Human consciousness arose but a minute before midnight on the geological clock. Yet we mayflies try to bend an ancient world to our purposes, ignorant perhaps of the messages buried in its long history. Let us hope that we are still in the early morning of our April day. ~Stephen Jay Gould
All right, class. When last we met in Part 1, I was waxing eloquent about Frank Drake's equation for determining the number of technical civilizations currently existing in the Milky Way galaxy. In particular, I looked at Carl Sagan's interpretations of this formula in a 1966 book, “Intelligent Life In The Universe”, and in his 1980 series, “Cosmos” (lordy, has it really been 26 years?).
It's interesting to note that Sagan (and the others who have considered this problem) always seem to assume that the odds of a civilization hanging around depend on the beings overcoming the temptation to blow themselves into oblivion. Certainly, that's an important factor, but it ignores the concept of extinction events. Human beings could actually learn to coexist for the next 10,000 years, but if an event equivalent to the one that caused the Siberian or Deccan Flats was to occur, we'd be getting along as cave-dwellers, if we survived at all.
Our planet has been around for around four billion years. The origins of life have been pushed back to as far as 3.8 billion years. That's good news, because it's an indication that life arises quickly. Microbial life has also survived planetary catastrophes including massive collisions and a global ice age (although there's still a lot of discussion about the ice age). So life is also very tough once it gets going. That bodes well for the life part of the Drake formula.
But, in 1966 and even in 1980, we were in a Cold War mentality that had most of us convinced that we were going to vaporize human life sooner or later, and the odds were in favor of sooner. Furthermore, humanity has shown that, given a choice between polluting the blazes out of the planet and conserving it, we'll go the slob route every time. So, Sagan reflected an outlook that said, “Human beings are going to screw up the good thing they've got.”
It's hard to argue with that, but the planet has proved to be far more resilient than Rachel Carson and friends thought. Our mistakes are reversible, even though governments around the world are currently trying to undo the efforts that cleaned up air and water in the 1960's and 1970's. Air quality is worsening and the slime is back in Lake Erie. Depressing as that is, we know that in a remarkably short time, we can correct these problems if we want to.
Still, we shouldn't get too cocky. Despite my dislike of catastrophists, they do bring to the fore one important point: Bad things happen to living things on this rock, over which the living things have little or no control.
Major extinction events have occurred many times over the Earth's lifetime, along with more minor ones. Climatic change has been a huge factor and will, no doubt, be one again some day. While experts wax eloquent about carbon dioxide and ozone, the fact is that no one really understands what causes the Earth to get very warm or very cold. Right now, we appear to be in a period of global warming, but the climate is nowhere near as warm as it has been in the past. Over the history of the Earth, ice caps have been a rarity, and much greater parts of the planet wer under water. The caps are beginning to disappear again. When they do, a lot of land where a lot of people now live is going to be very wet.
Continents continue to drift. Recently, it was discovered that there has been a widening in parts of the Great Rift Valley in Africa, signaling a possible upwelling of magma at this juncture of two plates. In the very long term, this indicates that there's going to be a new ocean one of these days (I will be offering shares in Rift Beach Estates soon). In a possibly shorter term, we could be looking forward to a volcanic event on a par with the Siberian Traps (which will louse up my real estate deal something fierce).
We have the technological means to mitigate these potential disasters. But, in the long run, Stephen Hawking is right when he says we'd better be working to find a way to get off the planet and a place to go, because things could go wrong at any time.
And I haven't even mentioned the potential of a rock the size of Dubuque bouncing off one of our hemispheres.
The point of all this is this: What has happened and will happen here would happen on any life-bearing planet. If taking 4 billion years to get smart enough to build computers is typical, the odds of a civilization actually hanging around long enough to talk to other ones is slim. If an extraterrestrial race gets smart enough to send signals and happens to send one our way, and we happen to be listening when it arrives, by the time we respond, they might not be around to complete the thought. The same goes for the likelihood that we'll be around to hear anyone responding to our few attempts.
None of this is to say that we should abandon all attempts to listen for intelligent signals. Just identifying a signal from some other interstellar race might work to change our shortsighted attitude toward our own existence. If we realize that we're not alone, we might work harder to ensure that the other guys won't end up all alone in our corner of the galaxy. Besides, a signal would mean that someone out there had worked hard to beat the odds of ever communicating with another intelligence. It would be a shame to let their effort go to waste without listening and responding, just in case they managed to beat the catastrophe odds.
As a species, we're pretty young, you know, not to mention inherently bright. We can resolve our short-term problems and work toward long-range plans that will ensure that we'll be around for far more than the foreseeable future.
Who knows, maybe someday we'll be sending out signals with advice on how to beat the odds against survival.