Photon energy is proportional to its frequency:
or with common weird variables:
This only makes sense if the photon exists, there is no classical analogue, because the energy of classical waves depends only on their amplitude, not frequency.
A detailed list of all transactions is kept at: ../sponsor/budget.js.
Ciro Santilli use the following accounting for this sponsorship calculations.
For significant one time donations, he takes the final money received in one of his cash GBP accounts, then he checks how much that is in dollars on Google at the time of cash out, and then writes that amount down as the final dollar value which is what ultimately counts. This exposes Ciro to USD/GBP fluctuations, but it simplifies accounting for donors which is more important, so it is likely worth it.
For small regular donations, Ciro just tallies it all up in GBP from time to time and converts it all to dollars in one go as it is not worth spending too much time updating those too often.
Advanced Placement by Ciro Santilli 40 Updated 2025-07-16
This is a good initiative. It doesn't go nearly as deep as it needs to go to fix students must have a flexible choice of what to learn, but it is a start!
archive.ph/Dd3aC web.archive.org/web/20230709141533/https://desuarchive.org/g/thread/94445084/#94448535 desuarchive.org/g/thread/94445084/#94448535
Title reply because they can't Ctrl+F: How Ciro Santilli manages to write so much
Most of the thread went into pro/anti gay trashtalk due to Ciro using Gay Putin at the time on his Stack Overflow profile as a useless way to protest the Russian invasion of Ukraine.
Some comments:
How does this guy manage to be so active on Stack Overflow? I feel like this disgusting avatar is on at least a quarter of all the active posts.
The answers are always pretty good though.
I came across this schizo's github once, but I had forgotten his name
Obviously severe autism. Also racism homophobia Looks like everything is ok if it's Russia/Chinese...
Reply: it is publicly known that Putin is homophobic as fuck and hates that picture. Therefore we use it. If Putin were heterophobic, we'd post him as hetero.
The only new information:
Reminds me of Xah Lee.
For example, if you write LaTeX files for you PDFs, give both PDFs and the LaTeX.
This allows other people to:
  • modify and reuse your material
  • make improvement suggestions that you can accept by clicking a button
    The perfect way to do this is to use GitHub pull requests
When you do get face to face time with students, don't teach a large group.
Everything you want to teach is already online.
The only goal of meeting students is talking to them individually or in small groups to:
  • understand what they feel
  • transmit your passion for the subject
and letting them do the same amongst themselves.
If you talk to a large group, you will only reach / understand a very small percentage of the group, so your time is wasted.
It is better to deeply understand what 25% of the students feel and adapt the course material, than to talk to everyone at once, and have only 5% understand anything.
2026-04: finally lost the second Cateye Viz450, the attachment is just too crap
2026-03-23: old Cateye Viz450 not charing anymore, it seems that the usb charging port disconnected from the PCB, if I bend it a bit it charges, but it is hard. Tried to prope it open with flat screwdriver but failed, shame, not very repairable, I'd be able to solder if if I could open it. So that's the failure mode. Rebuying.
2025-11-06: bought another Cateye Viz450 for baby trailer.
2022-02: lost my Karrimor REFLEKT, must have fallen off from trouses somewhere.
2022-02: bought Burg Wachter Sold Secure Bike Chain, Lock and Ground Anchor Kit 1m, 10mm chain width: www.amazon.co.uk/Burg-Wachter-Sold-Secure-Gold-Chain/dp/B09MMGL9B7
2022-02 bought Kryptonite Kryptoflex double loop cable 1.2m length 10mm diameter braided steel cable: www.kryptonitelock.com/en/products/product-information/current-key/210818.html
2022-02: bought a Trelock BC 115/110/4 chain white for my saddle after Liv Flourish 2 (2018) the saddle of was stolen at home. Same as this but white: www.trelock.com/en/lock/locks/chain-locks/bc-115-110-4-green. The keys are a bit larger than I'd like.
2021-11: buying a Cateye ViZ450 www.cateye.com/intl/products/safety_lights/TL-LD820/ 51 dollars after CatEye RAPID X2 was stolen. Unfortunately, it is not very compatible with my Topeak saddle bag... the attachment is to wide to fit the saddble bag, and even if it did it is slanted to account for seat tube slant so it would not be very verfical. Arghh, they have futher options on the website: www.cateye.com/intl/products/parts/5342460/ that is the one I need, Clip C-2 or Clip C-1N. On Amazon it didn't have clear choices for that... mine came with the BracketSP-15. Ah, can buy on Amazon for 3 dollars, OK then.
