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Everything posted by juanrga

  1. There are lots of alternatives: Q-stars, gravastars... A recent paper on gravastars is Francisco S N Lobo and Aarón V B Arellano 2007 Class. Quantum Grav. 24 1069. Moreover recent studies give doubts about the ordinary computation that leads to the concept of black holes in general relativity. Check No More Black Holes? Personally I am more familiarized with the compact objects that arise in the field theory of gravity when the energy of gravitons is taken into account. The consideration of gravitons shows that an event horizon is a crude geometrical idealisation and thus that black holes are not real. There is some dispute on the specialised literature on if the black hole model has been already observationally disproved or not.
  2. When you repetitively ignore what is being said to you, whereas attribute to me nonsensical stuff as "we can'y observe a multi-electornic atom", which I have never said [*], then the discussion makes no sense... [*] What I said was:
  3. I am perplexed by reading that. The quantity [math]d_i E[/math] is the well-known production of energy. The law of conservation of energy states [math]d_i E = 0[/math] for isolated, closed, and open systems. The first time I meet the equation [math]d_i E = 0[/math] was when I studied a well-known thermodynamics monograph by a famous Nobel Laureate, who precisely won the Nobel Prize for his extension of classical thermodynamics. Do you really need a snapshot of the page of his very famous monograph, with the equation [math]d_i E = 0[/math] being his equation (2.1), to be submitted here as image? Whereas you think your response, you can also find the equation [math]d_i E = 0[/math] in this biologists textbook. Contrary to your claims, it is self-evident that total energy E is conserved in both closed and open system. Again this is all well-known even at the undergrad level and I do not need to go into details. If you are interested you can check, for instance, the section "15.4 Energy conservation in open system" in the well-known textbook Modern thermodynamics by Prigogine and Kondepudi. No offence was intended, of course. But the above is a natural consequence of your incorrect viewpoint! You cannot consider [math]dE = dQ + dW[/math] "the law of conservation of energy", if you still insist on that energy is not conserved when [math]dE \neq 0[/math]. The rest of scientific community names to [math]dE = dQ + dW[/math] the first law of thermodynamics or "the law of conservation of energy", because the conservation of energy is given by [math]d_i E = 0[/math] and not by [math]dE = 0[/math].
  4. The part explaining the origins of the term and the history seems correct, but I have not checked the details. The rest is not only obsolete but even incorrect. If you take a look to the Talk page of the wikipedia article, you can find that already a pair of years ago Wiki-editors did comments such as: Yes, I think that their analogy with "relativistic mass" is a good one. You find many old references, and some recent low-quality ones talking about a supposed relativistic mass, but any modern and rigorous reference does not even mention it except, maybe, in the introductory chapter about the history of the subject. You are mixing up it all. Wave mechanics also uses operators! Atomic orbitals and the double slit experiment can be accurately described by quantum mechanics (aka I mean the Dirac ket formulation). I already explained how wavefunctions can be obtained from kets under a determined representation |x> (I repeat the inner product <x|Psi>), and I also explained to you that representation is not universal (i.e. there are quantum situations where wavefunctions do not work). Any quantum chemistry student is taught that atomic orbitals are only crude approximations that do not account for electron-electron correlation. One electron in a multi-electronic atom or in a molecule cannot be found in a 1s, 2p, or a 4d orbital, for instance. If you assume the contrary and compute observables as energy you get values in disagreement with observations. I only want to remark, finally, that orbitals (even for Hydrogen atom) are not observables (unlike properties as mass, energy, momentum, spin...) but only mathematical constructs and that the nodes of the orbitals have the same ontological status. quoted from the linked wiki page. There is nothing interesting about that. The page was automatically modified by one Wiki-bot that corrected a word in French "particule --> corpuscule". Look to the change done by the bot http://en.wikipedia....oldid=488482596 More concretely, the solutions to both the Klein-Gordon and the Dirac equations are operators defined in a dummy spacetime [math] \hat{\psi}(x,t) [/math]. However, if you go to very old textbooks you find all their authors trying to interpret those solutions as wavefunctions. Such interpretation is not possible and gives lots of paradoxes. The experiment is fine. The interpretation flawed. It is, more or less, if the buckyball does not behave as a ping-pong ball then we found a duality! Some people believes that particle is a synonym for classical particle.
