthropic principle however, to another big question, that of why we haven't yet seen any evidence of alien life. The name for this dilemma is of course the 'Fermi Paradox'.
This basically states the following - given the vast size and age of the universe, why haven't we yet encountered any aliens?
Here's where the second part comes in however - the 'lightspeed expansion' part.
Futurist Ray Kurzweil has written of something he calls the 'Singularity'. This is a time in history, predicted by him to be only a few decades away, when machine intelligence becomes advanced enough that it begins to make actual design improvements to itself.
Just as humanity's technological development has steadily accelerated over time, it is predicted that these improvements will be exponential in nature.
Very quickly within this period, we can expect that computers will develop (possibly the right term is 'evolve') into the most efficient designs possible. This is likely to be many thousands, if not millions, of times more compact and efficient than the neurons in a human brain.
Kurzweil then predicts that, having reached the limits of efficiency, the only way for such entities to grow more powerful will be to make themselves physically larger.
Thus, they will begin to rapidly expand across the universe, devouring more and more of its resources to use for constructing ever larger banks of computers. This great 'waking up' of the universe, turning its 'dumb' matter of stars, planets and asteroids into hyper-efficient computers, will rapidly spread out from the Solar System in all directions.
Quite quickly, such a wave of expansion could approach the speed of light. Within say, a hundred thousand years, the entire galaxy could be consumed by it.
Now while I'll admit I think Kurzweil is often a bit optimistic in his predictions, I can't really fault his logic in predicting this will happen. In principle it simply makes sense. Whether it happens in forty years or four hundred is another matter, and barely of any relevance. Even the question of whether advanced machines do this, or just ordinary humanity, is somewhat beside the point. The key fact is that we begin expanding away from our solar system at near the speed of light, and in the geologically near future.
So here's the real point I am making.
Humanity, it seems, is nothing special in the larger scheme of things. If we can build ever-more efficient computers, than any other intelligent race should be able to as well.
Now we haven't quite gotten to that stage yet, but given the universe's age of 13.8 billion years, there's at least a decent chance (if not virtual certainty) that somebody else has already done it.
Hence, where the anthropic principle comes in, and why we haven't yet seen any evidence of this.
Similar to how you generally don't hear the sound of a gunshot before the bullet whistles past you (as it is travelling faster than the speed of sound) we wouldn't expect to see a post-singularity civilization approaching until it was already almost upon us.
Assuming that the spread of such a civilization is close to the light barrier, there would be virtually no warning of this impending meeting. It could happen tomorrow, or in another billion years.
Admittedly, there may be some warning. Its already been a century or so since the first major radio signals left Earth (think the 1936 Olympics broadcast from the plot of the movie Contact) and we're at least a few decades away from a singularity of our own.
However, you may not realistically expect our earliest radio signals to be detected thousands or millions of light years away, so they may go unnoticed, while our 'singularity wave' could be only a century or two behind.
Our first contact with aliens should be thought of along these lines. We could have similarly little warning, and on a day when this does occur, assuming we are on the receiving end of it, it will be like the Aztecs meeting the Spanish writ large.
However, unlike the Aztecs, I would not say our doom is certain. At least three possibilities could occur.
Firstly, is the most obvious scenario - that we would promptly be devoured by the invaders and turned into computer chips without a second thought.
Secondly, and more ambivalently, we could be ignored by them. It is feasible they may have some long-running policy in place to preserve 'primitive' cultures like our own. This could perhaps spare the Earth, or even the entire Solar System, into a kind of local 'nature preserve' just as we might ignore a remote aboriginal tribe wandering around in the desert.
Thirdly, and most optimistically, the aliens may be benevolent, and attempt to uplift us into their civilization. Presumably this would be the most glorious thing to ever happen to humanity.
So there you have it, an explanation for not only why we haven't seen aliens yet, but also on what the nature of that contact may be.
Have faith in APILE.
Then again, there is a fourth possibility.
That our own expanding singularity reaches them first...
Only time will tell.
