<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";
color:black;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:Consolas;
color:black;}
span.EmailStyle19
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.EmailStyle20
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.EmailStyle21
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.EmailStyle22
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</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'><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'>>…</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> <b>On Behalf Of </b>Anders Sandberg<br></span><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D'>>…</span></b> <br><br>On 26/11/2013 16:31, spike wrote:<o:p></o:p></p></div></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><br><br></span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>>>…</span><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.</span><o:p></o:p></p></blockquote><p class=MsoNormal><br><span style='color:#1F497D'>>…</span> Wikipedia mentions that alphas can incite fission in Pu240, I have not yet checked out <a href="http://prola.aps.org/abstract/PR/v144/i3/p1046_1">http://prola.aps.org/abstract/PR/v144/i3/p1046_1</a><br><br><span style='color:#1F497D'>>…</span>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.<br><br><span style='color:#1F497D'>>…</span>So maybe there would not be a big boom, just regular geysers of molten metal and nuclear plasma. Still awesome.<br><br><span style='color:#1F497D'><o:p></o:p></span></p><pre>-- <o:p></o:p></pre><pre>Anders Sandberg,<o:p></o:p></pre><pre><span style='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><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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.<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><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Anders this was a terrific thought experiment you spawned, me lad.<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><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>spike<o:p></o:p></span></pre></div></body></html>