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

Sun Oct 19 12:02:56 UTC 2025

On Sun, Oct 19, 2025 at 3:45 AM Keith Henson <hkeithhenson at gmail.com> wrote:

>
> *> wikipedis "whereas Tabby's Star appears to be a normal F-type star
> displaying no evidence of a disc.[148]*
>

*That study is ancient, it's from 2016. Since then observations have shown
that when the intermittent dimming of Tabby's Star occurs the dimming is
much larger at short wavelengths of light than longer wavelengths, so
whatever is causing the dimming it can NOT be a solid object, but it's just
what you would expect from a dust cloud.  The visible light dimming is more
pronounced than the infrared, it's more constant, but Tabby's Star produces
more infrared light then you'd expect from a typical F-type Star, but it's
what you'd expect if a dust cloud was involved. *

*Today the overwhelming consensus of astronomers and astrophysicists is
that an uneven dust cloud orbits around Tabby's Star, although there is
still debate about the exact nature of that cloud. Some think it's composed
of comets and large fragments in the process of forming planets. But others
think it is much younger than that and the dust is composed of the debris
produced by the collision of two large planets. After all, something like
that happened in the solar system, the moon is probably the result of a
collision between the Earth and a Mars sized planet about 4.5 billion years
ago, although in Tabby's case the planets involved would have been larger.*

*Also, Tabby's star is only about 1 billion years old, so it's very hard to
believe a super advanced megastructure building life form could have
evolved in such a short time, it would be amazing if even bacteria had. In
fact it's very unlikely that complex life forms will EVER evolve around
Tabby's Star because the Earth will become too hot for complex lifeforms to
exist in about 500 million years, and the longevity of a star is inversely
proportional to its mass take it to the power of 2.5, and Tabby's Star is
1.4 times the mass of the sun. Stellar lifetime =(Mass)^-2.5= (1.4)^-2.5 =
0.43.  So Tabby's Star will only live 43% as long as the sun, so forget
about super intelligent beings, complex life forms such as worms would die
of excess heat exhaustion just about the time they managed to evolve into
existence.*

* John K Clark*

>
> Keith
>
> On Sat, Oct 18, 2025 at 5:47 PM John Clark <johnkclark at gmail.com> wrote:
> >
> >
> >
> > 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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