A Brief History of Time by Stephen Hawking
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Book Reviews of A Brief History of Time
Book Review: Absolutely wonderful book, read it!
Summary: 5 Stars
Overview:
As the title says this book is a brief overview of the current state of theoretical physics circa 1988 as written by one of the field's brightest minds, Stephen Hawking. It is not so intimidating as it may at first sound as it does not utilize any equations but simply expresses complex ideas in the simplest terms available to the author.
Points of Interest:
Where to begin!? This is a book that should be required reading in my mind as it presents ideas that define the universe we live in as developed by the brightest minds the human species has produced. But before I get ahead of myself let me add this caveat: the book does present very complex ideas and if you are a layperson coming to the subjects of cosmology and theoretical physics then this may be a bit overwhelming. I have a very large interest in the subject and have managed to familiarize myself with many of the topics presented. If you would like to educate yourself a bit about these things (and you should, as they are fascinating!) then I would suggest checking out some TV specials (yes I am breaking a cardinal rule and suggesting that you watch TV) on the subjects of cosmology, quantum physics, and relativity. Do not be intimidated by these subjects! With a little effort you can open doors for your mind that will expand your perspectives on life.
Now, this book in particular does a brilliant job of exploring the big topics of theoretical physics: where did we come from, where are we going and why are we here? Sound familiar? They should, because those are the big questions that every religious and many philosophical systems have attempted to answer since man began painting on cave walls.
The primary difference between most religions' approach to these questions and science is simply that religions propose to have the answers without verifiable proof, where science presents a theory with available evidence and says, prove me wrong. This fundamental difference is what fascinates me with the topic. Religions are static and unchanging (or at least claim to be) whereas science is dynamic and ever changing, adapting to new information.
Hawking begins by describing some of the models human beings have had of the universe. The model used previously was that of the Earth at the center, with everything else rotating around it. Hawking discusses the idea that the earth had also been thought to be flat, or supported on the back of a giant tortoise as believed by some indigenous peoples.
We now know all of these to be untrue. Hawking then goes on to stress the importance of asking questions and to not simply accept that which has been held as truth but has not been proven to be true. For example we now know that the idea held in western society that the earth was the center of the universe (which the catholic church threatened to excommunicate Galileo for challenging, and another Philosopher, Girodono Bruno, was burned at the stake for the same reason) is no less silly than the idea that it rested on the back of a giant tortoise. Yet this was held to be undeniable truth for centuries. Another example of this resistance to new ideas is the story told by Hawking of a meeting he had with the Pope where he was told to study only the events after the Big Bang (the proposed beginning of the universe) but not the Big Bang itself as this was believed to be the act of creation and forbidden knowledge to man. The Church forbade this because they were afraid of what would be discovered just as they had been afraid of Copernicus' model of a Universe in which the Earth was not at the center. These ideas challenged doctrine and the uncovering of the Big Bang could have revealed a universe in which there was no room for God as defined in the Bible.
This is an interesting point also because Hawking addresses the difficulty many scientists' have in reconciling there religious beliefs and scientific knowledge. Einstein for example refused to believe Quantum Physics because it showed us that the universe is fundamentally chaotic. He stated that he would not accept the theory as he felt that God did not play dice. However, we now know that Quantum Physics do dictate the actions of fundamental particles (which is a bit ironic of a statement as fundamental particles are inherently unpredictable!).
One of the structural devices Hawking's uses throughout the book is to present similar previously held notions at the beginning of a chapter and then to explain how they were overturned and by whom. This creates within the reader a sense that the foundations of science have been laid over many years built up in steps with each proceeding step reliant on the previous. It is also interesting to me that the science community places such a large emphasis on giving credit to those who made the crucial discoveries. It makes me think of the Pyramids of Egypt, these men trying to write their names into history. As for longevity though, I would say that an essential law or equation that defines the universe in which we live would have a far greater impact than a man-made mountain. The mountain fades with time; a fundamental truth will endure and is a hell of a lot more useful to the rest of us.
Hawking also takes pains to mention his contributions to the field and his interactions with his colleagues, which at times are all too human. Even a man humbled by a broken body is not free of his ego! That made me chuckle, but it also colors the book with Hawking's personality which I found gave it a personal touch lacking in many similar works I have read.
