summary ofA Brief History of TimeBook by Stephen Hawking, PhD

first KEY POINT

Big Bang, or how the universe began

Every person in the world once asked themselves, “How did the universe begin?” Some of our ancestors considered that it dated approximately 5000 BC. Of course, archeological findings proved this suggestion wrong, as Earth formed 4.5 billion years ago. Greek philosophers believed that the universe existed for an infinite amount of time and would last forever.But in 1929, astronomer Edwin Hubble made one of the most remarkable discoveries in the field. He found that distant galaxies were moving away from us at speeds that increased with their distance, implying that the farther away the galaxy, the faster it moved. This discovery showed that the universe was expanding, which led scientists to suggest that everything in the universe must have once been gathered together in one place, leading to the development of the Big Bang cosmological model.There are, however, more popular theories, like Isaac Newton's theory of gravity and Albert Einstein's general theory of relativity. Nowadays, scientists apply both of them to interpret the world. While Einstein's approach characterizes the universe on the macro scale, quantum mechanics apply to a micro level. Yet, these two theories contradict each other. One of the crucial tasks for Stephen Hawking was to find a way to combine both sets of principles. His search started with the analysis of space and time models.

Join this expedition into the universe. Hawking has described how the latter looks, why objects act in certain ways, and how physics developed over time. While exploring these topics, you will realize the power of human intellect and the world's complexity. Physics is a highly counterintuitive field. So get ready to be astonished!