High flying bird vs gophers Updated 2025-07-16
Ciro once read that there are two types of mathematicians/scientists (he thinks it was comparing Einstein to some Jack of all trades polymath who didn't do any new discoveries):
- high flying birds, who know a bit of everything, feel the beauty of each field, but never dig deep in any of them
- gophers, who dig all the way down, on a single subject, until they either get the Nobel Prize, or work on the wrong problem and waste their lives
TODO long after Ciro forgot where he had read this from originally, someone later pointed him to: www.ams.org/notices/200902/rtx090200212p.pdf Birds and Frogs by Freeman Dyson (2009), which is analogous but about Birds and Frogs. So did Ciro's memory play a trick on him, or is there also a variant; of this metaphor with a gopher?
Ciro is without a doubt the bird type. Perhaps the ultimate scientist is the one who can combine both aspects in the right amount?
Ciro gets bored of things very quickly.
Once he understands the general principles, if the thing is not the next big thing, Ciro considers himself satisfied without all the nitty gritty detail, and moves on to the next attempt.
In the field of mathematics for example, Ciro is generally content with understanding cool theorem statements. More generally, one of Ciro's desires is for example to understand the significance of each physics Nobel Prize.
This is also very clear for example after Ciro achieved Linux Kernel Module Cheat: he now had the perfect setup to learn all the Linux kernel shady details but at the same time after all those years he finally felt that "he could do it, so that was enough", and soon moved to other projects.
If Ciro had become a scientist, he would write the best review papers ever, just like in the current reality he writes amazing programming tutorials on Stack Overflow.
Ciro has in his mind an overly large list of subjects that "he feels he should know the basics of", and whenever he finds something in one of those topics that he does not know enough about, he uncontrollably learns it, even if it is not the most urgent thing to be done. Or at least he puts a mention on his "list of sources" about the subject. Maybe everyone is like that. But Ciro feels that he feels this urge particularly strongly. Correspondingly, if a subject is not in that list, Ciro ignores it without thinking twice.
Ciro believes that high flying birds are the type of people better suited for venture capital investment management: you know a bit of what is hot on several fields to enough depth to decide where to place your bets and how to guide them. But you don't have the patience to actually go deeply into any one of them and deal with each individual shit that comes up.
Cosmos: A Personal Voyage (1980) episode 1 mentions as quoted by the Wikipedia page for Eratosthenes:That's Ciro.
According to an entry in the Suda (a 10th-century encyclopedia), his critics scorned him, calling him beta (the second letter of the Greek alphabet) because he always came in second in all his endeavors.
Ciro Santilli's hardware House 2018-01 Aluminium extractor filter Updated 2025-07-16
This is the exact model: shop.elica.com/en/accessori/filtro-grassi-in-alluminio-cod-gf03fc.html | web.archive.org/web/20190707053526/https://shop.elica.com/en/accessori/filtro-grassi-in-alluminio-cod-gf03fc.html
Searching by th epart name "GF03FC" leads to other sellers besides Elica however, which could reduce shipping costs: www.cookerhoodsupplies.co.uk/filters-and-lamps/188-metal-grease-filter-gf03fc.html
Brand on filter itself: "ARMA Filtre a.s." based on markings: www.armafiltre.com.tr/uygulamalar/7/3/en/Home-Appliances.html Cannot find any model on website however... looks like Elica's B2B supplier only.
July 2019 message:
Aluminium extractor filter for 208298104403Hi there,I'm trying to buy a spare aluminium extractor filter for an Elica extractor, but I can't find the right size on the website.My 12NC is : 208298104403My filter looks a lot like this: shop.elica.com/en/accessori/filtro-grassi-in-alluminio-cod-GRI0077330A.html but the dimensions are different: I measured 45.9cm x 17.6cm on my old one.Do you have that for sale?
Ciro Santilli's hardware House 2018-01 Fire alarms Updated 2025-07-16
Kitchen: 2021-04: nine-volt battery battery at 8.79V. Not sounding.
Maxwell's equations Updated 2025-07-16
Explains the propagation of light as a wave, and matches the previously known relationship between the speed of light and electromagnetic constants.
The equations are a limit case of the more complete quantum electrodynamics, and unlike that more general theory account for the quantization of photon.
The system consists of 6 unknown functions that map 4 variables: time t and the x, y and z positions in space, to a real number:and two known input functions:
- , , : directions of the electric field
- , , : directions of the magnetic field
Due to the conservation of charge however, those input functions have the following restriction:
Equation 1.
Charge conservation
. Also consider the following cases:
The goal of finding and is that those fields allow us to determine the force that gets applied to a charge via the Equation "Lorentz force", and then to find the force we just need to integrate over the entire body.
Finally, now that we have defined all terms involved in the Maxwell equations, let's see the equations:
Equation 2.
Gauss' law
. Equation 3.
Gauss's law for magnetism
. Equation 4.
Faraday's law
. Equation 5.
Ampere's circuital law
. You should also review the intuitive interpretation of divergence and curl.
