From: Michael Tarbell <mtarbell.nul> Date: Fri, 14 Dec 2012 15:36:08 -0700 Archived: Sat, 15 Dec 2012 10:20:15 -0500 Subject: Re: Update To Our View Of The Drake Equation >From: Edward Gehrman<egehrman.nul> >To:<post.nul> >Date: Fri, 14 Dec 2012 08:08:53 -0800 >Subject: Re: Update To Our View Of The Drake Equation >>From: David Rudiak<drudiak.nul> >>To: post.nul >>Date: Thu, 13 Dec 2012 10:22:33 -0800 >>Subject: Re: Update To Our View Of The Drake Equation >>Quite! There is the hidden assumption in these calculations that >>interstellar migration is impossible. This is not a scientific >>assumption but dogma. There are many conceivable ways that such >>migrations could take place without resorting to assumptions of >>Star Trekian warp drives, but at sub-light speeds. >>E.g., assume machine intelligence and length of travel doesn't >>really matter. Time to nearest star at a very modest 1% light >>speed is then less than 500 years. NASA propulsion experts for >>years have been thinking in terms of 10% light speed for a >>probe. >If Einstein is correct, then travel by even a grain of sand, >using external energy (so fuel wouldn't have to be carried), at >the speed of light would require all the energy in the universe. >So if we travel at 10% of the speed of light, does that require >10% of the energy in the universe? And that's just to power a >grain of sand. >Under these circumstances, I don't think star travel is probable >or will ever be possible. Yes we have visitors, but a more >mundane explanation is possible: we share our planet with an >ancient civilization. Ed, At 0.1c, the relativistic change in mass is ~0.5%, which I think may be reasonably neglected. The energy required to bring a typical (0.01 gm) grain of sand to 0.1c is thus on the order of (0.5)x(.01gm)x(3x10^9cm/sec)^2, or ~4.5 gigajoules. This is equivalent to the detonation of ~1 ton of TNT, not a trivial amount, but substantially less than 10% of the energy in the universe. If this has been the basis of your pessimism about interstellar travel, you may want to reconsider. Although, if interstellar travel is occurring routinely, I must say I'd be surprised if the brute-force acceleration of mass were the predominant technique. Mike Listen to 'Strange Days... Indeed' - The PodCast At: http://www.virtuallystrange.net/ufo/sdi/program/ These contents above are copyright of the author and UFO UpDates - Toronto. They may not be reproduced without the express permission of both parties and are intended for educational use only.
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