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Everything posted by juanrga

  1. here Steven Weinberg ( not introductory level) takes the opposite view. In my opinion it is a matter of opinion. http://arxiv.org/pdf...h/9702027v1.pdf quote from page 2 "In its mature form, the idea of quantum field theory is that quantum fields are the basic ingredients of the universe, and particles are just bundles of energy and momentum of the fields. In a relativistic theory the wave function is a functional of these fields, not a function of particle coordinates. Quantum field theory hence led to a more unified view of nature than the old dualistic interpretation in terms of both fields and particles." At contrary, Weinberg and me share a common view (although we differ in some details). First, the part that you quoted is in the context of a historical description of how the subject was born. By "In its mature form" Weinberg refers to the work done about the 30s. The whole quote, including context, is: Second, in no part of that whole talk he says that a particle was a wave. At contrary, he writes stuff as: and Third, as I said here photons are particles and the matter-wave duality is an outdated concept. Again Weinberg confirms this: Fourth, as explained above the quote that you reproduce is an old vision about quantum field theory and particles. Precisely Weinberg, writes after the part that you quoted (note that he starts writing in past sense): Where the bold emphasis is from mine. Effectively, Weinberg starts from the unambiguous definition of particle. He then goes with the development and introduces the concept of fields after equation (3) for the interaction Hamiltonian. Technically he introduces fields as a way to satisfy certain requirements for the interaction between particles. The fields are not fundamental ingredients of nature but a technical help to write down a physically admissible S-matrix. There exists theories whose interactions cannot be written using fields and those theories only use particles. That is why today quantum field theory is not believed to be a fundamental theory:
  2. [math]\frac{d^2S}{dE^2} = -\frac{1}{T^2 C}[/math] Thus the black hole 'entropy' cannot be a maximum.
  3. I did not say that was simply that, although it is true that I expressed myself badly. Maybe I would have said that "a main role" or "one of the roles" of synthetic chemistry is the creation of new substances. We must be in agreement. The axiomatic definition of synthetic science is: science related with the combination of two or more components to form a whole system. Synthetic chemistry is a subset of this and includes the theoretical studies about mechanisms and paths. See, for instance, the definition of synthetic organic chemistry by Francesco Nicotra. In any case, the main point here was that the above quote by Marcelin Berthelot emphasizes one of the reasons which chemistry is distinct than physics and why physicists' definitions of science are not acceptable. A complete and sound definition of science is given in #20.
  4. Synthetic chemistry. The main role of synthetic chemistry is not to create theories or laws but to create new substances. This is a particular characteristics of chemistry, that makes it different from physics. As stated by Marcelin Berthelot, La chimie crée son object –chemistry creates its object. Moreover, the definition that you reproduce defines science as a systematic enterprise, somewhat as the Science Council also does. But as stated by David Edgerton: It defines science as a pursuit, an activity, related to the creation of new knowledge, rather than established knowledge itself. Science is seen as a species of research. Yet a definition of science needs to define the nature of the knowledge not the means of its creation only. A more complete and accurate definition is given in science.
  5. This is as saying an apple is not an cat because is two.
  6. That is not the definition of particle, not even close. Wikipedia is not usually a good place for looking for academic stuff. The first phrase in that wiki-page already needs technical corrections, for instance. But the page says "it is impossible (for various reasons) to define a wavefunction for a single photon." That is correct. I already pointed to the limits of the wavefunction formulation. It makes no sense to say that "photons are described as waves" when the old wave formulation of QM does not apply to particles as photons.
  7. No apologize is needed, because both quantum mechanics and experimental evidence support the idea of that a quantum particle is not a wave but... a particle.
