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</o:shapelayout></xml><![endif]--></head><body 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><div><div><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> extropy-chat-bounces@lists.extropy.org [mailto:extropy-chat-bounces@lists.extropy.org] <b>On Behalf Of </b>Kelly Anderson<br><br></span><o:p></o:p></p></div><div><p class=MsoNormal>The "earth like" definition used by the scientists that wrote the paper include approximately three variables. Rare Earth proposes around 12 such variables if I remember correctly<span style='color:#1F497D'>…</span><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'>Ja, but the three variable case makes more sense for reasons I will give.<o:p></o:p></span></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='color:#1F497D'>>…</span>For example, we need a molten core and plate tectonics in order to get the right metals to the surface<span style='color:#1F497D'>…<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>A molten core follows directly in most rocky core planets. They have an enormous amount of heat from potential energy conversion as the rocky dust congeals.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>>…</span>provide both land and ocean (for the evolution of land animals, since hands evolving on a fish seems like a bit of a long shot) and other reasons<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'>Perhaps. But I haven’t been able to convince myself that intelligence could never evolve in the sea.<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><p class=MsoNormal><span style='color:#1F497D'>>…</span>Then there is Jupiter and Saturn filtering out the comets. Very useful that<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'>Useful but not necessarily critical. If you had a Goldie with oceans 50km deep, a good sized comet or other hunk of space debris could strike the planet without wiping out all the biota. An ocean planet could still reasonably have ice caps, or for that matter be ice everywhere, with liquid oceans below. Then it is conceivable that life could be air breathing on a planet with no rocky surface anywhere.<o:p></o:p></span></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='color:#1F497D'>>…</span>If you refigure all of the Rare Earth variables in with NASA's numbers, I'm guessing you would end up with a MUCH smaller number.<span style='color:#1F497D'> –</span>Kelly<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'>Ja. I found Ward’s Rare Earth a bit too narrow minded on what kind of life forms could become tech enabled. He might be right. But it just felt like he was over reaching just a bit.<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></div></div></div></div></div></body></html>