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There Is No Way Of Detecting Useful Radio Signal From Far.

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Posted by Alexander on December 18, 2001 20:42:28 UTC

If you are far enough, the quality of information you detect essentially degrades because it is quantizied by E=hf "bits". So, if on planet X you receive less quanta per antenna area per second than the signal content (in bits/sec), you will not be able to distinguish content from noise even if antennas are covering entire planet. Simple calculations show that our Earth's becomes practically radioinvisible from distances of a few light-days only. Account for Sun's background radio-noise makes it even less visible. Accounting for inherent detector noises -even less.

There is technical possibility to beam very little information - small number of bits per second (like a Morse code) to a few light-year distances IF YOU KNOW WHERE EXACTLY TO DIRECT NARROW RADIO-BEAM (to where certain planet will be in several years when the beam will arrive). Also,I wonder, will it have much sense to communicate with the speed of few bits per second anyway? How much info can we send and receive?

And still what to do with 1000s years delay in getting answer if indeed civilisations are scattered over large distances? (Actually, 1000 light years is quite optimistic - it basicly means that there is about 10^4 civilizations in it at any given time. Most likely, the # of civilisations is much less, so mean distance between them is in 10^4 + light years range.

At such distances radiocommunication is likely impossible at all.

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