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Showing posts from February, 2021

MathJax in blogger. How I did it.

Copy the code from  http://irrep.blogspot.com/2011/07/mathjax-in-blogger-ii.html  or from the bottom of this post. 1.Go to Layout then 2.Sidebar(Top) "Add Gadget" then 3.HTML from third party. and 4.Paste the code. That's it.  $\star$ $\blacksquare$ $\Psi$ < script src=' http://cdn.mathjax.org/mathjax/latest/MathJax.js' type='text/javascript ' > MathJax . Hub . Config ({ HTML : [ "input/TeX" , "output/HTML-CSS" ], TeX : {  extensions : [ "AMSmath.js","AMSsymbols.js" ],  equationNumbers : { autoNumber : "AMS" } }, extensions : [ "tex2jax.js" ], jax : [ "input/TeX" , "output/HTML-CSS" ], tex2jax : { inlineMath : [ [ '$' , '$' ], [ "\\(" , "\\)" ] ], displayMath : [ [ '$$' , '$$' ], [ "\\[" , "\\]"...

E and D

According to the source below, E is a 1-form. Not a vector! (According to other reputable sources, the 2-form in full Minkowski spacetime is a better representation.) D is a 2-form. (BUT, according to  https://physics.stackexchange.com/questions/86510/maxwells-equations-using-differential-forms  they are both 2 forms in 4d spacetime .) $\star$dx=dydz $\star$dy=dzdx $\star$dz=dxdy And D= $e_0$ $\star$E "The surfaces of E are perpendicular to the tubes of D" And "The star operator relates 1-form surfaces to perpendicular 2-form tubes." And "...the star operator depends on a metric. If the metric is related to the permittivity or the permeability tensor, anisotropic star operators are obtained, and the constitutive relations become D= $\star_a$ E. Graphically, an anisotropic star operator acts on 1-form surfaces to produce 2-form tubes that intersect the surfaces obliquely rather than orthogonally." https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?articl...

my old stackexchange account

 https://physics.stackexchange.com/users/9267/madscientist?tab=questions

A photon travels in a vacuum from A to B to C. From the point of view of the photon, are A, B, and C at the same location in space and time?

 https://physics.stackexchange.com/questions/612895/a-photon-travels-in-a-vacuum-from-a-to-b-to-c-from-the-point-of-view-of-the-pho

Can we make a symmetric wavefunction out of two anti-symmetric wavefunctions?

 https://physics.stackexchange.com/questions/612929/can-we-make-a-symmetric-wavefunction-out-of-two-anti-symmetric-wavefunctions

An electron behaves as if it lives on a Mobius strip… Why don't we just say that electrons live on Mobius strips?

 https://physics.stackexchange.com/questions/613068/since-an-electron-behaves-as-if-it-lives-on-a-mobius-strip-its-a-spinor-wh

Nice physics things.

 An Introduction to Spinors.  https://arxiv.org/pdf/1312.3824.pdf Spinor Calculus Mit Lecture  Chapter 5 illustrates how a Spinor behaves like a cone on a cone. https://ocw.mit.edu/resources/res-8-001-applied-geometric-algebra-spring-2009/lecture-notes-contents/Ch5.pdf Teaching E&M using differential forms. https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=1668&context=facpub David Tong Lectures http://www.damtp.cam.ac.uk/user/tong/teaching.html [Highlights: First 3 Chapters on Statistical Mechanics. E&M on Magnets and Units. Spinors in Relativistic Dynamics. QFT, Popular Lecture on Newton.]   Can You See the Lorentz–Fitzgerald Contraction?  Or: Penrose–Terrell Rotation https://math.ucr.edu/home/baez/physics/Relativity/SR/penrose.html John Baez’s Stuff https://math.ucr.edu/home/baez/ https://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html The Meaning of Imaginary Time on Physics.Stackexchange How to be a good Theorist 't ho...

the best books i've read. approximately. maybe.

Surely You're Joking Mr. Feynman.  Geometry, Relativity and the Fourth Dimension. Rudy Rucker.  Theoretical Minimum by Susskind V1-V3. The Road to Reality by Penrose. The Remains of the Day. Ian McEwan. Amsterdam. The Gospel in Brief by Tolstoy. The Shadow of a Great Rock. Bloom. [and corresponding sections of the bible] Hamlet. Poem Unlimited. Bloom. Hamlet. King Lear. Letters to a Young Contrarian. Hitchens.  Time's Arrow. Amis. The Complete Stories of J.G. Ballard. The Gold Bug. Poe. The Rhyme of the Ancient Mariner.  The Double Helix. Watson. The Essential Gore Vidal. Arguably. Hitchens. Goodstein. Classical Mechanics. Griffiths. E&M.   Griffiths. QM. Zee. QFT. Zee. Einstein. Zee. Groups. Schutz. GR. Schutz. Geometrical Methods. Flanders. Differential Forms. Longair. Theoretical Concepts in Physics. Joyce. Ulysses. Nabokov. Pale Fire.  Nabokov. Complete Short Stories.  Nabokov. Invitation to a Beheading. 

The falling slinky and QM.

 The seemingly strange behavior of the falling slinky can be explained by referring to what the universe, at a particular point in spacetime "knows" versus what the universe, or person, at another point in spacetime knows.  The person knows that the slinky has been released before the bottom of the slinky knows.  QM is all about what the universe knows at various locations in spacetime. Sometimes and someplaces the universe happens to be a person.