Raspberry Pi 3 Updated +Created
Model B V 1.2.
SoC: BCM2837
Serial from cat /proc/cpuinfo: 00000000c77ddb77
Energy-momentum relation Updated +Created
Cutoff energy Updated +Created
Effective field theory Updated +Created
www.youtube.com/watch?v=WB8r7CU7clk&list=PLUl4u3cNGP60TvpbO5toEWC8y8w51dtvm by Iain Stewart. Basically starts by explaining how quantum field theory is so generic that it is hard to get any numerical results out of it :-)
But in particular, we want to describe those subtheories in a way that we can reach arbitrary precision of the full theory if desired.
Ruby on Rails React integration Updated +Created
Integrations React integration:
Time-independent Schrödinger equation for a free one dimensional particle Updated +Created
so the solution is:
We notice that the solution has continuous spectrum, since any value of can provide a solution.
Project Gutenberg remove line breaks Updated +Created
Their txt formats are so crap!
E.g. for;
wget -O pap.txt https://www.gutenberg.org/ebooks/1342.txt.utf-8
a good one is:
perl -0777 -pe 's/(?<!\r\n)\r\n(?!\r\n)( +)?/ /g' pap.txt
The ( +)? is for the endlessly many quoted letters they have, which use four leading spaces per line as a quote marker.
Proton-to-electron mass ratio Updated +Created
Proton VPN Updated +Created
God, I love this company so much.
Fermat's last theorem Updated +Created
A generalization of the Pythagorean triple infinity question.
Python classes Updated +Created
Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979) Updated +Created
Talk title shown on intro: "Today's Answers to Newton's Queries about Light".
6 hour lecture, where he tries to explain it to an audience that does not know any modern physics. This is a noble effort.
Part of The Douglas Robb Memorial Lectures lecture series.
Feynman apparently also made a book adaptation: QED: The Strange Theory of Light and Matter. That book is basically word by word the same as the presentation, including the diagrams.
According to www.feynman.com/science/qed-lectures-in-new-zealand/ the official upload is at www.vega.org.uk/video/subseries/8 and Vega does show up as a watermark on the video (though it is too pixilated to guess without knowing it), a project that has been discontinued and has has a non-permissive license. Newbs.
4 parts:
  • Part 1: is saying "photons exist"
  • Part 2: is amazing, and describes how photons move as a sum of all possible paths, not sure if it is relativistic at all though, and suggests that something is minimized in that calculation (the action)
  • Part 3: is where he hopelessly tries to explain the crucial part of how electrons join the picture in a similar manner to how photons do.
    He does make the link to light, saying that there is a function which gives the amplitude for a photon going from A to B, where A and B are spacetime events.
    And then he mentions that there is a similar function for an electron to go from A to B, but says that that function is too complicated, and gives no intuition unlike the photon one.
    He does not mention it, but P and E are the so called propagators.
    This is likely the path integral formulation of QED.
    On Quantum Mechanical View of Reality by Richard Feynman (1983) he mentions that is a Bessel function, without giving further detail.
    And also mentions that:
    where m is basically a scale factor.
    such that both are very similar. And that something similar holds for many other particles.
    And then, when you draw a Feynman diagram, e.g. electron emits photon and both are detected at given positions, you sum over all the possibilities, each amplitude is given by:
    summed over all possible Spacetime points.
    TODO: how do electron velocities affect where they are likely to end up? suggests the probability only depends on the spacetime points.
    Also, this clarifies why computations in QED are so insane: you have to sum over every possible point in space!!! TODO but then how do we calculate anything at all in practice?
  • Part 4: known problems with QED and thoughts on QCD. Boring.
This talk has the merit of being very experiment oriented on part 2, big kudos: how to teach and learn physics
Video 1.
Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979) uploaded by Trev M (2015)
Source. Single upload version. Let's use this one for the timestamps I guess.
Video 2.
Richard Feynman Lecture on Quantum Electrodynamics 1/8
. Source.
This book has formulas on it, which is quite cool!! And the formulas are basically not understandable unless you know the subject pretty well already in advance. It is however possible to skip over them and get back to the little personal stories.
David Tong's 2009 Quantum Field Theory lectures at the Perimeter Institute Updated +Created
14 1 hours 20 minute lectures.
The video resolution is extremely low, with images glued as he moves away from what he wrote :-) The beauty of the early Internet.
Ladder operator Updated +Created
The operators are a natural guess on the lines of "if p and x were integers".
And then we can prove the ladder properties easily.
The commutator appear in the middle of this analysis.
Omniscient debugging Updated +Created
What it adds on top of reverse debugging: not only can you go back in time, but you can do it instantaneously.
Or in other words, you can access variables from any point in execution.
TODO implementation? Apparently Pernosco is an attempt at it, though proprietary.

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