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joigus

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Everything posted by joigus

  1. Oh well. That probably changes everything then.
  2. This did come across as threatening. I take it that's not what you meant, but it did sound like that. Ok. Yes. That's my personal idea. You say you have no academic background and a prestigious journal asks you to referee for them? Seriously? It's like when a very hot young lady asks me to contact her on FB. Do you seriously think life is just that kind? I'm just trying to be helpful here. And Bufofrog probably was too, although by using humour.
  3. If you don't have a previous trajectory as a referee for anything in the way of 'well known brand of journal group's member journal', I would suggest you might just have been targeted for a phishing attempt, and you should be careful. There are other less dangerous attempts to scam you that would look very much like that. The very fact that you feel compelled to 'investigate the reason for the case' suggest to me there might be something 'phishy' behind this. It's just a gut feeling. I hope none of this negatively affects anyone.
  4. Global phase invariance. IOW, \[ \psi\rightarrow e^{i\alpha}\psi \] where \( \alpha \) is a constant phase shift in the wave function. You can easily prove charge is conserved via Noether's theorem if you have a Lagrangian that produces the equations of motion. It's the global version of gauge invariance. When you have local gauge invariance, not only gauge charge is conserved, but a field has to step in to guarantee it is preserved. And god says, Let there be light, Let there be gluons, Let there be Z and W bosons, and (hopefully), Let there be gravitons, even if nobody can calculate anything with them.
  5. I can do better than that: https://people.math.harvard.edu/~knill/teaching/mathe320_2017/blog17/Hermann_Weyl_Symmetry.pdf According to Hermann Weyl, something is symmetric when it looks the same after you change a condition. The 'thing' is thus symmetrical under the change of such 'condition'. A sphere is symmetrical under rotations around its centre. A fly is symmetrical under reflection through a mirror. The laws of physics are symmetrical under changing particles for antiparticles. ... And so on The usefulness of Weyl's definition stems from the fact that certain transformations can be expressed in very simple terms as functions of few parameters.
  6. I'm glad you noticed. Two thousand years after and more than 2000 miles away from the alleged origin of the story (northern Iran & Uzbekistan for Al-Tabari and Al-Bukhari respectively). That's pretty far away from Mecca and Medina both in time and space. Add to that the fact that 'muhammad' (MHMD in most Semitic scripts) just means 'the praised one' and we are pretty much where we are with many other founders of religions. Nothing much except the hope of human group from centuries upon centuries ago to become relevant on the grounds of a religious preacher who might or might not have existed even. No religion should be taken seriously. But the more modern ones are the more ridiculously off-base. Take Scientology, for example. Patricia Crone died some 9 years ago. Her book Meccan Trade and the Rise of Islam is just a pacient and meticulous gathering and exposition of facts as recorded from contemporary records from the 5th-6th centuries (and somewhat before) AFAIK. She very patiently shows how and why the "centre-of-trade" theory of Mecca is a physical/historical impossibility. Maybe aliens from Proxima-Centauri could have made Mecca a commercial hub of the Nabateans. Camels just couldn't have done it. All the Nabatean know-how couldn't make up for the fact that Mecca is about 1000 meters below the main route to Ta'if, and extremely inconvenient --to say the least-- to be any kind of rendezvous in the trade route. Impossible. What other things happened in Mecca in the 6th century? We don't know. Trade certainly was not one of them. That's probably why Mecca appears in NO book from before the 9th century. Crone got many death threats from that and decided to keep a low profile from then on. That's what I know.
  7. Beautiful! Thank you. Here's the hook-up to why this happens: https://en.wikipedia.org/wiki/Frost_flower_(sea_ice)
  8. Ah, so OP maybe is trying to say, 'could the electron be there just because charges need to balance out?' If that's the case, I know of a class of theorems called 'soft boson theorems' in QFT that say that something very weird would happen if charges didn't balance out at distances long enough, and that would make QFT inconsistent. That alone wouldn't explain why the universe is not just a soup of photons from all the particle-antiparticle pairs having annihilated each other long in the past... https://en.wikipedia.org/wiki/Baryon_asymmetry
  9. Conservation of charge bears out an elementary symmetry. The electron is a carrier of that symmetry. How could bilateral symmetry (a quality of a thing) be the thing itself? Flies have bilateral symmetry. Is bilateral symmetry of a fly the fly itself? Please, come to your senses.
