From: Mike Lorrey (mlorrey@datamann.com)
Date: Fri May 17 2002 - 15:19:25 MDT
Hal Finney wrote:
>
> I never understood thermodynamics that well, but something bothers me
> about this stealthiness concept.
>
> Ignoring black holes for the moment (which are super-cold),
What about the Hawking radiation?
> a star is
> radiating a certain amount of power into an artificially constructed
> shell which surrounds it. It seems to me that in equilibrium, the same
> amount of power has to be radiated from the shell.
Not necessarily. You want to dump waste power to the zero point field,
squeezing every last possible quanta out of your photons.
>
> Equilibrium in this context means that the shell is just rearranging
> matter. It is not absorbing energy by storing it into batteries or the
> equivalent, because that obviously cannot go on forever. All the energy
> the shell "uses" is ultimately dissipated as heat and therefore radiated.
Yes, but if you use the tungsten tech I had posted earlier, you are able
to squeeze more quanta out of your photons in a heat-pump sorta way,
thus you can do more work with the same amount of energy, and stealthing
yourself in the process.
>
> So in practice the same amount of power comes from outside the shell
> as from the star, and the only difference is that because the shell is
> larger, the temperature is less. The outgoing shell temperature depends
> solely on the temperature of the star, and the ratio of the size of the
> shell to the size of the star.
That is essentially right.
>
> I don't see where "cooling" comes into play here, except that you could
> redistribute the outgoing radiation to be stronger in some directions
> and weaker in others. But it seems like for a given star, the radiated
> temperature will depend solely on the size of the shell, and you can't
> cool it.
I don't think you are considering everything here. Heat isn't just
'warmness'. You have x calories or quantas of energy you are using. You
can use y amount of matter to conduct that energy, or z number of
electrons, or p number of photons. Each possible transmission method can
function at a nearly infinite number of wavelengths.
An ideal M-Brain shell will radiate photons to the universe in a manner
that is indistinguishable from a) empty space or b) a star devoid of
planets or other significant matter outside of a dust disk. To simulate
an empty star system, your shell would be coated with laser diodes,
radiating the spectrum of the simulated star in all directions (note
that using laser radiation, the size of the star will appear to be much
smaller than the shell).
To simulate empty space, you would emit radiation from the surface in
all directions at COBE wavelengths. Note that unlike the laser diode
situation above, each point on the surface can radiate low grade
radiation in a hemispherical loci, rather than just a straight line.
Because of this lack of coherence, a lot of energy can be radiated from
each point in a hemispherical loci versus a narrow beam.
>
> Now, adding black holes changes the equation, because they are effectively
> black bodies at the Hawking temperature, which will probably be very low.
Depends on the size. THe problem with simulating a black hole is that
the bigger your MBrain shell, the higher the gravity of the hole you are
trying to simulate, so scanners could detect your fakery that way.
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