Antoine Lavoisier and the Law of Conservation of Mass

We have been taught in science courses that “matter cannot be created or destroyed”. In many occasions, I have heard this important scientific theory erroneously attributed to either Newton or Einstein. I will dedicate this post to the man behind such important paradigm, in hopes that it may divulge a bit more about his scientific achievements. That man was Antoine Lavoisier.

Antoine-Laurent Lavoisier and His Wife painted by the French painter Jacques-Louis David.
This majestic portrait is exhibited at the Metropolitan Museum, in New York. 

Lavoisier was a French nobleman of the Era of Enlightenment (XVIII century) and is considered today the father of modern chemistry for his scientific discoveries.

Among them is the widely known scientific Law of Conservation of Mass or Conservation of Mass-Energy, which states, “matter is neither created nor destroyed”, which he proposed in 1785. This law simply postulates that the total mass of the reactants or starting materials must be equal to that of the product or end result of any chemical, nuclear or radioactive decay reaction. That mass cannot be destroyed, but only modified or rearranged in space. It also implies that it could change form, but could not exist from anything.

It is not until the work of Julius Robert Mayer, who proposed the Law of Conservation of Energy, that Lavoisier’s main postulation takes hold, as this new law becomes the First Law of Thermodynamics.

Einstein knew, like Newton, that if he saw further into the scientific horizon, it was no doubt because he stood on the shoulders of giants. Those giants like Lavoisier and Mayer, who came before him, and laid the foundation for him to state, in 1907, that “the total amount of mass and energy in the universe is constant”. This allowed for his own Theory of Special Relativity.

So there. It was largely in part of Lavoisier’s discoveries, in a special sense that of Conservation of Mass, which paved the way for other important discoveries on the functioning of our Universe, and from them branched other more important theorems, laws, and theories, which today provide us with a myriad of applications. Knowledge, thus, stems upwards. Sort of in a spiral: the uppermost loops are the widest and deepest. Built on preexisting knowledge.

Antoine Lavoisier was guillotined on May 8th, 1794, at the height of the French Revolution.

I extend my sincere thanks to Enrique Sara for reminding me of Lavoisier's importance. Specially on gas laws.