Exist because double bonds don't rotate freely. Have different properties of course, unlike enantiomer.
Key exmaple: d and L amino acids. Enantiomers have identical physico-chemical properties. But their biological roles can be very different, because an enzyme might only be able to act on one of them.
Nothing personal, just Ciro Santilli strongly disagrees with the moderation philosophies of these users.
One particular type of user Ciro particularly dislikes are those who do more moderation than content. Ciro finds it very hard to understand why some people spend so much time moderating. Maybe that's how politicians exist, some people just like that kind of activity.
The moderators tend to have lower intermediate rep. They spend too much time moderating and too little time coding.
- Users who are publicly against the ability to criticize the character of politicians, shown after "I think Trump is disgusting as a person" was removed from Ciro's profile: cirosantilli.com/china-dictatorship/stack-overflow-forbids-criticizing-the-character-of-genocidal-political-leaders-like-xi-jinping
- Journeyman Geek:
- is also against political speech against the CCP in Stack Overflow
- deletionism: single handedly deletes opposing answers without giving any explanation TODO example;
- closurism: superuser.com/questions/248517/show-keys-pressed-in-linux
- Journeyman Geek:
- Yvette Colomb deleted a few of Ciro's answers, related: Ciro Santilli's Stack Overflow suspension for vote fraud script 2019.
- chrisF: envorces Stack Overflow no duplicate answers policy: stackoverflow.com/questions/9242135/how-to-force-rsync-to-create-destination-folder/72178249#72178249
- meta.stackexchange.com/users/361484/luuklag meta.stackexchange.com/questions/18614/style-guide-for-questions-and-answers/326746?noredirect=1#comment1283471_326746Fair comment, but do you need to flag before comment, and downvote? That answer was clearly a labour of love, on a subject that will never ever make anyone any money (markup style). Too much meta rep, too little programming rep.
Flagged as spam, there obviously is affiliation between the first link and the poster, which is not disclaimed.
- Cody Gray
- Charcoal bot people: charcoal-se.org/
- askubuntu.com/users/10616/thomas-ward Thomas Ward deletionism:
- e.g. convert here's a bug report answer to comment: askubuntu.com/questions/1464992/cant-drag-clip-to-timeline-in-kdenlive-in-ubuntu-23-04/1469359#comment2575312_1464992
- askubuntu.com/questions/524242/how-to-find-out-which-nvidia-gpu-i-have/1469351#1469351 deleted a perfectly valid "Settings -> Details -> About" GUI answer
- Machavity stackoverflow.com/users/2370483/machavity.Deletionism: stackoverflow.com/questions/13714454/specifying-and-saving-a-figure-with-exact-size-in-pixels/64632093#64632093. Edit: reverted.
- askubuntu.com/users/10616/thomas-ward Thomas Ward deletionism:
- Dharman
- security.stackexchange.com/users/6253/schroeder: deletionism security.stackexchange.com/questions/231637/signal-contact-people-or-have-people-contact-me-without-revealing-phone-numbe/245665?noredirect=1#comment591690_245665
TBD:
- webapps.meta.stackexchange.com/users/88163/rubén: possible deletionist webapps.stackexchange.com/questions/149933/why-does-the-archive-org-of-most-youtube-videos-fail-with-sorry-the-wayback-mac, but: might reconsider: webapps.meta.stackexchange.com/questions/4502/why-were-not-customer-support-for-your-favorite-company/4503?noredirect=1#comment5167_4503. Didn't: archive.ph/wip/EyZS7
Not so strong, but bad experience:
- Zac67 networkengineering.stackexchange.com/users/36720/zac67: you cannot mention any specific device, even if it is for illustrationa purposes...That's like, the opposite of reproducibility...
Deleted answers are dumped at: github.com/cirosantilli/cirosantilli.github.io/issues
Basic component in spintronics, used in both giant magnetoresistance
Leads to the Dirac equation.
The Dirac equation, OK, is a partial differential equation, so we can easily understand its definition with basic calculus. We may not be able to solve it efficiently, but at least we understand it.
But what the heck is the mathematical model for a quantum field theory? TODO someone was saying it is equivalent to an infinite set of PDEs somehow. Investigate. Related:
The path integral formulation might actually be the most understandable formulation, as shown at Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979).
Quantum electrodynamics by Lifshitz et al. 2nd edition (1982) chapter 1. "The uncertainty principle in the relativistic case" contains an interesting idea:
The foregoing discussion suggests that the theory will not consider the time dependence of particle interaction processes. It will show that in these processes there are no characteristics precisely definable (even within the usual limitations of quantum mechanics); the description of such a process as occurring in the course of time is therefore just as unreal as the classical paths are in non-relativistic quantum mechanics. The only observable quantities are the properties (momenta,
polarizations) of free particles: the initial particles which come into interaction, and the final particles which result from the process.
Quantum Mechanical View of Reality by Richard Feynman (1983) by 
Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16Sample playlist: www.youtube.com/playlist?list=PLW_HsOU6YZRkdhFFznHNEfua9NK3deBQy
Basically the same content as: Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979), but maybe there is some merit to this talk, as it is a bit more direct in some points. This is consistent with what is mentioned at www.feynman.com/science/qed-lectures-in-new-zealand/ that the Auckland lecture was the first attempt.
Some more information at: iucat.iu.edu/iub/5327621
By Mill Valley, CA based producer "Sound Photosynthesis", some info on their website: sound.photosynthesis.com/Richard_Feynman.html
They are mostly a New Age production company it seems, which highlights Feynman's absolute cult status. E.g. on the last video, he's not wearing shoes, like a proper guru.
Feynman liked to meet all kinds of weird people, and at some point he got interested in the New Age Esalen Institute. Surely You're Joking, Mr. Feynman this kind of experience a bit, there was nude bathing on a pool that oversaw the sea, and a guy offered to give a massage to the he nude girl and the accepted.
youtu.be/rZvgGekvHest=5105 actually talks about spin, notably that the endpoint events also have a spin, and that the transition rules take spin into account by rotating thing, and that the transition rules take spin into account by rotating things.
Can be thought as being produced from gluon-gluon lines of the Feynman diagrams of quantum chromodynamics. This is in contrast to quantum electrodynamics, in which there are no photon-photon vertices, because the photon does not have charge unlike gluons.
Most of the helium in the Earth's atmosphere comes from alpha decay, since helium is lighter than air and naturally escapes out out of the atmosphere.
Wiki mentions that alpha decay is well modelled as a quantum tunnelling event, see also Geiger-Nuttall law.
As a result of that law, alpha particles have relatively little energy variation around 5 MeV or a speed of about 5% of the speed of light for any element, because the energy is inversely exponentially proportional to half-life. This is because:
Quantum tunnelling and the Alpha particle Paradox by Physics Explained (2022)
Source. - youtu.be/_f8zeEI0oys?t=796 George Gamow and Edward Condon proposed the quantum tunnelling explanation
- youtu.be/_f8zeEI0oys?t=1725 worked out example that predicts the half-life of polonium-210 based on its emission energy
Pinned article: 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!
Intro to OurBigBook
. Source. 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/derivativeVideo 2. OurBigBook Web topics demo. Source. - 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 3. Visual Studio Code extension installation.
Figure 4. Visual Studio Code extension tree navigation.
Figure 5. Web editor. 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. 
- Infinitely deep tables of contents:
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