X-Message-Number: 20906 From: "michaelprice" <> References: <> Subject: Re: Pauli etc Date: Sat, 18 Jan 2003 12:23:21 -0000 Bob Ettinger writes: > Michael Price writes in part: > >> we can actually *prove* whether two electrons (or two anythings) >> are identical. Simply determine whether they are subject to the >> [Pauli] Exclusion Principle (x)or can form a Bose-Einstein >> condensate together. If the objects in question have *any* >> differences (*including* any currently beyond our powers of >> observation to resolve) then they will exhibit neither property. >> It's as true for electrons as it is for elephants. > > Also: > >> identical objects are swapping positions with each other all the time > > Sorry--this is language confusion combined with unproven assumptions. > > First, if "objects" are "swapping positions" you have already said the > number of objects is more than one. So? Of course. I never said that two identical objects were one, just that you can't distinguish between them in any sense whatsoever. According to quantum mechanics any two identical objects are swapping identity to some extent. That does not change the number of objects under consideration. > You can prop up the language by talking about "instantiations" > if you like, but that is just more verbal manipulation. I don't need to resort to verbal manipulation. My argument is based physics. > Second, the implication that there are no hidden variables > underlying current quantum theory is simply unproven, and > a number of eminent people have thought that hidden variables > do exist, and have proposed experimental tests (not yet feasible). My argument only rules out hidden complexity within each subatomic particle. It does not rule out all hidden variable formulations of quantum mechanics. Bohm's original (non-relativistic) formulation of hidden variables did not add complexity to particles, instead it introduced a new "quantum potential", which is a separate, non-particulate construct. (Unfortunately no one has been able relativise Bohm's theory, which also suffers from epistemological problems, but that's another story.) > Fourth, an analogy. Two objects differ, as far as anyone can tell, > only in location and color. To a color-blind person they differ only > in location, and no experiment available to him can distinguish between > colors. So he has a choice. He can say, "These are the same except > for location, as far as I can tell," or he can say, "They do not differ at > all," meaning he isn't interested in location and does not acknowledge > the possibility of hidden variables. The last type of assertion is just > over-reaching, trying to impose your own definition. The above statement would be true in 19th century classical physics. But nowadays we have quantum physics: Mr Colour-Blind can see if they interfere with each other quantum mechanically. If they do they are identical and therefore must be of the same colour. If they don't they're not identical and so may differ in colour. It's not a matter of imposing definitions or over-asserting, it is simply a matter of (modern) physics. Agreed it is strongly non-intuitive, perhaps more so than anything else, but true nevertheless. > Fifth, the whole concept of "quantum state" is easily glossed over. > Every quantum calculation is an approximation. All systems appear > to be entangled, according to current ideas--by gravitational effects > if nothing else, and probably in countless other ways looking > backwards. The "Bohr atom" is a theoretically isolated one--but in > reality they aren't isolated. A perfect calculation would presumably > require the wave equation for the whole universe, which won't > happen any time soon. The occurrence of the Pauli exclusion or the formation of Bose-Einstein condensates (both forms of quantum interference between identical objects) demonstrates that the entanglements you speak of are irrelevant to the question of identity. > Once more, I think we should clean up our language and > use operational definitions. Which is exactly what I'm proposing. Rather than argue philosophically about whether two objects can ever be identical, just check for quantum interference effects. Checking for the occurrence of interference effects is an operational test of indenticality. > Applied to the "identities" of persons or to criteria of survival, the > problem remains open, and for the time being at least we should > certainly be conservative and try to maintain physical continuity. What Feynman's path integral formulation of QED -- subsequently applied to all of physics -- shows is that our notion of physical continuity is an illusion; any notion of identity based on physical continuity is doomed to failure. Identity, therefore, is purely an informational thing. A copy is the original. Mike Perry writes: > Under the many-worlds formulation worlds can split but > can also fuse. Depends on how we define 'world', which can be a bit of a slippery concept, but the number of splittings always exceeds the number of fusings, by virtue of the past having a lower entropy than the future. > (A "world" also is not necessarily a whole universe but can > be a localized region.) The fusion, if it occurs, will obliterate > any differences in histories between the components that fuse, > thus, I think, rendering their distinguishing pasts unrecoverable. 'Obliterate' can be a bit misleading. Rather it is the loss of information that permits the fusion. So if two histories, differing only by some event, lose information on said event, then they become, henceforth, one history (or world or universe). > The loss of information inherent in this fusion in effect > makes the past ambiguous. Absolutely. Fusion reflects the loss of information. > It seems, then, that, along with many worlds, > each world will, as a rule, have many histories. I would rather say each world has one ambiguous or incomplete history. Which is what we find, of course. It's the flip slide of information loss. Cheers, Michael C Price ---------------------------------------- http://mcp.longevity-report.com http://www.hedweb.com/manworld.htm Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=20906