JoSH@RUTGERS.ARPA (12/09/83)
From: JoSH <JoSH@RUTGERS.ARPA> One arguable limit to the life of the "I Love Lucy" episodes fleeing outward into the universe is that at some point the signal becomes just too weak to detect. Assume you are a radio-archeologist on a far world. You have an antenna 1000 kilometers in diameter capable of detecting any single photon falling anywhere on it. (all this for I Love Lucy...) Assume you can reconstruct the show by detecting one photon per pixel (ignore sound). Assume ILL is transmitted at 50 MHZ with 50kW and radiates in a sphere. Assume 600x400 pixels 60 frames/sec, ignore retrace, sync, etc. Our radioarcheologist can only pick it up out to 8.4 lightyears. (Somebody check my arithmetic or provide more reasonable assumptions. This seems to contradict the popular notion that all that radiated noise lasts forever and ever...) --JoSH -------
dya@unc-c.UUCP (12/18/83)
References: sri-arpa.14468
But, you couldn't have one photon per pixel. To receive this with
an adequate C/N to actually "see this " (let's say TASO grade 4--, just
barely recogniseable) or a video S/N of 10 dB, with the given antenna,
this works out to something less than a light year, albeit the antenna
is 1000 km in diameter. This, as a practical matter........
-dya { duke!mcnc!unc-c!dya }