Drake's Equation is a theory formed in the 1960s to try and provide a framework for guessing at how often intelligent life evolves elsewhere. (Creationist types, this conversation isn't for you, so please file out of the topic in an orderly fashion.) The idea behind it is to fill a template with some guesses about how often certain things occur and try to figure out, based on that, how likely it is we'll encounter other life.
It's not a law, and it's completely garbage in, garbage out, but it's a useful tool for conceptualizing how something as improbably as life might appear in a universe as incredibly ginormous as ours.
http://en.wikipedia.org/wiki/Drake%27s_equationThat established, the continued lack of SETI discoveries have had people scratching their heads. "Why is it," they ask, " that even with incredibly conservative numbers, we still get N >> 1 answers (eg, strong suggestion that the universe should be teeming with life) but still nothing from the radio telescopes?"
I have a thought about a possible modification to the equation that might result in the number of likely civilizations staying the same, but dramatically decrease the time they would be detactable.
Back in the 1960s, the planet was putting out exponentially more and more RF as time went by. Transmitters for radio stations got bigger, satellites started appearing and signals were being beamed out into space, powerful new radar that literally heated up the air started being used, it was a cornucopia of high powered radio being broadcast, and it seemed obvious that this would continue.
Implicit in the original equation seems to be the assumption that, once they've reached the detectable level (via radio), the civilization would definately STAY there until the end of life.
Fast forward to today, and a different pattern seems to be emerging with relation to our planet. RF output, in spite of predictions 30 years ago, has started to decrease planet wide. The number of transmitters has increased, but the cellularization of communications and widespread infrastructure has reduced the wattage needed, even as high frequencies (which are less likely to survive over long distances) have gotten higher.
Satellite data links, once the norm, are being phased out in favor of high speed, low latency fiberoptic links that stretch to every continent.
The actual amount of detectable radiowaves outside the solar system is probably decreasing.
It's not unreasonable to imagine that eventually, RF will be replaced with some other communications method that offers improvements in range, speed, or cost.
With this in mind, the visualization of the detactable civilizations in the galaxy might be more accurately seen, not as beacons, but instead ephemeral 50-100 year bubbles that expand in all directions for a fraction of the total lifetime of the civilization.
So maybe the numbers people have come up with are right, but the odds of us catching them in their radio phase are worse then we thought.
I wanted to run this by y'all here before posting elsewhere, any thoughts?
