Cirac–Zoller controlled-NOT gate Updated +Created
PostgreSQL GIST Updated +Created
The highly underdocumented built-in module, that supports SQL spatial index and a lot more.
Quite horrendous as it only seems to work on geometric types and not existing columns. But why.
And it uses custom operatores, where standard operators would have been just fine for points...
Minimal runnable example with points:
set -x
time psql -c 'drop table if exists t'
time psql -c 'create table t(p point)'
time psql -c "insert into t select (point ('(' || generate_series || ',' || generate_series || ')')) from generate_series(1, 10000000)"
time psql -c 'create index on t using gist(p)'
time psql -c "select count(*) from t where p <@ box '(1000000,1000000),(9000000,2000000)'"
The index creation unfortunately took 100s, so it will not scale to 1B points very well whic his a shame.
Ciro Santilli's children Updated +Created
Count: 0.
Isaac Asimov Updated +Created
Star Trek: The Next Generation Updated +Created
Ciro Santilli likes this.
He doesn't have the patience to actually watch full episodes with rare exceptions, rather just watching selected scenes from: www.youtube.com/channel/UCdeIGY2DIjpGf0A2m9GSE3g, but still, it is interesting.
What appeals to Ciro in this series is how almost nothing is solved by violence, almost everything is decided in the bridge, at the "cerebral" level of the command structure. This reminds Ciro of a courtroom of law sometimes.
Maybe there's also a bit of 90's nostalgia involved too though, as this is something that would show on some random cable channels a bored young Ciro would have browsed during weekends, never really watching full episodes.
One crime of many episodes is being completely based on some stupid new scientific concept, which any character to back it up.
Another thing that hurt is that due to their obsession with the senior members of the crew, sometimes those senior members are sent in ridiculously risky operations, which is very unrealistic.
Episodes that Ciro watched fully and didn't regret:
Semi worth it:
Not worth it:
  • Cause and effect
TODO
  • s06e11 Chain of command
Quadratic form Updated +Created
Multivariate polynomial where each term has degree 2, e.g.:
is a quadratic form because each term has degree 2:
but e.g.:
is not because the term has degree 3.
More generally for any number of variables it can be written as:
There is a 1-to-1 relationship between quadratic forms and symmetric bilinear forms. In matrix representation, this can be written as:
where contains each of the variabes of the form, e.g. for 2 variables:
Strictly speaking, the associated bilinear form would not need to be a symmetric bilinear form, at least for the real numbers or complex numbers which are commutative. E.g.:
But that same matrix could also be written in symmetric form as:
so why not I guess, its simpler/more restricted.
2019-03 Giant Control Tower 3 floor pump bike pump Updated +Created
20 pounds. Works on both Schrader and Presta.
Moving magnet and conductor problem Updated +Created
This is a well known though experiment, which Richard Feynman used to emphasize
  • infinite wire with balanced positive and negative charges, so no net charge, but a net magnetic field
  • a single charge moves parallel to wire at the same speed as the electrons
In the above experiment:
  • from the wire frame, the charge feels electromagnetic force, because it is moving and there is a magnetic field
  • from the single charge frame, there is still magnetic field (positive charges are moving), but the body itself is not moving, so there is no force!
The solution to this problem is length contraction: the positive charges are length contracted and the moving electrons aren't, and therefore they are denser and therefore there is an effective charge from that frame.
This is also mentioned at David Tong www.damtp.cam.ac.uk/user/tong/em/el4.pdf (archive) "David Tong: Lectures on Electromagnetism - 5. Electromagnetism and Relativity" "5.2.1 Magnetism and Relativity".
Video 1.
How Special Relativity Fixed Electromagnetism by The Science Asylum (2019)
Source.
Micro Bit Updated +Created
Bluetooth support: not enough RAM for it, though in principle its chip/transceiver could support it! microbit-micropython.readthedocs.io/en/v1.0.1/ble.html
Supported editors: microbit.org/code/
MicroPython web editor and compiler: python.microbit.org/v/2
Everything in this section is tested on the Micro Bit v1 from Micro Bit v1 unless otherwise noted.
https://upload.wikimedia.org/wikipedia/en/thumb/a/a3/Micro-bit_v1_%26_v2.JPG/1024px-Micro-bit_v1_%26_v2.JPG
Twin prime conjecture Updated +Created
Let's show them how it's done with primes + awk. Edit. They have a -d option which also shows gaps!!! Too strong:
sudo apt install bsdgames
primes -d 1 100 | awk '/\(2\)/{print $1 - 2, $1 }'
gives us the list of all twin primes up to 100:
0 2
3 5
5 7
11 13
17 19
29 31
41 43
59 61
71 73
Tested on Ubuntu 22.10.