  5. The answer to your question "Are the boundary elements part of the system or the environment?" is "it depends!" If your system is a gas in a closed container, the walls are not part of the system. If your system is the gas plus the container, then the walls are part of the system. For a living cell the membrane is part of the system. This is the reason which the formal definition introduced in the article does not use the concept of boundary, but the value of deY. This deY is a function of the variables of the system. This formal definition works even for systems for the which (spatial) localization fails. I will add some of these remarks in the discussion section. Again thanks . In my original post I wrote: Your post confirms my suspicion that one part of the physics literature (I have never found this problem in chemical or biological literature) confounds conservation of a quantity with the 'invariance' or 'time-independence' of that quantity. By definition, a quantity Y is conserved when its production (or destruction) is zero: diY=0. Otherwise the quantity is not conserved. Entropy is not a conserved quantity in a dissipative process because diS>0, energy is a conserved quantity because the identity diE=0 holds always. The statement diE=0, in words, is the usual "Energy can neither be created nor it is destroyed" that you can find in many textbooks. Evidently diE=0 does not imply that E was constant. Substituting diE=0 into the balance law (see first equation in the knowledge article) dE= diE + deE we obtain the law [1] dE= deE. If the system is isolated, deE=0, and then E is constant. For a thermometer (not in equilibrium) deE /= 0 and E is not constant. But in both cases energy has been conserved because its production is zero: diE=0. For both isolated and closed systems deE = dQ + dW. Substituting this back in [1] we obtain the well-known "law of conservation of energy" dE = dQ + dW or first law of thermodynamics. Please, notice that if you insists on your viewpoint, you would be obligated to rename the first law of thermodynamics as the law of non-conservation of energy, each time that you are applying the law to a closed system for the which dE /= 0. Thank you. I will add something of all this in the discussion section of the current article. Although the bulk of a detailed discussion of what is a conserved quantity and what is not will go to another specific article (maybe an article about balance laws or maybe in an article about conservation laws I do not know still)
  6. Well, I think that I already explained why "wave mechanics" is a misnomer, there is none wave, which is the historical origin for this misnaming, and why "wave mechanics" gives only an approximated description (i.e. it is far from being fundamental). Regarding your other claims, an operator does not "generate numbers", but gives the observable (mass is not a number, energy is not a number...). When scientists write something as H |Psi> = E |Psi>, with H the Hamiltonian operator, the E is not a number but a physical quantity. I have not checked the entire thread, but in #19 you wrote that "electrons are waves". Even without the "only", what you said in #19 was not true.
  7. Thank you. If the system interact in some way, then it is not isolated, but closed or open. Greiner, Neise, & Stöcker write in their textbook: Initially I was ready to add their remark to the article, but finally I did not because I disagree. The universe as a whole is, by definition an isolated system. This is not an idealization. Thank you very much. After reading your comment about isolated systems I think that I will add these thoughts to the article, explaining why the concept of isolated system is not an idealization and giving as example of an isolated system the universe, as a whole.
  8. In agreement with one administrator I am posting this here. The topic is multidisciplinary but my main doubts are for physicists. I have just uploaded a draft about Open, closed, and isolated systems. I am using the standard terminology, although, in the discussion section, I notice that some physicists use a coarse-grained terminology. I suppose that their terminology is motivated by their lack of interest in problems of chemical or biological interest. I do not recommend the use of this coarse-grained terminology, because I do not find any reason for using it. If someone disagree, please state your views. I also criticize the textbook by physicists Walter Greiner, Ludwig Neise, & Horst Stöcker. They seem to be confused about the laws of conservation of matter and energy. For instance, they claim that the particle number is conserved in closed systems, but this is clearly wrong in presence of chemical reactions. I would like to see your points, specially because it seems that a part of physics literature confounds conservation laws (i.e. zero production) with 'invariance' or 'time-independence'. The part about atoms in molecules will be changed after the comments sent by Prof. Chérif F. Matta. I would like to receive further review, comments, and suggestions.
