Chapter 2

In this chapter of A Brief History of Time, Hawking discusses the theories of Galileo, Newton, and Einstein and how they revolutionized our understanding of space and time. He starts by explaining how Galileo's observations of the acceleration of falling objects led to Newton's laws of motion, which rejected the idea of absolute, static position. He then discusses the idea of relative space and the measurement of time at different speeds, and how the discovery of the fixed speed of light in 1676 led to the development of the theory of relativity. According to this theory, the laws of science should be the same for all freely moving observers, regardless of their speed. This led to the concept of space-time, which is four-dimensional and includes the element of time in addition to the traditional three dimensions of space. Hawking also discusses the development of Einstein's general theory of relativity, which explains how gravity works by warping space-time. He explains how this theory has been tested and supported by various observations and experiments, and how it has led to a better understanding of the universe.