[ExI] Alien Civilizations May Only Be Detectable For A Cosmic Blink Of An Eye

[John Clark]

On Sat, Oct 18, 2025 at 7:25 PM Keith Henson via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

*> Tabby's star is well beyond the planet-making dust stage.*
>

*There is no evidence of that. The sun is about 5 billion years old but
Tabby's star is only about 1 billion years old. And the sun is only about 1
billion years older than the Earth. So Tabby is in its planet building
stage. *

*John K Clark*




> On Sat, Oct 18, 2025 at 3:06 PM Adrian Tymes via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:
> >
> > The same way that dust in most early solar systems sticks around long
> > enough to clump into planets, despite there being an active star -
> > more active at that time than later on - in the middle?
> >
> > On Sat, Oct 18, 2025 at 5:56 PM Keith Henson via extropy-chat
> > <extropy-chat at lists.extropy.org> wrote:
> > >
> > > How do you account for dust not being blown out of the system by light
> > > pressure like a comet tail?
> > >
> > > Keith
> > >
> > > On Sat, Oct 18, 2025 at 11:19 AM John Clark <johnkclark at gmail.com>
> wrote:
> > > >
> > > >
> > > >
> > > > On Sat, Oct 18, 2025 at 1:28 PM Keith Henson <hkeithhenson at gmail.com>
> wrote:
> > > >
> > > >> > How do you distinguish dust from computronium discussed on this
> list
> > > >> since sometime in the 1990s?
> > > >
> > > >
> > > > Occam's razor. If simple and very common dust particles can explain
> the observed phenomenon, and it can, then why conjure up exotic and ultra
> complex computronium?
> > > >
> > > > John K Clark
> > > >
> > > >
> > > >
> > > >>
> > > >>
> > > >> Best wishes,
> > > >>
> > > >> Keith
> > > >>
> > > >> On Sat, Oct 18, 2025 at 3:36 AM John Clark <johnkclark at gmail.com>
> wrote:
> > > >> >
> > > >> > On Fri, Oct 17, 2025 at 11:35 PM Keith Henson <
> hkeithhenson at gmail.com> wrote:
> > > >> >
> > > >> >>> >>"That's why I think, at least in the observable universe, we
> are alone. "
> > > >> >>
> > > >> >>
> > > >> >> > That's what I thought until the astronomers found almost 2
> dozen blinking stars in a 2000 ly volume around Tabby's Star.
> > > >> >
> > > >> >
> > > >> > That's an old claim from 2019, and even then the paper says the
> question of whether the 21 stars are really "Tabby-alikes" requires further
> investigation, but as of 2025 the claim remains unconfirmed and is now
> considered dubious by nearly all professional astronomers. The paper about
> the odd behavior of those 21 stars was based on data from a ground-based
> telescope over a period of just 11 months, but the data about Tabby's Star
> came from the Kepler space telescope over a period of 9 years and 7 months,
> so there was insufficient data to say that the two phenomenon were the
> same. And those 21 stars were "close" to Tabby in that they were near to it
> in the night sky as seen from earth, but that doesn't necessarily mean they
> were close to it physically.
> > > >> >
> > > >> > And the theory that the dimming of Tabby's Star is caused by an
> uneven cloud of small dust particles orbiting the star explains
> observations quite well, but the theory that the dimming is caused by a
> megastructure built by ET does not. In short, that 2019 paper has been
> largely superseded by subsequent astronomical research and astronomers have
> moved on to more interesting things.
> > > >> >
> > > >> > John K Clark
> > > >> >
> > > >> >
> > > >> >>
> > > >> >> >
> > > >> >> >
> > > >> >> > That makes absolutely no sense to me! What does AI have to do
> with it? It makes no difference if the brain that develops Drexler style
> Nanotechnology is wet and squishy or dry and hard because then they could
> make a von Neumann probe, and even if they couldn't move them faster than
> 0.001 C, which they almost certainly could, they could send one to every
> star in the galaxy in less than 50 million years (a blink of the eye
> cosmically speaking) and then a blind man in the fog bank could tell that
> the galaxy had been engineered. But even with our most powerful telescopes
> we've never seen a hint of such a thing. That's why I think, at least in
> the observable universe, we are alone.
> > > >> >> >
> > > >> >> >  John K Clark
> > > >> >> >
> > > >> >> >
> > >
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> >
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