Re: Fermi's Paradox, again

Michael M. Butler (butler@comp*
Tue, 08 Jul 1997 23:45:10 -0700

As I seem to recall, in the dim mists of antiquity (1970s) I got from a book
co-authored by Chandrasekhar (yes, the "Chandrasekhar's limit" Chandrasekhar)
the story as follows:

What are called Population I stars (that might be a Roman numeral, I forget)
are the products of *two* supernovae, and they and their planets are the
loci for concentrations of heavy atoms. As I understand it, the posited
fusion processes in a "fresh" (H-He) star going nova can only get you to
something like Calcium or Silicon. Those elements, present during a
*second* supernova event, can get transmuted "up the hump" of binding energy
to yield the heavy stuff, even all the way to transuranics.

Paradoxically, given the names, Pop I stars are *older* than Pop II stars.

If this is still an accepted model, then any civilization developing on
a Pop II star's planet *might* have a hard time discovering/developing
nuclear physics & tech. If they don't have very much metal in their planet's
crust, they *might* not get past the pottery stage. Poul Anderson used
this as a plot element at least once.

So we might be the first race with the wherewithal to get off their rock.
Wait for the elder race? No time for that, they might be us...

Like Eric, I don't really know what the current story is.
Maybe Carl F has a clue?


At 10:38 PM 7/8/97 -0700, you wrote:
>EvMick writes:
> > Doesn't (mumble mumble)'s Law indicate that there has already been time
> > enough for the entire galaxy to have been colonized?
>Well, I've been trying to look into this, although I'm hampered by my lack
>of expertise in astrophysics. The Solar system formed about five billion
>years ago. One of the reasons that life could form here is that the cloud
>from which it formed was already enriched with oxygen and carbon. The Big
>Bang (if that's what happened) produced only hydrogen and helium, and
>happened only some seven to thirteen billion years before the formation of
>the Solar system. It would take a certain amount of time for enough large
>stars to form and go supernova to enrich the interstellar clouds of our
>galaxy with the oxygen and carbon that were available at the time the Solar
>system formed. When I try to answer the question "How much time at a
>minimum would be required to form and disperse the necessary amount of
>heavier elements?" I find I get led into astrophysics textbooks and papers
>that are too hairy for me to understand without devoting a lot of time to
>it, and they don't present "the Answer" to this question in the abstracts
>or conclusions from which a layperson could easily grab it. So to me, it
>seems like an open queston. If anyone can close it for me, I'd appreciate
>In the meantime, though, it seems entirely possible to me that we just
>happen to be the first on the block, and that's my hypothesis (shared by
>several others, some of whom suggested it to me) about Fermi's Paradox.
>Eric Watt Forste ++ Q: What is the meaning of life? ++ A: You're soaking
in it!
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