[ExI] Old Chemically Mature Galaxies and Fermi Paradox

[Anders Sandberg]

Dan wrote:
> Maybe the age estimates are wrong, but it still seems like that 
> wouldn't explain nearer ones being less "chemically mature." Is your 
> suggestion that there's a process that resets the clock here -- and, 
> further, that this process is technological?

One reset mechanism that was suggested by Milan Circovic (and then, with 
some minor input from me, developed by him into a paper with Robert 
Bradbury) is that gamma ray bursts acts as the reset. The data suggests 
that gamma ray bursts were much more common in the past, and it is not 
hard to imagine that every time one hits a biosphere it slides back to a 
simple stage. If there is a number of "ladders" to climb and the GRBs 
act as "snakes", then a model with exponentially declining GRBs and lots 
of biospheres has a decently sharp transition from simple to complex 
biospheres. I don't think this is a good enough reset mechanism to 
answer the Fermi question, but it might be part of an answer.

-- 
Anders Sandberg,
Future of Humanity Institute 
Oxford Martin School 
Faculty of Philosophy 
Oxford University