Internal combustion engine Updated 2025-07-16
Internal and spacetime symmetries Updated 2025-07-16
The different only shows up for field, not with particles. For fields, there are two types of changes that we can make that can keep the Lagrangian unchanged as mentioned at Physics from Symmetry by Jakob Schwichtenberg (2015) chapter "4.5.2 Noether's Theorem for Field Theories - Spacetime":
- spacetime symmetry: act with the Poincaré group on the Four-vector spacetime inputs of the field itself, i.e. transforming into
- internal symmetry: act on the output of the field, i.e.:
From the spacetime theory alone, we can derive the Lagrangian for the free theories for each spin:Then the internal symmetries are what add the interaction part of the Lagrangian, which then completes the Standard Model Lagrangian.
Interactive Linear Algebra by Margalit and Rabinoff Updated 2025-07-16
Ciro Santilli's hardware Cycling clothes Updated 2026-02-08
2026-02-07: might have lost a the left North Face etip recycled gloves black with white signs, rebuying without too much thinking, redundancy is fine now that I'm old and don't have time: www.amazon.co.uk/dp/B08BDPDNH7
2025-12-28: after losing the Karrimor X Lite Run Black Headband for good going to try a few ones online:
- www.amazon.co.uk/Flintronic-Headbands-Headband-Stretchy-Running/dp/B0D3V4JQHS Chinese generic, 2 for 6 pounds. Band Material Type Cationic fleece.
- www.amazon.co.uk/Columbia-Weather-Headband-Heather-X-Large/dp/B08MQS7NYB Columbia Men's Fast Trek Ii Cold Weather Headband. Size: L/XL, Colour: City Grey Heather
2024-11: OK, I give up, going to try and find the Extremities XDRY again, as these are the perfect gloves for the UK. Buying www.amazon.co.uk/dp/B00OISFUQ4. Their marketing is very confusing and there are several different names for the product, but the label reads "extremities insulated waterpoof sticky power liner glove", black, large. This is the official page: www.terra-nova.co.uk/products/insulated-waterproof-sticky-power-liner-gloves X-Dry Stretch, 100% polyester.
2024-10: going to try Endura Men's Strike Glove - Hi-Viz Yellow, Large www.endurasport.com/strike-glove-hi-viz-yellow/12929542.html | www.wiggle.com/endura-strike-gloves-930526#colcode=93052613. These gloves are high quality, but they are too hot and fleecy for the UK, unless it is an exceptionally cold winter day around 0. This means that they get quite wet from sweat, and they are not that breathable. Also they are very hard to take off and put on, which is painful if you are like me who uses your cell phone for navigation, and while it works with touchscreens, sometimes it's just too annoying and you have to take them off.
2024-05: going to try www.sealskinz.com/products/water-repellent-all-weather-glove Sealskinz Tasburgh Water Repellent All Weather love black large because Extremities XDRY has a hole on right thumb due to gear shifting. This glove is very similar to the Nike academy hyperwam, not really a winter glove feels like. Weird branding...
2023-11: Endura Windchill Bibtights XL - Black: www.endurasport.com/windchill-bibtights-black/12926004.html because knees of dhb one open. I'm an idiot for getting XL... it's just that L felt too short on the top. But ultimately XL was too baggy, this became quite apparent on first usage, L would likely have been better, just would have needed to pull it a bit more. Quality is very good, very water repellent, kept me warm on 2C under very light rain. Also tried www.endurasport.com/xtract-bibtight-black/12926142.html but the sizing was completely different. L on that one as obviously too large, M felt correct.
2023-07: lost my waterproof cap, not cycling specialized, but was useful. Was by itself in crappy backpocket of cheap muddy fox jersey, lots of wind, some fence jumping... Hadn't noted know the brand/model... sad. Let's try Castelli A/C 2 Cycling Cap? www.castelli-cycling.com/US/en/Men/Collection/Hot-Weather-Kit/A-C-2-CYCLING-CAP/p/4523032_008 Single size. Slightly small, but hard to be sure.
2023-07: www.dhbsport.com/products/aeron-short-sleeve-jersey-2-0 dhb Aeron Short Sleeve Jersey 2.0 Colour Ink Blue Size (Standard) L. To prevent crap from falling again hopefully. Felt too small. Material: 100% polyester, inserts, 64% polyester, 6% elastane. Compared to the non 2.0 which I have, the material feels more glossy/slippery. Slightly weird.
2023-05: www.wiggle.com/p/dhb-classic-shorts?color=black&sizeStandard=M dhb Classic Shorts, medium.
2022-05: buying another "dhb Lightweight Mesh Long Sleeve Base Layer", small www.wiggle.com/p/dhb-lightweight-mesh-long-sleeve-base-layer. I notice that it is actually a bit not long enough. Doesn't make a huge difference, but maybe medium or large next time.
