[ExI] Von Neumann Probes

[John Clark]

On Tue, Jan 27, 2026 at 8:03 AM Jason Resch via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

*>> So ET is so obsessed with wringing ever last joule of energy out of
>> their heat engine that they **think** the 2.7 degree temperature of the
>> Cosmic Microwave Background Radiation isn't cold enough so they use a LARGE
>> black hole as a heat sink instead to slightly improve the efficiency of
>> their heat engine.*
>>
>
> *> Ite not a "slight improvement." It's an efficiency improvement of many
> billions of times. Even a small black hole (a few meters across, with the
> mass of Jupiter) is 10^-8 degrees, so close to a billion times colder than
> background radiation. A galactic center black hole can be a trillion times
> colder than the background radiation. So it is not a "slight improvement in
> efficiency," it's equivalent to being able to perform billions or trillion
> of times as many non-reversible computations for the same expenditure of
> energy.*
>

*Nope, you'd barely increase the efficiency at all. The Carnot
Efficiency (X) depends entirely on the temperature of your heat source (Th)
and your cold sink (Tc), formula is: *

*X=1- Tc/Th*

*The surface of the sun is at 5,800 K and the CMBR is at 2.7K, and you're
right that a Black Hole with the mass of Jupiter would have a temperature
of about **10^-8 K, so let's plug in some numbers: *

*If we use the CMBR as the cold sink then*

*X= (1-(2.7/5800) = 0.99353 efficiency *

*If there was something that was just twice as efficient then you'd have
something that was nearly 200% efficient, in other words you'd have a
perpetual motion machine. And you were talking about something that was
many billions of times more efficient.   *


*Now let's look at what would happen if we used a Jupiter mass black hole
for the cold heat sink:*

*X = 1 - 0.00000001/5,800 = 0.9999999999983 efficiency *

*To summarize, if you use empty space as your cold heat sink you'd only
lose about 0.047% of your energy, and I think that's pretty damn good. If
you use a Jupiter size black hole as your cold sink you'd lose about
0.00000000017% of your energy. Doesn't  seem worth all the trouble to me,
and I wonder where you'd get the vast amount of energy necessary to
compress Jupiter into a black hole. I think ET should be more concerned
with trillions upon trillions of suns radiating all that nice juicy energy
uselessly into infinite space. *

*John K Clark*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20260127/a9e1791e/attachment.htm>