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Everything posted by joigus

  1. I think what Seth means is QM allows for the final state in a complex multi-step reaction being "there" as a potentiality, so to speak, in the form of a quantum amplitude driving the process. Classical thinking, OTOH, seems to require first one step, then another, then another. Something like that?
  2. I really don't want to butt in on the very interesting discussion you were having with Seth. But here's an interesting point: It is precisely because microscopic variables are so extremely sensitive to initial conditions, these systems (called ergodic) become highly indifferent to initial conditions (reach thermal equilibrium quite efficiently) macroscopically. How about that for pointing out that nothing is as simple as it might seem in physics?
  3. Outcome of what? Thermodynamics of system can be predicted under certain circumstances. Where molecule X is going to be, no. Absolute certainty doesn't exist.
  4. Not necessarily. Thermal equilibrium isn't.
  5. Linearity is applied to sets of variables and how they depend on each other. So it's not like a presence, "linearity is here" or "it smells of non-linearity".
  6. "More than lack of food" implies lack of food and other factors, which I don't think is what you mean. I think you mean something other than lack of food. Because it seems obvious to me that lack of food there was not, at least for the general population before the situation got to the dramatic point it has. And I didn't. But I admit was somewhat lazy with my criterion. So here's some analysis taking your definition as the starting point. This doesn't seem to be the case for Gaza/Israel. Unless you're willing to accept several million people of the same ethnic and/or religious minority have met a very different fate for absolutely no identifiable reason. Some of those people of exactly the same ethnic and religious group seem to have made their way to the Supreme Court, the Knesset or the IDF. They are Israeli citizens: These data are from Israel only, not Gaza or the West Bank. More: https://en.wikipedia.org/wiki/List_of_Arab_members_of_the_Knesset For 20 years Gaza has been under the rule of Hamas. I'm not sure that Palestinians have been forcibly retained in Gaza for all that time. But I do get from testimonies that leaving is considerably difficult, and it must go through special permission, and ridiculously elaborate security measures, including digital cards and such. Nevertheless, here's a screenshot from the World Bank data webpage corresponding to Gaza+West Bank Which seems to imply that some people seem to have managed to trickle out, in spite of all those guards watching them from the turrets. Let's see about life expectancy Similar to Albania, considerably higher than Rwanda, about the same as Tunicia. All of those well-known concentration camps? https://data.worldbank.org/country/west-bank-and-gaza Population growth of only Gaza: Population of Gaza in 2005: 1,299,000 people. Population of Gaza in 2023: 2,300,000 people. Although I can imagine that it must not have been easy for many of them to leave due to the economic conditions --and that in spite of the large amounts of money thrown at them that could have been invested otherwise, as @MigL has observed before. Moreover, it is apparent that no Arab countries are willing to take regugees from Gaza, or no Arabs from Gaza are willing to go to other Arab countries, or both. They seem to like to go to NY or London, for some reason. Prisoners in their territory? Quite a number of them enjoyed work permits and crossed the border on a daily basis to work in the kibbutzim with their socialist benefactors. An opportunity to collect intelligence for the attacks that Hamas couldn't and didn't miss. So no, Gazans were not under guard when the attacks of October 7th happened. Frankly I find it impossible to recognize any condition from the definition you presented that applies here. What about the bit "those deemed political enemies" in your definition? Well, the logistics of the map of the West Bank doesn't look to me as the places where part of the population is divided according to what they think. It looks more like the logistics of urban guerrilla: Isolating places where the chances of getting shot from a window are more than so-and-so percent. And that's what they are. So there's nothing political about it. But of course the main issue is not political, in spite of many people trying to make it political. It's mostly that thing that shall not be named. It's that thing that shall not be named what gives it the character of an unsolvable problem. If you misdiagnose an illness you guarantee that it will never get better. If tomorrow all the Muslims of Palestine converted at once to, say, the Ahmadi Muslim faith --which are now a tiny, tiny minority there, the problem would be solved in a matter of months. Unfortunately, they are mostly Sunni followed by a minor amount of Shia, and the rest of the Muslims consider the Ahmadi heretics. So no, it won't work. And it never will. It takes a religious component for a problem to become so vicious, so stagnant, so irredeemably impossible as this one. It will never get better. Not for as long as the religious component of it survives. I grew up seeing the buildings of Beirut smashed to smitherines on the TV, and I'm pretty sure I'll leave this world with a similar scenery from the Middle East. Only this time on YT. Etc, etc. The situation is a tragedy for everyone involved, and it breaks my heart seeing Palestinian kids used as cannon fodder by Hamas, but pretending that the State of Israel is some kind of Khmer Rouge of the Middle East is just ridiculous. And no, it's not going to solve the problem either. It's going to make it worse and worse. This kind of hiperbolic discourse (like those morons saying "apartheid", "genocide", etc in the campuses) only weakens the arguments coming from any kind of progressive thinking. And if you ask me, they only make the Trumps and the Wilders and the far-right extremists more likely to seize power, not less. They're biding their time, make no mistake about it. Sorry for the lengthy diatribe. I will probably shut up pretty soon. It's a pain to participate in these debates, because the fog of propaganda makes the main arguments almost invisible.
  7. Well, you're right. You must assume quantum mechanics, of course. It's not just plain non-commutativity. You must assume in particular the correspondence between observables-operators and eigenvalues-spectrum of measurement. That's why I didn't say Bell's theorem can be described in terms of non-commuting observables. I said they are the essence, but QM must be in the back of your mind. Bell's theorem is about whatever variables that can take on definite values at the same time. As the theoretical structure of QM forbids non-commuting operators to take on a definite value at the same time, there's the connection. But you do need the apparatus of QM, sure.
