quark@dartvax.UUCP (10/27/83)
this is more of an engineering problem (for the hypothetical receiving civilization) than a physics problem. the I Love Lucy signal propagates at nearly the speed of light in vacuum. by further assuming that the initial broadcast was/is spherically symmetric with respect to the (point-like source) earth, it is easy to calculate the photon density per area of spherical shell after any given time (given in addition the initial intensity of the broadcast). it's then just a matter of building a large enough detecting device given the sensitivity of the materials used in the detector. if i remember correctly, i or a friend did a calculation some time ago with the result being that given the relatively low broadcast intensity, it would be only several tens of light years before the signal lost enough information to become meaningless. the real problem is, however, that if a civilization did pick up the signal and saw a few episodes, they would probably assume that there was no intelligent civilization in this corner of the galaxy.
quark@dartvax.UUCP (10/27/83)
I didn't say the energy decreased, but rather that the energy density (per unit area of spherical shell) decreased. Yes, the spherical propagatin assumption is not ideal but the sumplest, perhaps, to get answers from.