The key difference between Einstein's theory of relativity and Newtonian mechanics when dealing with motion at low speeds compared to high speeds lies in their respective formulations of space, time, and the behavior of objects in motion.
Newtonian mechanics, formulated by Sir Isaac Newton in the 17th century, provides accurate descriptions of the motion of objects at everyday speeds that are much slower than the speed of light. It is based on three fundamental laws: the law of inertia, the relationship between force and acceleration (F = ma), and the principle of action and reaction. According to Newtonian mechanics, time and space are absolute and separate entities, and objects move according to well-defined laws within this framework.
Einstein's theory of relativity, on the other hand, introduced a revolutionary perspective on space, time, and motion. It consists of two main theories: special relativity and general relativity.
Special Relativity: Special relativity, formulated by Einstein in 1905, deals with the behavior of objects moving at constant velocities relative to each other, including high speeds. In special relativity, the speed of light in a vacuum is regarded as a universal constant, denoted by 'c.' The theory establishes that the laws of physics are the same for all observers in uniform motion relative to each other. Special relativity introduces concepts like time dilation, length contraction, and the relativity of simultaneity. As an object approaches the speed of light, its mass appears to increase, and time dilation occurs, meaning time passes more slowly for the moving object relative to a stationary observer.
General Relativity: General relativity, formulated by Einstein in 1915, extends the principles of special relativity to include gravity. General relativity describes gravity as a curvature of space and time caused by the presence of mass and energy. It proposes that massive objects, such as planets and stars, create curves or distortions in the fabric of spacetime, and the motion of objects is influenced by these curves. General relativity predicts phenomena like gravitational time dilation and the bending of light around massive objects.
In summary, the main difference between Einstein's theory of relativity and Newtonian mechanics regarding motion at low speeds compared to high speeds is that Newtonian mechanics provides accurate predictions for most everyday situations at low speeds, whereas Einstein's theories of special and general relativity are required to accurately describe phenomena involving high speeds, strong gravitational fields, and the behavior of light. Relativity theories fundamentally changed our understanding of space, time, and motion, allowing for precise predictions and explanations in realms beyond the reach of classical Newtonian mechanics.