[ExI] Von Neumann Probes

Sun Jan 25 16:16:34 UTC 2026

Why do we think a Dyson swarm is the most efficient or most practical
source of power?

Stars only convert 0.7% of a stars mass into energy, and it takes 5 billion
years or longer to get it.

A black hole engine, on the other hand, can convert 100% of mass into
energy via hawking radiation, and can be made to output energy at any
desired rate (smaller back holes radiate more). And this is what we can
already envision with our *incomplete* 21st century understanding of
physics.

It is probably a little silly to think an idea from a few hundred years
after we found the scientific method represents the pinnacle of technology.
We forget that we're trying to find civilizations whose technology is
likely millions of years after their civilization discovered the scientific
method.

Jason

On Sun, Jan 25, 2026, 7:44 AM John Clark via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

>
> On Sat, Jan 24, 2026 at 5:52 PM Ben Zaiboc via extropy-chat <
> extropy-chat at lists.extropy.org> wrote:
>
> *>>* *John K Clark wrote:  You don't need interstellar travel to make a
>>> Dyson sphere/swarm, and something like that should be very noticeable, but
>>> we have noticed nothing. And any technological civilization worth its salt
>>> should be able to get a Von Neumann Probe moving at 1% the speed of light
>>> because its mass would be very small, and so it could get from one side of
>>> the galaxy to the other in just 10 million years, a blink of the eye
>>> cosmically speaking. *
>>
>>
>> * > "Very noticeable"? I'm not sure that is true.*
>>
>
> *From the Earth a Dyson sphere (or swarm) would look like a point source
> of extremely intense infrared radiation caused by waste heat, and if
> anything like that existed in the Milky Way we would've noticed it by now,
> but we have seen nothing like it. And because of the theoretical
> possibility of Von Neumann probes, I wouldn't expect to see just one Dyson
> Sphere, I would expect to see either lots and lots of them or none at all. *
>
> *Also, astronomers have scanned about 100,000 nearby galaxies looking for
> aKardashev Type III civilization, one that has Dyson Spheres around every
> star in their galaxy, but we have never seen the slightest sign of such a
> thing. We might not be able to detect a Type III if the galaxy was very
> very distant, but remember the more distant a galaxy we're looking at is,
> the closer to the Big Bang it is, and the less time Evolution would have to
> produce even primitive life, much less intelligent life capable of building
> a Dyson Sphere around every star in a galaxy. And the very early universe
> was made up of nothing but hydrogen, helium and a tiny trace of lithium,
> and you can't make much with just that. **That's why I think that,
> although life may be common, we are almost certainly the only intelligent
> life in the observable universe. *
>
> *John K Clark*
>
>
>
>
>
>
>
>> How near would a Dyson sphere or swarm need to be before we could stand a
>> chance of detecting it?
>> It's a tricky question, because it depends on the conditions (density of
>> stars, interstellar dust, etc.). I think the idea is that we would only be
>> able to detect the waste heat from such a thing, correct? So we'd be
>> looking for an anomalous infrared signature from the location of a single
>> star, which of course is invisible to us. I don't see how this would be
>> 'very noticeable'. Wouldn't this signature be lost amongst the infrared
>> radiation from billions of other stars? We have detected what we think are
>> anomalous signatures from the Tabby group of stars which are, if I recall,
>> about 1k light-years from us. Somewhere between 1.5k and 0.5k ly? The
>> galaxy is something like 100k ly across, and we are near the outer edge. So
>> if we guess that we could detect a Dyson swarm within say 2k ly, but no
>> farther, that would mean that, um, I don't know how to do the maths, but I
>> can draw a circle 100mm across to represent the galaxy seen from the top,
>> on a scale of 1k ly per mm, then a do!
>>  t about 26mm from the centre, to represent roughly where we are, and a
>> circle around that, 2mm in diameter, to represent the area we can
>> reasonably expect to be able to detect a Dyson swarm from its heat
>> signature. That's probably less than 1% of the galaxy. No, that's
>> definitely much less than 1% (0.025%?). I'd conclude that noticing nothing
>> under these circumstances means nothing. Well, it means there are no Dyson
>> swarms in our local tiny corner of the galaxy.
>>
>> Am I missing something that would mean we could reliably detect any Dyson
>> swarms in the other 99.975(ish)% of the galaxy? Or indeed any respectable
>> percentage of the galaxy?
>>
>> Even if we expand the hypothetical detection range by x100, we could
>> still only be able to reliably look at less than maybe 3% of the galaxy.
>>
>> To make things even more difficult, there's also the matter of
>> directional radiation of waste heat. I think someone here said at some time
>> that it would make more sense to radiate waste heat out of the plane of the
>> ecliptic than in it. We probably wouldn't be able to detect that (would we?
>> Could back-scatter from dust and gas reveal it?).
>>
>> So overall, I'm not feeling optimistic about the chances of detecting
>> even nearby Dyson swarms. Maybe under-construction ones (maybe that's what
>> the Tabby stars are), but not completed ones.
>>
>>
>> The other thing I'm trying to understand is how a bacterium-sized probe
>> travelling at 1%c would last more than a few decades in interstellar space.
>> Just one single collision with a grain of dust would destroy it. I'd think,
>> for this reason, that von Neumann probes would need to be at least
>> millimetre or perhaps centimetre scale objects, capable of maintaining an
>> active power source to be able to self-repair. Maybe a few hundred sent as
>> a group might work.
>>
>> They would have to be capable of some data-processing and navigation, so
>> they could tell when to, and be able to, decelerate into orbit around a
>> suitable star, and then scan for, and dock with, suitable raw material and
>> start converting it into more probes.
>>
>> Presumably there would be protocols for deciding when to stop reproducing
>> and start making other things, like data-centres. That should be simple,
>> something like bacterial quorum-sensing algorithms would be fine (I'm also
>> wondering how many stellar systems have the right materials, in the right
>> proportions, not locked up in large gravity wells, to enable Avogadro's No.
>> of probes to be constructed?).
>>
>> Then what? Maybe my imagination is limited here, but I'd assume that
>> building a physically modest structure capable of receiving and
>> transmitting signals on a reliable long-range wavelength would be the goal,
>> so that the intelligent entities that designed and spread this whole system
>> could come and visit.
>>
>> If our own solar system had one, two, or even a few dozen of these data
>> centres already, how would we know?
>>
>> Ok, I can see one answer. They wouldn't be just building modest data
>> centres, they would be building more Dyson swarms, using the available
>> matter in each system. I'd expect some kind of intelligence to be involved
>> in making a decision first, though, unless we assume they'd simply not care
>> about wiping out any existing ecosystems. Assuming any intelligent life
>> wouldn't want to wantonly destroy information in this way, perhaps we can
>> assume they'd avoid doing that to systems with existing life (so we'd be
>> back to undetectable data centres in those systems).
>>
>> So where's Fermi's Paradox now? There doesn't seem to be one (or at least
>> it needs to be re-stated to: "Where is everybody (in the tiny fraction of
>> one percent of our one galaxy in which we could possibly detect another
>> civilisation that overlaps ours in time)?").
>>
>> Or, unlikely as it seems, we might really simply be the first.
>>
>> Will we ever know? Maybe not. Probably best to just assume that we are.
>>
>> ---
>> Ben
>>
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