Only certain battery voltages exist, because this voltage depends intrinsically on the battery's chemical composition.
learn.sparkfun.com/tutorials/battery-technologies/all (CC BY-SA) has a very good summary list, reordered from lowest to highest voltage:
| Battery Shape | Chemistry | Nominal Voltage | Rechargeable? |
|---|---|---|---|
| AA, AAA, C, D (Rechargeable) | NiMH or NiCd | 1.2V | Yes |
| AA, AAA, C, and D | Alkaline or Zinc-carbon | 1.5V | No |
| Coin Cell | Lithium | 3V | No |
| Silver Flat Pack | Lithium Polymer (LiPo) | 3.7V | Yes |
| 9V | Alkaline or Zinc-carbon | 9V | No |
| Car Battery | Six-cell lead acid | 12.6V | Yes |
Atoms exist and last for a long time, while in classical electromagnetic theory punctual orbiting electrons should emit radiation quickly and fall into the nucleus: physics.stackexchange.com/questions/20003/why-dont-electrons-crash-into-the-nuclei-they-orbit
In other sections:
- black-body radiation experiment
- Einstein solid experiments, which are analogous to black body radiation experiments
- emission spectrum
- electron diffraction experiments such as:
Bibliography:
- web.mit.edu/course/5/5.73/oldwww/Fall04/notes/Experimental_Evidence_for_Quantum_Mechanics.pdf Experimental Evidence for Quantum Mechanics
Small splits present in all levels due to interaction between the electron spin and the nuclear spin if it is present, i.e. the nucleus has an even number of nucleons.
As the name suggests, this energy split is very small, since the influence of the nucleus spin on the electron spin is relatively small compared to other fine structure.
TODO confirm: does it need quantum electrodynamics or is the Dirac equation enough?
The most important examples:
- hydrogen line useful in astronomy, and also the simplest possible case between 1s
- caesium standard, which is used to define the second in the International System of Units since 1967.
The cause of variable number tandem repeat.
List of personal knowledge base software by 
Ciro Santilli 35 Updated 2025-01-29 +Created 1970-01-01
Ciro Santilli 35 Updated 2025-01-29 +Created 1970-01-01Lists:
- www.bibsonomy.org/user/bshanks/education fantastic list, presumably by this guy:
- www.reddit.com/r/Zettelkasten/comments/168cmca/which_note_taking_app_for_a_luhmann_zettlekasten/
- www.reddit.com/r/productivity/comments/18vvavl/best_free_notetaking_app_switching_from_evernote/
- github.com/topics/note-taking has a billion projects. Oops.
- www.noteapps.ca/
Personal knowledge base recommendation threads:
TODO look into those more:
- roamresearch.com/ no public graphs
- nesslabs.com/roam-research-alternatives a bunch of open source alternatives to it
- Trillium Notes. Notable project! Pun unintended!
- Stroll giffmex.org/stroll/stroll.html. How to publish? How to see tree?
- tiddlyroam joekroese.github.io/tiddlyroam/ graph rather than text searchable ToC. Public instance? Multiuser?
- Athens github.com/athensresearch/athens rudimentary WYSIWYG
- Logseq github.com/logseq/logseq no web interface/centralized server?
- itsfoss.com/obsidian-markdown-editor. Closed source. They have an OK static website publication mechanism: publish.obsidian.md/ram-rachum-research/Public/Agents+aren't+objective+entities%2C+they're+a+model but leaf node view only for now, no cross source page render. They are committed to having plaintext source which is cool: twitter.com/kepano/status/1675626836821409792
- But no upvotes/topics. Favorites could be used as upvotes, but it does not seem like you can favorite other people's work. It's just not their focus, will never be.They have an education push: www.notion.so/product/notion-for-education but it's likely hopeless.
- CherryTree github.com/giuspen/cherrytree written in C++, GTK, WYSIWYG
- github.com/dullage/flatnotes: Python
- github.com/usememos/memos: Go
- github.com/siyuan-note/siyuan: Go
- github.com/vnotex/vnote: C++
- github.com/Laverna/laverna: JavaScript
- github.com/taniarascia/takenote
- github.com/silverbulletmd/silverbullet: TypeScript, Markdown, web-based WYSIWYG, focus on querying
Major downsides that most of those personal knowledge databases have:
- very little/no focus on public publishing, which is the primary focus of OurBigBook.com
- either limited or no multiuser features, e.g. edit protection and cross user topics
- graph based instead of tree based. For books we need a single clear ordering of a tree. Graph should come as a secondary thing through tags.
Closed source dump:
- www.toodledo.com
- Simplenote: en.wikipedia.org/wiki/Simplenote, by WordPress.com operator company Automattic
Contains a large database of instruments, and allows you to edit them. This is a fun toy.
Instruments are edited on a GUI. It is a multi-window program, and you open new windows from new windows from new windows, all filled with hundreds of virtual knobs that you drag with your keyboard, and which would be better done from textual software like Csound. It is a thing of beauty.
It does not seem possible to program arbitrary modular synthesizer circuits therefore. But if you understand additive synthesis and subtractive synthesis well, you can make some funky sounds with it.
It is basically a superset of all popular hardware synthesizers ever made.
Has its own built-in MIDI keyboard which is nice.
