All Those Civilizations Out There

I read an interesting article on Yahoo News a few days ago and I thought I’d comment on it.  Entitled “Aliens May Be Out There, But Too Distant For Contact,” it detailed the reasons why we citizens of Earth may have a difficult time communicating and interacting with aliens from other planets.  (Go to the website LiveScience and click the “Space” tab for the complete article.)  The original report was made by Michael Garrett, head of the Dutch astronomical research foundation, ASTRON, who gave this report at the International Astronomical Congress in Toronto recently.  His basic reasoning was that the distances between civilizations advanced enough to communicate with each other are very likely to be much too great for any  meaningful communication.  It’s possible that 3000 or more extra-terrestrial civilizations exist out there, out of approximately 40 billion possible habitable worlds, but they would be distributed throughout the galaxy and the distances between them would be so large as to make communication virtually impossible.  Remember, light and radio waves operate according to the inverse-square rule.  As you get farther and farther away from a source of light or source of communication such as a radio transmitter, the intensity of the waves decreases substantially.  If you double the distance from the source, the amount of light drops by one-quarter.  Triple the distance and it drops by one-ninth.  So, if an advanced civilization exists, say, a thousand light-years away, they would have to have one hell of a transmitter to deliver a signal that would be strong enough for us to, first, detect and, second, recognize when it got here.  Even a civilization a simple 50 light-years away would have to have a huge transmitter. The amount of power they’d have to put into it would be absolutely immense.

Travel between planets that have sophisticated civilizations likewise would be all but impossible.  The nearest star system to Earth is the Alpha Centauri system, a little over 4 light-years away.  That means that traveling at the speed of light a spaceship would take over 4 years to complete the journey, and that’s just one way.  Einstein says it’s almost impossible to travel at the speed of light, so a spaceship traveling at 1/1000 the speed of light (still very fast) would take 4000 years to get there.  That’s grossly unrealistic.  And that’s not even considering a civilization on the other side of our Milky Way Galaxy, which is about 100,000 light years across.  Travel that far isn’t likely.

Some say that a highly sophisticated civilization might travel by wormhole, shortening the distance traveled.  Space-time is curved and shortcuts are postulated to exist between points that are otherwise very far apart.  I suppose wormholes may exist, but they require huge amounts of energy to open, and just aren’t feasible, at least not by those of us living in a civilization whose sophistication in space travel consists of barely being able to get to their own planet’s moon and back.  (Forget wormholes.  They’re good only in science fiction.  I’ve even used them myself in some of my stories.)

In short, I’ve been saying for a long time that I don’t think travel or communication between planetary systems is very likely, and now a report has come out saying the same thing.  The distances are just too great.  No good evidence exists that anyone from outer space has visited us here on Earth, and I can certainly understand why.

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