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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Doh! I meant 640C, not 640K. Embarrasskin!<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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. At about 900K starting temperature, the radiative heat loss to space isn’t much, and there is gravitational heating as the helium bubbles to the surface and the radius decreases, resulting in heating.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Wowsers I need to get to work on a sim of this, oy. My intuition tells me it eventually creates enough Pu240 to create a critical mass. It alphas down to Uranium 236 with a half-life of about 6600 years. Then some of that alphas to 232U and a little of it undergoes honest fission to lead and magnesium. What I don’t know is if a critical mass in the center of an enormous ball of Pu244 does what we are so accustomed to critical masses doing.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Any nucular physicists, do feel free to jump in and help me here.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hey I wonder if the feds are getting nervous watching me google around on plutonium and uranium?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>spike <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> extropy-chat-bounces@lists.extropy.org [mailto:extropy-chat-bounces@lists.extropy.org] <b>On Behalf Of </b>spike<br><b>Sent:</b> Tuesday, November 26, 2013 8:02 AM<br><b>To:</b> 'ExI chat list'<br><b>Subject:</b> Re: [ExI] Double-Earth (Was: kepler study says 8.8e9 earthlike planets)<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>>…</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> <b>On Behalf Of </b>Anders Sandberg</span><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D'><o:p></o:p></span></b></p></div></div><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>>>>…</span> Even I agree that a planet with plutonium oceans is unlikely to be habitable for life. -- Dr Anders Sandberg<o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>>>…I learned a new thing by thinking about this. There is an isotope of plutonium which is non-fissile, 244. Get a sphere of the stuff, heat it to 900 and some Kelvin, you have an ocean of plutonium, with radioactive particles up the kazoo but no fission. Until Anders’ offhanded comment about an ocean of plutonium, I never knew there was such a critter. Ain’t science kewallll? {8-]</span><o:p></o:p></p></div></div><p class=MsoNormal><br><span style='color:#1F497D'>>…</span>Sounds like a great practical joke to do when re-engineering a solar system. A hot ecology based on plutonium as a solvent for some weird metal-oxide biochemistry/mechanochemistry. <span style='color:#1F497D'> </span>-- Dr Anders Sandberg<span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>As practical jokes go, that one would be elaborate.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>As Anders’ comments often do, this notion of a plutonium sea has me pondering. Assume into existence a sphere of molten plutonium 244. The melting point of plutonium is not so high, about the same as magnesium and lower than that of aluminum, both of which are easy to melt for the home hobbyist, and even if not, most of us here have tossed aluminum soda cans into the campfire, so it isn’t glowing red when it melts.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>So I was starting to work on a heat model that has some interesting properties. If you assume the liquid plutonium planet out in space far from anything, at about 650K, ten over the melting point, it is easy to calculate the heat loss from radiation to space with Boltzmann’s law. Now take the radioactive decay energies, 80 million year half life for Pu244, then see what happens. There is an alpha decay to Neptunium 240 plus a helium atom at first, and helium reacts with nothing so that stuff comes bubbling to the surface, and the 240Np beta decays with a half life of about an hour to Pu240, which is fissible. The model’s future may depend on the initial radius of your planet, but it looks to me like the thing eventually explodes.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanks Anders!<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>spike <o:p></o:p></span></p><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></pre></div></body></html>