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General Relativity and Gravitation (pdf)

Martin Rees

Just Six Numbers

In 'Just six numbers' Rees examines the question of why the universe seems so finely tuned for life. He looks at six dimensionless parameters of the universe, and explains why each had to have the value that it does in order for life to arise. The book is well written, by an expert in the subject, although sometimes I felt that it lacked the enthusiasm that a less knowledgable writer might bring. But there are no equations, and a few well placed diagrams, so I can recommend it to anyone who wants an expert view on some of the intruiging questions of life in the universe.

The first number is N, the ratio of the electric force to the gravitational force between two protons. This is followed by the efficiency of hydrogen fusion ε and then the two cosmological parameters Ω and λ. The last two numbers are Q,the measure of inhomogeneity in the early universe and 3, the number of space dimensions.

In between the chapters on the numbers themselves there are 'Our Cosmic Habitat' chapters, leading towards Rees' favoured explanation of the fine tuning - that of multiple universes. Possibly Rees decided that the 6 numbers weren't the best way to get his ideas across, since a couple of years later he wrote a whole book with the same title as these intermediate chapters.

Amazon.com info

Paperback 208 pages
ISBN: 0465036732
Salesrank: 189770
Weight:0.5 lbs

Published: 2001 Basic Books

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Amazon.co.uk info

Paperback 176 pages
ISBN: 0753810220
Salesrank: 9168
Weight:0.44 lbs

Published: 2000 Phoenix

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Amazon.ca info

Paperback 208 pages
ISBN: 0465036732
Salesrank: 198911
Weight:0.5 lbs

Published: 2001 Basic Books

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Product Description
The genesis of the universe elegantly explained in a simple theory based on just six numbers by one of the world's most renowned astrophysicists

Product Description

The genesis of the universe elegantly explained in a simple theory based on just six numbers by one of the world's most renowned astrophysicists

fabulous *****
i love reading about physics and the big bang theory. i know a little science and am fascinated by it. this book is well-written and extremely thought provoking. it touches on alot of modern scientific thought and i think most amateur scientists will thoroughly enjoy it. i was not disappopinted at all and i learned a great deal.

fabulous *****

i love reading about physics and the big bang theory. i know a little science and am fascinated by it. this book is well-written and extremely thought provoking. it touches on alot of modern scientific thought and i think most amateur scientists will thoroughly enjoy it. i was not disappopinted at all and i learned a great deal.

An easy, delightful read -- *****
An easy, delightful read -- It's easy reading, well written -- Rees introduces new concepts for the novice, but upon coming back to them later he reminds you what it was all about. "Everything should be made a simple as possible, but not simpler" : ) ~~ NowScape~com

An easy, delightful read -- *****

An easy, delightful read --
It's easy reading, well written -- Rees introduces new concepts for the novice, but upon coming back to them later he reminds you what it was all about. "Everything should be made a simple as possible, but not simpler" : )

~~ NowScape~com

Absolutely fascinating! *****
I could barely put this book down! It is dense, but so well-organized and written in such an accessible way, that you need not have any prior understanding of cosmology to grasp the concepts it addresses. It provided a much-needed workout for MY brain and, as well as answering many questions, it put a great deal into perspective for me.

Absolutely fascinating! *****

I could barely put this book down! It is dense, but so well-organized and written in such an accessible way, that you need not have any prior understanding of cosmology to grasp the concepts it addresses. It provided a much-needed workout for MY brain and, as well as answering many questions, it put a great deal into perspective for me.