  10. Ok. But slavery is allowed (halal), adoption forbidden (haram), sex with minors allowed (halal), etc, if political conditions allow. A lot of what you can or cannot apply from sharia depends on political climate, as stated clearly in the Qu'ran concerning taqiyya. From: https://reliefweb.int/ with my emphasis I for one prefer Zoroastrianism, as long as you're careful with fire. All religions are OK, I suppose, as long as you don't take them seriously --actually apply certain/a few/most of their principles. All religions are OK if you reduce them to wearing of certain gear and handling of certain ritual objects and ceremonies. In that sense, they're not very different from a funny sport.
  11. Some of these coincidences happen to be very useful as mnemonics.
  12. Well the liquid nitrogen example that @MigL provided goes in that direction. This reminds me of some quick notes on geometric optics concerning one such Lensmaker's equation, which led me to think something along the lines of 'Isn't it cute, that this equation was derived by someone called Lensmaker?' I soon realised of course, it was a typo or the author made a mistake, and it should have said 'lens maker'.
  13. The objection is expressed at 33:50 of the lecture I linked (without mentioning Dyson). If gravity were classical and gauge fields were quantum, you could beat the position-momentum HUP. Dyson's position basically is that Einstein's tensor is a classical field. But on the RHS of the equations you have the expected value of the energy-momentum tensor of quantum fields. You could, of course argue that there are <T²>-<T>² quantum fluctuations of these quantities, and thereby similar quantum fluctuations in the Einstein tensor. Yes, ER = EPR is due to Leonard Susskind and Juan Maldacena. I don't know about the state of the art of it, but it's a way to deal with quantum gravity that's being explored recently.
  14. I stand corrected. Thank you, gentlepeople. Sexes there are < 10 Behaviours there are > 1000 Something like that.
  15. Anyway. Sex is a biological fact that can be settled at cell-level. Behaviour is another matter. Sexes there are two. Behaviours there are millionfold.
  16. Oh, yes. What Stanley Deser defined as 'denial' in this lecture: https://www.youtube.com/watch?v=Yh36XEX7yTk IOW, the gravitational field is one of a kind. Everything else is quantum. It's only gravity that's classical. Doesn't sound like a sound alternative. People have pointed to paradoxes and the like. And it's no surprise really.
  17. This walks in the direction of what I was saying. GR as a theoretical standalone is not reliable to tell us what a BH (or any other trans-horizon-hidden singularity of the EFE) is telling us about. QM has to play a big role in it. Rupture of space-time, as if ST were some kind of elastic medium is clearly not the ticket. Every direction I know in which people are thinking has to do with generalising QFT to the appropriate degrees of freedom accounting for gravitation or proposing a unifying principle (EPR = ER) that achieves the concept-bridging between GR and QFT that everybody dreams of. There must be a reason why entropy has to be included in the mix, and it's almost a certainty that the reason has to do with QM. PD: From what I know, @Genady is right, and the singularity is a time rather than a spatial point. Assuming BHs are not better represented by other solutions that haven't been found yet and nobody knows anything about. Such is the plight of the non-linear physicist. But you're right. You shift to the E, t HUP and your point is still valid --at this point I don't know whether the pun is intended or not!! Sorry for the acronym shower.
  18. Interestingly though, it has spawned a few questions: 5, and counting...
  19. This is an outdated package of ideas otherwise known as Copenhagen's school. Decoherence is the key, not the observation, whatever that means. I don't think that makes much sense. Decay is already understood as an interaction, but not between matter and time, but mediated by W and Z bosons. What would interaction between matter and time even mean? Interactions, as we understand the concept, require a position representation.
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