The book does a wonderful job of making understandable such complex topics as singularities, gravity, quantum mechanics, space time, the fundamental laws of the universe and black holes. Hawking's breaks down the basic mechanics of these complex subjects and explains how they determine the universe we live in. He then goes on to explain how these have led him to construct a model of the universe that he believes to be accurate. The theories and questions he raises should elicit thought in any mind, regardless of personal belief. They are independently verifiable by anyone willing to take the time to understand them, which is what has always drawn my mind to theoretical physics and science and mathematics in general. This does not require any leap of faith, only a verification of facts. An individual is not confined to simply accepting and obeying the laws and origins of the universe but to interact with and help shape the discovering of them. That for me empowers man instead of an unseen deity and makes the journey of life so much more exciting as the emphasis is on the now and not a potential afterlife. In this system man is the key player and star of the show with the present being the critical time, not the past and all of its collected ghosts and myths or a hereafter which may or may not exist.
Hawking addresses this when he discusses the fact that the Universe as far as we know it had to exist exactly the way it does in order to have produced intelligent life capable of observing and questioning it. This proposes some fascinating questions about our place and purpose. Are we here to give order and purpose to a Universe that would otherwise go unappreciated, and unobserved? Perhaps simply existing is the meaning of our lives; perhaps we need to look for no further justification than that to explain our purpose here. These are just some of the many ideas that buzz through my mind when I consider this book.
Some of the possibilities proposed by Hawking in the book will twist your mind into pretzels: infinite alternate dimensions expanding infinitely, multitudes of dimensions beyond the four we operate in that exist all around us yet we are unaware of, just to name a few. This book is a roller coaster ride for your mind.
The conclusion to the book was profound for me as it proposed further models for the universe which are even now being explored. To unify all of physics with a single theory is the ultimate goal. Hawking's closes with the statement that to achieve the unification of physics would be to understand the mind of God.
Book Review: Fascinating story of cosmology, relativity & quantum mechnx
Summary: 5 Stars
Stephen Hawking's A Brief History of Time was originally published in 1988 and helped thousands of lay-people keep up with the latest ideas about the nature of the universe. This 10th anniversary edition adds the latest advances in science and technology in the last decade and adds a new chapter on the subject of time travel and wormholes. (This is my rehash.)Since the beginning of history, mankind has pondered the origins of the universe. In ancient civilization, humans believed the earth was flat. Aristotle was perhaps one of the first people to postulate that the earth was not flat, but spherical. However, prior to Copernicus, it was believed that the earth was the center of the universe. Now we know that our sun is just one in millions of stars in a vast array of galaxies. It was Edwin Hubble that demonstrated that the universe was expanding. The idea that the universe is expanding means that there must have been a beginning, and a beginning of time. This was the first time that the origin of the universe had become a matter of science.
Newton's theory of gravity was always assumed to be accurate, until Einstein came along with the general theory of relativity. Einstein came up with the theory that no mass can travel faster than the speed of light. In his formula, E=mc˛, the more energy an object has, the more mass it has, and thus the more resistance. The only constant that can be really sure is speed, or rate, while time and distance can be relative. Time, is another dimension of our universe. Because of the distance of the stars and galaxies away from us, we are seeing what happened in the past.
Prior to the uncertainty principle, scientists held a very deterministic view of the universe that reflected the modernistic Enlightenment era. The uncertainty principle shows that you cannot predict the future state of a particle. This showed that there is a limit to which science can predict future events based on the laws of physics. As a result of the uncertainty principle, quantum mechanics was formulated to deal with the limitations arising from the uncertainty principle. Rather than trying to define the exact locations of particles, they had a quantum state which factored position and velocity.
Democritus, the Greek philosopher who coined the term atom, was perhaps the first philosopher who thought that there was an indivisible element of matter. It was not until the past century that it was discovered that an atom itself had an internal structure. According to quantum mechanics, an atom's particles move in waves because of the nature of its wave/particle duality. The exclusion principle says that a particle cannot exist in the same state or location at the same time. The exclusion principle explains why matter does not collapse into a very high density.
Hawkings describes how force-carrying particles can be grouped into four categories based on varying strength: gravitational force, electromagnetic force, weak nuclear force, and a strong nuclear force. There have been attempts to combine these forces into a grand unified theory. However, grand unified theories do not include the force of gravity, which has been the subject of general relativity. A future quantum theory of gravity would hopefully unite quantum mechanics with general relativity.