  8. Oh, man. If something is it. That is it. A logic that sometimes doesn't allow you to say this and that. That's the essence of Bell''s theorem without a doubt.
  9. (My emphasis.) Ok. I promised myself I wouldn't participate in this thread. Its centre of gravity is soooooo far removed from the real root of the problem that I just don't think there's any chance of setting it in the right direction. But, Modern-day concentration camp? Really? Prisoners in Gaza (image from today 12-8): Prisoners in actual concentration camp (Dachau): The first photo doesn't look like people in misery to me, tbh. Concentration camp? An impressive concentration of beer bellies more like it. Some of these men should give up on compulsive eating and start watching their glucose/LDL cholesterol levels. Seriously. They should stop hogging all that food down in the tunnels, or their heart disease will catch up with them long before Israel's bombs do. Having said that, peace to all.
  10. I'm just an old geezer with an inclination for the philosophically spicy aspects of science, but thank you. I disagree. The relativistic version is: https://en.wikipedia.org/wiki/Dirac_equation which is linear. It's the one that's used in the standard model, for example. Klein Gordon is also linear: https://en.wikipedia.org/wiki/Klein–Gordon_equation You can also play with it and introduce a non-linear self-interaction term. You also have sine-Gordon, which was extensively studied by Sidney Coleman, for example: https://en.wikipedia.org/wiki/Sine-Gordon_equation which has beautiful, beautiful solutions called "breathers"... There is a non-linear model of the Schrödinger non-relativistic equation which is cubic in the quantum amplitude: https://en.wikipedia.org/wiki/Nonlinear_Schrödinger_equation Etc. The subject is extraordinarily rich and full of forks in the way. Non-linearisation of evolution has been tried. One example is this modified non-relativistic Schrödinger equation with a self-interacting term \( \psi \left| \psi \right|^{2} \). Another one is the NL Dirac equation, which is relativistic, but non-linear in evolution. Another more drastic attempt to refurbish the whole thing is non-linear quantum mechanics, in which the whole suite of postulates is re-defined in terms of non-linear functionals instead of linear operators. If anyone is interested and has an alternative life to study it, I think here's a "reports" kind of article (that I haven't read): https://arxiv.org/pdf/1901.05088.pdf And so on, and so on.
  11. They are linear in at least two different senses I know of: 1) Evolution is linear [quantum state](at time t'>t) = [Linear operator][quantum state](at time t) and, 2) probabilities of observing property Q with particular value q: amplitude(Q=q, at time t) = [linear operator on q][quantum state](t) The probability being the square of the absolute value of this probability. So linearity plays a big role in QM to say the least. So, mathematically, what it's telling you is "dynamical states are vectors" and "observable attributes are special matrices acting on those vectors".
  12. Yes. I must say I don't know a lot about the transactional interpretation. Now that I think of it, I wouldn't call the transactional interpretation a flight of fancy. It's taking known physics and putting it to good use, which is what I think is likely to be the answer to the questions most people would like to see answered. Yes. From what I remember in the Wheeler-Feynman theory of radiation, they devised a perfect absorber at spatial infinity that guaranteed that no causality-violating effect would take place. One of the big misteries about quantum mechanics has been this one precisely. I'd phrase it like, where does non-linearity come into play in quantum mechanics? Non-linearity is ubiquitous in Nature. How come linearity seems to be a sine qua non of QM? It's very strange. Exactly. You'd expect microscopicity to be the realm of non-linearity. Instead of that, the operational rules (the prescriptions to relate the maths to the measurables of the experiments) become considerably weird and unintuitive --but linear!!--, while the evolution law of the state becomes... linear too??!!
  13. Sorry for being obscure. At this point I'm sure I've been. I think we all agree there is something about measurement in QM that isn't entirely satisfactory. We have this wave function that seems to interact with electric, magnetic fields and so on. So it seems physical enough. But on the other hand, every time we obtain information from it about the corpuscular properties of matter, we are forced to update it in a way that's blatantly incompatible with the evolution law (smooth updating law) of Schrödinger's equation. Some people have thought of wildly new ways of thinking about it. New dimensions? Maybe quantum evolution is non-linear, and instead of linear operators we have to think of non-linear functionals? (Nelson, Madelung, Weinberg at some point,...) who else? Maybe in some sense the universe splits, and the quantum state is only relative to these infinitely many splittings? Maybe the only thing that makes sense is coherent/decoherent histories? (Everett, Wheeler, De Witt, Gell-Mann, Griffiths, Omnés, etc) Maybe waves are coming from the future? (Cramer et al.) Maybe QM only tells us about collectivities of experiments? (Leslie Ballentine and other people I forget?) Or maybe we should just take the theory seriously, do like Einstein did, and try to be what Nima Arkani Hamed has called "a revolutionary conservative": Instead of pushing the envelope, try to develop the envelope. Meaning: Try to update the principles without giving up the principles. I suppose what I mean is that the next idea is not likely to be suggested by a flight of fancy. Rather, it's likely to be about taking the principles dead seriously and wholeheartedly trusting that the solution would come from a re-interpretation/re-examination of the old principles rather than the finding of new principles. It's always been that way. SR, GR, QM, QFT,... It's always been that way. The conservatives --while listening very intently to the revolutionaries-- always found a way out. A conservative revolution. No need to demolish any edifice. That's what I mean by developing the envelope. Thank you. I hope I made clear what I meant now. I used to be quite fluent in French. But that was a long time ago, unfortunately.
  14. Really? It's lame, but it's a play with words. Sorry, I meant a "play on words". Was that the problem? It's more of an alliteration, now that you mention it.
  15. This allows me to try a play with words that's not as idle as it might seem: I'd rather work on developing the envelope.
  16. It would take something of those proportions, I guess. Not even a galactic-scale catastrophe would impede a tomorrow. Typically the effect of supernova explosions doesn't go beyond increasing the sky's opacity or something of that kind, AFAIK. We are pretty safe in our outer spiral arm, fortunately.
  17. How's your recovery going?

