In the book, Hawking explains how Einstein changed the way we view the universe by introducing time as the fourth dimension to the traditional three dimensional setting of the universe.
Quantum Mechanics, which deals with matter at the atomic and subatomic levels, is explored. In the second half of the book, Stephen Hawking deals with the subjects that are connected to his own research areas like Black Holes and Hawking Radiation.
The books starts off by presenting an interesting story about an elderly woman who challenges the views presented by an astrophysicist and claims that the earth is flat and is supported on the back of a tortoise. This sets a reader friendly tone that’s followed throughout the course of the book!