An article on Bad Astronomy.
I'm somewhat pessimistic about the possibilities of finding a radio signal from another civilization. The radio geeks can weigh in on how faint a omnidirectional broadcast signal gets over interstellar distances. Sure, NASA is talking to Voyager 1 and 2 at phenomenal distances, but the probes are sending out highly directional signals that are being received by honking huge antennas. I don't know what the power output is of the transmitters aimed at the Voyagers, but it's probably enough to fry somebody unfortunate enough to be in front of the antenna.
So we'd have to pick up a directional signal that was, by sheer coincidence, aimed in our direction. If the transmitter is so gross in control that it can only be aimed in steps of one degree, there are 129,600 possible aiming points (if by minutes of degree, then that jumps to over 466 million). It'd probably be a signal sent to either a probe or another celestial body in the same solar system, for unless a species has lifespans that make ours seem like mayflies, radio communications over interstellar distances would make sending a letter across the pond in the 1700s seem speedy by comparison
Then we'd have to recognize that a signal contains information. Which could be rather tricky if the signal is a digital one. If you've ever tuned in a scanner on a digital transmission, it woulds like noise. So if a really faint signal is there that sounds like noise, would it even be picked up?
Maybe they'll find something. I think the odds of finding something are about as astronomical as those of willing a $500 million Powerball jackpot, but maybe that's no reason not to be listening.
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6 comments:
I think Calvin said it best: The surest sign of intelligent life in the universe is that none of it has tried to contact us. ;)
Maybe it's because they're speciesist because we're made of meat.
Wait! WAIT! I just received communications from the ZurmGG the Galactic Overlord on the Planet Dingbat using my trusty crystal radio. Take THAT unbelievers!
Radio is still a black art. If we keep fooling with it we may gain some understanding. In a thousand years we may have learned enough to find that space is full of radio communications from other civilizations, it's just that we didn't know enough to recognize them.
Perhaps, just by chance, a broadcast of the old Jack Benny radio show from the 1940s shot off into space and, traveling at the speed of light, was intercepted by a kid with a crystal radio on the Planet Ummfrog six months ago.
And the kid, listening through his ear phones, said to himself as Jack played "Love In Bloom," that "this sounds like chalk on a blackboard" and tried tuning into something else. What would the moral(s) be?
• Odds are there's no other intelligent life in the Universe, but if there is....
• Odds are our radio signals won't reach that life, but if the signals do...
• Odds are they'll be intercepted by some pimply kid who doesn't speak our language and and decides our desperate pleas for help are interstellar static, best dealt with by tuning out.
Yours crankily,
The New York Crank
Our own radio signals are contained in a sphere about 40 parsecs in radius. That is TINY even compared to the size of our galaxy, let alone the universe.....
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