Carl Victor Page, Jr. Updated +Created
Larry Pages's older brother.
It is hard to find information on this little bugger! Not a single photo online!
As suggested by the "Jr.", he is named after Larry's father, Carl Victor Page.
Carl Jr. is mentioned in a few places in the book The Google Story. The full name "Carl Victor Page Jr." is never given in that source, only "Carl Page Jr." is used. These crazy Anglo-Saxons and their semi-optional middle names!
The Google Story does not cite its sources, but it likely got much of its insider information through interviews, e.g. Chapter 2. "When Larry Met Sergey":
Carl Jr. recalls Larry as an inquisitive younger brother with wide-ranging interests
which suggests the authors actually interviewed Carl Jr., since interviews with Carl Jr. cannot be found anywhere else on the Internet. It would be interesting to know more how they got that level of access.
Chapter 2 mentions that Carl Jr. is nine years older than Larry. Therefore, he must have been born in 1963 or 1964. It also states that Carl studied at the University of Michigan, like his father and like Larry would also do later on:
He also enjoyed helping Carl Jr. - who was nine years older - with his college computer homework when Carl came home from the University of Michigan during breaks.Their father was a professor at the Michigan State University, which is a different university from the University of Michigan, and not in the same city, so by breaks they mean term breaks.
Chapter 2 also mentions that he was working in Silicon Valley by the time their father died in 1996:
Despite his grief [for the death of their father at the early age of 58], Larry remained enrolled at Stanford. It helped that his older brother, Carl Jr., lived and worked in Silicon Valley. They had each other, so Larry wasn't left to bear the loss alone, and the two spent time together, fondly recalling their dad and reflecting on their childhood memories.
In 1997, Carl co-founded the mailing list management website eGroups together with Scott Hassan, programmer of an early version of Google when he was a research assistant at Stanford University. Carl and Scott presumably met through Larry, but we don't have a source. The company was sold to Yahoo! in 2000. The Google Story Chapter 8. "A Trickle" mentions:
Google's deal with Yahoo!] had special significance for Larry Page, since his brother, Carl Jr., also was in serious negotiations with Yahoo! over a major business transaction. The following day, June 27, Yahoo announced plans to buy eGroups, a technology firm that Carl Page had co-founded, for $413 million.
Carl is listed as a co-founder in the SEC filing: www.sec.gov/Archives/edgar/data/1105102/0000950149-00-000584.txt as "Carl Page". He does not appear on the 5% stockholders however, poor Carl.
In 2006, he brought a company he founded called "Handheld Entertainment" public through a reverse merger with a shell company: archive.nytimes.com/dealbook.nytimes.com/2006/03/21/brother-of-google-co-founder-uses-shell-company-for-handheld-start-up/. "Handheld Entertainment" made an iPod competitor apparently. SEC filing: www.sec.gov/Archives/edgar/data/1309710/000095013606009480/file1.htm.
September 27, 2023 marked Google's 25 th aniversary and the page cirosantilli.com/carl-victor-page-jr had a small surge of views according to Google Analytics. On that day, this page was one of the top Google search results for "Carl Victor Page, Jr."[ref]. Wikipedia also had a large bump in searches for "Larry Page" on the same day: pageviews.wmcloud.org/?project=en.wikipedia.org&platform=all-access&agent=user&redirects=0&start=2023-09-11&end=2023-10-01&pages=Cat|Dog|Larry_Page which must be the root cause, Larry actually managed to beat "Cat" and "Dog" on that day.
Limestone Updated +Created
Lighter Updated +Created
Lightweight markup language Updated +Created
Life difficulty level meme Updated +Created
TODO there was one which was relly good, can't find it anymore. One day.
Figure 1.
Life difficulty level meme with West Europe, East Europe, Turkey and Middle east
. Source.
Light year Updated +Created
Banheiros da USP Updated +Created
Semi-comical student website to review the toilets of the University of São Paulo. Some of the toilets had a reputation for being terrible.
One is reminded of Crushbridge.
Baryon vs meson vs lepton Updated +Created
"Barys" means "heavy" in Greek, because protons and neutrons was what made most of the mass of known ordinary matter, as opposed notably to electrons.
Baryons can be contrasted with:
  • mesons, which have an even number of elementary particles. The name meson comes from "medium" since their most common examples have two quarks rather than three as the most common baryons such as protons. So they have less mass than a proton, but more than an electron, this medium mass.
  • leptons, which are much lighter particles such as the electron. "Leptos" means "fine, small, thin".

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