Some examples by Ciro Santilli follow.
Of the tutorial-subjectivity type:
- This edit perfectly summarizes how Ciro feels about Wikipedia (no particular hate towards that user, he was a teacher at the prestigious Pierre and Marie Curie University and actually as a wiki page about him):which removed the only diagram that was actually understandable to non-Mathematicians, which Ciro Santilli had created, and received many upvotes at: math.stackexchange.com/questions/776039/intuition-behind-normal-subgroups/3732426#3732426. The removal does not generate any notifications to you unless you follow the page which would lead to infinite noise, and is extremely difficult to find out how to contact the other person. The removal justification is even somewhat ad hominem: how does he know Ciro Santilli is also not a professional Mathematician? :-) Maybe it is obvious because Ciro explains in a way that is understandable. Also removal makes no effort to contact original author. Of course, this is caused by the fact that there must also have been a bunch of useless edits not done by Ciro, and there is no reputation system to see if you should ignore a person or not immediately, so removal author has no patience anymore. This is what makes it impossible to contribute to Wikipedia: your stuff gets deleted at any time, and you don't know how to appeal it. Ciro is going to regret having written this rant after Daniel replies and shows the diagram is crap. But that would be better than not getting a reply and not learning that the diagram is crap.
rm a cryptic diagram (not understandable by a professional mathematician, without further explanations
- en.wikipedia.org/w/index.php?title=Finite_field&type=revision&diff=1044934168&oldid=1044905041 on finite fields with edit comment "Obviously: X ≡ α". Discussion at en.wikipedia.org/wiki/Talk:Finite_field#Concrete_simple_worked_out_example Some people simply don't know how to explain things to beginners, or don't think Wikipedia is where it should be done. One simply can't waste time fighting off those people, writing good tutorials is hard enough in itself without that fight.
- en.wikipedia.org/w/index.php?title=Discrete_Fourier_transform&diff=1193622235&oldid=1193529573 by user Bob K. removed Ciro Santilli's awesome simple image of the Discrete Fourier transform as seen at en.wikipedia.org/w/index.php?title=Discrete_Fourier_transform&oldid=1176616763:with message:
Hello. I am a retired electrical engineer, living near Washington,DC. Most of my contributions are in the area of DSP, where I have about 40 years of experience in applications on many different processors and architectures.
Thank you so much!!remove non-helpful image
Maybe it is a common thread that these old "experts" keep removing anything that is actually intelligible by beginners? Section "There is value in tutorials written by beginners"Also ranted at: x.com/cirosantilli/status/1808862417566290252
Figure 1. Source at: numpy/fft_plot.py. - when Ciro Santilli created Scott Hassan's page, he originally included mentions of his saucy divorce: en.wikipedia.org/w/index.php?title=Scott_Hassan&oldid=1091706391 These were reverted by Scott's puppets three times, and Ciro and two other editors fought back. Finally, Ciro understood that Hassan's puppets were likely right about the removal because you can't talk about private matters of someone who is low profile:even if it is published in well known and reliable publications like the bloody New York Times. In this case, it is clear that most people wanted to see this information summarized on Wikipedia since others fought back Hassan's puppet. This is therefore a failure of Wikipedia to show what the people actually want to read about.This case is similar to the PsiQuantum one. Something is extremely well known in an important niche, and many people want to read about it. But because the average person does not know about this important subject, and you are limited about what you can write about it or not, thus hurting the people who want to know about it.
Notability constraints, which are are way too strict:There are even a Wikis that were created to remove notability constraints: Wiki without notability requirements.
- even information about important companies can be disputed. E.g. once Ciro Santilli tried to create a page for PsiQuantum, a startup with $650m in funding, and there was a deletion proposal because it did not contain verifiable sources not linked directly to information provided by the company itself: en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/PsiQuantum Although this argument is correct, it is also true about 90% of everything that is on Wikipedia about any company. Where else can you get any information about a B2B company? Their clients are not going to say anything. Lawsuits and scandals are kind of the only possible source... In that case, the page was deleted with 2 votes against vs 3 votes for deletion.is very similar to Stack Exchange's own Stack Overflow content deletion issues. Ain't Nobody Got Time For That. "Ain't Nobody Got Time for That" actually has a Wiki page: en.wikipedia.org/wiki/Ain%27t_Nobody_Got_Time_for_That. That's notable. Unlike a $600M+ company of course.
should we delete this extremely likely useful/correct content or not according to this extremely complex system of guidelines"
In December 2023 the page was re-created, and seemed to stick: en.wikipedia.org/wiki/Talk:PsiQuantum#Secondary_sources It's just a random going back and forth. Author Ctjk has an interesting background:I am a legal official at a major government antitrust agency. The only plausible connection is we regulate tech firms
For these reasons reason why Ciro basically only contributes images to Wikipedia: because they are either all in or all out, and you can determine which one of them it is. And this allows images to be more attributable, so people can actually see that it was Ciro that created a given amazing image, thus overcoming Wikipedia's lack of reputation system a little bit as well.
