Chicago Updated 2025-07-16
Knol Updated 2025-07-16
Very similar to OurBigBook.com!
People who worked on it:
Video 1.
How to use Google Knol by Hack Learning (2011)
Source. One of the last users of the website for sure! The owner of that YouTube channel is a Mark Barnes:
Video 2.
Jimmy Wales on Google's Knol (2008)
Source.
Replying to a listener phone-in question WNYC radio, mediated by Brian Lehrer.
It was about to launch it seems, and it was not clear at the time that anyone could write content, as opposed to only selected people.
Jimmy then corrects that misinformation. He then clearly states that since there can be multiple versions of each article, including opinion pieces, like OurBigBook.com, Knol would be very different to Wikipedia, more like blogging than encyclopedia.
Video 3.
Google Knol: the future of academic journals? by Doug Belshaw (2010)
Source.
Bibliography:
cyclotrons produce the better images, but they are expensive/you have to move to them and order a timeslot.
Lab-based just use some X-ray source from the lab, so it is much move convenient e.g. for a pharmaceutical company doing a bunch of images. The Wikipedia image shows such a self-contained lab system: en.wikipedia.org/wiki/File:Freezed_XRD.jpg
Atomic clock Updated 2025-07-16
Video 1.
How an atomic clock works, and its use in the global positioning system (GPS) by EngineerGuy (2012)
Source. Shows how conceptually an atomic clock is based on a feedback loop of two hyperfine structure states of caesium atoms (non-radioactive caesium-133 as clarified by the Wikipedia page). Like a quartz clock, it also relies on the piezoelectricity of quartz, but unlike the quartz clock, the quartz is not shaped like a tuning fork, and has a much larger resonating frequency of about 7 MHz. The feedback is completed by producing photons that resonate at the right frequency to excite the caesium.
Video 2.
Inside the HP 5061A Cesium Clock by CuriousMarc (2020)
Source.
A similar model was used in the Hafele-Keating experiment to test special relativity on two planes flying in opposite directions. Miniaturization was key.
Contains a disposable tube with 6g of Caesium. You boil it, so when it runs out, you change the tube, 40k USD. Their tube is made by Agilent Technologies, so a replacement since that opened in 1999, and the original machine is from the 60s.
Detection is done with an electron multiplier.
youtu.be/eOti3kKWX-c?t=1166 They compare it with their 100 dollar GPS disciplined oscillator, since GPS satellites have atomic clocks in them.
Video 3.
Quick presentation of the atomic clock at the National Physical Laboratory (2010)
Source. Their super accurate setup first does laser cooling on the caesium atoms.
Atomic orbital Updated 2025-07-16
In the case of the Schrödinger equation solution for the hydrogen atom, each orbital is one eigenvector of the solution.
Remember from time-independent Schrödinger equation that the final solution is just the weighted sum of the eigenvector decomposition of the initial state, analogously to solving partial differential equations with the Fourier series.
This is the table that you should have in mind to visualize them: en.wikipedia.org/w/index.php?title=Atomic_orbital&oldid=1022865014#Orbitals_table
Audio editor Updated 2025-07-16
Australia Updated 2025-07-16
Author Updated 2025-07-16
Since Snakes and Ladders is nothing but a Absorbing Markov chain, the results are exactly the same as for that general problem.
www.jstor.org/stable/3619261: How Long Is a Game of Snakes and Ladders? by Althoen, King and Schilling (1993), paywalled.
AWS service Updated 2025-07-16
Axiom Updated 2025-07-16
B4 Oxford physics course Updated 2025-07-16
2015 professor: Alan J. Barr.
Possible 2022 professor: Guy Wilkinson (unconfirmed): www.chch.ox.ac.uk/staff/professor-guy-wilkinson
Backpropagation Updated 2025-07-16
Video 1.
What is backpropagation really doing? by 3Blue1Brown (2017)
Source. Good hand-wave intuition, but does not describe the exact algorithm.
BackRub Updated 2025-07-16
This was the original name of Google Search.
One wonders if this name has some influence from the LGBT culture in San Francisco! The sexual innuendo is palpable.
"Back" is of course a reference to "backlinks", since Google Search relies on incoming links (AKA backlinks) to a webpage to determine its importance.

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