“Resistance is usually ascribed to bodies at rest, and impulse to those in motion, but motion and rest, as commonly conceived, are only relatively distinguished; nor are those bodies always truly at rest, which commonly are taken to be so.”
- January 4, 1643 – March 31, 1727
- Born in England (UK)
- Natural philosopher, mathematician, physicist, astronomer, theologian
- Proposed the laws of universal gravitation and motion, built the foundations of modern science, and systematized theories of natural philosophy and mathematics.
Quote
“Resistance is usually ascribed to bodies at rest, and impulse to those in motion, but motion and rest, as commonly conceived, are only relatively distinguished; nor are those bodies always truly at rest, which commonly are taken to be so.”
Explanation
In this quote, Isaac Newton is questioning the common distinctions between motion and rest and exploring the concepts of resistance and impulse in the context of classical mechanics. Newton points out that we usually associate resistance with objects that are stationary (at rest) and impulse with objects that are moving. However, he suggests that motion and rest are not absolute conditions but relative to each other. This means that what we perceive as “rest” is actually motion in relation to other bodies or reference points. For instance, the Earth might appear “at rest” to us, but it is actually in motion relative to the Sun and other celestial bodies.
Newton’s insight highlights the importance of choosing a reference frame when discussing motion and rest. An object is not inherently at rest or in motion; its state depends on the perspective from which it is being observed. This view is foundational to the later development of relativity, particularly in Einstein’s theory of relativity, which would further explore the idea that motion is relative to the observer and that there is no absolute state of rest in the universe.
Additionally, Newton remarks that objects commonly thought to be at rest—like objects on Earth—are not truly stationary, as the Earth itself is constantly in motion due to its rotation and orbit around the Sun. Even on the Earth’s surface, every object experiences minute movements due to the rotation of the planet and other forces.
In modern physics, this understanding of relative motion and the concept that there is no true “absolute rest” aligns with modern mechanics and relativity theory, where motion is always described relative to a specific frame of reference. Newton’s thinking paved the way for future scientific breakthroughs that would redefine the way we think about motion, time, and space, and his views continue to influence our understanding of the dynamic and interconnected nature of the universe.
