Blog.CarlRobitaille.org

Indiscriminate laziness

This is how corner reflectors work

Posted on 2020/12/02 by Carl Robitaille

This is how corner reflectors work. A signal sent from *any* direction gets reflected back toward the sender. Simple maths with great applications. We even put some on the Moon!

Gif by @panlepan pic.twitter.com/RqyaVOeaJ5
— Tamás Görbe (@TamasGorbe) November 24, 2020

Days Without an Accident

Posted on 2020/11/23 by Carl Robitaille

My latest cartoon for @newscientist

See more of my science cartoons online here: https://t.co/wiOfPL1e96
Or get a book of them here: https://t.co/ge0OmPYgCM pic.twitter.com/KEPPXWVVL9
— Tom Gauld (@tomgauld) November 23, 2020

If you write down the digits of e you quickly find a 649 digit prime

Posted on 2020/11/23 by Carl Robitaille

Here's an interesting surprise: if you write down the digits of e you quickly find a 649 digit prime! pic.twitter.com/7CxDf59I6x
— Fermat's Library (@fermatslibrary) November 23, 2020

Freiner la seconde vague

Posted on 2020/11/22 by Carl Robitaille

«Infliger à la population des sacrifices lorsque (..) le nombre de cas détectés est faible, politiquement, ce n’est pas payant. Mais c’est ce qu’il faut faire d’un point de vue de santé publique.»
En plein ça.
À écouter au complet, la phrase-choc à la fin.https://t.co/8rUhSsSozT
— Patrick Déry (@Patrickdery) November 23, 2020

“I turn away with fright and horror from the lamentable evil of functions which do not have derivatives.” – Hermite in a letter to Stieltjes

Posted on 2020/11/22 by Carl Robitaille

“I turn away with fright and horror from the lamentable evil of functions which do not have derivatives.” – Hermite in a letter to Stieltjes
— Tamás Görbe (@TamasGorbe) November 22, 2020

The History of Stokes’ Theorem

Posted on 2020/11/21 by Carl Robitaille

The History of Stokes’ Theorem

Just for fun:

The History of Stokes' Theorem

by Victor J. Katzhttps://t.co/hlCGT2sCw3
— Lautaro Vergara🏑 🇺🇦🐘 (@VergaraLautaro) November 18, 2020

700 years of secrets of the Sum of Sums (paradoxical harmonic series)

Posted on 2020/11/21 by Carl Robitaille

Rhombic Penrose tilings can be 3-colored

Posted on 2020/11/21 by Carl Robitaille

Rhombic Penrose tilings can be 3-colored

Colouring Penrose-deBruijn tiles based on their shape and orientation can look very nice (I have an applet that does that: https://t.co/I3iY3hbE2D), but I only recently learned that they can always be 3-coloured, as shown by Sibley & Wagon 20 years ago:https://t.co/Fjw7fyTvHr pic.twitter.com/DIYorKdhzd
— Greg Egan (@gregeganSF) November 21, 2020

Pathological function: Volterra’s function

Posted on 2020/11/21 by Carl Robitaille

Pathological function: Volterra's function. This function V is differentiable but V' is not integrable! It seems like this is a counterexample to the Fundamental Theorem of Calculus, but it isn't. In calc textbooks, the FTC requires the function to be continuous, which V' isn't. pic.twitter.com/oyCTNDi1pA
— Dave Richeson (@divbyzero) November 20, 2020

Red area = Green area = 4r²

Posted on 2020/11/20 by Carl Robitaille

pic.twitter.com/O6v0c9gC3w
— Idan Tal (@MagicPi2) November 20, 2020