On the second day of March in the year 2021, my friend Quentin and I paid you a visit in prep school Stanislas in Paris to express our gratitude on behalf of many students for imparting upon us the satisfaction mark. For almost two decades, I have made use of this punctuation, and it has made me feel as though I belong to a guild of enlightened scholars, much like yourself, who continue to teach us even today. It is difficult for me to accurately convey to others the significance of this mark, but I will attempt to explain why it holds such special meaning for me.
To escape the gravitational pull of our planet, it requires a certain amount of kinetic energy such that Earth can no longer hold us in its grasp. By showing us how to resist gravity’s influence, you have enabled us to understand the concept of Earth’s escape velocity. What a magnificent expression that is! I must confess that I am tempted to repeat it: the Earth’s escape velocity! This velocity is not dependent on my mass, it is only through the use of our intelligence and hard work that we are able to find it. Humanity was able to calculate this velocity long before any rocket was able to reach it. It is almost at this velocity that one can cut the engines and continue on their journey through space, having successfully overcome the gravitational pull of our planet.
At the moment of the coup de grâce, as you were about to proceed for the numerical calculation, you turned to us and asked if we had arrived at the result of this calculation that was about to be revealed. Although I am not good at mental calculations, I spoke up a bit too quickly and declared: “11 kilometers per second!” You looked at me in amazement, like the excellent actor that you are, and asked: “How did you do it?” I lowered my head and replied: “Tintin Objectif Lune” (Tintin Moon Destination). The entire class chuckled, including you, and I knew at that precise moment that I would pursue a career in science.
In October of 2020, while defending my Ph.D. in Applied Mathematics (or artificial intelligence, if that term can mean anything), I remembered that all of my scientific instincts were instilled in me by you: verifying orders of magnitude, contemplating what would happen if we removed certain elements from our reasoning, and questioning whether our hypotheses were verifiable. Are all of the forces at play truly necessary, or are some of them superfluous? What can be considered negligible? It was with these thoughts in mind that my classmate at the time and childhood friend Quentin and I returned to school to present you with a trophy that we had the pleasure of creating in the form of your satisfaction mark.
The satisfaction mark is a celebration of the victories of our minds against every calculation that dared to intimidate us. To inscribe the satisfaction mark with chalk on a board in order to conclude a proof is to deliver the final blow to the villains of our childhood heroes. To write down the satisfaction mark on a sheet of paper is to reveal the joy of a nebulous idea that has been transformed into a scientific result, offering hope for a tangible impact. It is the sign of triumphant will and elegance. Above all, it is our way of expressing our respect and gratitude for our esteemed teacher.
Oh, Professor, our beloved Professor, we thank you for your energy, your passion for science, and your dedication to sharing your knowledge with us.
Warith Harchaoui, Paris, 4th of March 2021
PS: I would like to thank the local newspaper of Stanislas L'Échos de Stan (page 30) for publishing this letter to my dear Professor