Re: [sl4] giant planets ignition - one more existential risk

From: Alexei Turchin (
Date: Fri Dec 12 2008 - 03:05:50 MST

Dear William!

Thank you you for your long post.
Unfortunately it is misleading, because:

1) You think that deiterium can''t partisipate in detonation. But
science said it can.
2) You think that if it detonate Jupiter will become slow burnung
star. But detonation means explosion, not a slow burning.

Lets look on the main article on the subject.
"Necessary conditions for the initiation and propagation of nuclear
detonation waves in plane atmospheres". Tomas Weaver and A. Wood,
Physical review 20 – 1 Jule 1979,

This article was poublished in good scientific journal "Physical
review" and is continuatuon of famous LA-602 made by Kompton in 1945
about the possibility that first nuclear explosion would detonate
Earth''s atmosphera via fusion of nitrogen.

There it is said: "We, therefore, conclude that
thermonuclear-detonation waves cannot propagate in the terrestrial
ocean by any mechanism by an astronomically large margin.

It is worth noting, in conclusion, that the susceptability to
thermonuclear detonation of a large body of hydrogenous material is an
exceedingly sensitive function of its isotopic composition, and,
specifically, to the deuterium atom fraction, as is implicit in the
discussion just preceding. If, for instance, the terrestrial oceans
contained deuterium at any atom fraction greater than 1:300 (instead
of the actual value of 1: 6000), the ocean could propagate an
equilibrium thermonuclear-detonation wave at a temperature £2 keV
(although a fantastic 1030 ergs—2 x 107 MT, or the total amount of
solar energy incident on the Earth for a two-week period—would be
required to initiate such a detonation at a deuter¬ium concentration
of 1: 300). Now a non-neg-ligible fraction of the matter in our own
galaxy exists at temperatures much less than 300 °K, i.e., the
gas-giant planets of our stellar system, nebulas, etc. Furthermore,
it is well known that thermodynamically-governed isotopic
fractionation ever more strongly favors higher relative concentration
of deuterium as the temperature decreases, e.g., the D:H concentration
ratio in the ~102 К Great Nebula in Orion is about 1:200.45 Finally,
orbital velocities of matter about the galactic center of mass are of
the order of 3 x 107 cm /sec at our distance from the galactic core.

It is thus quite conceivable that hydrogenous matter (e.go, CH4, NH3,
H2O, or just H2) rela¬tively rich in deuterium (1 at. %) could
accumu¬late at its normal, zero-pressure density in substantial
thicknesses or planetary surfaces, and such layering might even be a
fairly common feature of the colder, gas-giant planets. If thereby
highly enriched in deuterium (£10 at. %), thermo¬nuclear detonation of
such layers could be initiated artificially with attainable nuclear
ex¬plosives. Even with deuterium atom fractions approaching 0.3 at. %
(less than that observed over multiparsec scales in Orion), however,
such layers might be initiated into propagating thermo¬nuclear
detonation by the impact of large (diam 102 m), ultra-high velocity
(^Зх 107 cm/sec) meteors or comets originating from nearer the
galactic center. Such events, though exceedingly rare, would be
spectacularly visible on distance scales of many parsecs."

On 12/12/08, Stuart Armstrong <> wrote:
> Thanks for an informed post on the subject. It's what was missing in
> the speculations and counter-speculations.
> > To fuse, deuterium nuclei have to come together physically in an area the
> > size of the atomic nucleus. This takes a great deal of pressure and heat.
> > More likely than two deuterium nuclei fusing is that a deuterium nucleus and
> > a hydrogen nucleus will fuse to form helium 3. I doubt that the pressures in
> > a gas giant are anything like high enough to support detonation of the whole
> > planet. Unlike nuclear fission, where fast neutron cause fission ahead of
> > the shock front resulting from the release of energy by prior fission events
> > and thus generate true detonations, fusion requires extremely high pressures
> > and temperatures such as are found in the centers of stars.
> ...
> > Bill
> >
> > William P. (Bill) Hall, PhD
> > Documentation and Knowledge Management Systems Analyst

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