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

[John Clark]

On Wed, Oct 22, 2025 at 3:12 PM Keith Henson <hkeithhenson at gmail.com> wrote:


> *> There is a world of difference between radiating a very small heat
> leakage on the JWT and GW scale radiation from a power satellite.*
>

*Not per square meter there isn't, big or small if it's in the same orbit
then it's receiving the same intensity of solar radiation. And I'm not
talking about a power satellite, I don't think they're practical unless the
electrical energy produced is used to power a nearby space based data
center for AI. *


*John K Clark*





>
>
> On Wed, Oct 22, 2025 at 3:48 AM John Clark <johnkclark at gmail.com> wrote:
> >
> > On Tue, Oct 21, 2025 at 5:17 PM Keith Henson <hkeithhenson at gmail.com>
> wrote:
> >
> >> > A hot heat sink is not desirable.
> >
> >
> > Sure, but that doesn't change the fact that the hot sun facing part of a
> planet still radiates away heat. The surface of Venus is at a scorching 464
> C, but the planet is at thermal equilibrium so the amount of solar
> radiation energy it absorbs is still equal to the amount of heat energy it
> radiates away.
> >
> >> > My work on low-pressure, low-temperature steam radiators optimised at
> 20 deg C.
> >
> >
> > Using no mechanical refrigeration and with just passive cooling (a.k.a.
> putting things in the shade) the James Webb telescope can get key
> components down to just 40 Kelvin or -233 C. And the telescope is only
> about 1% further from the sun than the Earth is.
> >
> > John K Clark
> >
> >
> >
> >>
> >>
> >> On Tue, Oct 21, 2025 at 5:57 AM John Clark <johnkclark at gmail.com>
> wrote:
> >> >
> >> >
> >> >
> >> > On Mon, Oct 20, 2025 at 10:50 PM Keith Henson <hkeithhenson at gmail.com>
> wrote:
> >> >
> >> >> > A heat sink facing the sun or a hot surface is not useful as a
> heat sink.
> >> >
> >> >
> >> > Yes it is. If you want to figure out how hot a planet is you've got
> to figure out how much solar radiation is being absorbed and how much is
> being radiated. If nothing is being radiated away, and the amount being
> absorbed is greater than zero, then the planet would keep getting hotter
> and hotter forever and its temperature would approach infinity. But that
> never happens.
> >> >
> >> > John K Clark
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >>
> >> >> >
> >> >> >> > 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.
> >> >> >
>
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