Enter through the narrow gate Updated 2025-07-16
Gospel of Matthew 7:13:
Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it.
Ciro Santilli really likes this one, because he feels that where many people go, it is useless to go again. It is much better to explore that which few can do, but which many will need.
LMMS Updated 2025-07-16
Very easy to use and pretty powerful MIDI creator!!!
One of the rare audio applications actually works with PulseAudio on Ubuntu 20.04 out-of-the-box, so you don't have to turn off every other audio application!!!
Has lot's of plugins built-in just working out of the box, e.g. ZynAddSubFX out-of-the-box without doing a gazillion complex setup connections.
Most plugins are just simple toys however, ZynAddSubFX is the only super powerful one. The others are more LMMS integrate however, and seem to use a more dedicated LMMS GUI style.
Logarithmic integral function Updated 2025-07-16
Sample software implementations:
Hertz electromagnetic wave experiments Updated 2025-07-16
Heinrich Hertz's main initial experiment used a spark-gap transmitter. It is not something that transmits recorded sounds like voice: it only transmits noisy beeps. And as such was used for wireless telegraphy.
- a piezo igniter from a barbequeue lighter
- a more powerful home-made transformer
Hertz and Radio waves Explained by PhysicsHigh (2016)
Source. Simple schematics showing the basics of the experiments. No choice of components rationale. MacOS Updated 2025-07-16
Nice looking and expensive operating system by Apple. Ciro Santilli believes that:
- if you want to be ripped off, just use Microsoft Windows which has more software available
- or if you want to attain Enlightenment, just use Linux, which is free and open source
Quotient group Updated 2025-07-16
Ultimate explanation: math.stackexchange.com/questions/776039/intuition-behind-normal-subgroups/3732426#3732426
Does not have to be isomorphic to a subgroup:
This is one of the reasons why the analogy between simple groups of finite groups and prime numbers is limited.
randyscotsmithey/feathers-realworld-example-app Updated 2025-07-16
FeathersJS entry for gothinkster/realworld.
MongoDB-based.
So once you install MongoDB, run with:
MONGODB_FEATHERS_REALWORLD=mongodb://localhost:27017/mydb npm startGot it working on Ubuntu 20.10 with both React and Vue.js front-ends at github.com/randyscotsmithey/feathers-realworld-example-app/commit/8bc3a09242285de624c75bb8345630df499a7d07 as mentioned at github.com/randyscotsmithey/feathers-realworld-example-app/issues/2 except for bad error reporting on UI.
Tests can be run with:but there were 10 failures and 55 passes: github.com/randyscotsmithey/feathers-realworld-example-app/issues/3
MONGODB_FEATHERS_REALWORLD=mongodb://localhost:27017/mydb npm run test Raspberry Pi OS Updated 2025-07-16
Change password without access:
Enable SSH on boot:
sudo touch /boot/ssh
Magnetic dipole Updated 2025-07-16
A tiny idealized magnet! It is a very good model if you have a small strong magnet interacting with objects that are far away, notably other magnetic dipoles or a constant magnetic field.
The cool thing about this model is that we have simple explicit formulas for the magnetic field it produces, and for how this little magnet is affected by a magnetic field or by another magnetic dipole.
This is the perfect model for electron spin, but it can also be representative of macroscopic systems in the right circumstances.
Different macroscopic magnets can be approximated by a magnetic dipole when shrunk seen from far away
. Source. Making the Cisco connection Updated 2025-07-16
Nothing phenomenally new on the early days to add on top of Video "Nerds 2.0.1 excerpt about Cisco (1998)", but a few new good points:
- Cisco at one point became the largest company by market capitalization. This wore off a bit as of 2020.They used this overvalued stock in part to buy many other (often also overvalued) up and coming companies. This acquisition spree strategy was apparently not the norm at the time. rohitnair.wordpress.com/2011/12/13/cisco-history-cisco-systems-history-and-trivia-brand-history-and-trivia/ mentions they have bought more than 140 companies since, and that they call this strategy "Build, Buy And Partner"
- a big part of what Cisco did was to allow cheap local communication in-campus. At that time, the ARPANET was already up and running, but their "routers", called Interface Message Processors were very expensive at about $100,000, and to send data across the campus you had to go through them, which meant expensive bandwidth. The routers sometimes failed, and the fallback was to send students around with disks: "sneakernet". They needed new local protocols and hardware to efficiently connect different campus networks.
- Sandy Lerner nude photo
- Cisco was a pioneer in having an Internet support forum. Customers could also help one another. This was fundamental in scaling support, as they grew so fast it would be impossible to hire a support team large enough without the help of the forum.
- Cisco gave out source code to some customers who would then implement protocols they cared about, and Cisco would then merge it back
Manhattan Project Updated 2025-07-16
Historic, unique Manhattan Project footage from Los Alamos by Los Alamos National Lab
. Source. Mostly the daily life part of things, but very good, includes subtitles explaining the people and places shown.
