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

[Keith Henson]

How do you distinguish dust from computronium discussed on this list
since sometime in the 1990s?

Best wishes,

Keith

On Sat, Oct 18, 2025 at 3:36 AM John Clark <johnkclark at gmail.com> wrote:
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> On Fri, Oct 17, 2025 at 11:35 PM Keith Henson <hkeithhenson at gmail.com> wrote:
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>>> >>"That's why I think, at least in the observable universe, we are alone. "
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>> > That's what I thought until the astronomers found almost 2 dozen blinking stars in a 2000 ly volume around Tabby's Star.
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> 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.
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> 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 In short, that 2019 paper has been largely superseded by subsequent astronomical research and astronomers have moved on to more interesting things.
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> John K Clark
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>> > 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.
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>> >  John K Clark
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