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  1. nomadreid

    I Are commuting observables necessary but not sufficient for causality?

    A couple of the sites that say that the vanishing commutator defines causality: https://www.physics.umass.edu/events/2020-02-07-causal-uncertainty-quantum-gravity https://phys.org/news/2019-11-aspects-causality-quantum-field-theory.html Is "define" too strong? Or, to put it another way: cannot...
  2. nomadreid

    TV antenna dish: depth, f/D, or focal distance

    I am covering parabolic antennas with a school student in elementary physics, and I was looking for the specs of the (offset) antenna on her family's roof in order to calculate things like focal distance. She sent me a photo (she is on another continent), I found the brand specs, which lists it...
  3. nomadreid

    Medical Toxicity for fetuses during 2-vaccine 2009/2010 season?

    The article https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3888271/ claims (if I read it correctly) that there was an unusual increase in fetal deaths reported via the VAERS reporting system (which, it must be said, anybody can report, so the data there has to be taken with a grain of salt-- but...
  4. nomadreid

    Medical Is a small tidal force on the body harmful over the long term?

    In the following page (which, despite examining a question that comes up in science fiction, raises valid scientific questions): http://pages.erau.edu/~andrewsa/sci_fi_projects_spring_2015/Project_1/Eilts_Mitchell/Enders%20Game%20Eilts/Enders%20Game%20Eilts/index_Eilts.html I encountered the...
  5. nomadreid

    Serious critique of Erikson's psychological theories?

    This is asking for suggestions for freely-available serious on-line sources (with links) for criticism of the theories of Erik Erikson. Details: The neo-Freudian psychologist Erik Erikson https://en.wikipedia.org/wiki/Erik_Erikson was and remains quite popular. However, looking through his...
  6. nomadreid

    I Shouldn't this definition of a metric include a square root?

    In https://mathworld.wolfram.com/InnerProduct.html, it states "Every inner product space is a metric space. The metric is given by g(v,w)= <v-w,v-w>." In https://en.wikipedia.org/wiki/Inner_product_space , on the other hand, "As for every normed vector space, an inner product space is a metric...
  7. nomadreid

    I Entangled particles in black hole decay?

    First, I was not sure whether this should go into the Relativity or the Quantum Physics rubric, but since the central question is about entanglement, I opted for the Quantum. I do not have the necessary sophistication to follow string theory arguments, and even most explanations in...
  8. nomadreid

    I Van der Waals attractive force: Why don't the imbalances average out?

    The summary refers, for example, to the Wikipedia explanation "The force results from a transient shift in electron density. Specifically, the electron density may temporarily shift more greatly to one side of the nucleus. This generates a transient charge to which a nearby atom can be either...
  9. nomadreid

    Where is the usual sensationalism? (Riemann Hypothesis)

    That there is yet another mathematician (Dr Kumar Eswaran, Hyderabad) claiming to have solved the Riemann Hypothesis is not surprising. That the institute for which he works for (SNIST) is satisfied that the proof is correct is also not surprising. The eyebrows started to lightly ascend upon...
  10. nomadreid

    I Confused about the spectrum of an observable

    This is a very elementary question, from the beginnings of quantum mechanics. For simplicity, I refer to a finite case with pure states. If I understand correctly, the spectrum of an observable is the collection of eigenvalues formed by the inner product of states and hence equal to...
  11. nomadreid

    I What is meant here by "quantum mechanics–free subsystem"?

    I only have the Abstract to https://science.sciencemag.org/content/372/6542/625, and an attempt to clarify it by referring to a popular science article https://scitechdaily.com/breaking-heisenberg-evading-the-uncertainty-principle-in-quantum-physics/ only made it worse. The former indicates a...
  12. nomadreid

    "Allow editing" absent in sent EXCEL file

    I am showing a school pupil (over the Internet) how to use EXCEL. He can work with an EXCEL file that he opens himself (on a free version of Microsoft office). However, when I send him a file (either one I opened on my computer or even one that he sent me and I send back to him), he finds that...
  13. nomadreid

    I "Filming" a quantum measurement

    The link is https://www.su.se/english/research/scientists-film-a-quantum-measurement-1.487234 How do they arrive at this distribution over time? It does not appear to be saying that this is the prediction (in it were, then why the "filming"?), and measurement of a single atom's superposition is...
  14. nomadreid

    Conflicting interpretations of rosemary oil study

    The journal in question is the International Journal of Neuroscience, which appears to be a respectable peer-reviewed journal. I give a link to a reproduction in a secondary source, with a note that I am not addressing the more subjective "mood" part of the paper...
  15. nomadreid

    Does OK hemoglobin make a low level of iron in blood OK?