Maxwell's equations in 2D Updated 2025-07-16
Reference mark Updated 2025-07-16
Ciro Santilli had to see this in a few separate places, until he underestood: that little pictur emust be a thing! Examples:
- mojim watermarks: mojim.com/twy105509x7x2.htm
- some Japanese website: kotobank.jp/word/%E5%A4%A7%E7%96%91-556655
Ciro Santilli's hardware Miele C2 Complete PowerLine vacuum cleaner Updated 2025-07-16
Similar to: www.miele.co.uk/e/cylinder-vacuum-cleaner-compact-c2-powerline-sdrf4-10931670-p but slightly different from image. Indistinguishable from: www.currys.co.uk/gbuk/home-appliances/floorcare/vacuum-cleaners/miele-complete-c2-pure-power-powerline-cylinder-vacuum-cleaner-graphite-grey-10208570-pdt.html
Power symbol meanings: images-eu.ssl-images-amazon.com/images/I/A14OZ5TuwGS.pdf
2020-12: buying Miele SF AP 50 AirClean Plus filter www.miele.co.uk/e/airclean-plus-filter-sf-ap-50-10107860-p. Once it arrived, changed the filter, which fit comes with plastic casing and accordion shaped filter. Also changed bag. But the bag full meter still goes to red on carpet even with everything new while vacuuming. Is it supposed to be checked while not vacuuming?
Ciro Santilli's hardware Orange Pi PC Updated 2025-07-16
- www.orangepi.org/orangepibbsen/forum.php?mod=viewthread&tid=470
- www.youtube.com/watch?v=ZtUn-dnJFdU says only one specific supply worked..
- www.reddit.com/r/raspberry_pi/comments/3jamn1/any_orange_pi_owners_here_help_with_power_imput/ Comment www.reddit.com/r/raspberry_pi/comments/3jamn1/any_orange_pi_owners_here_help_with_power_imput/cy79a7w says it only worked with the official supply...
Ciro Santilli's hardware Panasonic NN-SF464M microwave (2017) Updated 2025-07-16
Ciro Santilli's hardware Park Tool PW-5 (2022) Updated 2025-07-16
Bought: 2022.
To remove pedals when they get stiff.
Ciro Santilli's hardware Park Tool SR-12.2 chain whip Updated 2025-07-16
Ciro Santilli's hardware Phillips D400 cordless phone Updated 2025-07-16
Reflections of the Moon on Erquan Updated 2025-07-16
Relationship between the quotient group and direct products Updated 2025-07-16
Although quotients look a bit real number division, there are some important differences with the "group analog of multiplication" of direct product of groups.
If a group is isomorphic to the direct product of groups, we can take a quotient of the product to retrieve one of the groups, which is somewhat analogous to division: math.stackexchange.com/questions/723707/how-is-the-quotient-group-related-to-the-direct-product-group
The "converse" is not always true however: a group does not need to be isomorphic to the product of one of its normal subgroups and the associated quotient group. The wiki page provides an example:
Given G and a normal subgroup N, then G is a group extension of G/N by N. One could ask whether this extension is trivial or split; in other words, one could ask whether G is a direct product or semidirect product of N and G/N. This is a special case of the extension problem. An example where the extension is not split is as follows: Let , and which is isomorphic to Z2. Then G/N is also isomorphic to Z2. But Z2 has only the trivial automorphism, so the only semi-direct product of N and G/N is the direct product. Since Z4 is different from Z2 × Z2, we conclude that G is not a semi-direct product of N and G/N.
This is also semi mentioned at: math.stackexchange.com/questions/1596500/when-is-a-group-isomorphic-to-the-product-of-normal-subgroup-and-quotient-group
I think this might be equivalent to why the group extension problem is hard. If this relation were true, then taking the direct product would be the only way to make larger groups from normal subgroups/quotients. But it's not.
Ciro Santilli's hardware Timberland Larchmont Chukka Updated 2025-07-16
Bought 2021-11, light brown, size EUR 44.5, 190$, waterproof: www.timberland.co.uk/shop/en/tbl-uk/larchmont-chukka-for-men-in-brown-a12es210
Ciro Santilli's hardware Virgin Media 256 Mps nominal Updated 2025-07-16
Maxwell's equations require special relativity Updated 2025-07-16
The following aspects of Maxwell's equations make no sense without special relativity:
- the Lorentz force would be different observers have different speeds, see e.g.: charged particle moving at the same speed of electrons thought experiment
- Maxwell's equations imply that the speed of light is the same for all inertial reference frames
When charged particle though experiment are seen from the point of view of special relativity, it becomes clear that magnetism is just a direct side effect of charges being viewed in special relativity. One is philosophically reminded of how spin is the consequence of quantum mechanics + special relativity.
Meal deal Updated 2025-07-16
x.com/Birdyword/status/1777591446612193667Singaporean taxi drivers are the cutest.
A while ago a Singaporean taxi driver asked me what a UK hawker centre lunch might cost. I explained that there aren't any. He asked what office workers ate, and I explained the concept of Meal deals. And he looked at me with such a powerful combination of pity and revulsion.
Measure theory Updated 2025-07-16
Main motivation: Lebesgue integral.
The Bright Side Of Mathematics 2019 playlist: www.youtube.com/watch?v=xZ69KEg7ccU&list=PLBh2i93oe2qvMVqAzsX1Kuv6-4fjazZ8j
There are unlisted articles, also show them or only show them.