A Brief History of Time
This is a popular science book first published on 1st April 1988 by British physicist Stephen Hawking. The book became the best seller and in 20 years 10 million copies had been sold. It was highlighted in London Sunday Times bestseller’s list for four years, longer than any book in history excluding Shakespeare and the Bible. By 2001, the book was translated into 35 languages. The great success of the book showed the great interest people have about their origin.
The book has an additional chapter on wormholes and time travel. According to Einstein’s General Theory of Relativity, there is a possibility that people could make and maintain wormholes, small tubes that connect various regions of space-time. This could be used for fast travel around the galaxy or even travel back in time. Travelling to the future is impossible.
The book also expounds on the recent progress in finding correspondences or dualities between the different theories of physics. The correspondences are an indication that there is a unified theory of physics. The correspondences also suggest that it is not possible to express this argument in just one theoretical formulation. However, different reflections of the basic theory have to be used in various situations. This phenomenon is likened to the map of the world. It is not possible to represent every part of the world on a single map. Instead, there are different maps for every region. This is a revolution of the unification of science’s laws, but it would not change the fact that the universe is ruled by a set of balanced laws that people can discover and comprehend.
When it comes to observation, the greatest development was the recording of changes in the cosmic microwave background radiation. The COBE satellite and other collaborations achieved this. These fluctuations are the sign of creation. They are the smooth, tiny, and uniform initial universe that later grew into stars, galaxies and all the structures people see around. The fluctuations approve the proposal that the universe has no edges or boundaries. However, further observations will be essential to distinguish this proposal from other probable explanations of the background fluctuations.
The first topic is quite fascinating. How do you picture the universe? Where did it originate from and where is it going? Many questions have been asked, and the answers provided seem to raise even more questions. Recent breakthroughs in the field of physics have made it possible to suggest answers to people’s endless questions. People started suggesting the answers to how the universe looks like back in 340 BC. Aristotle, a great Greek philosopher, documented an argument for believing that the earth is sphere shaped, and not flat.
In the second century, AD Ptolemy modified Aristotle’s idea into a complete cosmological model. Other people like Nicholas Copernicus, Johannes Kepler, Galileo Galilei, Isaac Newton, Aristotle and other Greek philosophers did not like the idea of creation because it was much of divine intervention. People who believe that the universe is not arbitrary, but governed by definite rules have to combine the various theories into a unified theory, which will describe everything found in the universe. The partial theories that exist can be used to search for the ultimate theory that seems difficult to validate on practical grounds. The deepest desire most people have is to know where they came from and why they exist.
The current ideas about the motion of bodies came from Newton and Galileo. Before 1915, time and space were assumed of as a static arena where events took place but was not influenced by what happened in it. This was correct even of the theory of relativity. Bodies move, forces attract and repel, but space and time remain unaffected. One could think that time and space went on forever. In the general theory of relativity, the situation is quite different. Time and space are dynamic quantities. When a force acts or a body move, it upsets the curvature of time and space. In turn, the structure of space and time influences the movement of the bodies and the forces that act on them. Space and time have a direct connection with everything that happens in the universe. They affect each other.
This is a bewildered world that makes people ask themselves series of questions. In the event of trying to answer the questions, theories are developed. The theories may be mathematically precise, but they lack something; observational evidence. For instance, no one has ever seen a superstring in the theory of superstrings.
The earliest theories that tried to explain the universe revolved around the idea that natural phenomena and events were controlled by spirits who acted in a very unpredictable manner. These spirits dominated natural objects like mountains, rivers, and even celestial bodies like the moon and the sun. However, with the passage of time, people discovered that whether or not the spirits had been appeased, some things were constant. The sun always rose from the east and in the evening set in the west. Additionally, the sun and other planets always followed a definite path across the sky which could be predicted earlier withy considerable accuracy.
Even if the celestial bodies are the gods, they obey strict rules, without any exception. These laws were only in astronomy. As civilization began, more laws were discovered. The emergence of these laws made Laplace postulate a scientific determinism. He suggested that there would be laws which will determine the evolution of the universe accurately, given its alignment at one time.
It is certain that Laplace’s idea can not be realized. The principle of quantum mechanics suggests that some parts of quantities, like velocity and position, can’t be predicted together with absolute accuracy. Particles do not have well-defined velocities and positions but are symbolized by a wave. The quantum theories are deterministic in that they provide laws for the advancement of the wave with time. Therefore, if the wave at one time is known, it is easy to calculate it at any other given time.
Even after all the discovery of laws, the question remains, why and how were the laws or the initial state of the universe chosen? This book has a particular prominence to the laws of gravity since gravity shapes the large-scale of the universe.
In his book, Hawking explains subjects in cosmology, such as the big bang theory to the non-specialist reader. There is an explanation of complex mathematics on the subject. The latest edition was published in 2005. It includes new issues that have risen with advanced scientific developments.