  8. Nowhere in the definition of a quantum particle, "wave" is used.
  9. You claim that you understand my argument, but then you completely ignore what I have said. For instance, I say that E is conserved in closed, isolated, and open systems and you read this as "Your point is that diE is conserved in a closed system", something that I have not said. It cannot be a problem of English language not being my native tongue, because E and diE are mathematical expressions... You repeat Greiner's point of that U is not conserved in a closed system, but he is wrong because there exist closed systems that conserve U. All those systems for which the production of internal energy is zero are systems that conserve internal energy. Greiner confounds diU=0 with dU=0 and the same are doing you. I will give another try, in a last hope that this discussion can be used to improve the article draft. As is well-known a quantity is conserved when its production is zero (otherwise the quantity is not conserved). Consider systems that conserve internal energy diU = 0 (1) This law can be written in the equivalent form dU - deU = 0 (2) Both (1) and (2) provide the general expression of the law of conservation of internal energy for closed, open, and isolated systems, because both (1) and (2) holds with independence of the value of deU. For a closed system the flow term is deU = dQ + dW (3) Substituting (3) in (2), we obtain the more popular form dU = dQ + dW (4) The same pdf that you have just linked states about (4): the "first law of thermodynamics is a statement of conservation of energy". I am pretty sure that you will not find a reference saying that the first law of thermodynamics is a statement of conservation of energy only when dU=0. Expression (4) is a statement of conservation of energy also for nonzero values of dU. In the same pdf that you link the author says about (4) "The physical content of the first law as a restriction on physical processes is clear. It is impossible to create a machine which creates energy out of nowhere". Effectively, for closed systems (4) is equivalent to (1), and (1) in words says that energy cannot be created out of nothing. No only energy is conserved in closed systems, but it is also conserved in open systems. I cited the section "15.4 Energy conservation in open system" of a celebrated modern textbook, but it seems that some people insists on ignoring that as well... The pdf that you link makes the same misguided statement about particles being conserved in closed systems. But at least it adds in the introduction that by particle he means a "particle that cannot be created or destroyed". By particle I mean... particle Any basic textbook in thermodynamics contains a chapter devoted to systems for which particles are not conserved but are created or produced by means of different kind of reactions.
  10. That is just the American Physicist Society definition of science, which misses whole scientific disciplines as synthetic chemistry. The definition of science given before was developed to improve that.
  11. Their 'heat capacity' is negative, which implies there is no maximum in their 'entropy'.
  12. Evidently bolding or colouring the word "particle" had a different goal . The goal was to show how CERN guys do not support your claims (although you said us the contrary, they affirm that an electron is a particle not a a wave). The concept of quantum particle applies to situations where quantum wave mechanics do not apply. This automatically invalidates your point about electrons being waves. You insist on that "QTF is more to describe how forces interact". This is nonsense. There is little that I can do here . There is nothing misleading in a word. Although it happens that some people incorrectly believes that "particle" is a synonym for "little sphere".
  13. Your 'evidence' is different from everyone else, what you say about quantum field theory is nonsense... You have alluded to the CERN guys before, but you would stop because they do not support your wrong point of view about electrons being... waves! Go to this page at the CERN, how many times you find the word "wave" or the word "wavefunction"? Yes, zero times. You only can find the word particle in that page by CERN. Yes, guys at CERN think that an electron is a particle (not a wave) and they even go beyond and write: They are completely right and I already explained why. People at CERN are not repeating the mistakes that your friend the 'chemist' and your friend the 'hydrologist' are doing. You can also go to this glosary from CERN and search the word particle or the word electron and check by yourself that CERN considers that the electron is a particle. You can also search the terms "wave" or "wavefunction" in the glosary and again you will not find them . And yes they consider themselves Since those guys at CERN are very consistent, they consider that the LHC is an particle accelerator and that they are an international laboratory for particle physicists, and they now are searching a new particle named the Higgs. The conclusion is pretty simple: An electron is a particle
  14. Very high relative to what? Really? Who showed that? The hypothetical 'entropy' associated to black holes is not the entropy of thermodynamics but a mere formal analogy. How could the black hole 'entropy' was a maximum when its 'heat capacity' is negative.
  15. The warped spacetime analogy can be used to explain part of the behaviour of objects under the influence of gravitation. At the same time, this analogy reveals the nature of gravitation according to a geometric theory as general relativity: An alternative model, sometimes named the non-geometrical approach, the flat-spacetime approach or the field theoretic approach (FTG), considers that gravitation is not due to curved spacetime but due to a force:
  16. I think that there exists a simple explanation on why when we measure the speed of light we find it to be always c. This explanation is that light is made of photons and photons are massless particles; it can be shown that a massless particle has a speed c always. The conclusion here seems obvious, if a particle 'of light' always has speed c, we cannot measure something different!
