uxor @uxor@mastodon.xyz

La conférence de Serge Brunier hier soir était super ! Des photos magnifiques, et tellement de passion chez ce monsieur…

Et en plus, il m'a dédicacé mon exemplaire du grand atlas de la Lune 👍

couché 1h, levé 5h, ça pique un peu, mais ce soir c'est le week-end 😃

bon courage à tous

Globular clusters (like M2, shown here) are balls of 10s to 100s of thousands of stars that orbit our Galaxy as well as other galaxies. Generally they are made up of older lower metal stars. We don't have a good idea on how they form or where they come from. #astrophoto

"Eigenvectors from Eigenvalues: a survey of a basic identity in linear algebra"

https://terrytao.wordpress.com/2019/12/03/eigenvectors-from-eigenvalues-a-survey-of-a-basic-identity-in-linear-algebra/

#mathematics

1. La personne qui développe l'appli mastodon @tootapp met au point l’algorithme BlurHash (https://blurha.sh/), pour donner un aperçu basse-résolution d'une image 👍
2. BlurHash est intégré dans le projet Mastodon lui-même 👏
3. Signal reprend l’algorithme pour l’utiliser dans son appli ! 😍 🎉 🤘

Bien joué, sérieux.

At the end of their lives stars greater than 8 times the mass of the Sun explode in a supernova. Pictured is the Crab Nebula, a remnant of a supernova witnessed in 1054. In the centre of the nebula is a rapidly spinning neutron star called a pulsar, the remnant of the star. #astrophoto

When I was very young and new to math I remember being very fascinated with repeating decimals, things like this

\[0.121212121212...\]

for the rest of this post I will use the bar notation and represent the above as this which is the same thing:

\[0.\overline{12}\]

Anyway what I found curious as a kid was that you can represent an infinitely repeating decimal as a fraction where it is just the repeating bit of decimals over the same number of digits of 9. So the fraction form of the above looks like this

\[\frac{12}{99}\]

This blew my mind as a kid, it seemed almost magical how denominators of multiples of 10 were for "regular" decimals and denominators of 9 were for repeating decimals. What is this voodoo!

Of course it didnt take me long to put two and two together and realize that the fraction \(\frac{9}{9}\) results in 1 and not \(0.\overline{9}\) as the above naive rules might expect.

Of course I went to the math teacher to try to get some help understanding this and having a math teacher try to explain to a kid in first or second grade that \(0.\overline{9}\) is actually the same as \(1\) wasn't easy for him I'm sure.

I remember his logical point was "well you cant have an infinitely small number, so if the 9's go on forever they are just approaching 1". As an adult looking back I realize he was thinking of it in calculus terms, which is all well and valid, but it didnt translate too well to a little kid. I remember coming back tot he teacher the next day, smug as hell, ready to prove him wrong and I came up with this equation:

\[0.\overline{9} = 1 - 0.\overline{0}1\]

He said "you cant do that" I replied "I just did!"

As an adult knowing limits and all that I understand what the teacher was saying, and of course he was right in a way. But then even older as I got deeper in math I learned of the concept of an infinitesimal, which is basically the very idea I was conveying as a kid just in a less refined way, without good wording. So now I look back and dont know if my teacher was outsmarted by child-me, or what.

Considérant la crise induite il faut de toute urgence s'intéresser à certaines issues de bon sens.

M103 is an open cluster in the constellation of Cassiopeia. As an open cluster, M103 is a collection of young stars that have left the nebula that they were formed in and are now starting to disperse into the galaxy. #astrophoto

TD de maths/analyse allégorie

Reprocess of data. First image is an HDR merge in photoshop of the two other images of M51. The other two images are the same data at different screen stretches. #astrophoto

Aujourd'hui, c'est le #BlackFriday, l'occasion de vous rappeler de bien penser à boycotter cette merde : https://grisebouille.net/black-fuckday/

#BlackFuckday #Arnaque

Je déclare officiellement ouvert le BLAGUES FRIDAY #BlaguesFriday

Faites des blagues

Apparently UNESCO officially decided that March 14 (also known as π Day) would be the International Day of Mathematics. Long live maths! Here is the website of this special day: https://www.idm314.org/.

#maths #mathematics