tag:blogger.com,1999:blog-17039304.post5141944141468698565..comments2023-03-20T09:47:16.508+01:00Comments on Fogonazos: Top 10 Bill Bryson's science quotesAntonio Martínez Ronhttp://www.blogger.com/profile/10437299428907114260noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-17039304.post-47421295985118330042007-10-19T16:13:00.000+02:002007-10-19T16:13:00.000+02:00about point 10..milions?http://en.wikipedia.org/wi...about point 10..milions?<BR/><BR/>http://en.wikipedia.org/wiki/Drake_equation<BR/><BR/>"...<BR/>Alternatively, making some more optimistic assumptions, and assuming that 10% of civilizations become willing and able to communicate, and then spread through their local star systems for 100,000 years (a very short period in geologic time):<BR/>R* = 20/year, fp = 0.1, ne = 0.5, fl = 1, fi = 0.5, fc = 0.1, and L = 100,000 years<BR/>N = 20 × 0.1 × 0.5 × 1 × 0.5 × 0.1 × 100,000 = 5,000<BR/>..."<BR/><BR/>5,000 or milions?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-17039304.post-82176925330133054312007-08-13T17:56:00.000+02:002007-08-13T17:56:00.000+02:00I don't quite understand how the time for a brick ...I don't quite understand how the time for a brick to reach the center of the earth is calculated... 3000 miles+ over 45 minutes, that's an average speed of 4000 miles/hour... that seems pretty fast to me...<BR/><BR/>It's all very speculative, does it take into account air resistance ? The fact that gravity decreases as you go deeper and the approximation of the center of gravity is no longer valid ? <BR/><BR/>The strange thing is I've read the book (A short history about everything) but can't remember being surprised by this...Unknownhttps://www.blogger.com/profile/14071431516356127627noreply@blogger.com