##### About numbers, episode 5 : Tensors

Updated (12/09/2016). The (foolish) purpose of this post is to tackle the concept of tensor, while trying to keep it accessible to the widest audience possible. For the layman (or specialist from another field of study) who just wants to know what this is about...

##### Tensors for the noob

If you are here, then it's because you don't like formulas and complicated calculations too much, but you're still curious about what is a tensor. So we will do a quick tour of the concept, in the easiest way possible....

##### About numbers, episode 4 : infinite numbers

« Eternity is really long, especially near the end. » Woody Allen (1935 - ) What is infinity ? How to grasp such a concept, by definition so immense that nothing can contain it ? As surprising as it may seem, the answer lies not...

##### About numbers, episode 3 : rational numbers

What is a fraction ? It seems easy to answer this question with the concept of proportion, but we will see that rational numbers possess some quite extraordinary properties....

##### About numbers, episode 2 : integers

A quantity of -2 objects, a marathon runner finishing -3rd, numbers smaller than nothing ?! What do negative numbers mean ? The answer to that question is easy only to those who are used to them. And for most of us, it doesn't matter what...

##### About numbers, episode 1 : Natural numbers

« God made the integers, all the rest is the work of man » Léopold Kronecker (1823-1891). There is no satisfying definition of the general concept of number. However, lots of particular numbers can be rigorously defined. Natural numbers, integers, imaginary, transcendent, algebraic, computable numbers,...

##### Groups in everyday life

La structure de groupe est un concept fondamental, dont l’usage dépasse largement les mathématiques. Il est très utilisé en physique, et nous verrons dans un prochain article un exemple de groupe important dans la théorie de la relativité restreinte. Ici nous nous contenterons d’en donner la...