[ExI] Gaian Bottleneck

[John Clark]

On Sun, Jan 24, 2016 at 7:28 AM, Anders Sandberg <anders at aleph.se> wrote:

​>​
>  I originally argued that the star is unlikely to be a Dyson because of
> the rapid construction (or decay); the chance of seeing that moment in
> history is small:
> http://aleph.se/andart2/space/likely-not-even-a-microdyson/
> So I was happy with the comet hypothesis. But the dimming doesn't fit at
> all, so it has to be something stranger.
> Meanwhile Phil Plait claimed the dimming was too *fast* to be Dyson
> construction, and I felt obliged to calculate some limits on Dyson
> construction:
>
> http://aleph.se/andart2/space/what-is-the-natural-timescale-for-making-a-dyson-shell/
> So what do I think it is? I suspect it is natural, but perhaps a rare
> phenomenon. Maybe there is a small and dense cloud of interstellar dust
> drifting past?


​
I agree, I
​ ​
think it's probably
​ ​
something odd but natural. It's a F3 star that is brighter than our G2 sun
and as a result it has a shorter lifetime.
​ ​
The sun will remain on the main sequence for about 10 billion years but a
F3 will leave the main sequence in only
​ ​
about
​ ​
2.5 billion years and become unstable. If the sun were a F3 and the Earth
were in a larger orbit around it in the habitable zone Evolution would have
had enough time to produce bacteria but then the sun would have vaporized
the
​ ​
bacteria and the
​​
entire planet
​ ​
as well
​ ​
a billion years before the Cambrian Explosion even started.
​
​
And if it's a Dyson Sphere it's odd we can't pick up any intelligent radio
signals from it; the star is only 1
​,​
480 light years away and the Arecibo Observatory could detect a similar
instrument 50,000 light years away but we don't hear a peep. People have
looked with optical telescopes
​for
 flashes of LASER light coming from the vicinity of the star and haven't
found those either.

 John K Clark
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