2021-11: COZYROOMY multitool broke apart already, like before, but much sooner this time. What a piece of junk!!! Buying the Topeak Mini 18+ Bike Multitool www.topeak.com/global/en/products/75-Mini-Tools/173-mini-18+ Has a spoke wrench.
  • Hex wrenches - 2 / 2-L / 2.5 / 3 / 4 (2 pcs) / 5 / 6 / 8 / 10mm
  • Torx wrench - T25
  • Spoke wrench - 14G / 15G
2021-09: COZYROOMY multitool stolen, even though it was completely in pieces already. 2021-09-21 12:30PM discovered, seat bag open, one tool on floor, and some leftovers inside, but black bag gone. Bicycle last seen 2021-09-20 6PM. Would likely have spotted it if it had happened before. Bicycle last used: 2021-09-19 6PM. Would almost for sure have seen it if it had happened by then. Rebought it.
2021-07 Topeak MTS Trunkbag EX Strap Type www.topeak.com/global/en/products/192-Rear-Rack-Bags/859-MTX-TRUNKBAG-EX Fit nicely on the back of the Kross bicycle (2017). 8L. Originally to carry some extra food and water on a long summer trip. 36 pounds.
2020-11-30: Bought more "Finish Line DRY Teflon Bicycle Chain Lube" 8oz/240ml www.amazon.com/dp/B00Z779GMO/ after previous disaster with the bottle because lock is a bit hard to open.
2020-11-30 WD-40 Bike, All Conditions Lube Bicycle Lubricant, 250ml. Markings: "Contains PTFE". www.amazon.com/dp/B00O8QF3PY Sprays out of bottle, so very thin.
2020-02: CatEye AMPP500 45 pounds www.cateye.com/intl/products/headlights/HL-EL085RC/ High mode 500 lumens: 1.5hrs, Daytime HyperConstant mode 500/250 lumens: 5hrs. 2020-11: noticed it was cracked on top front between button and light, I think I dropped it the other day from waist height.
2020-02: Karrimor REFLEKT Band 2 pounds from Sports Direct to replace old that I destroyed by playing with it with hands on work desk www.karrimor.com/karrimor-reflect-band-765007
2020-01: Halfords Microfibre Heavy Duty Cloths www.halfords.com/motoring/car-cleaning/sponges-brushes-buckets/halfords-microfibre-heavy-duty-cloths (archive) 87% polyester, 13% polyamide.
2019-12: www.amazon.co.uk/gp/product/B07GQSXN8B SENZEAL Bicycle Spoke Wrench Tool Spoke Key Spanner 6 in 1 for Bike Wheel Cycle Wrench 10-15 Gauge. TODO 2024: can't find those for the life in me.
2019-11: Multitool: www.amazon.co.uk/dp/B07MW3K2GK "COZYROOMY Bike Repair Kits - Bicycle tool kit with 10 in 1 Multi-Function Bike Tool, multi-purpose bone wrench And related spare tools, 1 Portable tool bag, 6 Month Warranty". No spoke wrench unfortunately. But does have 15mm bone wrench, which opens Kross front wheel. Some months later, the thing came apart, quality was a bit shit. But I kept it in the saddle bag anyways for a long time, and just used it by putting part of it manually together.
  • Universal Hex Wrench (Allen keys) - 2, 2.5, 3, 4, 5, 6, 8mm
  • Flat Head Screwdriver/Philips Screwdriver&Bicycle chain separator (Additional chain hook, spare thimble and 5mm wrench)
2019-11: "CatEye RAPID X2" real lights, 40 dollars. Hopefully to increase side visibility at night, and day visibility on fast roads when cycling further on weekends. www.cateye.com/intl/products/safety_lights/TL-LD710-R/ (archive) USB rechargeable. 80 lumens in high mode lasting 1 hour, 5 hours in low mode, 30 hours flashing, 16 hours rapid/pulse. Lost 2021-11 in a big city, didn't know the path well, had to cross a bunch of streets, was on back of back bag, likely stolen.
2019-10 WD-40 Smart Straw 450ml www.amazon.com/dp/B01MEHN4VC (archive)
2019-10 Finish Line Dry Teflon Tube www.amazon.com/dp/B00B704LZW (archive) Tube broke while opening the first day. I glued it with some superglue, but two months later found it leaked into my "oils bag", so I threw it away... it must have penetrated through the super glue.
2019-08: "CatEye CA475RAPMIN Rapid Mini Rear Lights and Reflectors, Black" stolen: www.amazon.co.uk/dp/B01I4193PY (archive). Very good quality. Those USB rechargeable lights you just have got to take off with you whenever parked in town or else drug addicts will steal them because they are easy to remove for recharging. Tempted to just stick to dynamo ones that are screwed in. Re-bought original back light: AXA Basta, was a bit different from previous one, cannot take in lamps anymore, even though there is the plastic casing for them! Just not metal / wires.
