Whereas the Drake faction thinks intelligent life is common in the galaxy, the Rare Earth Hypothesis argues the opposite, that Earth and its intelligent life (that’s you) are freakishly rare. I think the Rare Earth people make some excellent points, but hashing all that out is beyond the scope of this post.
I want to state up front that none of the following opinions is scientific. This post is the idle speculation of someone who has read too much science fiction.
My guess is that life is probably common, but intelligent life is probably not. I base this on one fact that we do know: in the four billion years that life has existed on Earth, intelligence has evolved exactly once, genus homo. Were it not for genus homo our planet might continue to spin for another two or three billion years until the dying sun turned red and expanded and incinerated Earth without there ever having been a concept thought on the planet.
(I wrote this idea on a science fiction message board once and was immediately attacked by the new age types because I dared to suggest humans are more intelligent than other mammals such as cats. “How do you know they’re not intelligent?! Maybe they’re just different.” Any beast that I can make run in circles with a laser pointer is not intelligent.)
But rare or highly improbable is not impossible, and our galaxy is a big place. With our current state of knowledge, it is impossible to estimate with any certainty how many stars there are in the Milky Way, but some estimates put the number in the low trillions. Even if that is wildly wrong and there are only, say, 400 billion stars, that’s a lot of stars. So many that I think it likely there are other intelligent life forms out there. Remember, we’re not talking about thousands of stars, tens of thousands, hundreds of thousands, millions, tens of millions, hundreds of millions, billions or tens of billions; we’re talking hundreds of billions and possibly trillions. Thinking about space is like thinking about the federal budget – the numbers are so large that it is hard to wrap your mind around them and make them real. And we’re just focusing on our galaxy here; I don’t even want to think about the rest of the universe.
If there were one technological civilization for every 100 billion stars, then there could be 10-20 civilizations like us in the galaxy. If the ratio is more like one civilization to every 10 billion stars, then the number could be 100-200. Whatever. It’s impossible to know, but the more stars there are, the greater the chance of life and intelligent life evolving.
Even if there are only a handful of technological civilizations in the galaxy, if one were of an explorative nature like humans, and if it had the capacity for interstellar travel and if it began moving out to the stars long enough ago, then it could have come to Earth by now. I know, that’s a lot of ifs, but play along.
That brings us to the Fermi Paradox: where are they?
My answer comes down to economics. Let’s look at how hard it would be for humans to travel to other stars.
The distance between stars is vast. It’s one of those things it is hard to make real in your mind. The nearest star to our sun, Proxima Centauri, is 4.3 light years away. Light travels almost 6 trillion miles in a year, so the nearest star is around 25 trillion miles away.
Traveling at one-tenth the speed of light, .1c, it would take us 40 years to get to Proxima Centauri, not including time for acceleration and deceleration. .1c is 10,000 times faster than man managed to travel in the 20th century!
Given our current state of technology, the only realistic way to move humans to another star is by using a slow generation ship. Shipping metal into space to build a generation ship is far too costly. One possible solution is to convert a metal-rich asteroid into a spaceship. Isaac Asimov called such a ship a “spome,” short for space home. Once the spome was launched, generations of humans would be born, live and die within the traveling world before it reached another star.
(To digress for a moment, can you imagine being the third or fourth generation born in such a traveling world? They would watch movies of Earth and know that they would never swim in an ocean, climb a mountain, feel the sun on their back, ride an inner tube down the Sacramento River or see Paris or New York or any of the glorious cities of Earth. Even if they managed to turn their spome around, they would die before it got back to Earth. Instead they’re stuck inside a rock. You think they might be a little pissed off? Preventing societal breakdown and general madness would be a major concern for the spomites.)
Building a spome and launching it would be an enormous, costly task that I believe would take generations of effort. The cost of building a small world would easily run into trillions of dollars. How do we pay for it? Three possibilities:
1. Government spending
2. Capital investment
We can rule out government spending. Setting aside the fact that governments are notoriously inefficient and would turn the project into a bureaucratic nightmare, what politician will vote to spend trillions of tax dollars on something that will not benefit his constituents in their lifetime?
Capital investment is out because the time horizons are too long to make a profit from interstellar space travel. The most we can hope for from corporations is that they might sponsor the effort in part for advertising purposes. A company might put its name on the project the way they do to sports stadiums. Imagine the AT&T Spome.
That leaves charity. Interstellar travel would depend on a society of committed visionaries collecting contributions and investing them over generations, probably centuries, to raise the funds.
This raises another problem. When a substantial pool of money exists, politicians want to steal it. Jesse Jackson and other socialists want to tap into America’s pension funds for their redistribution schemes. Can you imagine how they would lust for a fortune of hundreds of billions or trillions that the visionaries created after a century or so of effort? Interstellar travel would depend on a capitalist country that protected private property with absolute vigilance. Such a civilization would have to last for centuries. Given the current degeneration of America and the world into the cesspool of socialism… well, it’s a longshot.
Building and launching one spome would be such a phenomenal achievement that it might very well stand as the technological highpoint and climax of Western Civilization.
So that’s my solution to the Fermi Paradox. Where are the aliens? They’re at home watching TV. When their visionaries knock on the door, they say, “I gave at the office,” then resume watching “Alien Idol.”
UPDATE: Welcome Centauri Dreams readers! CD is a fascinating blog that I read daily.