Odds of alien life

I am so excited that there will be a new Star Wars movie out in a few months. I saw a trailer recently with an aged Harrison Ford reprising his role as Hans Solo. It should be fun, probably campy, with lots of light-saber and spaceship action. I can't wait.

Most of the sci-fi shows imagine a universe teeming with life, and not just any life, but space-faring life that conflicts with a space-faring human race. And like on the original Star Trek show, most of our interactions are modeled after the U.S. - Soviet relationship...mistrustful, fearful, possible mutual annihilation always present, and an eventual détente where we either become allies, are enemies but with a neutral zone in between, or the aliens are so far above or below us technologically that we can move onto the next planet for more adventures and conflicts.

This got me thinking about the odds of actual intelligent, advanced alien life on other planets. Since we have no contact with other aliens and can't ask how widespread alien life is, we are left to speculate. Some of that speculation is based on the facts that we know, which are basically two: intelligent life exists on earth, and roughly one-tenth of the planets in our solar system have life.

The universe is seemingly infinite, and there may be multiple universes, so the odds of some intelligent life elsewhere have got to be 100%. But we have another fact which points to such life being extremely rare, and that is we have no evidence of it, despite searching the skies for radio signals or other types of anomalies.

Since the universe is like 13 billion years old, and earth is like four billion, there has been plenty of time for other civilizations to exist and to broadcast their existence. Not being able to even catch a whiff of anybody else seems strange. It would seem much more likely that we would catch faint glimpses of others, perhaps fleeting, weak signals, that could be millions or billions of years old, but would still show evidence of aliens.

We have another fact about life on earth, and that is that the variety is great and life is abundant. We have produced millions of different species of life over hundreds of millions of years, so it would appear that when life exists, there is an abundance.

So if a planet is able to sustain life and life takes hold, it could develop like ours has through evolution and eventually produce a species intelligent enough to build radio towers and computers and space ships. Those would be three good indications of the type of life with which we could theoretically communicate.

But intelligent life with advanced technology is extremely rare on earth, even with millions of species and billions of years of life. As far as we know, we are the only animals to ever use fire, to create money, to smelt metal, to build a wheel and then a machine, to talk with a written language, to invent paper, and to build on these inventions to make a radio tower or a computer. Our technology that would put us in the "advanced" category is only around 100 years old. Out of a four-billion-year-old planet, that is nothing. Just one part out of 40 million.

To put this in perspective, the dinosaurs ruled the earth for millions of years and never developed technology, nor do we think they could have. There could be millions of planets in the universe ruled by dinosaur-like creatures who will never build a computer because they have no need or they don't have the resources.

It is also very possible that advanced technological life does not continue for long because such societies self-implode. We have already done something that may be extremely rare, so perhaps we will also survive as a species long-term and accomplish another rare feat.

But if we extrapolate from these known facts, we have a 10% chance of a planet being suitable for life as we know it, and we have a one out of 40-million chance of life being advanced enough to build a radio transmitter so that is one-out-of-400-million odds of advanced life on any given planet as of right now.

If an alien had visited earth a million years ago, there would be no evidence of space-faring intelligent life. So the question isn't whether a planet "could ever" have intelligent life, it is whether such life exists at the present time.

Perhaps there are other resources besides trees that would allow for the creation of paper and the harnessing of fire, and perhaps other resources besides silicon that would make computer chips, and perhaps other technologies to make electricity and then circuits, but if technology has to follow a similar path as ours, then the chances of the same raw materials being present on other planets would make the overall odds against space-faring intelligent life even longer.

And assuming there are no short-cut "wormholes" that allow travel between galaxies faster than the speed of light, there aren't any aliens hanging out on earth to watch us. They would not have had time to get here once they figured out we were a potential candidate for advanced technology. If they did visit, they probably watched the dinosaurs make no progress over millions of years and left for better prospects to observe on other worlds. Back then, our ancestors were the size of shrews and hardly good candidates for technologically advanced life.

Time to beam me up, Scotty!

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The trekkie side emerges. Fun

The trekkie side emerges. Fun and thoughful article!

Mark Lo has been covering the suburban Boston dining scene since 1995. His work has appeared both in print and on the web.