  17. And again you ignore the technical details given, the quotes from standard textbooks claiming the contrary, and so on... In that well-known branch of physics known as particle physics, we have a precise definition of what is a particle, and using this precise definition of what is a particle we can know when, or when not, particles are detected in some accelerator experiment and if some of the particles detected has a set of properties that no other known particle has, then scientists claim that they have discovered a new particle. We also have beautiful tables with all the known elementary particles and its properties Yes, contrary to what you believe, the electron is a particle, not... a wave
  18. Well as explained before the solutions to the Dirac equation cannot be interpreted as wavefunctions, although outdated and non-rigorous literature still consider the Dirac equation as if it was a wave equation. You allude to a chemist and a hydrologist. Well, I know several recent textbooks written by chemists where it is still said that the Dirac equation is a wave equation. This same people is unaware of the proofs demonstrating why their claim makes no sense and if you were to say them that the Dirac equation is now reinterpreted as an identity for a field operator, they would look you as this . Modern and rigorous formulation of quantum mechanics does not use the old wave mechanics formulation by reasons stated before. The "wave-particle duality" is a myth that would be eliminated from the literature. Finally the term "wave mechanics" has a historical origin in the initial work by Schrödinger, but it would be best abandoned today because is the source of much confusion [*]. [*] Even for the own Schrödinger.
  19. Maybe I could use other words but I would say the same that I said in the quotes.
  20. Ambiguous and imprecise statements as this can be eliminated from science when, as I suggested before, we define what is the system under study and what are its properties. An example of how we can initially restrict the system to one block and obtain a closed system was given above (ASCII diagram included). The lesson here is that if you are ambiguous and imprecise in the definition of the system, you will obtain ambiguities and imprecisions. I agree with your colourful example, but it is not what is happening here. The criticism to Greiner et al is of a different kind. It is more like if they had said "red and yellow are not colours" and I had replied "no, that is wrong, red and yellow are colours! " The law of conservation of energy is stated as diE=0, which holds for both open and closed systems. This law is often written in the equivalent form dE=deE and named the law of conservation of energy in textbooks. Greiner et al confound diE=0 with dE=0 and then make the incorrect claim that energy is not conserved in open and closed systems. That energy E is conserved in both closed and open systems is well-known (or would be well-known). In #11, I already cited the section "15.4 Energy conservation in open system" of a celebrated textbook, but it seems that you did not notice. Not only Greiner et al are confused about the conservation of energy, but they are also confused about matter. They make the claim that the number of particles is conserved in closed systems. The 'blog' explains why this is not true. I notice that neither you nor DH have commented about this point.
  21. I welcome again your contribution, but both in the 'blog' and in this same thread I have said many times that the energy of a closed system can vary. For instance in #16 I said that for a closed system [math]dE \neq 0[/math]. And in the 'blog' I give as example of a closed system a thermometer exchanging heat with surrounds.
  22. As is clearly stated in the 'blog', E is the total energy of the system. Therefore your emphasis on "clearly Greiner is talking about the energy of the system" is welcomed but does not add much to this thread, really. The difference between the internal energy U and the total energy E was already noticed in this same thread. It was also mentioned that textbooks dealing with classical thermodynamics only consider systems at rest in absence of external fields. For those systems dE=dU. For more general thermodynamic systems this is not the case. The confusion about the conservation laws was also discussed before in this same thread and in the 'blog'. Does "adding 100 joules of heat" to an isolated system makes sense for you? If your system is isolated the above 'system process' makes no sense. Period. This is why we need to define first what is the system under study. Yes, I am convinced that your glass of water, is a different system that studiot solitary perfect crystal.
  23. I already stated, explained, and supported my point in many occasions. And you have already quoted me explaining what is an electron and what is not.
  24. It is good that now you give quotations of entire phrases and paragraphs that I wrote.
  25. Very beautiful diagram, but the original problem was: You are lacking a third block over which the block is being moved. It was said that the system is "the solitary right hand block", but you are re-defining the system as the original block plus an arbitrary space around. That is another system. What has this to see with the "aura" that you claim is around a block of crystal?
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