2022-12 Rohan Polar Gloves, black, large, 45 pounds. Shell: 85% polyamide, 15% elastane. Insulation: 100% polyester. 100g insulation on back of the hand. www.rohan.co.uk/mens/accessories-polar-gloves Let's see how they perform after hands were very cold on a bike ride with the Extremities XDRY.
2022-08 dhb Aeron Short Finger Gel Gloves 2.0 medium white www.wiggle.co.uk/dhb-aeron-short-finger-gel-gloves-20. For sun/fall protection. In theory should be small according to size guide, but small was over, and I have my doubts it is correct.
2021-12: bought a North Face etip recycled gloves black with white signs, large about 40 dollars: www.thenorthface.co.uk/shop/en-gb/tnf-gb/mens-etip-gloves-4sha?variationId=KY4 let's see how that goes. These ended up being very good. They are not very warm, good for 10-15 C maybe, which is a important range. Water performance is very good
2021-12:
- dhb Windproof Cycling Gloves Small Black 33 dollars to replace the Nike academy hyperwam gloves which I lost a pair of recently. It already had a hole in the thumb anyways from shifting the small gears all the time. S was way too small despite me making hand measurement, returned.
- dhb C1.0 Crossover Helmet Matte Black 58-61cm 40 dollars after recent crash to ensure helmet integrity
2021-06: Castelli UPF 50+ Light Arm Sleeves (Skins) Large White, 29 pounds www.castelli-cycling.com/bg/upf-50-+-light-arm-sleeves/p/451603621P-001. Felt really good. Really does not trap much heat, and completely blocks off sun. It makes you develop a small layer of sweat that keeps you cool, cooler than without the sleeves.
2021-02 Castelli PRO THERMAL SKULLY red www.wiggle.co.uk/castelli-pro-thermal-skully www.castelli-cycling.com/gb/pro-thermal-skully/p/452054220A to help with cold, the X Lite Run Black Headband is just not made for winter.
2021-01: Madison Cycle Everywear Sportive Toe covers. L/XL. www.madison.cc/shop/sportive-thermal-toe-covers/VARCLA121/CLA12104
2021-01: "Endura FS260-NEMO Glove II" Neoprene Winter Handwarmer Large. www.endurasport.com/Gants-Nemo-FS260-Pro-II/p/E1216-Black Let's see how neoprene feels like. Basically it becomes wet with your transpiration, but is still relatively warm, would take it well down to 5C. Likely would work well with heavy rain. Not bad. But does feel a bit cooler than the Extremities XDRY, especially after you walk for a bit, and your hand becomes cold, and it is very hard to warm it because it is also wet.
2020-12-21: "dhb Neoprene Nylon Overshoes" www.wiggle.co.uk/dhb-neoprene-nylon-overshoes large black. After 2 rides, noticed that the front lower part of left foot (the one I put on and off the most) had a hole in it, not sure where it was made. Edit: I later noticed that it is because I have the reflex of braking slightly with my shoes in certain conditions, e.g. at lower speeds in close proximity to pedestrians, the sounds of which also serve as a way to alert them without the need for a loud bell. But it destroys the overshoe, so I have to undo that reflex.
2020-11-06 www.alpinetrek.co.uk/castelli-perfetto-ros-long-sleeve-cycling-jersey/ "Castelli Perfetto RoS Long Sleeve - Cycling jersey" size L Large. On Wiggle: www.wiggle.co.uk/castelli-perfetto-ros-long-sleeve-jersey Feels great. Together with the dhb Merino Long Sleeve Base Layer, I can gown down to 0 Celcius, no problem, and up to 14 with the "Mesh Long Sleeve Base Layer". Breathes great, blocks wind and rain reasonably, and can holds mild rain out on a short 1.5h ride without problem. I used this so much it is unbelievable.
2020-10-17:
- last ride top was a bit cold on shoulders where not covered by arm warmers, about 10C, so going to try: www.wiggle.co.uk/dhb-aeron-rain-defence-polartec-jacket-1 "dhb Aeron All Winter Softshell Jacket", 109.25 pounds, Fluro Yellow, small to match previous tops that worked, approx: 50 polyester, 40 polyamide, 10 elastane, recommended temperature: 2-12 degrees Celcius. Material felt OK, not amazing but OK. Returned because a bit too small.
- the "dhb Classic Thermal Bib Tights" is a bit too warm for lower tens, so going to try "dhb Aeron FLT Roubaix Bib Tight", 85.50 pounds, medium, navy color, recommended temperatures: 6-14 deg C, 84% polyamide, 16% elastane. Hopefully not being marked as "thermal" means it is less warm. Also hopefully being DHB Aeron it will be a bit less baggy behind knees. Returned later because felt indistinguishable from the "dhb Classic Thermal Bib Tights".
