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Author Topic: Would SETI find life on Earth?  (Read 2262 times)

Offline krool1969

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Would SETI find life on Earth?
« on: 27/03/2012 20:12:02 »
SETI has very strict rules for finding ET radio signals. I was wondering if, operating under those rules, SETI would be able to determine that the signals from Earth are of intelligent origin from say 50 - 100 LY away?


 

Offline Æthelwulf

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Re: Would SETI find life on Earth?
« Reply #1 on: 27/03/2012 20:43:23 »
I am a bit confused, are you asking how far these signals can go?

To be honest, I am under the impression these signals do not propogate far without being substantially disturbed by the background temperatures that effect these signals. In other words, projects like the Arecibo Complex, their signals have not even and will not reach their destinations because they will be effected by the background activities of space (and time).
 

Offline Soul Surfer

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Re: Would SETI find life on Earth?
« Reply #2 on: 27/03/2012 22:49:18 »
Assuming that the signals have had time to arrive  (100 years ago radio communication was in its infancy) a good standard earth based transmitter beamed at a target should be easily detectable at short interstellar distances like 100 light years and television and other reasonably high power high frequency radio signals unintentiunal detected with some effort.  Anything below 100 MHZ could be mucked up by the earth's ionosphere and other electromagnetic disturbances.
 

Offline CliffordK

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Re: Would SETI find life on Earth?
« Reply #3 on: 27/03/2012 23:16:25 »
I would think it would be easiest to pick up directional signals beamed at things, such as satellites, or the Voyager probes. 

However, a beam directed at a geosynchronous satellite would sweep across space at 100 light years very rapidly, even if it diffuses somewhat.  I suppose it would depend on the width of beam in degrees, and the intensity difference from the middle to the edges of the beam.

A beam directed at Voyager would have some annual variation, but would be much more stable for the observers
 

Offline syhprum

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Re: Would SETI find life on Earth?
« Reply #4 on: 28/03/2012 00:13:40 »
From what I recall SETI consider Arecibo type installations both for transmitting and receiving are good for communication over 1000 ly at a low data rate with the correct alignment of dishes at both ends.
I do not believe that TV broadcasts ect would be receivable to any great distance.
 

Offline CliffordK

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Re: Would SETI find life on Earth?
« Reply #5 on: 28/03/2012 02:36:34 »
One question that comes up...
While Earth does "leak" radio waves, especially those directed at satellites, should SETI also purposefully broadcast?  Perhaps every time a new star cluster is listened to, also shoot out a "Hello", along with an estimated distance, so that future SETI observers will know when to check back for a response.

Of course, one would have to calculate where the star will be when the signal should arrive.
 

Offline CliffordK

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Re: Would SETI find life on Earth?
« Reply #6 on: 28/03/2012 04:03:15 »


I found this illustration that shows the maximum extent of how far our radio signals have travelled across the Milky Way to date (assuming they can observed).  Certainly it will be a long wait for Andromeda to pick them up.

http://zidbits.com/2011/07/how-far-have-radio-signals-traveled-from-earth/



However, according to the article, it would be exceedingly difficult to pick up random broadcasts.
Quote
Because of this ‘inverse square law’, all of our radio signals become indistinguishable from background noise at around a few light-years from earth. For a civilization only a couple hundred light-years away, trying to listen to our broadcasts would be like trying to detect the small ripple from a pebble dropped in the pacific ocean off the coast of California – from Japan.
 

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Re: Would SETI find life on Earth?
« Reply #6 on: 28/03/2012 04:03:15 »

 

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