    1. Show previous comments  2 more
    2. StringJunky


      I  hope you find respite, somehow. 

    3. J.C.MacSwell


      I just saw this. I hope things are going better and your eye still improving.

    4. MigL


      Thanks guys.
      Hopefully these operations will ensure that I can keep the same ( bad ) quality of eyesight, without further losses, for the next 20 years; it has already been a 30 year battle that I was slowly losing.
      Your concern and encouragement is appreciated.

  18. One way could be a filtering measurement, like the ones I suggested. All the interactions had to happen as consistency conditions for the particle to be "summoned" within the region of interest. So you can rest assured the spin, momentum, kinetic energy (a "diagonal" function of momentum if the particle is a free particle) have the values that are consistent with the experimental setup. You don't have to "touch" the particle ever again. Other term to look up would be "weak measurement" (which has become quite fashionable as of late, I think). People have been working on this for quite some time now, so I'm probably quite rusty on this.
  19. The word "tomorrow" already implies that the Sun rises (otherwise I can picture no tomorrow), so I'm guessing we're talking about conditional probability and the answer is "yes".
  20. There are some nuances here I have to learn more about. I've heard physicists say this or that is "emergent" or an "epiphenomenon" as if they were synonyms. Maybe the "or" was an exclusive "or"...
  21. I think after a while one develops an intuition for when a poster is waiting for the right moment to unpack the real message.
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