For sizing see also: Ciro Santilli's body.
2020-11: Castelli Thermoflex 2 Arm Warmers, Large, 28 pounds: www.wiggle.co.uk/castelli-thermoflex-2-arm-warmers | www.castelli-cycling.com/gb/men/accessories/cycling-leg-and-arm-warmers/p/451953020A-010 advertized 8°-20°C. Was going to buy the DHB ones for 10 pounds less, but always out of so Castelli it is.
2020-08: started getting getting cold, so let's do it:
- www.wiggle.co.uk/dhb-lightweight-mesh-long-sleeve-base-layer "dhb Lightweight Mesh Long Sleeve Base Layer", small, 93% polyester 7% Elastane. Felt a little bit tight on first try, but I think I'll keep it, it might be correct, it's hard to say, and it's not worth my time. If it is too bad I'll just get another one later.
- www.wiggle.co.uk/dhb-classic-thermal-bib-tights "dhb Classic Thermal Bib Tights", medium, 86% polyamide, 14% elastane, 56 pounds. Very slightly tight, but felt right on first try. Some similar URLs www.wiggle.co.uk/dhb-classic-thermal-bib-tights-1 | www.wiggle.co.uk/dhb-thermal-bib-tight
- www.wiggle.co.uk/dhb-extreme-weather-neoprene-overshoe "dhb Extreme Weather Neoprene Overshoe", large, 81% polyamide, 18% polyurethane. Wanted to buy www.wiggle.co.uk/dhb-neoprene-nylon-overshoes which is lighter, but was out of stock. The material felt good, but it did not fit with 2020-04 Giro Rumble VR Off Road Shoe, I should have checked better, maybe it is only for road shoes.Incompatible with 2020-04 Giro Rumble VR Off Road Shoe, so returned it. That shoe is too large.
2020-05 www.wiggle.co.uk/dhb-aeron-short-sleeve-jersey-4/ dhb Aeron Short Sleeve Jersey 100% polyester, Red Large. This one fit OK. Length feels right. When on cycling position, a bit baggy under arms though, but guessing M would be too short? Still already feels less baggy than the cheap muddy fox jersey. Aeron is the second lowest level of DHB top, after the super basic 25 pound one. Material is thin polyester, could be better, but OK.
2020-05 www.wiggle.co.uk/castelli-perfetto-light-2-short-sleeve-jersey/ Castelli Perfetto Light 2 Short Sleeve Jersey 84% Nylon, 16% Lycra. When it arrived, was WAY too small, so returned. Material looked and felt amazing.
2019-12 www.wiggle.co.uk/dhb-merino-long-sleeve-base-layer-1/?sku=5360752872 "dhb Merino Long Sleeve Base Layer", black, small, was right size, wool is a bit itchy, but does feel like it dries off more quickly on long rides than the cheap Muddy Fox polyester cycling Jersey. Pretty warm, too much for 15C.
2019-12 www.wiggle.co.uk/dhb-aeron-winter-weight-merino-sock/?sku=100335580 dhb Aeron Winter Weight Merino Sock, blue, UK 9.5-12. Did not seem to make much of a difference, feet still cold, not wet.
2019-11 Nike academy hyperwarm gloves: www.nike.com/gb/t/hyperwarm-academy-football-gloves-s9Dd8D/GS0373-013 (archive) for 17.99 Pounds from physical retailer. Good intermediate between the Extremities gloves when it gets a bit warmer. 60% polyester/27% nylon/5% rubber/4% elastane.
2019-10 XGC Men's Cycling Shorts/Bike Shorts And Cycling Underwear With High-Density High-Elasticity And Highly Breathable 4D Sponge Padded www.amazon.co.uk/dp/B07BDJP64W (archive). Grey color, red inner butt padding. 2020-08: after using it a lot, noticed that the padding stiches started to come off a bit.
2018 (?) Extremities XDRY gloves Looks like: www.sportsdirect.com/extremities-wp-p/line-glove-91-907293 (archive) Gets wet after a few minutes of medium rain. But does dry quickly. Baggy, multilayer. Says 40 pounds, but always at 20 pound discount, so it is just a marketing trick. On website: Outershell 96% Polyester/4% Lycra (Spandex)Palm 45% Polyester/55% PolyurethaneLining 100% Polyester
2017-09 Trespass Cruzado Male Gloves size S. www.trespass.com/cruzado-unisex-gloves (archive) Markings: crossover gloves. Technical Performance TP75: www.trespass.com/advice/trespass-tp-ratings-guide/ Lost right hand around 2018/2019.
