Mortal matrix problem by Ciro Santilli 35 Updated +Created
One of the most simple to state undecidable problems.
The reason that it is undecidable is that you can repeat each matrix any number of times, so there isn't a finite number of possibilities to check.
Quantum computing news by Ciro Santilli 35 Updated +Created
Google Docs by Ciro Santilli 35 Updated +Created
The National Byway by Ciro Santilli 35 Updated +Created
It runs along quiet roads, rather than a mixture of roads and tracks like the National Cycle Network, making it more appropriate for road bikes.
TODO interactive online app? Ahh, those charities that try to make money by individual transactions... when they die, nothing will be left of all their work.
Edit: noticed that it is on by default on OpenStreetMaps web UI under the "Cycle Map" layer marked at "NB".
Sandbox AQ by Ciro Santilli 35 Updated +Created
www.zdnet.com/article/googles-quantum-focused-sandbox-division-is-being-spun-off/ Google's quantum-focused Sandbox division is being spun off (2022)
Wave function collapse by Ciro Santilli 35 Updated +Created
Similar to quantum jump in the Bohr model, but for the Schrödinger equation.
The idea the the wave function of a small observed system collapses "obviously" cannot be the full physical truth, only a very useful approximation of reality.
Because then are are hard pressed to determine the boundary between what collapses and what doesn't, and there isn't such a boundary, as everything is interacting, including the observer.
The many-worlds interpretation is an elegant explanation for this. Though it does feel a bit sad and superfluous.
First-order logic by Ciro Santilli 35 Updated +Created
Google Passwords by Ciro Santilli 35 Updated +Created
When they disabled this from Chromium, it was one of the things that prompted Ciro Santilli to switch to Proton Pass.
IP address by Ciro Santilli 35 Updated +Created
Video 1.
The Internet Protocol by Ben Eater (2014)
Source.
Spacetime by Ciro Santilli 35 Updated +Created
Keyhole Markup Language by Ciro Santilli 35 Updated +Created
Originally by Keyhole Inc., which the nbecame Google Maps, but the format seems standardized and has non-Google support, so should be OK.
Special relativity by Ciro Santilli 35 Updated +Created
This was first best observed by the Michelson-Morley experiment, which uses the movement of the Earth at different times of the year to try and detect differences in the speed of light.
This leads leads to the following conclusions:
  • to length contraction and time dilation
  • the speed of light is the maximum speed anything can reach
All of this goes of course completely against our daily Physics intuition.
The "special" in the name refers to the fact that it is a superset of general relativity, which also explains gravity in a single framework.
Since time and space get all messed up together, you have to be very careful to understand what it means to say "I observed this to happen over there at that time", otherwise you will go crazy. A good way to think about is this:
  • use Einstein synchronization to setup a bunch of clocks for every position in your frame of reference
  • on every point of space, you put a little detector which records events and the time of the event
  • each detector can only detect events locally, i.e. events that happen very close to the detector
  • then, after the event, the detectors can send a signal to you, who is sitting at the origin, telling you what they detected
Wireshark by Ciro Santilli 35 Updated +Created
Amazing tool that captures packets and disassembles them. Allows you to click an interactive tree that represents Ethernet, TCP/IP and application layer like HTTP.
Start capture immediately from CLI, capture packets to/from 192.168.1.102:
sudo wireshark -f 'host 192.168.1.102' -k
Electronvolt by Ciro Santilli 35 Updated +Created
After the 2019 redefinition of the SI base units it is by definition exactly Joules.
Timberland Larchmont Chukka by Ciro Santilli 35 Updated +Created
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
Made four blisters on back of foot on first two days after walking a few hours on them, but then put on some tape on foot, and stopped hurting after that, so the shoe broke quickly.
Tarski's circle-squaring problem by Ciro Santilli 35 Updated +Created
Does not require straight line cuts.
Micro Bit by Ciro Santilli 35 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
Pinned article: ourbigbook/introduction-to-the-ourbigbook-project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Video 1.
Intro to OurBigBook
. Source.
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
    Video 2.
    OurBigBook Web topics demo
    . Source.
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    • to OurBigBook.com to get awesome multi-user features like topics and likes
    • as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact