- 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.
The study of cavity radiation was not just about establishing theoretical principles, however. It was also of interest to the German Bureau of Standards as a reference for rating electric lamps.
- 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.Maybe I'm an idiot and should have bought a much smaller rear wheel stand, only thought of that later, e.g.: www.amazon.co.uk/dp/B00G7ZO3GE or www.amazon.co.uk/dp/B00SD7NL44
Rope attached to rear rack + door knob: www.youtube.com/watch?v=teUsJt1WL1g
This is an interesting initiative which has some similarities to Ciro Santilli's OurBigBook project.
The fatal flaw of the initiative in Ciro Santilli's opinion is the lack of user-generated content. We will never get there without UGC and algorithms, never.
Also as of 2021, it mostly useless business courses: learn.saylor.org unfortunately.
But it has several redeeming factors which Ciro Santilli aproves of:
- exam as a service-like
- they have a GitHub: github.com/saylordotorgo
Licensing appears to be a mixed mess between the dreaded CC BY-NC-SA and the good CC BY, e.g.:?
The founder Michael J. Saylor looks a bit crooked, Rich people who create charitable prizes are often crooked comes to mind. But maybe he's just weird.
Michael Saylor interview by Lex Fridman (2022)
Source. At the timestamp:What statement... maybe he's actually not crooked, maybe it was just an accounting mistake... God, why.
When I go, all my assets will flow into a foundation, and the foundation's mission is to make education free for everybody forever.
If only Ciro Santilli knew how to contact him and convince him that his current approach is innefective and that Ciro has something better! Michael, please Google into this page some day, Ciro Santilli needs funding for OurBigBook.com. A hopeless Tweet at: twitter.com/cirosantilli/status/1548350114623660035. Also tried to hit his
saylor@strategy.com.20 pounds. Works on both Schrader and Presta.
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