Ciro Santilli views humans as biological robots, and therefore RTA videos can be thought of as probabilistic TAS with human achievable reflex constraints.
This aspect is especially highlighted in "speed run record evolution videos", which can be quite fun, e.g. www.youtube.com/watch?v=pmS9e7kzgS4 Ocarina of Time - World Record History and Progression (Any% Speedrun, 1990s-2017) by retro (2017)
From a similar point of view, Ciro also sometimes watches/learns a bit about competitive PvP games from a "could a computer play this better than a human" point of view.
Ciro also likes to watch commented manual speedruns of games as a way of experiencing the game at a high level without spending too much time on it, often from Games Done Quick. Their format is good because it generally showcases one player focusing more on the gameplay, and three couch commentators to give context, that's a good setup.
It is a
This is a major feature: we have now started to inject the following buttons next to every single pre-rendered header:
  • "Like"
  • "By Other On The Same Topic"
  • "Discussions", i.e. the issue tracker for the header
  • "Create my own version" or "View my version of the page" or "Edit" button depending on wether the user can edit or already has a version of the article or not
This crucial feature makes it clear to every new user that every single header has its own separate metadata, which is a crucial idea of the website.
Figure 1.
Screenshot showing metadata next to each header
. The page is: ourbigbook.com/donald-trump/chemistry. Note how even the subheaders "Chemical element" and "Hydrogen" show the metadata.
Although most of the key requirements were already in place since the last update, as usual doing things with the complex reference content stresses the system further and leads to the exposition of several new bugs.
The upload of OurBigBook Markup files to ourbigbook.com was done with the newly added OurBigBook CLI ourbigbook --web option. Although fully exposed to end users, the setup is not super efficient: a trully decent implementation should only upload changed files, and would basically mean reimplementing/using Git, since version diffing is what Git shines at. But I've decided not to put much emphasis on CLI upload for now, since it is expected that initially the majority of users will use the Web UI only. The functionality was added primarily to upload the reference content.
This is a major milestone, as the new content can start attracting new users, and makes the purpose of the website much clearer. Just having this more realistic content also immediately highlighted what the next development steps need to be.
Once v1.0 is reached, I will actually make all internal links of cirosantilli.com to point to ourbigbook.com/cirosantilli to try and drive some more traffic.
The new content blows up by far the limit of the free Heroku PostgreSQL database of 10k lines. This meant that I needed to upgrade the Heroku Postgres plugin from the free Hobby Dev to the 9 USD/month Hobby Basic: elements.heroku.com/addons/heroku-postgresql, so now hosting costs will increase from 7 USD/month for the dyno to 7 + 9 = 16 UDS/month. After this upgrade and uploading all of cirosantilli.com to ourbigbook.com, Heroku dashboard reads reads:
  • 30,918 rows out of 10,000,000
  • 61.0 MB (out of 10 GB)
so clearly if we are ever forced to upgrade plans again, it means that a bunch of people are using the website and that things are going very very well! Happy how this storage cost turned out so far.
One key limitation found was that Heroku RAM memory is quite limited at 512MB, and JavaScript is not exactly the most memory economical language out there. Started investigation at: github.com/ourbigbook/ourbigbook/issues/230 Initially working around that by simply splitting the largest files. We were just on the verge of what could be ran however luckily, so a few dozen splits was enough, it managed to handle 70 kB OurBigBook Markup inputs. So hopefully if we manage to optimize a bit more we will be able to set a maximum size of 100 kB and still have a good safety margin.
The name cirodown should not appear anywhere now, except with very few exceptions, e.g.:
I have also squatted OurBigBook on all major social media handles for near future usage, e.g.: twitter.com/ourbigbook and so on.
I was going to do this sooner or later, it was inevitable, but the timing was partly triggered due to noticing that English speakers (and likely many other nationalities) are not able to easily read/hear/pronounce "Ciro".
Anyon by Ciro Santilli 40 Updated 2025-07-16
The name actually comes from "any". Amazing.
Can only exist in 2D surfaces, not 3D, where fermions and bosons are the only options.
All known anyons are quasiparticles.
Aufbau principle by Ciro Santilli 40 Updated 2025-07-16
Boring rule that says that less energetic atomic orbitals are filled first.
Much more interesting is actually determining that order, which the Madelung energy ordering rule is a reasonable approximation to.

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!
We have two killer features:
  1. 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-calculus
    Articles 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
  2. 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.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    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.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant 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