How does Einstein's theory of relativity differ from preceding theories?

Einstein's theory of relativity is one of the most significant scientific breakthroughs in history. Prior to Einstein's theory, the prevailing view was that space and time were absolute, fixed and independent of each other. However, Einstein's theory revolutionized this view and introduced a new understanding of the universe by showing that space and time are intimately connected, and that they are relative to each other. This theory changed the way we think about gravity, time, space and the structure of the universe.

The theory of relativity is divided into two parts: the special theory of relativity and the general theory of relativity. The special theory of relativity deals with the laws of physics in the absence of gravity, while the general theory of relativity deals with the laws of physics in the presence of gravity.

One of the key differences between Einstein's theory of relativity and preceding theories is that it predicts that the laws of physics are the same for all observers, regardless of their relative motion. This principle, known as the principle of relativity, is a fundamental concept in modern physics. Another significant difference is that Einstein's theory predicts that the speed of light is constant and is independent of the motion of the observer. This was a major departure from previous theories, which assumed that the speed of light was relative to the motion of the observer.