THE THEORY OF EVERYTHING pdf download

The Theory Of Everything – THE ORIGIN AND FAIE OF IRE UNIVERSE

Book Description

“The Theory of Everything” by Stephen Hawking is a remarkable exploration of the fundamental concepts in theoretical physics and cosmology. In this book, the renowned physicist delves into the mysteries of the universe, offering a comprehensive journey through some of the most profound and captivating ideas in the field. Below, below is a detailed book description, capturing the key topics covered in each lecture.

INTRODUCTION
The book commences with an introduction that sets the stage for the enlightening journey that lies ahead. Stephen Hawking invites readers to embark on a voyage through the cosmos, promising to unravel the most intriguing and perplexing questions about the universe’s nature.

CONTENTS
The contents page offers a glimpse of the book’s structure, highlighting the various lectures that make up the chapters of this enlightening work.

FIRST LECTURE: IDEAS ABOUT THE UNIVERSE
In the first lecture, Hawking presents a panorama of the prevailing ideas and concepts regarding the universe. He discusses the historical and philosophical perspectives that have shaped our understanding of the cosmos. This lecture provides the foundation for exploring more complex topics in the subsequent chapters.

SECOND LECTURE: THE EXPANDING UNIVERSE
The second lecture takes us into the heart of one of the most groundbreaking discoveries in cosmology—the expanding universe. Hawking explains how the universe’s expansion challenges our preconceived notions and introduces readers to the Big Bang theory, a cornerstone of modern cosmology.

THIRD LECTURE: BLACK HOLES
Black holes, enigmatic and incredibly dense regions in space, are the focus of the third lecture. Hawking unravels the intriguing physics of these cosmic phenomena, exploring how they form, behave, and impact the fabric of the universe. Readers will gain an understanding of the unique properties of black holes and their gravitational effects.

FOURTH LECTURE: BLACK HOLES AIN’T SO BLACK
This lecture builds upon the previous one, delving deeper into the peculiar properties of black holes. Hawking challenges the conventional idea that nothing can escape a black hole’s grasp, introducing the concept of Hawking radiation, which suggests that black holes are not entirely “black” and can emit radiation.

FIFTH LECTURE: THE ORIGIN AND FATE OF THE UNIVERSE
Hawking takes readers on a journey through time and space, exploring the origins and ultimate destiny of the universe. This lecture touches on the Big Bang theory, the expansion of the cosmos, and the critical questions surrounding its future, whether it will continue expanding indefinitely or eventually contract.

SIXTH LECTURE: THE DIRECTION OF TIME
The sixth lecture delves into the nature of time, a fundamental dimension of our existence. Hawking explores the concept of time’s arrow, discussing why we perceive time as moving in a specific direction and how this relates to the expansion of the universe.

SEVENTH LECTURE: THE THEORY OF EVERYTHING
In the final lecture, Hawking tackles the ambitious concept of a “Theory of Everything.” This theoretical framework seeks to unify the fundamental forces of nature and provide a comprehensive understanding of the universe. Hawking discusses the challenges and prospects of discovering such a theory.

INDEX
The book concludes with an index, allowing readers to quickly access specific topics and concepts discussed throughout the lectures.

Condensed Book Contents

• INTRODUCTION
• FIRST LECTURE
• IDEAS ABOUT THE UNIVERSE
• SECOND LECTURE
• THE EXPANDING UNIVERSE
• THIRD LECTURE
• BLACK HOLES
• FOURTH LECTURE
• BLACK HOLES AIN’T SO BLACK
• FIFTH LECTURE
• THE ORIGIN AND FATE OF THE UNIVERSE
• SIXTH LECTURE
• THE DIRECTION OF TIME
• SEVENTH LECTURE
• THE THEORY OF EVERYTHING
• INDEX

THE THEORY OF EVERYTHING

He says,

I shall try to give an outline of what we think is the history of the universe from the big bang to black holes. In the first lecture I shall briefly review past ideas about the universe and how we got to our present picture. One might call this the history of the history of the universe.

