Doubledodge 🇺🇦🇪🇺🇬🇧🐧 @doubledodge@qoto.org

Cosmic rays strike the Earth's atmosphere from deep space, creating a shower of particles in the atmosphere. The most energetic can have at least ten petaelectronvolts, and astronomers have struggled to find their sources. This is partly because they must have come from somewhere extreme, but also, magnetic fields across the Universe redirect their pathways, obscuring their source. Now, astronomers have identified an enormous gamma-ray bubble generating these particles.

https://english.cas.cn/newsroom/research_news/phys/202402/t20240222_657352.shtml

Being found guilty of sexual assault would be an automatic disqualifier for most jobs in the US.

Except the presidency.

Absolutely brutal evisceration of Thomas Heatherwick’s new book on #architecture:

https://www.theguardian.com/artanddesign/2023/oct/27/thomas-heatherwick-humanise-vessel-hudson-yards

Time to update my satellite pollution talk for this weekend.

There are 500 more Starlink satellites today than when I gave this talk in July.

4,924 Starlinks in orbit now (56% of the total 8,728 active satellites in orbit).

Just your periodic reminder that one company owned by one pretty awful dude effectively controls outer space now.

This week I've been invited to Cambridge by Jamie Vicary and Birmingham by our very own @MartinEscardo. I'm giving a talk about how to use category theory to help build models in epidemiology. This is work with people who did COVID modeling for the Canadian government.

Software for Compositional Modeling

Mathematical models of disease are important and widely used, but building and working with these models at scale is challenging. Many epidemiologists use “stock and flow diagrams” to describe ordinary differential equation (ODE) models of disease dynamics. This talk introduces the mathematics of stock and flow diagrams and two software tools for working with them. The first, called StockFlow.jl, is based on category theory and written in AlgebraicJulia. The second, called ModelCollab, runs on a web browser and serves as a graphical user interface for StockFlow.jl. Modelers often regard diagrams as an informal step toward a mathematically rigorous formulation of a model in terms of ODEs. However, stock and flow diagrams have a precise mathematical syntax. Formulating this syntax using category theory has many advantages, but I will focus on three: functorial semantics, model composition, and model stratification. This is joint work with Xiaoyan Li, Sophie Libkind, Nathaniel Osgood, Evan Patterson and Eric Redekopp.

In Cambridge I'm speaking in the Logic and Semantics Seminar on Wednesday October 18, 2023 at 14:00 in room LT1 of the Computer Laboratory.

In Birmingham I'm speaking in the Theoretical Computer Science Seminar on Friday October 20 at 11:00 in room LG12 of the Old Gym.

As far as I know the talks are not hybrid and will not be recorded. So, join us in person if you can!

(1/2)

If you like numbers don't just study math - study tuning systems in music! In music there are names for many individual numbers, like the 'schisma', which is 32805/32768.

Lots of people say they don't like math because they don't like numbers. In reaction, many mathematicians say that math is not really about numbers. Indeed, I don't spend most of my days messing with numbers: I spend a lot of time thinking about shapes, abstract structures, ideas from physics, and so on.

But some mathematicians *do* love numbers and spend a lot of time on them. I love them as a kind of hobby. The properties of the number 24, for example, are utterly mind-blowing, connecting higher-dimensional spheres to lattices and string theory.

The study of tuning systems offers humbler fun with numbers. If you go up a fifth you multiply the frequency of your sound by 3/2. Do this twelve times and you *almost* go up 7 octaves. But you're off by a factor of

531441/524288 ≈ 1.01346

This is called the 'Pythagorean comma' - a slight glitch in the Pythagorean tuning system.

There's also a tuning system called 'just intonation', based on simple fractions as shown below. In this setup if you play the sequence C G D A E C you don't get back where you started: you wind up higher by a factor of

81/80 ≈ 1.0125

This is called the 'syntonic comma' - a glitch in just intonation.

In the 6th century, Boethius noticed that these two commas are close but not quite the same - a kind of meta-glitch. He called their ratio the 'schisma'. It's

(531441/524288)/(81/80) = 32805/32768 ≈ 1.00113

It's also the difference between 8 justly tuned perfect fifths plus a justly tuned major third and 5 octaves.

I find this fun!

We would be greatful if you could amplify our voice & let your followers know that the Auschwitz Memorial is present in #fediverse: @auschwitzmuseum

Every day we commemorate the victims & educate about the tragic human history of #Auschwitz.

Auschwitz is a place that shows where hatred, antisemitism and contempt for a fellow man led people decades ago.

