motion is uniform and not fluctuating this way and that. You will discover not the least change in all the effects named, nor could you tell from any of them whether the ship was moving or standing still.[194]
This principle provided the basic framework for Newton's laws of motion and is central to Einstein's special theory of relativity
Falling bodies
See also: History of gravitational theory § European Renaissance, and Free fall § History
John Philoponus, Nicole Oresme, and Domingo de Soto
That unequal weights would fall with the same speed may have been proposed as early as by the Roman philosopher Lucretius.[195] Observations that similarly sized objects of different weights fall at the same speed are documented in sixth-century works by John Philoponus, of which Galileo was aware.[196][197] In the 14th century, Nicole Oresme had derived the time-squared law for uniformly accelerated change,[198][199] and in the 16th century, Domingo de Soto had suggested that bodies falling through a homogeneous medium would be uniformly accelerated.[200] De Soto, however, did not anticipate many of the qualifications and refinements contained in Galileo's theory of falling bodies. He did not, for instance, recognise, as Galileo did, that a body would fall with a strictly uniform acceleration only in a vacuum, and that it would otherwise eventually reach a uniform terminal velocity.
Delft tower experiment