In the second lecture I shall describe how both Newton’s and Einstein’s theories of gravity led to the conclusion that the universe could not be static; it had to be either expanding or contracting. This, in turn, implied that there must have been a time between ten and twenty billion years ago when the density of the universe was infinite. This is called the big bang. It would have been the beginning of the universe.

In the third lecture I shall talk about black holes. These are formed when a massive star or an even larger body collapses in on itself under its own gravitational pull. According to Einstein’s general theory of relativity, anyone foolish enough to fall into a black hole will be lost forever.

They will not be able to come out of the black hole again. Instead, history, as far as they are concerned, will come to a sticky end at a singularity. However, general relativity is a classical theory-that is, it doesn’t take into account the uncertainty principle of quantum mechanics.

In the fourth lecture I shall describe how quantum mechanics allows energy to leak out of black holes. Black holes aren’t as black as they are painted.

In the fifth lecture I shall apply quantum mechanical ideas to the big bang and the origin of the universe. This leads to the idea that space-time may be finite in extent but without boundary or edge. It would be like the surface of the Earth but with two more dimensions.

In the sixth lecture I shall show how this new boundary proposal could explain why the past is so different from the future, even though the laws of physics are time symmetric.

Finally, in the seventh lecture I shall describe how we are trying to find a unified theory that will include quantum mechanics, gravity, and all the other interactions of physics. If we achieve this, we shall really understand the universe and our position in it.

As long ago as 340 B.C. Aristotle, in his book On the Heavens, was able to put forward two good arguments for believing that the Earth was a round ball rather than a flat plate. First, he realized that eclipses of the moon were caused by the Earth coming between the sun and the moon.

The Earth’s shad- ow on the moon was always round, which would be true only if the Earth was spherical. If the Earth had been a flat disk, the shadow would have been elongated and elliptical, unless the eclipse always occurred at a time when the sun was directly above the center of the disk.

Second, the Greeks knew from their travels that the Pole Star appeared lower in the sky when viewed in the south than it did in more northerly regions. From the difference in the apparent position of the Pole Star in Egypt and Greece, Aristotle even quoted an estimate that the distance around the Earth was four hundred thousand stadia. It is not known exactly what length a stadium was, but it may have been about two hundred yards. This would make Aristotle’s estimate about twice the currently accepted figure.

The Greeks even had a third argument that the Earth must be round, for why else does one first see the sails of a ship coming over the horizon and only later see the hull? Aristotle thought that the Earth was stationary and that the sun, the moon, the planets, and the stars moved in circular orbits about the Earth. He believed this because he felt, for mystical reasons, that the Earth was the center of the universe and that circular motion was the most perfect.

This idea was elaborated by Ptolemy in the first century A.D. into a complete cosmological model. The Earth stood at the center, surrounded by eight spheres, which carried the moon, the sun, the stars, and the five planets known at the time: Mercury, Venus, Mars, Jupiter, and Saturn. The planets themselves moved on smaller circles attached to their respective spheres in order to account for their rather complicated observed paths in the sky.

The outermost sphere carried the so-called fixed stars, which always stay in the same positions relative to each other but which rotate together across the sky. What lay beyond the last sphere was never made very clear, but it certainly was not part of mankind’s observable universe.

Ptolemy’s model provided a reasonably accurate system for predicting the positions of heavenly bodies in the sky. But in order to predict these positions correctly, Ptolemy had to make an assumption that the moon followed a path that sometimes brought it twice as close to the Earth as at other times. And that meant that the moon had sometimes to appear twice as big as it usually does. Ptolemy was aware of this flaw but nevertheless his model was generally, although not universally, accepted.

 It was adopted by the Christian church as the picture of the universe that was in accordance with Scripture. It had the great advantage that it left lots of room outside the sphere of fixed stars for heaven and hell.