Twitter Updated +Created
Sparse matrix Updated +Created
IBM 705 Updated +Created
SVG tutorial Updated +Created
SVG version Updated +Created
Chemical vapor deposition Updated +Created
Siemens spinoff Updated +Created
Einstein notation for partial derivatives Updated +Created
The Einstein summation convention works will with partial derivatives and it is widely used in particle physics.
In particular, the divergence and the Laplacian can be succintly expressed in this notation:
In order to expresse partial derivatives, we must use what Ciro Santilli calls the "partial index partial derivative notation", which refers to variales with indices such as , , , , and instead of the usual letters , and .
Covariance and contravariance of vectors Updated +Created
Elliptic curve university course Updated +Created
Secret society Updated +Created
Quantum Field Theory book by Mark Srednicki (2006) Updated +Created
Author affiliation: University of California, Santa Barbara.
Number of pages: 616!
Don't redistribute clause, and final version by Cambridge University Press, alas, so corrections will never be merged back: web.physics.ucsb.edu/~mark/qft.html. But at least he's collecing erratas for the published (and therefore draft) versions there.
The book is top-level organized in spin 0, spin half, and spin 1. Quite ominous, really.
The preface states that one of its pedagogical philosophies is to "Illustration of the basic concepts with the simplest examples.", so maybe there is hope after all.
Philosophy Updated +Created
Nichols radiometer Updated +Created
Experimental setup to observe radiation pressure in the laboratory.
Solar sail Updated +Created
Application of radiation pressure.
First live example: en.wikipedia.org/wiki/IKAROS
Figure 1.
A 1:64 scale model of the IKAROS spacecraft
. Source.
History of Amazon Updated +Created
I wonder where the spray painted sign went: twitter.com/profgalloway/status/1229952158667288576/photo/1. As mentioned at officechai.com/startups/amazon-first-office/ and elsewhere, Jeff did all he could to save money, e.g. he made the desks himself from pieces of wood. Mentioned e.g. at youtu.be/J2xGBlT0cqY?t=345 from Video 4. "Jeff Bezos presentation at MIT (2002)".
Video 1.
Amazon.com report by Computer Chronicles (1996)
Source. Contains some good footage of their early storehouse.
Video 2.
Jeff Bezos interview by Chuck Films (1997)
Source. On the street, with a lot of car noise. CC BY-SA, nice.
Video 4.
Jeff Bezos presentation at MIT (2002)
Source. Good talk:
Video 5.
Jeff Bezos Revealed by Bloomberg (2015)
Source.
Video 6.
cosine by Jeff Bezos (2018)
Source.
PDE mention in another video from 2009: youtu.be/TYwhIO-OXTs?t=118
Full original video from The Economic Club of Washington, D.C. (2018): youtu.be/zN1PyNwjHpc?t=1544
Bezos also told PDE stuff in interviews as early as 1999: archive.ph/a3zBK.
Bibliography:
  • archive.ph/ucSHN This is what it was like to work at Amazon 20 years ago (2015). Good annecdotes from the first offices.
Unicellular organism Updated +Created
Magnet Updated +Created

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