It is quite incredible to think about how much physics has developed in the last 300 years. Although we think of the ancient Greeks as being pretty competent the truth is they weren’t really that good on the science front. It was the work of Issac Newton and his contemporaries that brought us the idea of forces and momentum. Of course now a days these are very basic concepts but were revolutionary when *Philosophiæ Naturalis Principia Mathematica* (*Mathematical Principles of Natural Philosophy*) was published. The very idea of using such rigorous mathematics to describe mechanical systems such as the motion of the planets was unheard of but by the end of the 1700s there was no doubt that force and momentum were inherent aspects of motion. Now Isaac Newton loved to make things difficult for everyone around him (anyone who has tried to use his calculus notation over Leibniz’s will know that) and so his seminal work was published in Latin. This meant that someone had to translate it. In France, this task fell to an Émilie du Châtelet (whose birthday is coincidentally today in 1706) , a woman who, thanks to her family being a member of the lower nobility, had managed to achieve a great standard of education to supplement her brilliance. Historically she is more remembered for being the partner of Voltaire, but her translation was truly her most brilliant work (from my possibly biased perspective). Not only did it perform the necessary task of opening the literature to the French scientific community, her commentary that accompanied the translated *Principa* was exemplary. In it Émilie derives the concept of the conservation of energy, an idea that had not been considered before. It was only a few years prior that she herself had proved that kinetic energy was proportional to objects velocity squared. Before her work, energy was thought to be synonymous with momentum and as such no new conservation for it had been considered. Unfortunately (or perhaps luckily) she had only just finished her translation before she died 1749.

Just an interesting tale to tell considering it is her birthday. Whenever you feel the need to say that “energy cannot be created of destroyed” perhaps you’ll remember this. Until tomorrow, goodnight.