Wikipedia is perfect for things like biographies, geography, or history, which have a much more defined and subjective expository order. But when it comes to "tutorials of how to actually do stuff", which is what mathematics and physics are basically about, Wikipedia has a very hard time to go beyond dry definitions which are only useful for people who already half know the stuff. But to learn from zero, newbies need tutorials with intuition and examples.
Bibliography:
- gwern.net/inclusionism from gwern.net:
Iron Law of Bureaucracy: the downwards deletionism spiral discourages contribution and is how Wikipedia will die.
- Quote "Golden wiki vs Deletionism on Wikipedia"
Allow us to determine with good approximation in a multi-electron atom which electron configuration have more energy. It is a bit like the Aufbau principle, but at a finer resolution.
Note that this is not trivial since there is no explicit solution to the Schrödinger equation for multi-electron atoms like there is for hydrogen.
For example, consider carbon which has electron configuration 1s2 2s2 2p2.
GPU accelerated, simulates the Craig's minimized M. genitalium, JCVI-syn3A at a particle basis of some kind.
Lab head is the cutest-looking lady ever: chemistry.illinois.edu/zan, Zaida (Zan) Luthey-Schulten.
- 2022 paper: www.cell.com/cell/fulltext/S0092-8674(21)01488-4 Fundamental behaviors emerge from simulations of a living minimal cell by Thornburg et al. (2022) published on Cell
- faculty.scs.illinois.edu/schulten/lm/ actual source code. No Version control and non-code drop release, openess and best practices haven't reached such far obscure reaches of academia yet. One day.
- blogs.nvidia.com/blog/2022/01/20/living-cell-simulation/ Nvidia announcement. That's how they do business, it is quite interesting how they highlight this kind of research.
This is not bad, but some divergences to the better BBC miniseries, which presumably sticks more closely to the novel:
- in the film Jim Prideaux is captured in a cafe in Prague, in the series it's in the woods. It is therefore much more plausible that he would have been shot.
- in the film Peter Guillam is played by Benedict Cumberbatch, who feels a bit young to be Ricki Tarr's boss. Not impossible, but still.
- the series is much less chronological, and more flashback based, as new information becomes available. The film is more chronological, which makes it easier to understand, but less interesting at the same time.
- in the film they shoot the Russian girl Irina in front of Jim, in the series the fact that she was shot is only known through other sources. The film has more eye candy, which weakens it.
- Toby Esterhase is not threatened in an airfield, only in a safe ;house in London.
Publicly released documents from the Los Alamos National Laboratory are marked with this identifier. This is for example the case of each video on ther YouTube channel: www.youtube.com/@LosAlamosNationalLab. E.g. Video "Historic, unique Manhattan Project footage from Los Alamos by Los Alamos National Lab" is marked with "LA-UR 11-4449".
www.osti.gov/biblio/1372821 contains "How to Get an LA-UR: Using RASSTI to Release Your Work" which is of interest: permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-17-26023. That document documents the acronym's expansion, plus it leaks some internal-only URLs such as lasearch.lanl.gov/oppie/service.
TODO is there somewhere you can search for the document for a given identifier? Some PDFs are listed at: sgp.fas.org/othergov/doe/lanl/index2b.html
Advantages over Riemann:
- Lebesgue integral of is complete but Riemann isn't.
- youtu.be/PGPZ0P1PJfw?t=710 you are able to switch the order of integrals and limits of function sequences on non-uniform convergence. TODO why do we care? This is linked to the Fourier series of course, but concrete example?
youtube.com/watch?v=PGPZ0P1PJfw&t=808 shows how Lebesgue can be visualized as a partition of the function range instead of domain, and then you just have to be able to measure the size of pre-images.
One advantage of that is that the range is always one dimensional.
But the main advantage is that having infinitely many discontinuities does not matter.
Infinitely many discontinuities can make the Riemann partitioning diverge.
But in Lebesgue, you are instead measuring the size of preimage, and to fit infinitely many discontinuities in a finite domain, the size of this preimage is going to be zero.
Which is why we then fall into measure theory!
Suppose that a rod has is length measured on a rest frame (or maybe even better: two identical rulers were manufactured, and one is taken on a spaceship, a bit like the twin paradox).
Question: what is the length than an observer in frame moving relative to as speed observe the rod to be?
The key idea is that there are two events to consider in each frame, which we call 1 and 2:Note that what you visually observe on a photograph is a different measurement to the more precise/easy to calculate two event measurement. On a photograph, it seems you might not even see the contraction in some cases as mentioned at en.wikipedia.org/wiki/Terrell_rotation
- the left end of the rod is an observation event at a given position at a given time: and for or and for
- the right end of the rod is an observation event at a given position at a given time : and for or and for
By plugging those values into the Lorentz transformation, we can eliminate , and conclude that for any , the length contraction relation holds:
The key question that needs intuitive clarification then is: but how can this be symmetric? How can both observers see each other's rulers shrink?
And the key answer is: because to the second observer, the measurements made by the first observer are not simultaneous. Notably, the two measurement events are obviously spacelike-separated events by looking at the light cone, and therefore can be measured even in different orders by different observers.
Decent encyclopedia of mathematics. Not much motivation, mostly statements though.
