Re: Really old aliens with an urge to expand - lil' help please
- From: "Mike Dworetsky" <platinum198@xxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 26 Sep 2008 07:48:51 +0100
"DarkHorse" <Archaeus225@xxxxxxxxx> wrote in message news:b4ae8cee-8a93-469f-b64c-815c5f4ff94a@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Sep 25, 11:50 pm, Brian Davis <brda...@xxxxxxxx> wrote:
On Sep 25, 3:59 am, DarkHorse <Archaeus...@xxxxxxxxx> wrote:
> I feel like the evolutionary pressure for these fellas to develop,
> let alone expand, is a bit shallow.
I actually have the opposite problem - positing a species that remains
in anything like its original state for *billions* of years, well...
that takes some extreme hand-waving to me. You've got a creature
that's moving towards a space-based civilization, and will maintain it
for longer than it takes sentience to evolve... I'm not seeing it.
Oh, yeah...I think I made an "oopsie" here.
These guys aren't still floating around in the relative *now*. They're
long gone, either dead or post-human (post-alien?) in the present
era.
This is a backstory exercise, trying to flesh out some moderately
plausible constraints - "how fast could a technology-using
intelligence develop after the Big Bang?" without being *too*
ridiculous.
I only tolerate low to moderate levels of ridiculous.
Thanks for the input.
Matt Perryman
Darwin, Australia
-----------------------------------------------------------------------------
OK, that wasn't clearly stated. Let's see...astronomers see good evidence for the fact that our galaxy started forming very soon after the Big Bang (13.7Gya). There are stars nearly as old as that (say 12 Gy) with substantial metal abundance (because the age is found from the abundances of thorium and uranium in their spectra). Assuming that, as on Earth, it might well take 4.5 Gy from formation of a planetary system to the rise of intelligent life (we have only one sample for this assumption), you could probably take the earliest possible origin of your aliens as somewhere around BigBang + 6.5 Gy, about half the age of the present universe. There should be enough metal-rich systems by +2Gy to permit formation of terrestrial planets and complex organic chemistry, though if you wanted to be conservative you could add another Gy to that. Some systems by that time could be as metal rich as ours. The astronomers' terminology for this is "Prompt Initial Enrichment" or PIE--the evidence is that the Universe started getting enriched in metallic elements very soon after the first stars formed after the era of darkness, and that this happened fast. Witness--the Hubble Deep Field(s).
My reasoning is based on the discovery that star formation rates were much higher in the early universe (and presumably in the galaxy) so that plenty of recycling and metal build up took place rapidly not long after BB, cosmically speaking; the rate has slowed to about 5% of that now, and will eventually diminish further and a long time hence, cease.
When I say "the galaxy" it needs to be remembered that we now think large galaxies of the present era were formed by successive mergers and cannibalization of smaller galaxies back then, a process that has slowed down a lot but is still taking place.
--
Mike Dworetsky
(Remove pants sp*mbl*ck to reply)
.
- References:
- Really old aliens with an urge to expand - lil' help please
- From: DarkHorse
- Re: Really old aliens with an urge to expand - lil' help please
- From: Brian Davis
- Re: Really old aliens with an urge to expand - lil' help please
- From: DarkHorse
- Really old aliens with an urge to expand - lil' help please
- Prev by Date: Re: Really old aliens with an urge to expand - lil' help please
- Next by Date: Re: asteroids with air, water, and life
- Previous by thread: Re: Really old aliens with an urge to expand - lil' help please
- Next by thread: Re: Really old aliens with an urge to expand - lil' help please
- Index(es):
Relevant Pages
|
