When Isaac Newton inscribed onto parchment his now-famed laws of motion in 1687, he could have only hoped we'd be discussing them three centuries later.
Writing in Latin, Newton outlined three universal principles
describing how the motion of objects is governed in our Universe, which have
been translated, transcribed, discussed and debated at length.
But according to a philosopher of language and mathematics,
we might have been interpreting Newton's precise wording of his first law of
motion slightly wrong all along.
Virginia Tech philosopher Daniel Hoek wanted to "set
the record straight" after discovering what he describes as a "clumsy
mistranslation" in the original 1729 English translation of Newton's Latin
Principia.
Based on this translation, countless academics and teachers
have since interpreted Newton's first law of inertia to mean an object will
continue moving in a straight line or remain at rest unless an outside force
intervenes.
It's a description that works well until you appreciate
external forces are constantly at work, something Newton would have surely have
considered in his wording.
Revisiting the archives, Hoek realized this common
paraphrasing featured a misinterpretation that flew under the radar until 1999,
when two scholars picked up on the translation of one Latin word that had been
overlooked: quatenus, which means "insofar", not unless.
To Hoek, this makes all the difference. Rather than
describing how an object maintains its momentum if no forces are impressed on
it, Hoek says the new reading shows Newton meant that every change in a body's
momentum – every jolt, dip, swerve, and spurt – is due to external forces.
"By putting that one forgotten word [insofar] back in
place, [those scholars] restored one of the fundamental principles of physics
to its original splendor," Hoek writes in a blog post about his paper.
However, that all-important correction never caught on. Even
now it might struggle to gain traction against the weight of centuries of
repetition.
"Some find my reading too wild and unconventional to take seriously," Hoek remarks. "Others think that it is so obviously correct that it is barely worth arguing for."
Ordinary folks might agree it sounds like semantics. And
Hoek admits the reinterpretation hasn't and won't change physics. But carefully
inspecting Newton's own writings clarifies what the pioneering mathematician was
thinking at the time.
"A great deal of ink has been spilt on the question
what the law of inertia is really for," explains Hoek, who was puzzled as
a student by what Newton meant.
If we take the prevailing translation, of objects traveling
in straight lines until a force compels them otherwise, then it raises the
question: why would Newton write a law about bodies free of external forces
when there is no such thing in our Universe; when gravity and friction are
ever-present?
"The whole point of the first law is to infer the
existence of the force," George Smith, a philosopher at Tufts University
and an expert in Newton's writings, tells journalist Stephanie Pappas for
Scientific American.
In fact, Newton gave three concrete examples to illustrate
his first law of motion: the most insightful, according to Hoek, being a
spinning top – that as we know, slows in a tightening spiral due to the
friction of air.
"By giving this example," Hoek writes,
"Newton explicitly shows us how the First Law, as he understands it, applies
to accelerating bodies which are subject to forces – that is, it applies to
bodies in the real world."
Hoek says this revised interpretation brings home one of
Newton's most fundamental ideas that was utterly revolutionary at the time.
That is, the planets, stars, and other heavenly bodies are all governed by the
same physical laws as objects on Earth.
"Every change in speed and every tilt in
direction," Hoek muses – from swarms of atoms to swirling galaxies –
"is governed by Newton's First Law."
Making us all feel once again connected to the farthest
reaches of space.
The paper has been published in the Philosophy of Science.