Created by:
Web of Stories contains amazing interviews with many (mostly American) winners.
See Surely You're Joking, Mr. Feynman chapter Alfred Nobel's Other Mistake's amazing comments about the Nobel Prize.
TODO who is the digital switch person he mentions?
- www.quora.com/unanswered/Who-was-Richard-Feynman-referring-to-in-the-book-Surely-Youre-Joking-Mr-Feynman-chapter-Alfred-Nobels-Other-Mistake-when-he-talks-about-A-friend-of-mine-whos-a-rich-man-he-invented-some-kind-of-simple-digital-switch on Quora
- github.com/cirosantilli/cirosantilli.github.io/issues/72
Name of the clade of archaea plus eukarya proposed at: www.frontiersin.org/articles/10.3389/fmicb.2015.00717/full. Much better term than prokaryote as that is not a clade. Let's hope it catches on!
Lie Groups, Physics, and Geometry by Robert Gilmore (2008) Updated 2025-05-21 +Created 1970-01-01
The author seems to have uploaded the entire book by chapters at: www.physics.drexel.edu/~bob/LieGroups.html
And the author is the cutest: www.physics.drexel.edu/~bob/Personal.html.
Overview:
- Chapter 3: gives a bunch of examples of important matrix Lie groups. These are done by imposing certain types of constraints on the general linear group, to obtain subgroups of the general linear group. Feels like the start of a classification
- Chapter 4: defines Lie algebra. Does some basic examples with them, but not much of deep interest, that is mostl left for Chapter 7
- Chapter 5: calculates the Lie algebra for all examples from chapter 3
- Chapter 6: don't know
- Chapter 7: describes how the exponential map links Lie algebras to Lie groups
One thing that makes such functions particularly simple is that they can be fully specified by specifyin how they act on all possible combinations of input basis vectors: they are therefore specified by only a finite number of elements of .
Every linear map in finite dimension can be represented by a matrix, the points of the domain being represented as vectors.
As such, when we say "linear map", we can think of a generalization of matrix multiplication that makes sense in infinite dimensional spaces like Hilbert spaces, since calling such infinite dimensional maps "matrices" is stretching it a bit, since we would need to specify infinitely many rows and columns.
The prototypical building block of infinite dimensional linear map is the derivative. In that case, the vectors being operated upon are functions, which cannot therefore be specified by a finite number of parameters, e.g.
For example, the left side of the time-independent Schrödinger equation is a linear map. And the time-independent Schrödinger equation can be seen as a eigenvalue problem.
WellSync, if you are gonna useSync this wonky language thing inSync one place, you might as well useSync it everywhereSync and make it more decent. See also: how to convert
async to sync in JavaScript.Their CLI debugger is a bit crap compared to GDB, basic functionality is either lacking or too verbose:Documentation at: nodejs.org/dist/latest-v16.x/docs/api/debugger.html
- stackoverflow.com/questions/65493221/how-to-break-at-a-specific-function-or-line-with-the-node-js-node-inspect-comman
- stackoverflow.com/questions/70486188/how-to-break-on-uncaught-exception-on-the-node-js-node-inspect-command-line-debu Some operations are only possible on the browser debug UI...
As mentioned at buzzard.ups.edu/courses/2017spring/projects/schumann-lie-group-ups-434-2017.pdf, what the symmetry (Lie group) acts on (obviously?!) are the Lagrangian generalized coordinates. And from that, we immediately guess that manifolds are going to be important, because the generalized variables of the Lagrangian can trivially be Non-Euclidean geometry, e.g. the pendulum lives on an infinite cylinder.
The most beautiful idea in physics - Noether's Theorem by Looking Glass Universe (2015)
Source. One sentence stands out: the generated quantities are called the generators of the transforms.The Biggest Ideas in the Universe | 15. Gauge Theory by Sean Carroll (2020)
Source. This attempts a one hour hand wave explanation of it. It is a noble attempt and gives some key ideas, but it falls a bit short of Ciro's desires (as would anything that fit into one hour?)The Symmetries of the universe by ScienceClic English (2021)
Source. youtu.be/hF_uHfSoOGA?t=144 explains intuitively why symmetry implies consevation!Setting: you are sending bits through a communication channel, each bit has a random probability of getting flipped, and so you use some error correction code to achieve some minimal error, at the expense of longer messages.
This theorem sets an upper bound on how efficient you can be in your encoding, for any encoding.
The next big question, which the theorem does not cover is how to construct codes that reach or approach the limit. Important such codes include:
But besides this, there is also the practical consideration of if you can encode/decode fast enough to keep up with the coded bandwidth given your hardware capabilities.
news.mit.edu/2010/gallager-codes-0121 explains how turbo codes were first reached without a very good mathematical proof behind them, but were still revolutionary in experimental performance, e.g. turbo codes were used in 3G/4G.
But this motivated researchers to find other such algorithms that they would be able to prove things about, and so they rediscovered the much earlier low-density parity-check code, which had been published in the 60's but was forgotten, partially because it was computationally expensive.
There are unlisted articles, also show them or only show them.