Isaac Newton’s first law of motion, the Law of Inertia, may have been slightly misinterpreted for over 300 years, according to a new study. This law, which he wrote in Latin in 1687, has been translated and extensively studied since then, but a mistranslated word may have altered our interpretation.

The English translation of the law occurred in 1729, and it was in this translation that philosopher Daniel Hoek noticed an error that was never corrected – the phrase “a menos” which gives the idea that an object will continue in uniform motion in a straight line or at rest unless an external force intervenes.

However, if we think about it, external forces like gravity and friction are always in action. Since Newton discovered gravity himself, it’s hard to believe he wouldn’t consider it when writing the Law of Inertia. In a recent paper published in the journal Philosophy of Science, Hoek explains what’s wrong.

A simple translation error:
Reviewing the archives, Hoek realized that the phrase “a menos” had been translated from the Latin “quatenus,” which actually means “to the extent.” This error was first noticed in 1999, and for the philosopher, this discovery changes everything.

With this change, the philosopher believes that Newton meant that any alteration in the uniform linear motion or rest of a body occurs due to an external force, rather than implying that they don’t act on it previously.

While it might seem like just a semantic error that doesn’t change physics at all, it can explain what the Law of Inertia really serves and what Newton was thinking when he wrote it.

From Newton’s perspective, every body in the universe is subject to forces, particularly gravity. Therefore, strictly speaking, force-free bodies do not exist. But if that’s the case, then Newton’s celebrated First Law of Motion begins to look like a failure. What is the purpose of a law of nature that governs nothing? Why make it your First Law?