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

[John Clark]

On Sun, Oct 19, 2025 at 6:43 PM <spike at rainier66.com> wrote:





> *> The further from the sun your Dyson sphere (or Dyson swarm ) is, the
> more massive it has to be and the more difficult it is to build. If you
> build it from the distance the Earth is from the sun it would receive
> about 1360 **w**atts** of solar radiation per square meter. Assuming it's
> a blackbody you can figure out what its equilibrium temperature will be by
> using the formula T=(2σ)^1/4 where σ is the Boltzmann constant, and the "2"
> is in there because it radiates from both sides. Plugging in the numbers we
> get (1360/(2*5.67*10^-8))^(1/4)= 331 kelvins = 58 °C = 136 °F.*
>
> *Modern microprocessors typically operate between the temperatures
> of 30 and 85°C, so they should not malfunction at 58°C, thus I see no
> reason why you'd want to build a Dyson sphere with a radius larger than the
> Earth's radius around the sun.  **John K Clark*
>
>
>
*> John that analysis has assumptions you didn’t state.  Using that
> equation assumes a thin shell or (if expressed in Dyson swarm language) a
> thin layer. But what if it isn’t that way?  What if a Dyson swarm is a few
> light seconds thick? *


*I don't see the advantage of doing that**, it would just make things more
complicated and require more mass.*


> * > Are you confident in using the black body thermal model for the
> inboard nodes?*
>

*Yes a Dyson sphere or swarm will radiate heat from both the inside and the
outside.  *



> *>  in order to prevent overheating your innermost nodes.*
>

*I just don't see why that's gonna be a big problem. *

*John K Clark*




> On Sun, Oct 19, 2025 at 5:03 AM John Clark <johnkclark at gmail.com> wrote:
> >
> > 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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