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.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.
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.This chick is hardcore.
Governments have lost all power to companies by 
Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01
Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01Beautifully argued at: Can't get you out of my head by Adam Curtis (2021).
- The Quantum Story by Jim Baggott (2011) page 10 mentions:and the footnote comments:
Early examples of such cavities included rather expensive closed cylinders made from porcelain and platinum.
- 1859-60 Gustav Kirchhoff demonstrated that the ratio of emitted to absorbed energy depends only on the frequency of the radiation and the temperature inside the cavity
- 1896 Wien approximation seems to explain existing curves well
- 1900 expriments by Otto Lummer and Ernst Pringsheim show Wien approximation is bad for lower frequencies
- 1900-10-07 Heinrich Rubens visits Planck in Planck's villa in the Berlin suburb of Grünewald and informs him about new experimental he and Ferdinand Kurlbaum obtained, still showing that Wien approximation is bad
- 1900 Planck's law matches Lummer and Pringsheim's experiments well. Planck forced to make the "desperate" postulate that energy is exchanged in quantized lumps. Not clear that light itself is quantized however, he thinks it might be something to do with allowed vibration modes of the atoms of the cavity rather.
- 1900 Rayleigh-Jeans law derived from classical first principles matches Planck's law for low frequencies, but diverges at higher frequencies.
Black-body Radiation Experiment by sciencesolution (2008)
Source. A modern version of the experiment with a PASCO scientific EX-9920 setup.This situation is the most bizarre thing ever. The dude was fired in 2020, but he refused to be fired, and because he has the company seal, they can't fire him. He is still going to the office as of 2022. It makes one wonder what are the true political causes for this situation. A big warning sign to all companies tring to setup joint ventures in China!
The development cycle time is your God by Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01
Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01New developers won't want to learn your project, because they would rather shoot themselves.
Of course, at some point software gets large enough that things won't fit anymore in 5 seconds. But then you must have either some kind of build caching, or options to do partial builds/tests that will bring things down to that 5 second mark.
A slow build from scratch will mean that your continuous integration costs a lot, money that could be invested in a new developer!
One anecdote comes to mind. Ciro Santilli was trying to debug something, and more experience colleague came over.
To reproduce a problem, ciro was running one command, wait 5 seconds, run a second command, wait 5 seconds, run a third command:
cmd1
# wait 5 seconds
cmd2
# wait 5 seconds
cmd3The first thing the colleague said: join those three commands into one:And so, Ciro was enlightened.
cmd1;cmd2;cmd3
The software engineer phrasing of simplicity is the ultimate sophistication.
Like all other principles, it is not absolute.
But it is something that you should always have on the back of your mind.
You aren't gonna need it is closely related, as generally the extra unnecessary complications are set in place to accommodate useless features that will never be needed.
Office space design and remote work by Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01
Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01Working remotely is hard if you don't already highly master the software and enterprise systems used.
Also you don't feel people's love as strongly, and usefulness is built on love, see also Steve Jobs's Pixar office space design philosophy.
But please, give workers a small silent office so that we can concentrate instead of a silly open space, and create an internal social network so people can see what others are doing.
Remote working is much better if the majority of the team also does it, otherwise you will get excluded. Maybe after VR...
Political division:
- nominal leader: British monarch
- toplevel arch-dioceses/provinces of Cantebury and York. One archbishop each, who is also bishop of Cantebury and York diocese
- within provinces: one cathedral and bishop per diocese
Causality and quantum jumps are incompatible by Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01
Ciro Santilli 37 Updated 2025-06-02 +Created 1970-01-01If something does a quantum jump, what causes it to decide doing so at a particular time and not another? It is expected that a continuous cause would have continuous effects.
This concern was raised immediately by Rutherford while reviewing the Bohr model in 1913 as mentioned in The Quantum Story by Jim Baggott (2011) page 32.
Unlisted articles are being shown, click here to show only listed articles.