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KJW

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  1. If by "present" one means the present defined by the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, while the idea probably doesn't conflict with known physics, it is probably quite meaningless in the sense of having no observable consequences contrasting with the notion of a block universe in which the future pre-exists. In other words, the idea violates Occam's razor.
  2. KJW replied to KJW's topic in The Sandbox
    [math]\overline{\underset{^{\large \sim}}{\partial}}{}^{}_{t} \overline{\mathfrak{T}}{}^{r_\lambda}_{s_\lambda}\ \ \ \underset{^{\large \sim}}{\partial}{}^{}_{k} \mathfrak{T}{}^{i_\lambda}_{j_\lambda}[/math]
  3. KJW replied to DrmDoc's topic in The Lounge
    It's my understanding that it is due to the dependency mismatch between the time it takes an engine to do anything, which is inversely proportional to the engine speed, and the constant time of deflagration of the fuel-air mixture in the combustion chamber.
  4. KJW replied to KJW's topic in The Sandbox
    This looks intimidating... What sort of beast is it? I should also remark that the mathematics is stock standard mathematics used in general relativity. That you call it "intimidating" is revealing about your understanding of general relativity. I personally regard the mathematics as beautiful, although actually doing the mathematics, especially the index manipulations, can be quite tedious to do manually.
  5. KJW replied to KJW's topic in The Sandbox
    Bear in mind this is "The Sandbox" used for testing how the forum behaves, such as LaTeX code. However, the mathematics itself is about the Lie derivative, a tensorial derivative that is different to the covariant derivative and is independent of the connection.
  6. KJW replied to KJW's topic in The Sandbox
    [math]\displaystyle {\large £}[V{}^{u}] \mathfrak{T}{}^{i_1\ .\ .\ .\ i_p}_{j_1\ .\ .\ .\ j_q} = V{}^{u} \partial{}_{u} \mathfrak{T}{}^{i_1\ .\ .\ .\ i_p}_{j_1\ .\ .\ .\ j_q} - \sum_{\phi = 1}^{p} \partial{}_{u} V{}^{i_\phi}\ \mathfrak{T}{}^{i_1\ .\ .\ .\ i_{\phi - 1}\ u\ i_{\phi + 1}\ .\ .\ .\ i_p}_{j_1\ .\ .\ .\ j_q} + \sum_{\phi = 1}^{q} \partial{}_{j_\phi} V{}^{u}\ \mathfrak{T}{}^{i_1\ .\ .\ .\ i_p}_{j_1\ .\ .\ .\ j_{\phi - 1}\ u\ j_{\phi + 1}\ .\ .\ .\ j_q} +\ w\ \partial{}_{u} V{}^{u}\ \mathfrak{T}{}^{i_1\ .\ .\ .\ i_p}_{j_1\ .\ .\ .\ j_q}[/math] [math]\displaystyle \overline{{\large £} [V{}^{v}] \mathfrak{T}}{}^{r_1\ .\ .\ .\ r_p}_{s_1\ .\ .\ .\ s_q} = {\large £}[V{}^{u}] \mathfrak{T}{}^{i_1\ .\ .\ .\ i_p}_{j_1\ .\ .\ .\ j_q} \left(\prod_{\lambda = 1}^{p} \dfrac{\partial \overline{x}{}^{r_\lambda}}{\partial x{}^{i_\lambda}}\right) \left(\prod_{\lambda = 1}^{q} \dfrac{\partial x{}^{j_\lambda}}{\partial \overline{x}{}^{s_\lambda}}\right) \left|\dfrac{\partial x{}^{j}}{\partial \overline{x}{}^{s}}\right|^w[/math]
  7. A particle's frequency corresponds to its energy, nothing more. To suggest anything more is to peddle woo. An eigenstate is one of the possible states that result from an observation.
  8. I looked at the video but the part I was most interested in was a secret. Even before I watched the video, I was expecting the liquid glass to be a silylating agent. There is nothing new about silylating agents in general. For example, they are used to render laboratory glassware hydrophobic. However, I was curious about the specific silylating agent in this case, which might be quite novel. I anticipate that the silylating agent would be more "glasslike" than typical silylating agents (which have organic groups attached).
  9. I doubt that Newton's laws or Kepler's laws were named by Newton or Kepler after themselves. More likely, they were named by other people somewhat later. Actually, it is quite common for a law to be given the name of someone who is not the person who originally discovered it. From Wikipedia article "Stigler's law of eponymy": Stigler's law of eponymy, proposed by University of Chicago statistics professor Stephen Stigler in 1980, states that no scientific discovery is named after its original discoverer. Examples include Hubble's law, which was derived by Georges Lemaître two years before Edwin Hubble; the Pythagorean theorem, which was known to Babylonian mathematicians and to Indian mathematicians before Pythagoras; and Halley's Comet, which was observed by astronomers since at least 240 BC (although its official designation is due to the first ever mathematical prediction of such astronomical phenomenon in the sky, not to its discovery). Stigler attributed the discovery of Stigler's law to sociologist Robert K. Merton. (From htps://en.wikipedia.org/wiki/Stigler%27s_law_of_eponymy)
  10. I assume that. However, it is reasonable to assume that a downvote came from the one antagonistic person who did post in the thread.
  11. some bigotries which very common in this forum. step 1: one demonstrates or proposes an opinion. step 2: a well known member attempts to disagree to that opinion. step3 : there is occuring of existence of many members downvoting that opinion (regardless the reality in that opinion, in fact this is a weakness of opinionating). And this is bigotry, isn't it? I don't understand who is who in the above. In the "Today I Learned in Mathematics" thread, only Genady and studiot were downvoted, and they were presumably by you (as the only person with the motive to downvote these two posters).
  12. KJW replied to KJW's topic in The Sandbox
    [math]R{}_{p}^{\mskip{0.05 cm}·}{}_{t}^{\mskip{0.05 cm}·}{}_{p}^{\mskip{0.05 cm}·}{}^{p}_{\mskip{0.05 cm}·}{}^{t}_{\mskip{0.05 cm}·}{}_{p}^{\mskip{0.05 cm}·}{}_{p}^{\mskip{0.05 cm}·}[/math] [math]R{}_l{}_q{}^r{}_s{}_t{}^g{}^v{}^h{}_x[/math]
  13. That's it!! Just to clarify, the definition says, "for each y in S", which includes x0, whereas y must not be equal to x0.
  14. I think I see it: y has to be not equal to x0.
  15. @Genady, is the mistake you see that subset S requires at least two elements and not merely be non-empty?

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