  9. My posts are rather precise, but you attribute to me stuff I have not said. Because particle spin (a quantum property) is one of the properties that define a quantum particle. As said before: If a given particle does not have mass me and spin 1/2, then it is not an electron but some other particle. In the first place, I never said that spin proves wrong anything. You seem to be misreading me again. In the second place, those operators describe the observable properties of the particles. For instance, the mass operator gives the mass of the particle, the spin operator gives the spin of the particle and so on. In the third place, I already explained to you why your viewpoint is both wrong and outdated. For instance, I already explained to you that the modern formulation of quantum theory uses Dirac ket formalism and that the kets are not wavefunctions. I explained to you that wavefunctions are not used in experiments done at CERN, where new particles are discovered. Scattering events are interpreted using kets |p> in the momentum basis. I also said you that solutions to Dirac and Klein-Gordon equations cannot be interpreted as wavefunctions although, in the early years of quantum mechanics (about 1930), physicists believed the contrary. We are not living in the year 1930. Physics has advanced. I have even cited a standard modern textbook which will give you the technical details on why the solutions to those equations cannot be interpreted as wavefunctions. There are much more stuff which I am not saying here because lacking time and because you seem to be lacking the adequate background. For instance, originally Schrödinger worked with one-particle systems and then confounded the solution to his equation with some kind of wave somewhat as electromagnetic waves. However, it is now well-understood that for a multiparticle system, the 'wavefunction' is defined in a parametrized 3N space, which is not the four-dimensional space where electromagnetic waves are defined. Precisely the strong differences between both spaces generate well-known difficulties when trying to mix relativity and quantum mechanics. And this is related to why the attempt to interpret the solutions to Dirac and Klein & Gordon as wavefunctions fails. I am also not citing (and still less discussing) here recent works as [1] where it is shown that wavefunctions, or even Dirac kets |Psi>, cannot describe a large kind of quantum systems. If you want study the dissipative behaviour of an electron in an electron transfer reaction you cannot use wavefunctions neither Dirac kets. [1] PETROSKY, T; PRIGOGINE, I. The Liouville Space Extension of Quantum Mechanics. Adv. Chem. Phys 1997; Vol. 99, pp.1–120.
  10. The same kind of 'evidence' that did that 19th century astronomers postulated the existence of unseen mass, a new planet which was named Vulcan. The first discovery of Vulcan was announced on 2 January 1860 during a meeting of the Académie des Sciences in Paris. Several re-discoveries and confirmations were done in posterior decades, somehow as discoveries of the hypothetical Dark Matter are announced in our days. This quote from a book of history must be relevant: «For the people of the late 19th century, Vulcan was real. It was a planet. It had theoretical credibility and had actually been seen. Even textbooks accorded it a chapter». In despite of the claimed 'evidence' and of the announced 'discoveries' and 're-discoveries' Vulcan does not exist.
  11. I am preparing an academic alternative to Wikipedia. In a well-known chemical forum the community has given some space to this project in a specific thread in their Education subforum. I can ask many questions in that forum, except those far from chemistry experts (cosmology, general relativity...) and I would like to know if this community would be interested in participating in this project, for instance revising and correcting the drafts or solving my occasional doubts. If the response is affirmative, where would I post? For instance, I have just uploaded a new draft Open, closed, and isolated systems. The part discussing the terminology used in atoms in molecules theory will be changed following received suggestions by Prof. Chérif F. Matta. I have not added the link to the draft because I am waiting moderators comments.
  12. The preprint (indexed by Scholar, submitted for publication...) gives a list of standard references, which summarize the null results of the hundred of direct and indirect search of dark matter. Since the preprint url has been deleted I will copy and paste some references from it. Particle dark matter: evidence, candidates and constraints 2005: Phys. Rep. 405(5–6), 279–390. Bertone, G; Hooper, D; Silk, J. First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory 2008: Phys. Rev. Lett. 100, 021303-1–5. Angle, J.; et al. (XENON Collaboration). Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope 2011: Phys. Rev. Lett. 107, 241302-1–6. Ackermann, M.; et al. (The Fermi-LAT Collaboration). etcetera. This resembles all the null results when searching the aether. No? People who cannot access to specialised literature cited still can find the related news. For instance check Fermi Space Telescope Fails to See Evidence Of Dark Matter It is a common myth to pretend that MOND only does galaxy rotation. The preprint remarks the different predictions done by MOND, all of which have been confirmed. This includes the use of MOND to study light deflection in galaxies and clusters. Again the references cited in the preprint give details. Again I am forced to copy and paste some of them: Modified Newtonian Dynamics as an Alternative to Dark Matter 2002: Ann. Rev. Astron. Astrophys. 40, 263–317. Sanders, Robert H.; McGaugh, Stacy S. The gravitational deflection of light in MOND 1994: arXiv:astro-ph/9406051v1. Bo, Q.; Wu, X.P.;Zou, Z. L. As has been explained up to exhaust, in multiple places, the Bullet cluster results do not falsify MOND. Moreover, it has been shown that dark matter cannot explain the Bullet cluster Bullet Cluster: A Challenge to ΛCDM Cosmology and has been shown that some aspects of the Bullet cluster are explained by MOND but not by dark matter: But some myths never die
  13. I have not said such thing. I never said that the spin of a quantum particle was a classical notion. I already explained why this is wrong. It was correct to discuss about a supposed "wave-particle duality" about 70 years ago, when quantum theory was in its infancy. It is no longer correct today within the modern theory of particle physics [yes, this discipline of physics is named particle physics not wave-particle physics or something as that]; although we can still find such discussions in very old references or in non-rigorous references (e.g. in some popular books written for general public).
