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Recent content by Trakk

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    Sci-Fi

    True, one can't reasonably expect to go over a nominal weight limit by a factor of 10 or 100, but to go over a nominal weight limit by 1% or less is another story. That would be well within a reasonable safety factor like 10% or more.
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    Sci-Fi

    (all morally unacceptable in some way) Nightfall -- a total eclipse every 2000 years of an otherwise well-lighted world. Without light, its people set their cities on fire to create light for themselves. Some scientists figure out what is going on, but they do so just before the next eclipse...
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    The Standard Model of Particle Physics -- where we are at

    Next up is the Fritzsch-Minkowski-Georgi SO(10) model. It breaks down into SU(5) * U(1), where the second group is related to a chargelike quantity related to (B-L), (baryon number) - (lepton number). Its multiplets are (SU(5) multiplet, U(1) "charge"). Gauge: 45 -> (24,0) + (1,0) + (10,-1) +...
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    The Standard Model of Particle Physics -- where we are at

    Awfully ingenious. But I'm so entranced with Grand Unified Theory simplification that I'll show how it works. The smallest simple-group GUT that includes the (Minimal Supersymmetric) Standard Model is the Georgi-Glashow SU(5) model. Its multiplets break down into the unbroken (MS)SM ones as...
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    Sci-Fi

    Any reasons for that?
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    What quality of evidence for extraterrestrials?

    IAA SETI Permanent Committee: Rio Scale is a proposed numerical scaling of how strong a claim of extraterrestrial-intelligence evidence is: 10 Extraordinary, 9 Outstanding, 8 Far-reaching, 7 High, 6 Noteworthy, 5 Intermediate, 4 Moderate, 3 Minor, 2 Low, 1 Insignificant, 0 None. That scale uses...
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    Foundation and Empire

    I remember reading the Foundation Trilogy long ago. I liked it -- it has a grandiose sweep of history. One could watch the Foundation grow from being a tiny colony of exiles from the Galactic Empire to the ruler of a new empire that spanned 1/3 or 1/2 of the Galaxy when the trilogy ended...
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    Sci-Fi

    Yes indeed. Speculative fiction is just about the only sort of fiction that I have much taste for, and that includes science fiction.
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    The Standard Model of Particle Physics -- where we are at

    (Me: ) The Standard Model has been very successful so far, but there are lots of things that don't fit. It would be a limiting case of another theory, just as Newtonian mechanics is. Of the known non-SM phenomena, neutrino masses and mixing angles are successfully handled as extensions of the...
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    The Standard Model of Particle Physics -- where we are at

    The "roundness" tests are electric-dipole tests -- how much a particle's charge distribution departs from sphericity. As to the LHC and SUSY, the LHC's operations divide SUSY particles into two main categories: with and without QCD interactions. That is because QCD interactions are relatively...
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    The Standard Model of Particle Physics -- where we are at

    Now for Grand Unified Theories. The simplest that includes the Standard model is the Georgi-Glashow SU(5) theory. All the gauge particles go into one multiplet, and the elementary fermions three multiplets per generation: Right-handed neutrinos Left-handed leptons and right-handed down-like...
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    The Standard Model of Particle Physics -- where we are at

    Now for supersymmetry or SUSY, a much-studied extension of space-time symmetry. It makes every elementary particle have a related one with spin differing by 1/2. All their other quantum numbers are the same. Unbroken SUSY makes partners have the same mass, but we don't observe unbroken SUSY...
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    The Standard Model of Particle Physics -- where we are at

    Without electroweak symmetry breaking, the Standard Model looks rather different. First the "gauge symmetry", described by "symmetry groups". With EWSB, it has two parts, SU(3) for QCD and U(1) for electromagnetism, combined as SU(3)*U(1). Without EWSB, it has three parts, SU(3) for QCD again...
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    The Standard Model of Particle Physics -- where we are at

    I included them as problems because they show that there is a lot that's observed that's outside the Standard Model. One can argue about whether the SM was *intended* to include them, but that's another story. But I'll go into detail about the SM, using Wikipedia as a source. First, its...
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    The Standard Model of Particle Physics -- where we are at

    The Standard Model has been very successful so far, but there are lots of things that don't fit. Empirical Neutrino masses Matter-antimatter asymmetry Gravity Dark matter Dark energy Inflation Theoretical Sources of neutrino masses -- seesaw mechanism? Strong CP violation -- why isn't it...
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