[ExI] Will Advanced Civilizations Ever Build Dyson Spheres?

[Keith Henson]

On Tue, Nov 12, 2024 at 2:23 AM Ben Zaiboc via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
snip

> So what does 'large areas' mean, when it comes to energy collection and heat dissipation?

The largest dip in light from Tabby's star is an object 409 times the
area of the Earth.  Even out at 7.8 AU it intercepts 1.4 million times
the energy humans use.  It does not seem to be in thermal equilibrium
which makes me think they are using directional radiation such as I
proposed for thermal power satellites years ago.

> And what is an acceptable minimal delay in communications?

As a square, the object would be around 450,000 km on a side.  That's
1.5 seconds edge to edge at light speed.

> A balance between these two would determine the size and shape of the individual data centres.
>
> It would seem to indicate a structure like a small spider in the middle of a large web, or a marble embedded in the centre of a large circular membrane. The marble would be the data centre, maybe on the metre

 scale, and the membrane the energy collection/dissipation part, on
the km scale (10s, 100s, or 1000s of km).
>
> Processing speed, or 'thinking speed' would determine the range of sizes needed, and I think at some time you mentioned a one-metre sphere sunk in the deep ocean as being suitable for a data centre for minds running at 1 million times biological thinking speeds. I'd assume that something similar in free space would be like I describe above.

https://web.archive.org/web/20121130232045/http://hplusmagazine.com/2012/04/12/transhumanism-and-the-human-expansion-into-space-a-conflict-with-physics/

That's my case for what it would take to run a million times faster.
If what we see at Tabby's star is an uploaded civilization, then they
went a different way.

> Slower speeds would mean larger structures.
>
> So how large do you think one data centre (including its energy collection and heat sink) would be likely to be?

Energy and heat sinks favor large areas,  Communication delays favor
small objects.

> I'm guessing something between 10km and 1000km in diameter, and very thin. So trillions of these could be spread out round a star, and probably be fairly invisible from a distance.
>
> Or do you think the data centres would be humungous?

At least the largest seen to date around Tabby's star is huge.  Supprised me.

Keith

> As you say, this conflicts with speed-of-light delay, and I'm wondering what would be the point of connecting individual collections of computing substrate with solid mass rather than empty space? Would this be necessary for the energy collection etc? So you'd have a huge plate of solar collectors and heat sinks, with individual processing centres dotted about in it? Or something else?
>
> I'm not a numbers guy, and I know that you (and others here) are, and I know better than to argue with the numbers, so what do the numbers say? Lots of small (relatively small, on a solar-system scale. Say no bigger than 5000km) units spread out around a star, or one (or a few) ginormously huge structures*, hundreds of times bigger in area than the surface of earth, easily detectable from a distance?
>
> Or are there other options that make more sense?
>
> And how does what we see at Tabby's star etc., fit in with this?
>
> --
>
> Ben
>
> * Interesting question: How big could a huge flat (or curved) continuous structure be? There must be factors that limit the size
> (gravitational forces, tensile strength, perhaps other things)?
>
> Ben
>
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