tag:blogger.com,1999:blog-8666091.post310016276191785686..comments2017-09-14T12:20:16.131+02:00Comments on The Reference Frame: Obama's science czar's plans for mass genocideLuboš Motlhttp://www.blogger.com/profile/17487263983247488359noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-8666091.post-68616871257538378292009-07-15T05:48:07.965+02:002009-07-15T05:48:07.965+02:00I agree with Barton. Isnt completely obvious that ...I agree with Barton. Isnt completely obvious that the human population cant keep on growing forever.<br /><br />Plus I would argue that the planetary intelligence of Gaia (yes the earth altogether is an integrated system in which everything is one way or another inter-connected) will inevitably, in one way or another, drastically reduce the our numbers for us--and it wont be pretty.Suehttps://www.blogger.com/profile/16166306300148053274noreply@blogger.comtag:blogger.com,1999:blog-8666091.post-7282676869820014052009-07-14T15:30:25.529+02:002009-07-14T15:30:25.529+02:00Population growth at a substantial, fixed positive...Population growth at a substantial, fixed positive rate cannot, of course, go on forever. Let us assume that A) growth continues at the present world population growth rate of about 1.2% per year. B) All that is necessary to move around the universe is the will to do so. C) Any matter, even dark matter, can be turned into food and consumed. D) Humans can survive unprotected in the vacuum of space.<br /><br /><br />How long before the entire visible universe is turned into food and eaten?<br /><br /><br />Let's assume 1 billion galaxies exist within the visible horizon and that each has a mass (including dark matter) of 1 trillion solar masses. With the Sun's mass at 1.9891 x 10^30 kg, the total mass is then 1.9891 x 10^48 kg.<br /><br /><br />Take the current human population as 6.7 billion and assume the mean mass of a human being is 50 kg. Total human mass is then 3.35 x 10^11 kg.<br /><br /><br />Human mass at a given time is:<br /><br /><br />M = Mo (1 + r)^N<br /><br /><br />where Mo is the initial value, r the growth rate as a decimal (1.2% = 0.012), and N the elapsed time in years. Solving for N, this becomes<br /><br /><br />N = log(M / Mo) / log(1 + r)<br /><br /><br />For M = 1.9891 x 10^48, Mo = 3.35 x 10^11, and r = 0.012, N is 7,098. In approximately 7,000 years, we run completely out of universe and the next year, everybody starves to death.<br /><br /><br />More realistically, we can assume we are merely colonizing planets and that we are constrained by the speed of light limit. At a 1.2% growth rate, the volume growth rate is 1.012^(1/3) or about 1.004% per year, and frontier expansion passes the speed of light when the radius exceeds about 100 light-years. This is a sphere with a volume of about 4.2 million cubic light-years, and with stars at about one per ten cubic light-years in the Orion Arm, 420,000 stars will be available. About a fourth of these will be of the sort to support habitable planets, but due to the possible problems with correct age of the star, location of a planet at the right range for comfortable temperatures, orbital and axial tilt stability for climate purposes, sufficient mass to hold down a reasonable atmosphere and permit plate tectonics but not enough for gravity to be overwhelming, etc., etc., probably no more than 1% of these stars will actually have habitable planets, or about 4,200 such planets will exist. At your proposed maximum of 20 billion people per planet, this amounts to 84 trillion people, or M = 4.2 x 10^15 kg. At 1.2% growth, we reach this level in 791 years.<br /><br /><br />Other problems might arise sooner, from the physical difficulty of moving billions of people from planet to planet to the political problems involved with doing so.<br /><br /><br />Actually, we already passed peak per capita grain production, so the time to stabilize population just might be now.Barton Paul Levensonhttps://www.blogger.com/profile/01924091877122623785noreply@blogger.com