Why SETI will have missed any cost conscious ET civilizations


If we want to contact any of those other civilizations out there, we’ll need a beacon to send messages with. But what to build?

Gregory Benford at the University of California Irvine and family (?) have done a cost/benefit analysis on the types of microwave generators out there that can produce the 10^17 W necessary to reach a significant proportion of the galactic habitable zone.

There are various ways that the cost can be optimised and the Benfords summarise them like this:

“Thrifty beacon systems would be large and costly, have narrow searchlight beams and short dwell times when the Beacon would be seen by an alien observer at target areas in the sky. They may revisit an area infrequently and will likely transmit at high microwave frequencies, ~10 GHz. The natural corridor to broadcast is along the galactic spiral’s radius or along the spiral galactic arm we are in.”

This has implications for the search for ET civilisations (as opposed sending messages for them). If ET civilisations are as cost conscious as we are,  then they may well have built beacons in this way.
And if so, say the Benfords, nearly all SETI searches to date would have missed them.


arxiv.org/abs/0810.3964: Cost Optimized Interstellar Beacons: METI

arxiv.org/abs/0810.3966: Cost Optimized Interstellar Beacons: SETI

3 Responses to “Why SETI will have missed any cost conscious ET civilizations”

  1. Peter henry Cheasley says:

    A cost efficient signal may now exist.La Tuque Que. St Zephyrin church bell,G pitch(alone in NA.Dec +45Since 1930.Rings twice a day,Location beside site of Nicolas Tesla transmission project.
    Detection 3.5ghz G pitch bell chord July 15 2006 July 17 2008 3.5ghz Argus Station FN35dm Target star 47 Auriga

  2. Robert says:

    Or, maybe, the aliens have different technology than us.

  3. Lanford says:

    Why do aliens need money?