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June 06, 2007

Faulty Logic

I too am of the belief that there's life out there but that doesn't excuse this rather faulty logic:

He added that aliens could now be eavesdropping on us. "As from 1927, we have been propagating outwards from Earth, a very specific indicator of our existence."

These radio waves are now 80 light years away. "That is going to encompass many hundreds of potentially habitable planets," he said. "It is not just a one way process. If there is intelligent life out there, they sure as hell know we are here."

Their hearing our radio transmissions presupposes that they have the technology of radio. In which case we should be able to hear their transmissions: and despite listening for a number of decades, we can't.

June 6, 2007 in Space | Permalink


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I recall that when I was a kid (70's, 80's) this was something I used to read about in the science books I had.

Carl Sagan expressed the fear, tongue-in-cheek I think, that aliens were going to be getting all those Hitler broadcasts and wonder who had won the war. They would have, he suggested, to wait until the post-war rush of Hollywood war movies to discover that it had been John Wayne.

Posted by: Mr Eugenides | Jun 6, 2007 10:37:55 AM

Logic for Tim

'If there is intelligent life out there, they sure as hell know we are here.' Scientist

To show that this is a false statement, you need to find inteligent life thast does not know we are here.

If intelligent life did not exist,as you assert, then the scientist's statement is true.

Posted by: james C | Jun 6, 2007 11:53:01 AM

Well, maybe they don't use radio any more; they use subspace or the ansible or something. But they would certainly still recognise radio waves, just as you would still recognise a record player if you saw one in a museum.

Posted by: Stephen | Jun 6, 2007 1:01:46 PM

There can't be any within 40 light years or they'd have heard our radio waves, fired up their antique transmitters and replied to us. But there's much more space between 40 and 80 light years away.

Posted by: dearieme | Jun 6, 2007 2:45:18 PM

Actually, Tim, this isn't true. From our history, and from various physical limits, we can be reasonably confident that as a civilization continues to use RF, two things happen: the proportion used of the detectable bandwidth goes up, and the degree of data compression goes up. The effect of both of these is to make the transmission look more and more like "noise", and so indistinguishable from the bright hot shiny thing next to them.

So, we'd only expect to be able to see one of the stars in the 80 ly sphere showing radio transmissions if they happen to be at the same interval in their history as we are. The chances of that are pretty slim.

Posted by: Charlie (Colorado) | Jun 6, 2007 5:05:58 PM

When you start thinking about where an alien race should have been or what they should have done, you can go further then "we would have heard their radio" to "we should have meet them" or "they should have colonized our planet and formed a thriving world spanning civilization long before we had a chance to evolve." http://en.wikipedia.org/wiki/Fermi_paradox key quote, "There have been estimates of anywhere from 5 million to 50 million years to colonize the entire galaxy; a relatively small amount of time on a geological scale, let alone a cosmological one."

I think we are alone.

Posted by: David Krumm | Jun 6, 2007 6:38:40 PM

Unless, David, we are unknowingly the colonists.

Posted by: dearieme | Jun 6, 2007 8:04:19 PM