It is also a place where we should reflect on our individual and collective responsibility for the world we live in.

BBC journalist Kriszta Satori @fulelo is posting summaries and links to BBC and other major media news stories about the current crisis in Israel.

#Israel #Palestine #Hamas #MiddleEast

It’s finally happened. Trump’s business empire is on the verge of total ruin as his decades-long practice of fraudulently inflating his property values led a NY judge to CANCEL the business certificates of the Trump Organization entities.

Kudos to NY Attorney General Letitia James for bringing this all to light and achieving accountability against Trump. He’s a fraud. He’s a rapist. And he’s a clear and present danger to our democracy.

But justice has caught up to him, and it is glorious to see.

This is cool.
https://home.cern/news/news/physics/alpha-experiment-cern-observes-influence-gravity-antimatter

A top advisor to Zelensky states that Elon Musk's decision to assist Russia by disabling Starlink for the Ukrainians led to the deaths of civilians, including children.

Just saw this on Twitter: Our new Machines Reading Maps tool that allows searching Text on Maps is now live at https://davidrumsey.com 100 million words indexed on 57,000 maps. Users can correct any errors. See our Text On Maps Help Guide for detailed descriptions on using this exciting new feature.

Tiny Mastodon Tip 🐘✨:

When you toot (post) about a news, event, movie, show, book, game, etc,

It is a good idea to use at least one hashtag in your toot ​

This gives several benefits:

1. It allows people to follow
the news/event/topic as a whole by following the hashtag #️⃣
Here’s how: https://infosec.exchange/@Em0nM4stodon/109632742444639128

2. It allows people who do not
want to hear about it to mute this news/event/topic using Filters 🔇
Here’s how: https://infosec.exchange/@Em0nM4stodon/109323462169819778

3. It allows people to search
for this specific news/event/topic using the search function 🔎

Also remember:

4. If your hashtag has more than one word, you should capitalize the first letter of each word to help with accessibility (CamelCase) 🐫

5. You can put your hashtag(s) at the bottom to help with readability like I do here 👇

6. Magic! ✨

#TinyMastodonTip #Mastodon

Wow! I never knew that Beethoven's "Für Elise" was actually written for a woman named Therese - and the letters these two names have in common:

E S E

may have inspired the alternating sequence of notes that starts this piece:

E E♭ E

Yes: in German E flat is called "Es" and pronounced like the letter S.

I also didn't know that Beethoven never published "Für Elise" in his life: he gave the score to Therese Malfatti, and it was transcribed and published by someone else after his death, and hers. Beethoven almost published an alternative more complicated version of the tune in 1822... but at the last minute decided not to.

I learned all this stuff from this video, which also includes a performance of the alternative version of "Für Elise". If you like the famous version, which is rather simple, this one may seem ludicrously fancy.

https://www.youtube.com/watch?v=jblFQ1whX5s

Apparently I’m going to hell.
Who else?
Feels like everyone who’s anyone will be there.
I’ll bring cupcakes.

I have so many questions about what just happened with Voyager 2. But let's review:

On August 20, 1977, Voyager 2 was launched from Earth.

In December 1977, it entered the asteroid belt.

In June 1978, its main radio receiver failed. Since then it's been using the backup receiver!

On July 9, 1979, it flew past many of Jupiter's moons and made its closest approach to Jupiter.

On August 26, 1981 it shot past Saturn.

On August 25, 1989 it shot past Uranus.

On November 5, 2018 it crossed the heliopause and entered interstellar space, 120 times farther from the Sun than we are.

On July 18, 2023, it overtook Pioneer 10 and became the second farthest man-made object from the Sun.

3 days later, some idiot sent a command that pointed its high gain antenna 2 degrees away from Earth. HOW EXACTLY DID THIS HAPPEN?

On August 4, 2023, NASA used its most high-powered transmitter to successfully command Voyager 2 to reorient towards Earth, resuming communications. HOW WAS THAT POSSIBLE?

How can you "shout" across 120 AU? It takes light about 16 hours to travel that far.

vim 创始者 Bram Moolenaar 过世。

https://groups.google.com/g/vim_announce/c/tWahca9zkt4

#vim #RIP

Telegram 原文

The company that

- Ran a secret, illegal, manipulative psychological experiment on hundreds of thousands of users
- Has documented proof of working to put competitors out of business
- Literally shopped our data around to other companies, including direct messages
- Conspired to manipulate a presidential election
- Has been proven to support or at least turn a blind eye to genocide

But ooh hey shiny new app let’s sign up

I don’t understand people. I just fucking don’t.