2017 Muddy fox cycling Jersey, orange, polyester, Large, cheap. Works well enough I guess. Could be a bit more tight fitting.
2017 www.amazon.co.uk/Nevica-Unisex-Reversible-Skuff/dp/B07GSD4R7Y Nevica Skuff black
2017 www.ebay.co.uk/itm/254646634761 Karrimor X Lite Run Black Headband. Had a hole in the ear for a long time. Miraculously surived being almost lost on several occasions, including once it fell off from bike and a dude coming behind pointed it to me. But then alas on 2025-12-28 I lost it, noticed next day wasn't there, by chance found it on neighboring park, but it had been torn very badly, a dog must have done that, so I had to throw it away!
Perturbation theory Updated 2025-07-16
Used a lot in quantum mechanics, where the equations are really hard to solve. There's even a dedicated wiki page for it: en.wikipedia.org/wiki/Perturbation_theory_(quantum_mechanics). Notably, Feynman diagrams are a way to represent perturbation calculations in quantum field theory.
Pendulum Updated 2025-07-16
Peer tutoring Updated 2025-07-16
Pauli exclusion principle Updated 2025-07-16
Initially a phenomenological guess to explain the periodic table. Later it was apparently proven properly with the spin-statistics theorem, physics.stackexchange.com/questions/360140/theoretical-proof-of-paulis-exclusion-principle.
And it was understood more and more that basically this is what prevents solids from collapsing into a single nucleus, not electrical repulsion: electron degeneracy pressure!
Bibliography:
- www.youtube.com/watch?v=EK_6OzZAh5k How Electron Spin Makes Matter Possible by PBS Space Time (2021)
Integrated development environment Updated 2025-07-16
IDEs are absolutely essential for developing complex software.
The funny thing is that you don't notice this until someone shows it to you. But once you see it, there is not turning back, just like Steve Jobs customers don't know what they want quote.
Unfortunately, after the Fall of Eclipse (archive), the IDE landscape in 2019 is horrible and split between:
Programmers of the world: unite! Focus on one IDE, and make it work for all languages and all build systems. Give it all the features that Eclipse has, but none of the bugginess. Work with top project to make sure the IDE works for all top projects.
Projects of the world: support one IDE, with in-tree configuration. Complex integration is often required between the IDE and the build system, and successful projects must to that once for all developers. Either do this, or watch you complex project wither away.
Build tool maintainers: make it possible for IDEs to support your tool! E.g., implement JSON Compilation Database output so that IDEs can read the exact compiler commands from that, in order to automatically determine how files should be parsed! Or better, just use libllvm in your IDE itself as the main parser.
Ciro is evaluating some IDEs at: github.com/cirosantilli/ide-test-projects
Integrated circuit layout Updated 2025-07-16
Instruction set architecture Updated 2025-07-16
The main interface between the central processing unit and software.
In-order depth-first search Updated 2025-07-16
This is the order in which a binary search tree should be traversed for ordered output, i.e.:
- everything to the left is smaller than parent
- everything to the right is larger than parent
This ordering makes sense for binary trees and not k-ary trees in general because if there are more than two nodes it is not clear what the top node should go in the middle of.
This is unlike pre-order depth-first search and post-order depth-first search which generalize obviously to general trees.
Innovate UK Updated 2025-07-16
Injective function Updated 2025-07-16
Inflation Updated 2025-07-16
Particle physics Updated 2025-07-16
Currently an informal name for the Standard Model
Chronological outline of the key theories:
- Maxwell's equations
- Schrödinger equation
- Date: 1926
- Numerical predictions:
- hydrogen spectral line, excluding finer structure such as 2p up and down split: en.wikipedia.org/wiki/Fine-structure_constant
- Dirac equation
- Date: 1928
- Numerical predictions:
- hydrogen spectral line including 2p split, but excluding even finer structure such as Lamb shift
- Qualitative predictions:
- Antimatter
- Spin as part of the equation
- quantum electrodynamics
- Date: 1947 onwards
- Numerical predictions:
- Qualitative predictions:
- Antimatter
- spin as part of the equation
Particle accelerator facility Updated 2025-07-16
Indian classical music Updated 2025-07-16
Automatic programming Updated 2025-11-30
The ultimate high level of which is of course to program with:which is basically the goal of artificial general intelligence, especially according to The Employment Test definition of AGI.
The term has not always had that sense:sums it up.
automatic programming has always been a euphemism for programming in a higher-level language than was then available to the programmer
Implosion-type fission weapon Updated 2025-07-16
Implosion-type fission weapons are more complicated than gun-type fission weapon because you have to precisely coordinate the detonation of a bunch of explosives.
There are unlisted articles, also show them or only show them.