About a year ago, I tried reading Brian Greene's The Fabric of the Cosmos (2004). While it started off well, it soon seemed quite a tedious read. Of course, Greene is recognized the world over as a master expositor of science, so I accept I am solely to blame if I couldn't enjoy the book. I was rather distressed that I was unable to digest a book that was at the cutting edge of physics.
Then I read somewhere that Stephen Hawking and Leonard Mlodinow's The Grand Design: New Answers to the Ultimate Questions of Life (2011) was as profound as Greene's book though much shorter. When I chanced upon this book in my University library I felt that I had been granted a second chance. And this book, boy, could I digest!
Stephen Hawking and Leonard Mlodinow have written a grand book, even grander I would say than A Brief History of Time (1988). The essence of the book is to explore fundamental questions: What is existence? Where did all this come from?
These are traditionally philosophical questions, but philosophy, the authors declare, is dead. "Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge."
The book is about a quest for a unified theory of the universe - the ultimate theory of everything. Hawking and Mlodinow state that physics has come up with just such a theory - something called M-theory (no one seems to know what the M stands for!). The authors state: "M-theory is not a theory in the usual sense. It is a whole family of different theories, each of which is a good description of observations only in some range of physical situations....The different theories in the M-theory family may look very different, but they can all be regarded as aspects of the same underlying theory."
The book is written in a lucid and entertaining style which even a layperson can follow. Hence it glosses over some of the scientific technicalities. So I couldn't figure out what M-theory really is. It seems to have to do something with string theory and supersymmetry (both of which are beyond my ken).
I have, however, studied quantum mechanics and could well understand the discussion on quantum physics. In particular, the Feynman path integral formulation (or "sum over histories" formulation) of quantum mechanics was well explained. When I read this book, I suddenly realized that Feynman had side-stepped the Heisenberg uncertainty principle simply by looking at all possible trajectories or histories that a quantum particle could take! This is mind-blowing. I learnt that all recent advancements in quantum mechanics has been due to use of Feynman path integral formulation rather than the Schrodinger formulation. Feynman diagrams - diagrams that show how bosons and fermions interact - are also introduced and I learnt that while Feynman diagrams had their origins in quantum electrodyanmics, (the quantum version of electromagnetism) they had spilled over into quantum chromodyamics (the theory of the strong nuclear force) and quantum gravity (the marriage of quantum mechanics with gravitation).
Why the authors talk about the Feynman approach is that physicists had used Feynman's approach to construct a model of the entire universe! This model would apply in the early times of the universe just after the big bang. Using Feynman's methods physicists concluded that the universe itself has several possible histories and that we are living in one of several possible universes.
As the authors state: "In this view, the universe appeared spontaneously, starting off in every possible way. Most of these correspond to other universes. While some of these universes are similar to ours, most are very different....In fact, many universes exist with many different sets of physical laws. Some people make a great mystery of this idea, sometimes called the multiverse concept, but these are just different expressions of the Feynman sum over histories."
Just after the big bang, there was an inflationary phase of the universe which was very expansionary. During this phase, the universe expanded by a factor of 10^(30) in 10^(-36) second!
If that is not weird enough, consider this: The physical constants in the universe such as the mass of the electron, the charge of the electron, the mass of the sun, the eccentricity of the earth's orbit, the value of the cosmological constant etc. seem extremely fine-tuned. If they had been off by a few percentage points, life as we know it would have been impossible. This brings us to the Anthropic Principle which says that the universe evolved in this particular fashion keeping the appearance of human beings in mind.
This would naturally lead to the conception of a Divine Creator but the authors dismiss any such concept. They hold that our universe is just one of several universes and our existence is but a freak accident.
While I found this ending a bit difficult to accept, I loved reading the book and hugely recommend it to anyone interested in the big questions.
Then I read somewhere that Stephen Hawking and Leonard Mlodinow's The Grand Design: New Answers to the Ultimate Questions of Life (2011) was as profound as Greene's book though much shorter. When I chanced upon this book in my University library I felt that I had been granted a second chance. And this book, boy, could I digest!
Stephen Hawking and Leonard Mlodinow have written a grand book, even grander I would say than A Brief History of Time (1988). The essence of the book is to explore fundamental questions: What is existence? Where did all this come from?
These are traditionally philosophical questions, but philosophy, the authors declare, is dead. "Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge."
The book is about a quest for a unified theory of the universe - the ultimate theory of everything. Hawking and Mlodinow state that physics has come up with just such a theory - something called M-theory (no one seems to know what the M stands for!). The authors state: "M-theory is not a theory in the usual sense. It is a whole family of different theories, each of which is a good description of observations only in some range of physical situations....The different theories in the M-theory family may look very different, but they can all be regarded as aspects of the same underlying theory."
The book is written in a lucid and entertaining style which even a layperson can follow. Hence it glosses over some of the scientific technicalities. So I couldn't figure out what M-theory really is. It seems to have to do something with string theory and supersymmetry (both of which are beyond my ken).
I have, however, studied quantum mechanics and could well understand the discussion on quantum physics. In particular, the Feynman path integral formulation (or "sum over histories" formulation) of quantum mechanics was well explained. When I read this book, I suddenly realized that Feynman had side-stepped the Heisenberg uncertainty principle simply by looking at all possible trajectories or histories that a quantum particle could take! This is mind-blowing. I learnt that all recent advancements in quantum mechanics has been due to use of Feynman path integral formulation rather than the Schrodinger formulation. Feynman diagrams - diagrams that show how bosons and fermions interact - are also introduced and I learnt that while Feynman diagrams had their origins in quantum electrodyanmics, (the quantum version of electromagnetism) they had spilled over into quantum chromodyamics (the theory of the strong nuclear force) and quantum gravity (the marriage of quantum mechanics with gravitation).
Why the authors talk about the Feynman approach is that physicists had used Feynman's approach to construct a model of the entire universe! This model would apply in the early times of the universe just after the big bang. Using Feynman's methods physicists concluded that the universe itself has several possible histories and that we are living in one of several possible universes.
As the authors state: "In this view, the universe appeared spontaneously, starting off in every possible way. Most of these correspond to other universes. While some of these universes are similar to ours, most are very different....In fact, many universes exist with many different sets of physical laws. Some people make a great mystery of this idea, sometimes called the multiverse concept, but these are just different expressions of the Feynman sum over histories."
Just after the big bang, there was an inflationary phase of the universe which was very expansionary. During this phase, the universe expanded by a factor of 10^(30) in 10^(-36) second!
If that is not weird enough, consider this: The physical constants in the universe such as the mass of the electron, the charge of the electron, the mass of the sun, the eccentricity of the earth's orbit, the value of the cosmological constant etc. seem extremely fine-tuned. If they had been off by a few percentage points, life as we know it would have been impossible. This brings us to the Anthropic Principle which says that the universe evolved in this particular fashion keeping the appearance of human beings in mind.
This would naturally lead to the conception of a Divine Creator but the authors dismiss any such concept. They hold that our universe is just one of several universes and our existence is but a freak accident.
While I found this ending a bit difficult to accept, I loved reading the book and hugely recommend it to anyone interested in the big questions.
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