[d_theorist]

A slightly-off-topic thought related to the Fermi question.

What actually is the point of communicating at sub-luminal speed between star systems or galaxies, other than CETI projects? The delay between transmissions would make such communication impractical for day-to-day purposes.

Perhaps this is one possible explanation for the apparent lack of such signals. Either the aliens don't bother much with communicating at galactic scales, or they have developed a system of doing so at super-luminal speeds that eludes our current understanding of physics.

If this is correct then you would expect most artificial radio signals to be easy to detect and decipher, because the only plausible use for such signals is long-term communication with alien civilisations. And you might also not expect to find many of them.

[talmand]

Seems logical to me that a civilization advanced enough for interstellar travel would have solved the problem of the extremely slow radio wave for interstellar communication. I would think we shouldn't be limiting such possible civilizations with the limitations we currently face.