@lorentzframe

Astrophysicist, EX-Meta, GSIT, Amazon, Microsft, NASA/JPL

rebcabin.github.com
Joined March 2009
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  • Followers2.2K
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Lie theory, featuring 3D rotations - Online Technical Discussion Groups—Wolfram Community community.wolfram.com/groups… All about su(2), so(3), SU(2), SO(3), packed into 21 pages with proofs. My latest staff pick.
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Why SU(2) is a better choice than SO(3): my latest staff pick at the Wolfram Community: community.wolfram.com/groups…
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How about calculating the dynamics of a pendulum or a symmetrical top from geodesics in a curved manifold, SO(3)? See my latest Staff Pick at the Wolfram Community SO(3) Gauge Theory for Classical Mechanics in UD community.wolfram.com/groups…
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As promised, here is the Schwarzschild metric ab-initio. No dragons this time. Only college maths are needed. It was found almost immediately after the publication of Einstein's General Relativity by Karl Schwarzschild while he was enlisted in WWI. community.wolfram.com/groups…

Schwarzschild metric from scratch via UD compilation

Open in Wolfram Cloud ↗ DOWNLOAD-DESKTOP-NOTEBOOK.nb (705 KB)

community.wolfram.com
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If you liked Schwarzschild black holes, you'll love spinning Kerr black holes, but beware the fearsome dragon! Read about the Wizard's Quest here, my latest Staff Pick at Wolfram Community: community.wolfram.com/groups…
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Truly excellent notes on non-quantum field theory: digitalcommons.usu.edu/lib_m…. While "charting" my own path through diff. geom and all that at Wolfram Comm. community.wolfram.com/web/bc…, I stumbled on Charles Torre's, aimed straight at the sweet spot for a physicist: just enough rigor.

Introduction to Classical Field Theory

This is an introduction to classical field theory. Topics treated include: Klein-Gordon field, electromagnetic field, scalar electrodynamics, Dirac field, Yang-Mills field, gravitational field,...

digitalcommons.usu.edu
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Interactive Black-Hole Dynamics with the Relativity Toolkit My latest Staff Pick at Wolfram community.wolfram.com/groups… source on GitHub: github.com/rebcabin/Relativi…
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Covariant derivatives etc. in the UD calculus: moving toward black-hole physics ab-initio. My latest staff pick at Wolfram :) community.wolfram.com/groups…
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How to Land a Rocket community.wolfram.com/groups…
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Travesties for Logic and for Types community.wolfram.com/groups…
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nice derivation of Planck's radiation law from first principles, 19th-century style thecuriousastronomer.wordpre…

Derivation of Planck’s radiation law – part 4 (final part)

In part 3 of this blog series I explained how Max Planck found a mathematical formula to fit the observed Blackbody spectrum, but that when he presented it to the German Physics Society on the 19th…

thecuriousastronomer.wordpress.com
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Overheard in the compiler commissary: "There are smart people who would rather work hard than think hard. We outsmart them by making them think they're working hard by working hard to save them from thinking hard."
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Lie Groups are both manifolds and groups. Being a group means that moving around on the manifold is group multiplication (you never leave, you can always go back, you're allowed to go nowhere).
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I forgot the last rule-of-the-road for groups -- "associativity:" doesn't matter if you go from A to B, have a coffee in B, then go to C; or if you go to A, have your coffee there, then go through B to C, so long as you go through A and B in that order.
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Brian Beckman retweeted
TeX and Typography@TeXtip1 Jan 2024
The margins aren't too wide, the paper's too big. johndcook.com/blog/2012/09/1…

LaTeX: the paper is too big

In response to the question "Why are default LaTeX margins so big?" Paul Stanley answers It's not that the margins are too wide. It's that the paper is too big! This sounds flippant, but he gives a...

johndcook.com
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My latest Staff Pick at Wolfram Community: Algebraic Travesties, or How to Generate Random Algebra Expressions from a grammar :) community.wolfram.com/groups…
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Why not power arctic data hypercenters with container-sized reactors? gao.gov/assets/gao-20-380sp.…
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Unified theory of Fourier analysis johndcook.com/blog/2017/08/2…

Unified theory of Fourier transforms: LCA groups

Fourier series, Fourier transforms, Discrete Fourier transforms, ... All these fit into one general theory: Fourier analysis on groups.

johndcook.com
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An unusual introduction to manifolds johndcook.com/blog/2023/12/2… "This tutorial offers a bridge between the abstract mathematics of manifolds and computational practice."
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Beyond Functional Programming: The Verse Programming Language [pdf] simon.peytonjones.org/assets…
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