Author: gandalf

Pourquoi la somme des angles d’un triangle fait-elle 180° ?

Post author By gandalf
Post date March 16, 2022
No Comments on Pourquoi la somme des angles d’un triangle fait-elle 180° ?

Introduction

Un triangle quelconque ABC Je me suis toujours demandé pourquoi la somme des angles d’un triangle était constante et égale à 180°. Comment parvient-on à une telle affirmation ?

L’histoire raconte que Blaise Pascal (mathématicien français du XVII ième siècle) aurait démontré cette proposition d’Euclide à l’âge de 11 ans … cela m’a toujours fasciné.

Comment un enfant de seulement 11 ans a-t-il bien pu parvenir à ce résultat ?!?

Bizarrement, une réponse m’est venue un jour sous la douche, alors que j’y pensais sans vraiment y réfléchir 🙂

Le raisonnement est géométrique et plutôt intuitif. Les figures se sont formées dans mon esprit et la solution m’est apparue d’un coup comme une évidence.

Plongée (French)

Pourquoi prend-on 1 bar tous les 10m ?

Post author By gandalf
Post date December 6, 2021
No Comments on Pourquoi prend-on 1 bar tous les 10m ?

Under Water — Rays of sun under water. The ocean is quiet.

Les plongeurs le savent bien : tous les 10 mètres, la pression à laquelle nous sommes soumis augmente d’1 bar.

Mais en fait pourquoi ?

Dans cet article, nous allons faire un peu de science physique. Rien de trop compliqué rassurez-vous.

En réalité, il s’agit de comprendre ce qu’est la pression, de différencier la masse et le poids, puis de jouer avec quelques conversions d’unités.

Tags plongée, science, scuba diving

System Admin

Joplin At Rest Encryption With Tomb On Linux

Post author By gandalf
Post date November 30, 2021
No Comments on Joplin At Rest Encryption With Tomb On Linux

To Encrypt At Rest Or Not To?

There has been a lot of (passionate) debates on Joplin’s forum about its SQLite 3 database showing everything in clear text.

And by everything, I literally mean “everything”. Including your master encryption password.

Now, my intention here isn’t to fuel another debate. Joplin passed several security audits. Long story short: if you want your computer to remain safe (as much as possible), encrypt your whole hard-drive.

This is indeed a best practice.

Instead of discussing whether or not Joplin should encrypt its database, I’ll share the additional layer of security I laid out on my Linux machines using tomb.

By the way, if you have no idea what I’m talking about (what the hell is Joplin?), I suggest you read my previous post: From Evernote To Joplin.

Tags Joplin

Miscellaneous

From Evernote To Joplin

Joplin’s Application Icon

I recently came across Joplin.

Simply put, Joplin is a free open source replacement for Evernote.

I’m an Evernote subscriber. However, I don’t use it that much. And I don’t have that many notes.

Let me be clear: Evernote offers a brilliant service, there is no denying that, it’s absolutely great and super convenient. But, in my case, for less than a 100 notes, I’m not fully convinced it’s worth the price.

Furthermore, Joplin has a few “punchy” arguments to put in a fair fight:

It’s free and open source (I know, I already said that, but it’s important).
It’s cross-platform (nodejs to the core). There are apps for Windows, MacOS, Linux, Android, and iOS. There is even an app to use it on the command line (Vim style)!
It works locally (no need for an internet connection), but enables synchronization with remote sharing services. Thus Yes! It can sync your notes across devices (using the WebDAV protocol).
It supports end-to-end encryption with zero knowledge: notes are encrypted locally before being transferred.
It integrates fully with Nextcloud!

Honestly, if the first few arguments weren’t enough, although I was definitely intrigued, the last 2 won me on the spot.

So let’s have a look at the beast.