Well-informed speculation, meandering text, ugly cover ****
Lame cosmic theories by would be experts are ubiquitous. This book is for amateurs who enjoy reading the ideas of someone who knows his science broadly and deeply. Sir Martin Rees' book informs the reader about "our cosmic habitat", thoroughly explains the significance of six crucial physical parameters that define the nature of the universe, shows where the limits of cosmological knowledge give way to hypotheses and includes many fascinating asides. The author's style is meandering and repetitious, but he generally manages to summarize complex concepts. The reader gets the story from the scientist and thus has no risk of false simplifications made by non-expert journalists. The explanations of the key concepts related to the six numbers are good enough for those who don't want formulae or underlying details. Rees' explanations and comparisons of phenomena by referring to orders of magnitude are particularly good, showing the significance of scale for "everything" between quantum physics and clusters of galaxies. The book's length, just under 200 pages, is good for an overview. It was fun to read insights and amusing reflections from a long career in the field. An example is the idea from Max Plank that theories are never abandoned until their opponents are all dead, so science advances one funeral at a time. According to the Big-Bang theory, time and space started with the Big-Bang, and therefore it makes no sense to speak of what happened in the seconds "before" the Big-Bang. In that sense, one can question whether it is worthwhile to speculate about anything "beyond" the known Universe. As the author admits, there is no concrete evidence of a Multiverse, therefore he is treading painfully close to metaphysics. His central argument about the whopping good luck of the proportions of physical forces related to the six numbers is worthy of short intellectual speculation. If evidence is found and falsifiable theories can be formulated, then further research is warranted, otherwise who cares? Fortunately the speculation is free of any religious tones, despite the facetious reference to Providence in the last sentence. At any rate, the book would be difficult reading for a creationist. The text requires some substantial editing. It is generally clear but not always. For example, the explanation of what strings are (page 159) too short and cryptic to be understandable. Are some tracts so repetitious just to meet the page count? The book was first published in 1999. I am not sure if subsequent books from the same author, such as the one called "Our Cosmic Habitat", are in fact revised editions of this book. The "Basic Books" edition from 2000 has an outstandingly ugly cover, but the contents are worth reading.

Well-informed speculation, meandering text, ugly cover ****

Lame cosmic theories by would be experts are ubiquitous. This book is for amateurs who enjoy reading the ideas of someone who knows his science broadly and deeply. Sir Martin Rees' book informs the reader about "our cosmic habitat", thoroughly explains the significance of six crucial physical parameters that define the nature of the universe, shows where the limits of cosmological knowledge give way to hypotheses and includes many fascinating asides. The author's style is meandering and repetitious, but he generally manages to summarize complex concepts. The reader gets the story from the scientist and thus has no risk of false simplifications made by non-expert journalists.

The explanations of the key concepts related to the six numbers are good enough for those who don't want formulae or underlying details. Rees' explanations and comparisons of phenomena by referring to orders of magnitude are particularly good, showing the significance of scale for "everything" between quantum physics and clusters of galaxies. The book's length, just under 200 pages, is good for an overview. It was fun to read insights and amusing reflections from a long career in the field. An example is the idea from Max Plank that theories are never abandoned until their opponents are all dead, so science advances one funeral at a time.

According to the Big-Bang theory, time and space started with the Big-Bang, and therefore it makes no sense to speak of what happened in the seconds "before" the Big-Bang. In that sense, one can question whether it is worthwhile to speculate about anything "beyond" the known Universe. As the author admits, there is no concrete evidence of a Multiverse, therefore he is treading painfully close to metaphysics. His central argument about the whopping good luck of the proportions of physical forces related to the six numbers is worthy of short intellectual speculation. If evidence is found and falsifiable theories can be formulated, then further research is warranted, otherwise who cares? Fortunately the speculation is free of any religious tones, despite the facetious reference to Providence in the last sentence. At any rate, the book would be difficult reading for a creationist.

The text requires some substantial editing. It is generally clear but not always. For example, the explanation of what strings are (page 159) too short and cryptic to be understandable. Are some tracts so repetitious just to meet the page count?

The book was first published in 1999. I am not sure if subsequent books from the same author, such as the one called "Our Cosmic Habitat", are in fact revised editions of this book. The "Basic Books" edition from 2000 has an outstandingly ugly cover, but the contents are worth reading.