  14. No. The specialized literature is full of alternative explanations.
  15. You cannot find something that does not exist url deleted
  16. I was not referring to "classical waves" but to waves. Quantum particles have properties of particles, not of waves (quantum or otherwise). The double slit experiment is the typical example given in that non-rigorous literature, which I alluded before. As has been explained to you the 'modern' [*] formulation of QM (e.g. that used in the CERN) uses Dirac ket formalism, kets as |p> are not wave functions. Moreover, any decent textbook in QFT (Mandl & Shaw, Weinberg...) explains why the solutions to the Klein & Gordon, and Dirac quantum equations cannot be interpreted as wave functions. The term wavefunction is still used in part of the literature for denoting the product <x|Psi>, but a wavefunction is not a particle (aka the converse "a particle is a wave" is incorrect), neither a property of a particle (aka "particles have many properties of waves" is not right). The properties of a particle (mass, energy, momentum, spin...) are obtained from the set of operators. Precisely particles are characterized (and discovered) by properties as mass and spin. An electron is a particle with mass m_e and spin 1/2. No 'wavelike' property is used to define what an electron is. Therefore an electron is a particle, not a wave. [*] Traced back to Dirac!
  17. As has been said to you before, orbitals in atoms and molecules are solutions to stationary systems. The wave functions do not evolve over time in such systems. The probability of that two electrons are in the same quantum state is 0. That is real and a fundamental principle for understanding the physics and chemistry of matter! Your claim that electrons do not "came into contact with" protons is false. Core electrons in heavy atoms directly interact with protons (more correctly they interact with the quarks that a proton is made of). As already said in a previous post, the Hydrogen-like orbitals are based in the approximation of a point-like nucleus. When both the structure and the finite size of nucleus are taken into account it, we can derive corrections to Hydrogen-like orbitals for small r. He used the correct term "weak interaction". "Weak force" is a misnomer. Electrons are particles, and their fundamental properties are studied in a branch of physics named particle physics. The belief that electrons are waves or behave as waves (electrons behave as quantum particles always) is a typical misconception that one finds in non-rigorous literature (science news, popular books...). For instance, the modern theoretical physics used in CERN does not longer work with the old "wave functions" but with Dirac kets in the momentum representation |p>.
  18. The 1s orbital, as other Hydrogen-like orbitals, assumes a point-like nucleus and does not give a correct description for small r. When those orbitals are corrected, by accounting for the finite size of the nucleus, then they no longer go to zero for r=0.
  19. I do not think so. Apart from the observational difficulties, the Hawking radiation model assumes that one can freely mix quantum field theory with the event horizon associated to general relativity. The problem is that GR+QFT is not a consistent theory. For instance, when we consistently take into account gravitons, the event horizon associated to the classical theory disappears. The so-named black hole thermodynamics (which is used to define the temperature of that radiation) is open to objections as well.
  20. That was my response to morgsboi and it seems evident that I am meaning the same than him when he wrote that "it is the light which follows the space-time". I have tried to state my point using his own wording for improving our communication. I was not trying to be technically precise and accurate. Neither your claim that the term matter is not "defined in chemistry and physics textbooks" nor your deleting of my citation to Feynman book does surprise me, although the definition of the term matter can be found in standard textbooks . However, your last claim that "matter is typically a vague term" after you initially stated that Einstein understood "light to be a form of matter" deserves some surprise .
  21. As shown in the other thread Einstein did many mistakes, his original thinking does not satisfy current scientific standards of rigour and precision (science has advanced a lot of since 1916), and his old quotes do not quality as an argument based in 'authority'. The standard definition of matter can be found in chemistry and physics textbooks and shows that light is not usually considered a form of matter. Feynman titled his book "QED: The strange theory of light and matter". Of course, he did not mean the strange theory of matter and matter
  22. And in general relativity, matter also follows the spacetime (which has been warped by gravity). One cannot say that matter is affected by gravity whereas light is not, when both are effected and 'bend'.
  23. There are several attempts to derive MOND from a first principle theory. Here is my favourite


  24. That radiation is highly hypothetical and has never been observed up to now.
  25. I keep them in my personal library. Reasons? Some are useful when I need to check something.
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