From: Amara Graps (amara@amara.com)
Date: Tue Jun 12 2001 - 16:17:11 MDT
From: Spudboy100@aol.com, Tue, 12 Jun 2001
>Question: Could a Jupiter Mind use ambient dust to re-create Og the Caveman
Dust doesn't have DNA ...!
(As much as Whipple and Wickramasinghe would like us to believe otherwise)
>and the environment he dwelt in, some 64,000 years ago?
Hmm, for some particle sizes, this number is near to the lifetime of
"loose" interplanetary dust. Due to Poynting Robertson drag,
micrometer-sized dust particles spiral into the Sun in only a
few tens of thousands of years. Larger, centimeter-sized particles
live a little bit longer -- tens of millions of years. A similar
fate exists for tiny planetary ring particles. So you would need to
look to grains locked up meterorites or in the near pristine conditions
of the early solar system (long-term comets from the Oort cloud), in
order to get some of the compositional information from that long
ago.
Imagine for a moment that the short lifetime doesn't exist. Then I think
the problem for the Jupiter Brain is akin to building a human brain from
NMR data- an inverse problem as I mentioned before.. One cannot solve
an inverse problem unless one understands the "forward" problem. For
dust you would have to know all of the values of the 3D magnetic field
over those tens of thousands of years, and you would have to know
the temperature and density of all plasma components (A simple
Mawellian distribution of electron temperature wouldn't work)
over that same time, and you would have to know the dust particles'
initial position and velocity. Plus you would have to know much
better than we know now about the charging processes of dust particles.
The charging of dust particles, is, at best, a rough science.
I'm using equations that experimentalists developed 20 years ago.
For example, secondary electron emission is that process where an
energetic ion or electron impacts onto the dust grain, releasing
an electron (even from the otherside of a tiny grain, since the
electron wouldn't have far to travel), constituing a postive charging
current. This process is difficult to test in the laboratory, yet,
it is the most sensitive charging process for dust particles. I
found for earth-bound particles that it caused a precarious balance
of currents in energetic environments like Earth's radiation belts,
inducing charge potentials of a few thousand volts (the particle would
break up by electrostatic emission by that time). Another interesting
effect of secondary electron emission is that it has a nontrivial
effect, contributing at least a volt or two (typical charge potentials
of dust particles in the solar wind is +5V), to the charge potential
of submicron sized particles in the placid calm of the solar wind,
and not just in highly energetic regions around planets.
Another issue regarding the dust composition is that the composition changes
over time- the outer mantle of the particle is sputtered away by UV
processes, and whatever supernovae happened to occur in the Local Fluff.
The dust particle 'ages' in other words.
And yet another issue is that for dust particles above a certain size
(say micron), is that gravity would the dominant force, which means
that we need to know much more about the planet/moon/asteroid/comet etc.
gravitational forces in our solar system over time. (That ol' nbody
problem again.)
>Question: How might the Jupiter-class, Mind differentiate the particles that
>had intermixed with Herr Docktor Caveman Og of some 64,000 years ago; versus
>dust containing data of not 64,000 years ago, but the Pre-Cambrian?
The distributions of interplanetary dust (space, velocity/momentum,
thermal temperatures, for example) in our solar system has changed over time,
in addition to the dust particle's composition. We can use that info.
Amara
********************************************************************
Amara Graps email: amara@amara.com
Computational Physics vita: finger agraps@shell5.ba.best.com
Multiplex Answers URL: http://www.amara.com/
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"Whenever I see an adult on a bicycle, I do not despair for the
future of the human race." -- H. G. Wells
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