X-Message-Number: 11332 From: Date: Sun, 28 Feb 1999 10:20:01 EST Subject: quickies A couple of quickies: 1. John de Rivaz had some interesting remarks about math vs. reality, with an example of "- 6 men" as an inadmissible solution to a ditch-digging problem. Of course, the whole concept of "negative numbers" probably seemed bizarre at one time--yet we know how useful it is. There aren't any "negative men," but there is such a thing as subtracting 6 men from 8, say, which can also be phrased as adding a negative 6 men to a positive 8. And complex numbers are extremely useful, whether or not there "really" is a square root of negative one. John is right about "proving mathematically" that nothing (with positive rest mass) can reach the speed of light only AFTER assuming (in deriving the Lorentz transformation) that the speed of light in vacuo is constant in any inertial system. (I used to go through that in the classroom for my students.) No conclusion is stronger than its premises, and the premises are often far weaker than realized or acknowledged. (Worse yet, sometimes the conclusion is the SAME as the premise, without this being realized, so you think you have proved something when you have merely restated a postulate.) 2. Thomas Donaldson asked about the Bekenstein Bound, and Mike Perry referred him to Tipler's THE PHYSICS OF IMMORTALITY. For those who don't have that book or time to find the reference, the Bekenstein Bound (slightly oversimplified) is an upper limit to the number of possible quantum states of a system with given mass and volume. Using Planck's constant and the uncertainty principle, one can show that a "point" in phase space must have a certain minimum volume; thus the number of "points" in the phase space of the system is finite, and not greater than the BB. It follows that the total number of people possible, and the total number of human experiences possible, must be finite (given a fixed maximum mass and volume for the human brain, say). Thus, if computing power becomes unbounded (as Tipler belives it will), then our far-future successors could emulate any person who ever lived or might have lived, at any or every stage of life. However! (Good joke coming up.) If computing power becomes unbounded, it seems to me (Have I goofed?) that the number of creatable people also becomes unbounded! The BB is based on PHYSICAL people made of real atoms etc.; Tipler's resurrected people are computer simulations! Why should a simulated person (or successors) be restricted to the limits of a physical person of fixed mass and volume? Thomas Donaldson has questioned the "right to life" (or the value to us) of an imaginary or potential person, as opposed to an historical person. Here again we get into questions that are usually approached merely on the basis of preference or comfort, when what we really need is a rigorously derived basis of value. Robert Ettinger Cryonics Institute Immortalist Society http://www.cryonics.org Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11332