X-Message-Number: 14244 From: "John Clark" <> Subject: Identity Of Indiscernibles Date: Sat, 5 Aug 2000 00:31:17 -0400 In #14233 Yvan Bozzonetti Wrote: >Sorry, if you cool down carbon atoms, they form a solid, not a Bose Einsein >condensate. True, but I don't recall saying anything about carbon, try hydrogen or one of the alkali elements. >Even if you take atoms that can do that, only paired system are >condensed, the individual atoms are not, they are a different quantum system. Wrong. I quote from The Encyclopedia Britannica: "Most condensed gases consist of a collection of atoms in different quantum states. If, however, it were possible to prepare a condensate in which all the atoms were in the same quantum state, the collection would behave as a single macroscopic quantum entity with properties identical to those of a single atom. This form of matter was dubbed a Bose-Einstein condensate" A few years ago Daniel Kleppner and Tom Greytak of MIT put 100 million hydrogen atoms in the same quantum state, I haven't checked recently but I think they've done even better with rubidium. >The square root of the probability is simply the wave amplitude, As I said before there is nothing simple about it. The square root of the probability yields A quantum wave function but not necessarily THE quantum wave function, and any wave function contains not only an amplitude but also a DIRECTION. Accordingly two different wave functions can produce the same probability, and being vectors you can not add them like they were tomatoes and get a meaningful answer because they are not scalars. >so what you say is that what is waving is the wave. What is waving can not be measured, we can measure probability but that does not uniquely determine the wave function. >Nothing is "waving", wave is simply an outdated way to represent some >properties Nonsense. The Schrodinger wave equation remains the most popular way of representing the quantum world and with good reason, it predicts the outcome of experiments just as well as any other system and it's much easier to work with. >of the dual vector space of differential forms. In euclidean space >that dual space maps on the vector space, so we can build systems >working with particle and other using "waves" in the same space. So what? It's like changing the origin of a coordinate system, it may or may not be a useful thing to do but one thing is certain, the physics is unaffected. All those things as well as the quantum wave function are real only in the way that lines of longitude and latitude are real, they are mental tools that help us figure out how things work. The measurable variables are exactly the same regardless, and we still can't calculate the position and momentum of something, the world is still non deterministic and atoms still have no individuality. >The classical example is the Young's slits experiment. The slits work in the >form space and the screen behind in the vector space. Like anything else Young's 2 slit experiment can be looked at from a variety of viewpoints, but no viewpoint can banish the profound strangeness of the results. Richard Feynman once said that is you have a deep understanding of the 2 slit experiment then you understand quantum mechanics, he also said that nobody understands quantum mechanics. >Bad vulgarization books write about the dual nature of particles and wave, People are only familiar with particles and waves in their everyday life but in the quantum world things don't act like either one so it seems bazaar, almost impossible, but not vulgar. >a nice trick for a circus clown as Young, by the way he was too a GP Huh? >A good book to see, with plenty of drawings is the track one of: >Gravitation by Missner, Thorn and Wheeler, edited by W.H.Freeman. "Gravitation" is probably the best book ever written on gravity, but as it deals primarily with General Relativity, Astrophysics, and Cosmology and not the foundation of quantum mechanics as we were discussing and as our understanding of the relation between gravity and quantum mechanics is far more tentative than it is with the other 3 forces of nature, your recommendation appears quite strange, inappropriate, and irrelevant. And one more thing Mr. Bozzonetti, It's going to take more than buzz words and name dropping to impress me. John K Clark Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=14244