The affect of gravity on light was not clarified until after the theory of general relativity. It was hypothesized that a star could have such a large gravitational force that light could not escape-that would be a black hole. Black holes are difficult to detect. There currently is evidence for a number of black holes, and even some hints that there are black holes at the center of galaxies.
At the big bang, the universe was infinitely small. Hawking notes something interesting in that if the rate of expansion was any slower, then the universe would have recollapsed under its own gravitational forces. Hawking suggests that it is possible that God might have picked the initial configuration of the universe, but that the weak anthropic principle states that we see the universe the way it is because if it was not that way, then we would not be here to see it. The strong anthropic principle says that there may be many different universes (multiverse) or many different regions in the universe so that the odds are that intelligent life may form somewhere. I believe that the universe appears to be so finely tuned for life because it was created that way, not because we happened to have lucky odds. The strong anthropic principle was developed as a way to avoid the idea of an intelligent designer. If there was a Creator, then we can believe that the universe was created this way on purpose. The "inflationary" model of the beginning of the universe has been formulated in order to show that many different initial configurations of the universe could have been possible so that life could be sustained. This means that the universe once expanded at an increasing rate, faster than today.
Nevertheless, even if we discover all of the laws of the universe, we still would not know why the universe was here to begin with. As Hawking asks, "Why does the universe go to all the bother of existing?"
Book Review: Great Read for Everybody
Summary: 5 Stars
One of my favourite books is A Brief History of Time, written by Stephen Hawking. This book is famous like its author. Its wonder lies in the fact that the forefront of physics is portrayed in laymen's terms. Thus the theories behind quantum mechanics, relativity, black holes, time travel, and wormholes can all be comprehended by the average person. Every time I pick up this paperback, I feel humbled by the grandeur of our mysterious universe. Needless to say, the origin of the universe may just provide a clue to the birth of life. Of all the theories described in the book, I was most intrigued by Einstein's special theory of relativity.
Before the dawn of the 20th Century, the Michelson-Morley experiment was conducted to substantiate the existence of a substance called "ether." Instead, it created a shock wave for the entire scientific community. Throughout the next twenty years, numerous futile attempts were made to explain the surprising results of the experiment. In the end, it was Einstein's special theory of relativity that came to the rescue.
A remarkable consequence of relativity is that it revolutionized our ideas of space and time. Before Einstein's heydays, Newtonian physics indicated that space was not absolute, meaning different observers of a moving object may conclude differently about the distance it travelled. However, time was always assumed to be absolute, i.e., different observers would always agree on the time it took an object to traverse through space. Einstein took Newton's theories and took a step back. He claimed that if one lets go of the idea of absolute time, then we need not "invent" the idea of ether. Nor would we be troubled by the Michelson-Morley experiment. The notion of absolute time, however, is so deeply engraved in our minds that even today, it is difficult to discard.
Einstein went on to come up with unconventional predictions of how objects behave when they approach the speed of light. These imaginary experiments came to be known as Einstein's paradoxes. Perhaps the most famous one is the twins paradox: A twin steps on a spaceship and travels at the speed of light for 20 years according to his watch. When he returns to Earth, he will find that much more time has indeed elapsed during his absence and his twin brother is now 100 years older than him. You might find it hard to accept this outcome. That is why it is called a paradox in the first place. However, this is not so difficult any more if you think of time being relative.
Einstein's brilliance in my opinion, lies not in his discovery of relativity, but the manner in which he did it. In order to reach his conclusions, he took a step back from well known physics principles. Instead of taking for granted the firmly-entrenched view that time was absolute, he chose to doubt it. In the end, he took a completely opposite stance. As a result, every road block baffling the scientific world then was instantly removed.
Einstein's work prompted me to wonder whether we can always take our assumptions for granted. Sometimes, moving a step backwards and re-evaluating popular opinion is not a bad idea. Of course, to his credit, Einstein also applied immense creativity and ingenuity to secure the fantastic success that he enjoyed. Nonetheless, I will keep this lesson in mind on my quest for knowledge.
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Book Review: Time is of the essence...
Summary: 5 Stars
The mark of a true educator, which Stephen Hawking certainly is, is that he would take time (very valuable time, in his case) away from research and contemplation of the great mysteries of the universe to write a piece that would serve to help explain to the greater number of less-scientifically-adept persons the fruits and implications of modern scientific research from the cutting edge of physics. Hawking is ranked in popular and scientific thinking on a par with Einstein, and has motor neuron disability that severely restricts his ability to move, even to type or write, so, when he takes time to write something for general consumption, it is probably going to be worthwhile. And indeed, this is.'Someone told me that each equation I included in the book would halve sales. I therefore resolved not to have any equations at all. In the end, however, I did put in one equation, Einstein's famous equation. I hope that this will not scare off half of my potential readers.'
