Ciro Santilli @cirosantilli 37 

Peptidoglycan Updated 2025-07-16

Forms the bacterial cell wall.

From the Wikipedia image we can see clearly the polymer structure formed: it is a mesh with:

sugar covalent bond chains in one direction. These have two types of monosaccharide, NAM and NAG
peptide chains on the other, and only coming off from NAM

Figure 1.
Peptidoglycan polymer structure
. Source.

Pernosco Updated 2025-07-16

pernos.co/

Proprietary extension to Mozilla rr by rr lead coder Robert O'Callahan et. al, started in 2016 after he quit Mozilla.

TODO what does it add to rr?

Physics education needs more focus on understanding experiments and their history Updated 2025-07-16

This is the only way to truly understand and appreciate the subject.

Understanding the experiments gets intimately entangled with basically learning the history of physics, which is extremely beneficial as also highlighted by Ron Maimon, related: there is value in tutorials written by early pioneers of the field.

"How we know" is a basically more fundamental point than "what we know" in the natural sciences.

In the Surely You're Joking, Mr. Feynman chapter O Americano, Outra Vez! Richard Feynman describes his experience teaching in Brazil in the early 1950s, and how everything was memorized, without any explanation of the experiments or that the theory has some relationship to the real world!

Although things have improved considerably since in Brazil, Ciro still feels that some areas of physics are still taught without enough experiments described upfront. Notably, ironically, quantum field theory, which is where Feynman himself worked.

Feynman gave huge importance to understanding and explaining experiments, as can also be seen on Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979).

'Making' - the best way of learning science and technology by Manish Jain (2018)

Source.

Physics Letters A Updated 2025-07-16

www.sciencedirect.com/journal/physics-letters-a

Physics research institute Updated 2025-07-16

Pineapple jelly with cream Updated 2025-07-16

December 2023: www.tudogostoso.com.br/receita/81176-gelatina-de-abacaxi-com-creme-de-leite.html Terribly explained recipe! Used 5 spoons of sugar rather than 10, and a 300ml cup of double cream. Turned out OK, except that the cream condensed all on top, and assumed the same coarse texture as when you do a fatty beef and let it cool, so not so nice,

Maybe this would be more successful: receitas.globo.com/tipos-de-prato/doces-e-sobremesas/gelatina-de-abacaxi-4e64345bddf17214b4003e71.ghtml They also use condensed milk, and beat the cream with the jelly, so it might mix better? It didn't really.

June 2024: Now going for:

4 cups of water
1 spoon of sugar
just drop 150 ml double cream on top after jelly and mix with spoon since anything else was pointless to get mixture

For some reason it became too liquid this time, the jelly didn't work very well. Not sure why. The pineapple was a bit large.

Pinto bean Updated 2025-07-16

This seems to be the "brown Brazilian bean" that many Brazilians eat every day.

Edit: after buying it, not 100% sure. This one felt smaller than what Ciro had in Brazil, borlotti beans might be closer. Pinto beans are smaller, and creamier, and have softer peel, possibly produced less natural gas.

2021-04: second try.

2021-03: did for first time, started with same procedure as borlotti beans 2021-03. Maybe 1h30 is too much. Outcome was still very good.

Pipa piece Updated 2025-07-16

TODO identify better:

Posing As a Wind Instrument Player In an Ensemble by Li Xuan

. Source. Part of "Chinese Ancient Music - Vol 2, High Mountains And Flowing Water", e.g. as seen at: www.youtube.com/watch?v=If7ARKoMiKI.

Plancherel theorem Updated 2025-07-16

Some sources say that this is just the part that says that the norm of a

L^{2}

function is the same as the norm of its Fourier transform.

Others say that this theorem actually says that the Fourier transform is bijective.

The comment at math.stackexchange.com/questions/446870/bijectiveness-injectiveness-and-surjectiveness-of-fourier-transformation-define/1235725#1235725 may be of interest, it says that the bijection statement is an easy consequence from the norm one, thus the confusion.

TODO does it require it to be in

L^{1}

as well? Wikipedia en.wikipedia.org/w/index.php?title=Plancherel_theorem&oldid=987110841 says yes, but courses.maths.ox.ac.uk/node/view_material/53981 does not mention it.

Planck's law Updated 2025-07-16

Used to explain the black-body radiation experiment.

Published as: On the Theory of the Energy Distribution Law of the Normal Spectrum by Max Planck (1900).

The Quantum Story by Jim Baggott (2011) page 9 mentions that Planck apparently immediately recognized that Planck constant was a new fundamental physical constant, and could have potential applications in the definition of the system of units (TODO where was that published):

Planck wrote that the constants offered: 'the possibility of establishing units of length, mass, time and temperature which are independent of speciﬁc bodies or materials and which necessarily maintain their meaning for all time and for all civilizations, even those which are extraterrestrial and nonhuman, constants which therefore can be called "fundamental physical units of measurement".'

This was a visionary insight, and was finally realized in the 2019 redefinition of the SI base units.

TODO how can it be derived from theoretical principles alone? There is one derivation at; en.wikipedia.org/wiki/Planck%27s_law#Derivation but it does not seem to mention the Schrödinger equation at all.

Quantum Mechanics 2 - Photons by ViaScience (2012)

Source. Contains a good explanation of how discretization + energy increases with frequency explains the black-body radiation experiment curve: you need more and more energy for small wavelengths, each time higher above the average energy available.

PlanetMath Updated 2025-07-16

planetmath.org/

Based on GitHub pull requests: github.com/planetmath

Joe Corneli, of of the contributors, mentions this in a cool-sounding "Peeragogy" context at metameso.org/~joe/:

I earned my doctorate at The Open University in Milton Keynes, with a thesis focused on peer produced support for peer learning in the mathematics domain. The main case study was planetmath.org; the ideas also informed the development of “Peeragogy”.

Planned obsolescence Updated 2025-07-16

European Union, I need you now.

2019 cell phones are glued together with adhesive, which makes them impossible to repair them unless you have a heat gun, spend hours and hours learning and planning, and accept the risk of breaking the screen

Repairability scores: www.ifixit.com/smartphone-repairability

If you take a phone less than 300 dollars to a repair shop in the first world, they will say: I've never repaired this crap, and likely for the price of the repair you should just buy a new one, and so to the trash goes the old one, polluting the planet, and in comes a new one, enriching the manufacturer further.

Oh, there is some 2017 EU action actually: (archive) www.europarl.europa.eu/news/en/press-room/20170629IPR78633/making-consumer-products-more-durable-and-easier-to-repair

Good article: www.androidauthority.com/device-repairability-807585/ (archive).

Plausible deniability of email password handover Updated 2025-07-16

protonmail.uservoice.com/forums/284483-feedback/suggestions/39962275-plausible-deniability

You need a secondary password that when used leads to an empty inbox with a setting set where message are deleted after 2 days.

This way, if the attacker sends a test email, it will still show up, but being empty is also plausible.

Of course, this means that any new emails received will be visible by the attacker, so you have to find a way to inform senders that the account has been compromised.

So you have to find a way to inform senders that the account has been compromised, e.g. a secret pre-agreed canary that must be checked each time as part of the contact protocol.

Plutonium Updated 2025-07-16

Vs uranium: uranium vs plutonium Quora answer by Ciro Santilli.

What a material:

only exists in trace amounts in nature,but it can be produced at kilogram scale in breeder reactors
it is only intentionally produced for one application, and one application only basically: nuclear weapons

Video 1. Source. Plutonium for self-respect scene from the 1987 film Edge of Darkness

Video 2.

Burning and Extinguishing Characteristics of Plutonium Metal Fires by RobPlonski

. Source. Commented by this dude: www.linkedin.com/in/robplonski/

Copley Medal Updated 2025-07-16

The Royal Society's Nobel Prize.

royalsociety.org/grants-schemes-awards/awards/copley-medal/ says it is now open to international citizens, but having a quick look at the 2010 awards still suggests that it is very British centric, or at least anglophone centric, much like the society fellowship itself. That's likely the reason why the Nobel prize won, being much more international from the start.

Good background: www.theguardian.com/science/the-h-word/2016/oct/07/prize-science-medal-history-nobel

Pokemon Updated 2025-07-16

One of the main children cartoons Ciro Santilli liked to watch. Part of the Pokemon Mania of the 90s of course.

Ciro could not understand why Nintendo won't make a proper 3D MMORPG Pokemon with actually 3D Pokemon roaming the land, which is obviously what everyone wants. There are even fan games getting there!

pokemon-mmo-3d.com Interesting concept here, where when you deploy a Pokemon, you start controlling the Pokemon rather than the main character
www.quora.com/Why-won-t-Nintendo-make-an-open-world-3D-Pokémon-RPG/answer/Ciro-Santilli

until this explaiend it beautifully Video 1. "The Downfall Of Mainline Pokemon Games by GONZ media (2020)":

Pokemon became an industrialized yearly game spitting machine, and therefore any new feature is just extra risk
Pokemon was kept mostly as a handheld exclusive to sell handlhelds, with a few early exceptions such as Pokemon Snap

Figure 1.
Instead of risking anything new, let's play it safe by continuing our slow decline into obsolecense cartoon by Tom Fishburne
. Source.

The Downfall Of Mainline Pokemon Games by GONZ media (2020)

Source. Great video, explains things Ciro had never thought about, e.g. how the Nintendo Switch unified handheld and console for Nintento, this could open the doors for a more ambitious Pokemon release.

Cool data embedded in the Bitcoin blockchain / Interesting AtomSea & EMBII uploads Updated 2025-07-16