    Suppose a blood test shows a value of 41 milligrams per deciliter, with a healthy range between 65-175, yet the hemoglobin levels in the same blood test are perfectly normal, as well as are other indicators in the blood test. A doctor explained that one would not need to be worried about the...
  16. nomadreid

    A question about consistency of in-text bracketed reference numbers

    This is not a contextual question, but a stylistic one; hence it doesn't seem to belong in the other threads. I am proof-reading a paper, and I am unsure about the way the author uses square brackets for the indication of (numbered) sources. In order not to be quoting a source without...
  17. nomadreid

    Strategy for scheduling with preference constraints

    A computer program that was supposed to handle this was bought and tried, and it made a mess of it, so the idea is that perhaps it would be easier to give a strategy to someone (computer savvy, but an amateur, not a professional ) to program (not requiring too much power of the computer on which...
  18. nomadreid

    2 questions: illusory "force" between hands, and "wave genetics"

    The first question concerns reports by people who claim that there is a "force" pulling or pushing their hands when they hold their hands in front of them, close to each other, and parallel to one another, or while slowly moving their hands apart. Obviously there are no significant forces...
  19. nomadreid

    I Does one need V not equal to L in order to do Cohen's forcing?

    Cohen's forcing essentially takes Gödel constructible universe L and adds sets from the larger universe of sets V until it provides a set having a cardinality between that of the naturals N and its power set. But in order to do that, you must assume that V has sets to add that are not in L...
  20. nomadreid

    I Why P(A), and not P(A)(1-P(A))

    The summary says it all: why is the probability of an event not calculated by the probability that it is the event AND that it is not any other? Sounds silly, and I am certain the explanation is simple, but I don't see it.
  21. nomadreid

    Typographical question (equation numbers)

    This is just an editing, not a conceptual, question. (Hence I don't put it in the other forums.) In a text, when one refers to a particular equation by number, as in "we see in Equation (12) that.....", the "equation" is capitalized (upper case). When it is not named, of course, not :"we see in...
  22. nomadreid

    Thermokinetics -- I'm finding varying definitions. What is the standard term?

    Wikipedia https://en.wikipedia.org/wiki/Thermokinetics says that "thermokinetics" studies the rate of chemical decomposition, whereas a dictionary https://www.yourdictionary.com/thermokinetic gets no further than saying that it combines thermodynamics and kinetics, and a book on it...
  23. nomadreid

    I Ratio of a real value to the max theoretical value: what term to use?

    If the Summary is not clear, the following is an example translated from: https://telecombloger.ru/7335 '.... air conditioning systems. For example, the efficiency of a compressor is about 85%. The remaining 15% is spent on friction, oil movement, overflows, heating, etc. The efficiency of...
  24. nomadreid

    I Did von Neumann coin the eth or dyet for the inexact differential?

    Today the inexact differential is usually denoted with δ, but in a text by a Russian author I found a dyet (D-with stroke, crossed-D) instead: In response to my question to the author about this deviation from normal usage, he stated that this was a suggestion from von Neumann. (Which of course...
  25. nomadreid

    I Does intrinsic (e.g., spin) imply elementary (irreducible)?

    Some time ago, before particles turned out to be mutable wave excitations (making Alchemist's dreams sound nicer, I guess :-) ) , to say that something was an "elementary particle" meant that it couldn't be broken down further. OK, that idea bit the dust, but now there are intrinsic...
  26. nomadreid

    I Connection of zeta to primes: less Euler than error or L-functions?

    Often I read that the Riemann Hypothesis (RH) is related to prime numbers because of the equivalence on Re(s)>1 of the zeta function and Eurler's product formula , but is it more accurate that the relevance of the RH to primes (or vice-versa) is either that the RH implies formulas for the...
  27. nomadreid

    I Why is this not a space-filling curve?

    On a plane with a selected origin point and a selected zero rotation direction, identify each point p with (rp,θp), where rp is the distance to the origin and θp is the angle in [0, 2π). Define an order ≤* between points p and q as b p=*q if they are identical, p <* q if [1] rp < rq, or [2]...
  28. nomadreid

    I Measurable cardinal to get inner model, also in cumulative hierarchy

    If κ is a(n inaccessible) measurable cardinal, then there exists an elementary embedding j:(V,∈)→(M,∈), with critical point κ, whereby (M,∈) is an inner model of ZFC and the construction of j can follow through taking a κ-complete, non-principal ultrafilter U and constructing κV/U. In the von...
  29. nomadreid

    I Probability of neutrino switching: more massive, more probable?

    In Scientific American, July 2020, the article "The Darkest Particle" by Louis and Van de Water, page 46, discussing the hypothetical sterile neutrino, there is the sentence: "Because sterile neutrinos are likely to be more massive than the regular flavors, however, particles could make the...
  30. nomadreid

    Solved: Instagram app: first two icons, uninstalled, one remains

    Original post: On my Android phone desktop I had my Instagram app.... and for some reason there were two icons (both worked). I uninstalled the app (in Manage apps in Settings), and one of the icons disappeared, but the other one is still there and working... but it does not not now show up in...
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