[ExI] Von Neumann Probes

[John Clark]

On Tue, Jan 27, 2026 at 11:40 AM Jason Resch via extropy-chat <
extropy-chat at lists.extropy.org> wrote:



>
>>> *> 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. *
>>
>
> *> Now work out the number of non reversible computations that can be
> performed under the two efficiencies you calculated.*
>

*The maximum number of bits any physical object can compute depends on how
massive it is. No computer, regardless of its serial or parallel, can
compute more than 1.36*1^50 bits per second per kilogram.*

*John K Clark*


>
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