Einstein's theory of relativity did not replace Newtonian mechanics because they operate in different domains of applicability. Newtonian mechanics, developed by Sir Isaac Newton in the 17th century, provides accurate predictions for most everyday objects and speeds that are much slower than the speed of light. It is still widely used in engineering, technology, and many practical applications because it is simpler and easier to apply in these scenarios.
Einstein's theory of relativity, on the other hand, was developed in the early 20th century and introduced a new understanding of space, time, and gravity. It consists of two major components: the special theory of relativity, which deals with objects moving at constant speeds, and the general theory of relativity, which incorporates gravity and describes the behavior of objects in the presence of gravitational fields.
The theory of relativity provides more accurate predictions in extreme conditions involving high speeds, strong gravitational fields, and cosmological scales. It has been extensively tested and confirmed in numerous experiments, such as the bending of light around massive objects and the precise measurements of the precession of Mercury's orbit.
However, despite its successes, the theory of relativity is mathematically complex and often requires advanced mathematical tools to apply. In everyday scenarios where the speeds involved are much slower than the speed of light and gravitational effects are negligible, Newtonian mechanics provides a simpler and sufficiently accurate description. Thus, Newtonian mechanics continues to be widely taught and used in many practical applications, while Einstein's theory of relativity is employed in specialized areas where its effects become significant.
In summary, Einstein's theory of relativity did not replace Newtonian mechanics because they describe different regimes and have different levels of complexity, with Newtonian mechanics remaining a practical and accurate approximation for many everyday situations.