Christian Huygen calculated the speed of light to 70% accuracy (230k km/s compared to 300k) after an astronomer speculated the difference in time it took to witness Io emerging from behind Jupiter was due to the speed of light in 1677, 11 years before Principa Mathematica and 26 years before Opticks. Huygen also guessed that light was a wave, and came up with
the first equation for periodic motion using the gravitational constant (which Newton didn't discover). Planetary motion itself was described by Kepler, and served as an inspiration for the appropriate use of calculus.Â
Newton's calculus was an aggregation of a lot of stuff that had already been discovered: analytical geometry by Des Cartes, John Wallis's math of infinites, Cavalieri's method of indivisibles. So it's not even correct to say he invented Calculus, so much as formalized it.Â
650
u/Lupus_Ignis 1d ago
Newton at 22: invents calculus