[ExI] Double-Earth (Was: kepler study says 8.8e9 earthlike planets)

spike spike66 at att.net
Tue Nov 26 21:57:32 UTC 2013


 

 

>. On Behalf Of Anders Sandberg
>. 

On 26/11/2013 16:31, spike wrote:





>>.Here's something cool: the Pu alpha decays to 240Np, which is denser, so
it sinks toward the center, but really doesn't have time to go far with that
hour half-life to 240Pu, but then the concentration of 240Pu goes up and
heats up, so I suppose it would boil, but under enormous pressure perhaps
not, so it isn't clear if a critical mass eventually results.


>. Wikipedia mentions that alphas can incite fission in Pu240, I have not
yet checked out http://prola.aps.org/abstract/PR/v144/i3/p1046_1

>.Hmm, if the Pu gets close to critical I assume there would be
mini-explosions or flare-ups that would be like mega-boiling: high
concentration zones have chain reactions, heat up a lot, turn to big nuclear
vapour bubbles and mix the ocean. You would only get a big detonation if it
all quietly congregated together and then something eating the neutrons
suddenly disappeared.

>.So maybe there would not be a big boom, just regular geysers of molten
metal and nuclear plasma. Still awesome.



-- 
Anders Sandberg,
 
 
Ja!  All our experience with this kind of thing is from small, just barely
critical masses assemble suddenly.  But what happens if you have critical
masses forming gradually?  Under enormous pressures with nowhere to go and
no good means of sending away the heat?  It isn't analogous to a huge ball
of hydrogen, which can go supernova and end up as a ball of neutrons.  The
heavy elements have already been there once (in a supernova.)  The heavies
can only go down as far as iron, which is the bottom of the energy well.
 
Anders this was a terrific thought experiment you spawned, me lad.
 
spike
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