Marked with identifier "LA-UR 11-4449".
Raspberry Pi Pico Updated 2025-07-27
Some key specs:
- SoC:
- name: RP2040. Custom designed by Raspberry Pi Foundation, likely the first they make themselves rather than using a Broadcom chip. But the design still is closed source, likely wouldn't be easy to open source due to the usage of closed proprietary IP like the ARM
- dual core ARM Cortex-M0+
- frequency: 2 kHz to 133 MHz, 125 MHz by default
- memory: 264KB on-chip SRAM
- GPIO voltage: 3.3V
Raspberry Pi Pico W MicroPython example Updated 2025-07-27
An upstream repo at: github.com/raspberrypi/pico-micropython-examples
Some generic Micropython examples most of which work on this board can be found at: Section "MicroPython example".
The examples can be run as described at Program Raspberry Pi Pico W with MicroPython.
- rpi-pico-w/upython/led_on.py: turn on-board LED on and leave it on forever. Useful to quickly check that you are still able to update the firmware.
- rpi-pico-w/upython/led_off.py: turn on-board LED off and leave it off forever
- rpi-pico-w/upython/pwm.py: pulse width modulation. Using the same circuit as the rpi-pico-w/upython/blink_gpio.py, you will now see the external LED go from dark to bright continuously and then back
Raspberry Pi Pico W UART Updated 2025-07-16
You can connect form an Ubuntu 22.04 host as:When in but be aware of: Raspberry Pi Pico W freezes a few seconds after after screen disconnects from UART.
screen /dev/ttyACM0 115200screen, you can Ctrl + C to kill main.py, and then execution stops and you are left in a Python shell. From there:- Ctrl + D: reboots
- Ctrl + A K: kills the GNU screen window. Execution continues normally
Other options:
- ampy
runcommand, which solves How to run a MicroPython script from a file on the Raspberry Pi Pico W from the command line?
Ciro Santilli's fetishes Updated 2025-07-16
University education level Updated 2025-07-16
University of Sussex Updated 2025-07-16
Facebook Updated 2025-07-16
Quantum electrodynamics Updated 2025-07-16
Theory that describes electrons and photons really well, and as Feynman puts it "accounts very precisely for all physical phenomena we have ever observed, except for gravity and nuclear physics" ("including the laughter of the crowd" ;-)).
While Ciro acknowledges that QED is intrinsically challenging due to the wide range or requirements (quantum mechanics, special relativity and electromagnetism), Ciro feels that there is a glaring gap in this moneyless market for a learning material that follows the Middle Way as mentioned at: the missing link between basic and advanced. Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979) is one of the best attempts so far, but it falls a bit too close to the superficial side of things, if only Feynman hadn't assumed that the audience doesn't know any mathematics...
The funny thing is that when Ciro Santilli's mother retired, learning it (or as she put it: "how photons and electrons interact") was also one of her retirement plans. She is a pharmacist by training, and doesn't know much mathematics, and her English was somewhat limited. Oh, she also wanted to learn how photosynthesis works (possibly not fully understood by science as that time, 2020). Ambitious old lady!!!
Combines special relativity with more classical quantum mechanics, but further generalizing the Dirac equation, which also does that: Dirac equation vs quantum electrodynamics. The name "relativistic" likely doesn't need to appear on the title of QED because Maxwell's equations require special relativity, so just having "electro-" in the title is enough.
Before QED, the most advanced theory was that of the Dirac equation, which was already relativistic but TODO what was missing there exactly?
As summarized at: youtube.com/watch?v=_AZdvtf6hPU?t=305 Quantum Field Theory lecture at the African Summer Theory Institute 1 of 4 by Anthony Zee (2004):
- classical mechanics describes large and slow objects
- special relativity describes large and fast objects (they are getting close to the speed of light, so we have to consider relativity)
- classical quantum mechanics describes small and slow objects.
- QED describes objects that are both small and fast
That video also mentions the interesting idea that:Therefore, for small timescales, energy can vary a lot. But mass is equivalent to energy. Therefore, for small time scale, particles can appear and disappear wildly.
- in special relativity, we have the mass-energy equivalence
- in quantum mechanics, thinking along the time-energy uncertainty principle,
QED is the first quantum field theory fully developed. That framework was later extended to also include the weak interaction and strong interaction. As a result, it is perhaps easier to just Google for "Quantum Field Theory" if you want to learn QED, since QFT is more general and has more resources available generally.
Like in more general quantum field theory, there is on field for each particle type. In quantum field theory, there are only two fields to worry about:
- photon field
- electromagnetism field
Lecture 01 | Overview of Quantum Field Theory by Markus Luty (2013)
Source. This takes quite a direct approach, one cool thing he says is how we have to be careful with adding special relativity to the Schrödinger equation to avoid faster-than-light information. Statistical physics Updated 2025-07-16
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