"[EMAIL PROTECTED]" <[EMAIL PROTECTED]> writes: > Original Message: > ----------------- > From: Gwern Branwen [EMAIL PROTECTED] > Date: Thu, 18 Jan 2007 23:39:06 -0500 > To: brin-l@mccmedia.com > Subject: Re: New take on Fermi Paradox > > > >>This seems way too pessimistic, or I'm missing something. If there are >>only 8^2 probes (each one builds 8 more, and the making stops there), >>that might make sense, but if each probe can make another 8 - which >>the article doesn't seem to clearly specify either way - then it >>doesn't take too many generations before the limit is something more >>reasonable like how long it takes to cross the galaxy: at ~100,000 >>light-years in diameter, and travelling at .10 c, one would expect to >>see visitors within one or 2 million years of the first batch of >>replicators sent out. > > If we were a long lived (in terms of millions of years) civilization and it > were important to us to explore the galaxy, then one obvious solution would > be the development of Von Neumann machines: self-replicating machines to > explore the galaxy. Even if it took each machine a century to build two > more, being used up by the process, within 5000 years, there would be > > 10^15 of these machines, spread through the galaxy. > > Thus, this type of solution to the Fermi Paradox asumes that there is a > very good reason that advanced civilizations do not build Von Neumann > machines to explore the galaxy. I bet many of us could write short stories > explaining why. > > Dan M.
I won't belabor y'all with the usual suspects, but I'd like to note an interesting and new one I saw recently on the SL4 mailing list: <http://sl4.org/archive/0701/16139.html> The germane bit is: "The key factor here is that ET can do a lot more in a lot less time than us. This may lead to an interest rate of, say, 100% per day. There is also the posthuman equivalent of discounting for death....If you do the math, you may find that the payoff from harvesting a sun's energy, is not high enough to justify the energy investment for a space probe, due to the very high discounting rate." A high-speed economy as the reason for stay-at-home aliens? Well, it's definitely a new one on me. --Gwern Inquiring minds want to know. _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
