[ExI] Eternity in six hours: intergalactic spreading of intelligent life and sharpening the Fermi paradox

[Tomaz Kristan]

> I find the hard-line 'Rare Earth' option rather unbelievable

I don't. Consider only one thing. Earth has been closer to Sun and rotated
more rapidly when the Sun was fainter. Then it slowed down and went out
toward the Jupiter. All just as fast as is necessary to maintain liquid
water.

Chances for a random planet to do this are minuscule.

Several such coincidence were needed.


On Tue, Sep 10, 2013 at 12:13 PM, BillK <pharos at gmail.com> wrote:

> On Tue, Sep 10, 2013 at 10:06 AM, Tomaz Kristan  wrote:
> > Instead of just recycling their initial star's energy, wouldn't they
> want to
> > recycle all around?
> > This self limitation is very unlikely. Even much less for "all those
> > millions civs everywhere".
> >
> > The Rare Earth is the only sane explanation for our apparent solitude.
> >
> >
>
> The Rare Earth hypothesis is not just one theory. It is a complicated
> system with many alternatives.
> (And many critics, of course).
>
> <http://en.wikipedia.org/wiki/Rare_Earth_hypothesis>
>
> One option is that civilisations might be plentiful, but spread so far
> apart that contact between civs is very unlikely. (The universe is
> really, REALLY big).
>
> Another time-dependent option is that we are at the right age in the
> universe for intelligence to have developed. And intelligent life is
> just starting to appear throughout the universe, all at almost the
> same time - within a few million years of each other.
>
> I find the hard-line 'Rare Earth' option rather unbelievable. That
> everything must be exactly the same as our Earth for life to appear
> seems extreme circular reasoning.
>
> BillK
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