Deep Science, Easy Read *****
I'm a big fan of anything that helps me make sense of the universe, and this book is at or near the top of my list. It is very readable and held me riveted to the end. If the deep physical structure of the universe fascinates you, you might want to check this one out.

Deep Science, Easy Read *****

I'm a big fan of anything that helps me make sense of the universe, and this book is at or near the top of my list. It is very readable and held me riveted to the end. If the deep physical structure of the universe fascinates you, you might want to check this one out.

Just Six Numbers ***
'Just Six Numbers' is a book with a fascinating premise, but one that I feel is lacking in execution. The amazon synopsis and other reviewers explain the content quite well so I won't duplicate it here. The ideas are well thought out, but I found Rees' style to be slightly rambling at times and it took him some time to get to the point being made. Each chapter is pretty much self contained and has some insightful facts about the universe, physics and cosmology in general and they are then tied together towards the end when Rees talks about multi-verses. If you're looking for a good entry book about cosmology then I'd suggest you check out Simon Singhs 'Big Bang' or Carl Sagan's 'Cosmos' first, but if these books have piqued your interest and you are looking for something more, or if the topic of this book particularly appeals, then this is a good place to turn to. Worth a look if you like popular science books and you are prepared to persevere with Rees' writing style.

Just Six Numbers ***

'Just Six Numbers' is a book with a fascinating premise, but one that I feel is lacking in execution. The amazon synopsis and other reviewers explain the content quite well so I won't duplicate it here. The ideas are well thought out, but I found Rees' style to be slightly rambling at times and it took him some time to get to the point being made. Each chapter is pretty much self contained and has some insightful facts about the universe, physics and cosmology in general and they are then tied together towards the end when Rees talks about multi-verses. If you're looking for a good entry book about cosmology then I'd suggest you check out Simon Singhs 'Big Bang' or Carl Sagan's 'Cosmos' first, but if these books have piqued your interest and you are looking for something more, or if the topic of this book particularly appeals, then this is a good place to turn to. Worth a look if you like popular science books and you are prepared to persevere with Rees' writing style.

Numbers that Govern the Universe. ****
This book falls marginally into popular science (note how the eponymous six numbers are given as dimensionless) but is an absorbing book nonetheless. An interesting idea (but I suspect a little too neat) is that the universe is the magnitude it is because of how long it is likely to take for sentient beings to form from atoms. I would have preferred if Prof. Rees had allowed the reader reach his own conclusions on the importance of this and other findings (the extraordinary precision of omega for example) rather than go down the tired (and somewhat trying) Dawkins road (why has Oxford become an atheist university far removed from the original intention?) Explaining away the existence of God with the unproved (if not unprovable) multi-verse in my opinion requires a leap of faith from the reader far greater than our well-founded millenia old theism.

Numbers that Govern the Universe. ****

This book falls marginally into popular science (note how the eponymous six numbers are given as dimensionless) but is an absorbing book nonetheless. An interesting idea (but I suspect a little too neat) is that the universe is the magnitude it is because of how long it is likely to take for sentient beings to form from atoms. I would have preferred if Prof. Rees had allowed the reader reach his own conclusions on the importance of this and other findings (the extraordinary precision of omega for example) rather than go down the tired (and somewhat trying) Dawkins road (why has Oxford become an atheist university far removed from the original intention?) Explaining away the existence of God with the unproved (if not unprovable) multi-verse in my opinion requires a leap of faith from the reader far greater than our well-founded millenia old theism.

