Final answer:
Newton's laws mark the foundation of classical mechanics but are constrained when objects move at or near the speed of light, where relativity and quantum mechanics provide a more accurate description.
Step-by-step explanation:
Understanding Newton's Laws in Relation to Modern Physics
Newton's laws of motion were pivotal in the development of classical mechanics, representing motion accurately for objects larger than molecules (~10-9 m) and moving at speeds significantly less than the speed of light. These laws, however, do not hold up under certain conditions, such as particles moving at or near the speed of light, a realm covered by Einstein's theory of relativity and quantum mechanics. In the twentieth century, Newton's laws faced challenges with the realization that no object with mass can travel at the light speed (c), and the measurable effects of relativity on time and space confirm this limitation, as verified through countless experiments.
Understanding the scope of Newtonian mechanics is crucial for comprehending the evolution of physics. Newton's assumptions, including instant effects of gravity over distances (action-at-a-distance), were called into question by modern discoveries. These advancements led to a new perspective on the fundamental concepts of time, space, and speed, fundamentally altering our understanding of the universe.