Hawking begins by exploring the large scale structure of the universe (time being part of the `fabric' of the universe, in spacetime), the connections of space and time as a relatively new concept in thinking of the universe, and the way the universe `acts' (cosmological dynamics). From there, he explores the universe at a very basic level, as elementary particles and forces of nature, introducing quarks.
'There are a number of different varieties of quarks: there are thought to be at least six "flavours", which we call up, down, strange, charmed, bottom and top. Each flavour comes in three "colours", red, green and blue. ...We now know that neither the atoms nor the protons and neutrons within them are indivisible. So the question is: What are the truly elementary particles, the basic building blocks from which everything is made?'
From this discussion Hawking proceeds to black holes (and the fact that they aren't so black and permanent as popular belief holds them to be), which circles back around to the origin and destiny of the universe (which relates back to the large-scale structure), which ultimately brings us to time. This is where things begin to get interesting.
'When one tried to unify gravity with quantum mechanics, one had to introduce the idea of "imaginary" time. Imaginary time is indistinguishable from directions in space. If one can go north, one can turn around and head south; equally, if one can go forward in imaginary time, one ought to be able to turn around and go backward.'
Hawking explains variations of the thermodynamic, psychological and cosmological laws that regulate the direction of time's arrow, which, despite the theoretical flexibility of time with regard to scientific principles, always apparently goes in one direction.
Finally, Hawking explores the most current topic in theoretical physics: unification theories, which may or may not be a wild goose on the loose. Hawking also explores what such a grand unified theory (also called sometimes the `theory of everything') would mean, and what it wouldn't mean. But Hawking assures us that the quest for understanding is worthwhile even it won't be the final word on everything.
Book Review: Fate of Space and Time: Blackholes to Big Crunch
Summary: 5 Stars
This is one of the early books written for those who prefer words to equations to understand cosmology of blackholes. The author attempts to answer basic questions such as; was there a beginning of time? Is there an end to the universe? What are similarities of blackholes, singularity, and Big Crunch? Is the universe infinite? Or does it have boundaries? What are the effects of the critical value of the universe's density on its rate of expansion? What is the role of God in the creation of the universe and how it can be evaluated by the anthropic principle? Did God creat laws of quantum mechanics and theory of relativity and let it evolve itself without leaving an option for him to intervene? How did he choose an initial state or configuration of the universe? What were the boundary conditions at the beginning of time? The author reviews the literature that includes Newton's laws of gravitational force, Einstein's theory of relativity, and quantum mechanics. Problems arise when one combines these theories to understand the four natural forces; the electromagnetic force; the strong and weak nuclear forces; and the gravitational force by one unified field theory (Quantum theory of gravity, and Superstring Theory). This theory must unify the forces of the cosmos and forces of microcosm so that it can explain the grand plan of God in the creation of heaven and earth. The author describes quite a few interesting anecdotes in academic research: The first experimental evidence in support of Einstein's theory of relativity contained errors that were as great as the effect they were trying to measure. In 1920s it was supposed that there were only three men who understood theory of relativity and now thousands of graduate students and many millions are familiar with this theory: Many readers should be encouraged at this. When the author presented his theory that black hole radiates like a hot body, many repudiated his assertion and later accepted it. Max Born, a Nobel Laureate in 1928 told a group that physics research will end in six months, when Dirac published equations for an electron, in the anticipation that the whole of physics problems are solved. This should remind all of us how far the science and mankind has progressed despite this prediction. Newton, one of the greatest scientists of this planet also had a streak of meanness in him. Einstein's honesty as a scientist could be found when he admitted that his universal constant to account for a static universe is a mistake, but he was also less willing to accept quantum mechanics; this is known by his well known comment that "God does not play dice." Hawking having a bet with Kip Thorne over the existence of black holes in Cygnus X-1 for Penthouse magazine to Private Eye magazine shows the fun side of academic rivalry. This is one of the very few books I have read that discusses God's role at the level of quantum mechanics. The reader should feel lucky to have such a book for his/her personal library.