On Ubuntu 20.04 Version: 3.0.5:as per askubuntu.com/questions/220802/no-sound-zynaddsubfx-and-jack-wont-run/1297988#1297988
To do anything of interest, switch to the Advanced UI:
sudo apt install zynaddsubfx
zynaddsubfx -O alsaTo do anything of interest, switch to the Advanced UI:
- Misc
- Switch Interface Mode
The UI is completely different form what is shown on the website as of 2020: zynaddsubfx.sourceforge.io/, it looks instead like: www.youtube.com/watch?v=iVPr6iUuO3g Maybe on the website it is the new zyn-fusion UI... www.reddit.com/r/linuxaudio/comments/bxn3ur/some_help_for_installing_zynfusion_zynaddsubfx/ so confusing.
And they have some crappy policy of asking for 45 USD for binary downloads.
Compiling from source:fails with:Ciro gives up for now.
git clone https://github.com/zynaddsubfx/zynaddsubfx
cd zynaddsubfx
git checkout a789866de4d45a784c1f4d95fcf5a1938347baef
sudo apt build-dep zynaddsubfx
mkdir build
cd build
cmake ..
make -j`nproc`Traceback (most recent call last):
File "/usr/bin/cxxtestgen", line 7, in <module>
import cxxtest.cxxtestgen
File "/usr/share/cxxtest/cxxtest/__init__.py", line 33, in <module>
from cxxtest.cxxtestgen import *
File "/usr/share/cxxtest/cxxtest/cxxtestgen.py", line 18, in <module>
import __release__
ModuleNotFoundError: No module named '__release__'It is cool how even for such a "simple looking" problem, we were still unable to prove optimality as of 2020.
How to convince teachers to use CC BY-SA by Ciro Santilli 35 Updated 2025-01-29 +Created 1970-01-01
Ciro Santilli 35 Updated 2025-01-29 +Created 1970-01-01A major difficulty of getting such this to work is that may university teachers want to retain closed copyright of their work because they:
- want to publish a book later and get paid. Yes, the root problem is that teachers get paid way too little and have way too little job security for the incredibly important and difficult extremely difficult job they are doing, and we have to vote to change that
- are afraid that if amazing material is made freely available, then they would not be needed and lose their jobs. Once again, job security issue.
- believe that if anyone were allowed to touch their precious content, those people would just "screw it up" and make it worse
- don't even want to publish their notes online because "someone will copy it and take their credit". What a mentality! In order to prevent a theft, you are basically guaranteeing that your work will be completely forgotten!
- don't want students to read the notes and skip class, because spoken word has magic properties and imparts knowledge that cannot otherwise conveyed by a book
- are afraid that mistakes will be found in their material. Reputation is of course everything in academia, since there is no money.So it's less risky to have closed, more buggy notes, than open, more correct ones.This can be seen clearly for example on Physics Stack Exchange, and most notably in particle physics (well, which is basically the only subject that really gets asked, since anything more experimental is going to be blocked off by patents/interlab competition), where a large proportion incredibly amazing users have anonymous profiles.They prefer to get no reputation gains from their amazing contributions, due to the fear that a single mistake will ruin their career.This is in stark contrast for example to Stack Overflow, where almost all top users are not anonymous:List of top users: physics.stackexchange.com/users?tab=Reputation&filter=all and some notable anonymous ones:
- physics.stackexchange.com/users/2451/qmechanic
- physics.stackexchange.com/users/50583/acuriousmind
- physics.stackexchange.com/users/43351/profrob
- physics.stackexchange.com/users/84967/accidentalfouriertransform
- physics.stackexchange.com/users/56997/curiousone
- physics.stackexchange.com/users/139781/probably-someone
- physics.stackexchange.com/users/206691/chiral-anomaly
Therefore the only way is to find teachers who are:The forced option therefore seems like a more bulk efficient starting point for searches.
- enlightened to use such licenses
- forced by their organizations to use such licenses
No matter how much effort a single person puts into writing perfect tutorials, they will never beat 1000x people + an algorithm.
It is not simply a matter of how much time you have. The fundamental reason is that each person has a different background and different skills. Notably the young students have radically different understanding than that of the experienced teacher.
Therefore, those that refuse to contribute to such platforms, or at least license their content with open licenses, will inevitably have their work forgotten in favor of those that have contributed to the more open platform, which will eventually dominate everything.
Perhaps OurBigBook.com is not he killer platform that will make this happen. Perhaps the world is not yet ready for it. But Ciro believes that this will happen, sooner or later, inevitable, and he wants to give it a shot.
Also worth checking:
- jornal.usp.br/universidade/usp-de-sao-carlos-oferece-aulas-de-graduacao-em-matematica-e-estatistica-abertas-ao-publico/ "Open Classroom" program from the University of São Paulo. We should Google for "Open Classroom" a bit more actually.
- open.ed.ac.uk/about/: talk only
TODO how close does it get to Shannon's limit?
Pinned article: ourbigbook/introduction-to-the-ourbigbook-project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivative - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 4. Visual Studio Code extension tree navigation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.Video 4. OurBigBook Visual Studio Code extension editing and navigation demo. Source. - Internal cross file references done right:
- Infinitely deep tables of contents:
Figure 6. Dynamic article tree with infinitely deep table of contents.Live URL: ourbigbook.com/cirosantilli/chordateDescendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact