Everything posted by Duda Jarek
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Electric field energy of the electron (split from Can infinities exist in nature?)
Regarding Heisenberg principle, notice that I am using "mean": what is mean energy density of electric field in distance r from electron? If one really needs a probe particle, e.g.: what is mean energy of electron - positron pair in distance r?
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Electric field energy of the electron (split from Can infinities exist in nature?)
https://en.wikipedia.org/wiki/Electric_field#Energy_in_the_electric_field Or this F_munu F^munu in QED https://en.wikipedia.org/wiki/Quantum_electrodynamics#Mathematical_formulation
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Electric field energy of the electron (split from Can infinities exist in nature?)
Regarding probing with other charged particle, there appears Coulomb potential V(r) ~ -1/r ... again having this infinity problem. There is scattering - extrapolating to energy of resting particles to remove Lorentz contraction contribution, we get ~100mb corresponding to size of electron in femtometers - we have discussed it here: But cannot we directly ask about field? Its mean energy density in r distance?
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Electric field energy of the electron (split from Can infinities exist in nature?)
Ok, but in annihilation there are usually two (for para-positronium, +1 for ortho to reach zero angular momentum) ... e.g. used in PET imaging. Sure, in practice we need a bit larger energy to get pair in a distance ... ... but, this final energy also includes Coulomb potential V(r) ~ -1/r, again infinity in the beginning r=0 ... requiring some regularization. From one side, "subtracting infinity by hand" in renormalization is only mathematical trick - there still remains the question "what is mean energy density of electric field in distance r from electron?" Asymptotically ~|E|^2 = 1/r^4, but it leads to infinity - requires some deformation in the center. From the other, there are classical regularization methods. For example use Higgs potential V(u) = (|u|^2 -1)^2. It has |u|=1 vacuum (energy minimum), but e.g. in the center of topological singularity like hedgehog u(x) = x/|x|, to prevent discontinuity (infinite energy) it allows to get to v=0 by activating potential:
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Electric field energy of the electron (split from Can infinities exist in nature?)
Energy conservation says that energy before and after should be the same. For 2gamma -> electron + positron pair creation: - energy before is 2x511keV in photons, which are EM waves - so this energy is initially in EM field, - energy after is, among others, energy of electric field of these two charges: integrating over energy density of E~1/r^2, we get infinite energy after this way. There is a problem, and just subtracting infinity in renormalization is only a mathematical trick without really understanding. We need to regularize this singularity: deform electric field to prevent E->infinity in the center. Running coupling ( https://en.wikipedia.org/wiki/Coupling_constant#Running_coupling ) can be seen as a consequence of such deformation: alpha increases e.g. to 1/127 in 90GeV - perfect point charges wouldn't need such deformation. Some discussion: https://physics.stackexchange.com/questions/386760/the-problem-of-infinite-energy-of-electron-as-point-charge Indeed the question of total energy of electric field of electron is extremely interesting - we only know the upper bound: 511keV. There are also other fields like magnetic of magnetic dipole: integrating energy density of all the fields, should we get 511keV or smaller? In other words: are particles more then just their fields? What more? Nice quote from 1961 Infeld "Evolution of Physics: The Growth of Ideas from Early Concepts to Relativity and Quanta.":
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Electric field energy of the electron (split from Can infinities exist in nature?)
At least some of physicists believe in energy conservation, requiring source e.g. for hypothetical infinite energy. For example there is pair creation: of electron + positron from 2x511 keV only, so energy of electric field of such electron shouldn't exceed 511keV. But electric field of point charge is E~1/r^2, energy density is ~|E|^2, what integrates to infinite energy. So is there infinite energy in electric field of electron? QFT "repairs" this problem by just subtracting this infinity in renormalization procedure - successfully swept under the rug. But maybe it contains some regularization - deformation of electric field to indeed integrate to at most 511keV energy?
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Similarity between particle physics and macroscopic quantum phenomena like fluxons?
Especially in superconductors/superfluids there are observed so called macroscopic quantum phenomena ( https://en.wikipedia.org/wiki/Macroscopic_quantum_phenomena ) - stable constructs like fluxon/Abrikosov vortex quantizing magnetic field due to topological constraints (phase change along loop has to be multiplicity of 2pi). There is observed e.g. interference ( https://journals.aps.org/prb/abstract/10.1103/PhysRevB.85.094503 ), tunneling ( https://journals.aps.org/prb/pdf/10.1103/PhysRevB.56.14677 ), Aharonov-Bohm ( https://www.sciencedirect.com/science/article/pii/S0375960197003356 ) effects for these particle-like objects. It brings question if this similarity with particle physics could be taken further? How far? E.g. there is this famous Volovik's "The universe in helium droplet" book ( http://www.issp.ac.ru/ebooks/books/open/The_Universe_in_a_Helium_Droplet.pdf ). Maybe let us discuss it here - any interesting approaches? For example there are these biaxial nematic liquid crystals: of molecules with 3 distinguishable axes. We could build hedgehog configuration (topological charge) with one these 3 axes, additionally requiring magnetic-like singularity for second axis due to hairy-ball theorem ... doesn't it resemble 3 leptons: asymptotically the same charge (+magnetic dipole), but with different realization/mass?
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Covid-19 vaccines thread
Obviously many are coming, naturally selected especially for faster spread, now e.g. also from South Africa: https://www.cnbc.com/2021/01/06/south-africa-covid-strain-a-guide-to-what-you-need-to-know.html Again good interview:
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Covid-19 vaccines thread
good interview:
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Covid-19 vaccines thread
Tomorrow EU starts mass vaccination https://www.france24.com/en/europe/20201226-european-union-begins-coronavirus-vaccine-rollout-as-new-strain-spreads ... as the new strains like UK's are quickly spreading - what do we know about vaccine efficiency for them? It is great that there are lots of them - covering various mechanisms, hopefully allowing for effective war with mutations (https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html 3 approved, 5 limited approved, 18 in phase III). Very nice explanation of Pfizer mRNA vaccine: https://berthub.eu/articles/posts/reverse-engineering-source-code-of-the-biontech-pfizer-vaccine/, especially: - it uses Psi (1-methyl-3’-pseudouridylyl) instead of U (uracil) - works the same, but with weaker immune response, - uses synonymous codons with increased numbers of C and Gs (e.g. CUU -> CUG both encode Leucine), which are converted more efficiently into proteins, - two amino acids are changed comparing to virus spike protein (K,V -> P) to handle the problem of difference between pre- and post-fusion spike protein - this exchange into Proline makes them fold into the proper shape without being mounted to a virus (known since 2017 thanks to work on SARS-CoV-1).
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Covid-19 vaccines thread
UK starts mass vaccination: https://www.bbc.com/news/uk-55218679
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Covid-19 vaccines thread
U.K. Approves Pfizer Coronavirus Vaccine, a First in the West https://www.nytimes.com/2020/12/02/world/europe/pfizer-coronavirus-vaccine-approved-uk.html
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Covid-19 vaccines thread
18th November Pfizer 95 percent https://www.theguardian.com/world/2020/nov/18/pfizer-covid-19-vaccine-95-effective-and-safe-further-tests-show Time for another bid for Sputnik and Moderna
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Covid-19 vaccines thread
9th November: Pfeizer "90 percent efficient" https://www.the-scientist.com/news-opinion/pfizers-covid-19-vaccine-90-percent-effective-initial-data-68138 11th November: "Sputnik V 92 percent" https://www.aljazeera.com/news/2020/11/11/russia-says-sputnik-v-covid-19-vaccine-is-92-percent-effective 16th November: "Moderna 94.5 percent" https://www.nytimes.com/2020/11/16/health/Covid-moderna-vaccine.html Who's next? ... in the meantime e.g. https://www.marketwatch.com/story/pfizers-ceo-sold-5-6-million-worth-of-shares-on-the-day-of-its-big-vaccine-news-so-what-11605280170
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Phosphine detected on Venus
Another very similar molecule is NH3 ... found e.g. on Pluto - not suggesting biological source only geological: https://advances.sciencemag.org/content/5/5/eaav5731 Detection of ammonia on Pluto’s surface in a region of geologically recent tectonism
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Phosphine detected on Venus
Oxygen-free environments seem characteristic for geological processes (?), and PH3 is similar to CH4 released by our geology - if phosphorus dominates instead of carbon, couldn't phosphine by synthesized in oxygen-free geological environments? "Geologic emissions of methane to the atmosphere": https://pubmed.ncbi.nlm.nih.gov/12430657/ ps. SH2 can be produced by bacteria: https://en.wikipedia.org/wiki/Hydrogen_sulfide#Biosynthesis_in_the_body Phosphine also occurs in Earth atmosphere ... and Jupiter: https://en.wikipedia.org/wiki/Phosphine#Occurrence Can be generated by bacteria: https://www.researchgate.net/publication/12507095_Phosphine_generation_by_mixed-_and_monoseptic-cultures_of_anaerobic_bacteria
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Covid-19 vaccines thread
Here is their recent Lancet paper: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31866-3/fulltext https://www.reuters.com/article/us-health-coronavirus-russia-vaccine/russias-covid-19-vaccine-showed-antibody-response-in-initial-trials-idUSKBN25V1I2 Looks promising, but there are some suspicions: https://www.cnbc.com/2020/09/10/scientists-question-russian-vaccine-trial-data-on-unlikely-patterns.html Yesterday WHO vaccine report: https://www.who.int/publications/m/item/draft-landscape-of-covid-19-candidate-vaccines A worse news, probably the most promising (AstraZeneca) trial is on hold: https://www.nature.com/articles/d41586-020-02594-w
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Covid-19 vaccines thread
... and approval for military use in China:
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Covid-19 vaccines thread
Also China and probably others ... and minimizing e.g. expected number of casualties, this might be a reasonable behavior. Personally, if having opportunity to participate in such test, if only not having some nasty side effects, I don't think if I would have any doubts.
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Covid-19 vaccines thread
https://www.bbc.com/news/world-europe-53735718 Coronavirus: Putin says vaccine has been approved for use Two more Stage III (8, +1 "approved") in https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html
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Covid-19 vaccines thread
Over a million doses of Oxford/AstraZeneca coronavirus vaccine possible by September, says researcher https://www.reuters.com/article/us-health-coronavirus-oxford-vaccine-res/over-a-million-doses-of-oxford-astrazeneca-covid-19-vaccine-possible-by-september-researcher-idUSKCN24L1TW Also two more Phase III (to 6 + 1 approved) in https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html
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Covid-19 vaccines thread
https://www.nejm.org/doi/full/10.1056/NEJMoa2022483 General optimism and preparation for vaccine this December:
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Covid-19 vaccines thread
There was added "approved" on this vaccine tracker ... for military use, also in phase II:
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Covid-19 vaccines thread
From https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html , third vaccine has entered phase III:
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Covid-19 vaccines thread
https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html Phase III: 2 Phase II: 8 e.g. Moderna to start Phase III in July, Phase I: 10 Preclinical: 125+