[ExI] [Extropolis] Crosspost

[Jason Resch]

On Wed, Apr 16, 2025, 6:05 PM Adrian Tymes via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Wed, Apr 16, 2025 at 1:27 PM Keith Henson <hkeithhenson at gmail.com>
> wrote:
>
>> On Wed, Apr 16, 2025 at 9:59 AM Adrian Tymes via extropy-chat
>> <extropy-chat at lists.extropy.org> wrote:
>>
> > I've read such a story.  I forget the author, but it could be the same
>> story you're thinking of.
>>
>> https://en.wikipedia.org/wiki/Dragon%27s_Egg
>
>
> That's the one.
>
>
>> https://en.wikipedia.org/wiki/Landauer%27s_principle
>>
>> Landauer's principle states that the minimum energy needed to erase
>> one bit of information is proportional to the temperature at which the
>> system is operating.
>>
>
This isn't that important of a limitation in my view given that reversible
computers and reversible logic gates can be made and they can perform any
computation, and they can compute without erasing bits.

Launder's limit would kick in when initializing the program, or reading the
result, but during the computation no energy would need to be expended so
long as information is conserved.

Consider all the computation involved in all the molecular collisions
taking place in a glass of water on your table. Far more computation takes
place in that glass than all the computers on earth, and it can sit there
perpetually never needing any more energy to run, and never expending any
waste heat.

This is possible because all physical transformations are reversible, so
information is neither created nor destroyed in any physical process. Thus
the glass of water can continue computing quantum mechanically detailed and
precise updates to all the particles in the glass perpetually.


> This rules out computers being made out of gas and plasma, how?
>
> Maybe they would need to use a lot more energy.  The Sun's temperature is
> around 15 million Kelvin, vs. room temperature being a few hundred Kelvin,
> so maybe a bit less than 100,000 times as much as a computer on Earth.
> Being literally inside the Sun, abundant energy would be available - more
> than 100,000 times what is available on Earth.
>

A difference in energy between two locations is required if the energy is
to be applied to perform work.

There's lots of usable energy at the sun's surface (because you can make
that heat do something useful before sending it off into cold space) but
very little can be done with all the heat within in the sun while inside
the sun.

Think of a combustion engine. The reason it can spin a wheel is because
inside the combustion chamber it is hot and high pressure while outside the
chamber it is cold and low pressure. If things were the same high
temperature and pressure both outside the combustion chamber as well as
inside, then piston would not move and the engine could not turn.

Any conceivable engine would fail for the same reason when inside the sun
(where it is essentially the same temperature and pressure in every
direction). Useful energy is concentrated energy (relative to some less
concentrated outside).

Jason
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