… and its implications for the Fermi paradox
Martin T. Barlow
This paper proposes a long term scheme for robotic exploration of the galaxy,and then considers the implications in terms of the `Fermi paradox’ and our search for ETI. We discuss the parameter space of the `galactic ecology’ of civilizations in terms of the parameters T (time between ET civilizations arising) and L, the lifetime of these civilizations. Six different regions are described….
Consideration of the points above, and Figure 1, leads to three broad categories of answer to Fermi’s question:
(F1) They have not visited us because they do not exist. (Regions R1 and R2.)
(F2) The ‘zoo hypothesis’: their probes are watching us now (Regions R3 and R4.)
(F3) They have not visited us because civilizations are all too short lived (Regions R5 and R6).
Of these, possibility (F3) relies all all civilizations being short lived, while the zoo hypothesis appears to be deeply unpopular (partly I suspect because it compromises human dignity.) The analysis above reduces the force of some of the objections that have been made to the zoo hypothesis, since in both cases R3 and R4(ii) we would lie in the zone of control of just one ETI.
If we exclude (F2) and (F3), then we are left with (F1), to which there are no objections except that it is uninteresting. It is worth noting that while astronomers have frequently given rather large values to fci – typically in the range 0.01–0.1, many evolutionary biologists have been much more pessimistic. Even if one is not convinced by all the arguments in , it seems very possible that the development of intelligent life requires evolution to pass through several gateways, and hence that fci is very small.
Read more: http://arxiv.org/pdf/1206.0953v1.pdf