Thought provoking ****
The central hypotheisis in this book is that if any of just six numbers, were different, our universe would be entirely different. Some critical consequence such as planets not been able to form, stars not emitting enough energy or evolution not having enough time for our species to develop would be the result of any of these numbers being different. When I first heard of this book, I was naievly thinking the numbers would include PI, the speed of light or some of the well other known constants from the scientific world. The numbers and their associated concepts are far more abstract. The six numbers are: 1. N This is the ratio of electrical force to gravitational force between atoms. This is 10 pow 37. If this number were slightly lower, molecules would behave similarly but less atoms would be needed to make a star and it wouldn't last as long. The star would die sooner, meaning planets such as our own wouldn't get the length of time needed for evolution to bring species such as our's into existence. 2. E This is the percentage of mass that is converted into energy, when hyrogen atoms fuse to form helium. Strong nuclear force, is the force which the particles that make up an atomic nucleus (protons and nuetrons) together. This force acts is the dominant force in the microworld where it overcomes the electrical repulsion which would cause the protons to fly apart. The amount of energy released when atoms undergo nuclear fusion depends on the strength of strong nuclear force as this force that is overcome. If E was lower (say 0.006) it would mean, that the strong nuclear force or nuclear glue was weaker and protons and nuetrons would never overcome the electrical repulsion and attach. Elements such as helium would never form. If E was larger (say 0.008) no hyrdogen (which has one proton, no nuetron) would have survived from the big bang. Two protons would have been able to bind as they would have easily overcome the electrical repulsion to each other. This would have happened in the early universe so that all hydrogen would quickly be gone. No hydrogen, amongst other things means no water. 3. Omega. The universe is quite empty. Omega is the ratio of actual density to critical density. If the universe were closer to critical density, gravitational force would over come explosive energy and the universe could collapse. If the actual density was too small, no stars or galaxies would have formed because gravitational energy would not be strong enough. 4. Lambda. This controls the expansion of the universe. It relates to the anti gravitational force (a new force and recent discovery) which determines the speed of expansions of the universe. I gathered that not a lot is known about this other than it is a small number. Had it not have been galaxies etc would not have formed. 5. Q: 10 pow -5. This ratio of ratio of energy required to break up stars and galaxies to their rest mass energy (i.e. E = mC pow2). This is 10 pow -5. If Q were less the universe would be structureless. If Q were too large no stars or solar systems would survive. 6. D: Number of spatial dimensions which is 3. If D was 2 or 4 life could not exist. Although this book is well written some of the concepts in it are difficult to grasp. There is a lot more in this book than just simple numbers. There are some very sophisticated concepts in this book. If you are doing a PhD in Theoritical Physics its probably quite easy, but I found myself having to re-read several passages to grasp the ideas. Other Universe-esque books such Stephen Hawkings' 'Brief History of Time' or Simon Singh's 'The Big Bang', I found a lot easier to understand and arguably better. That said, the overall hypotheisis that just 6 numbers play a critical role in shaping our universe is fascinating, mind boggling and well presented.

Thought provoking ****

The central hypotheisis in this book is that if any of just six numbers, were different, our universe would be entirely different. Some critical consequence such as planets not been able to form, stars not emitting enough energy or evolution not having enough time for our species to develop would be the result of any of these numbers being different.

When I first heard of this book, I was naievly thinking the numbers would include PI, the speed of light or some of the well other known constants from the scientific world. The numbers and their associated concepts are far more abstract.

The six numbers are:

1. N
This is the ratio of electrical force to gravitational force between atoms. This is 10 pow 37.
If this number were slightly lower, molecules would behave similarly but less atoms would be needed to make a star and it wouldn't last as long. The star would die sooner, meaning planets such as our own wouldn't get the length of time needed for evolution to bring species such as our's into existence.

2. E
This is the percentage of mass that is converted into energy, when hyrogen atoms fuse to form helium.
Strong nuclear force, is the force which the particles that make up an atomic nucleus (protons and nuetrons) together. This force acts is the dominant force in the microworld where it overcomes the electrical repulsion which would cause the protons to fly apart. The amount of energy released when atoms undergo nuclear fusion depends on the strength of strong nuclear force as this force that is overcome.

If E was lower (say 0.006) it would mean, that the strong nuclear force or nuclear glue was weaker and protons and nuetrons would never overcome the electrical repulsion and attach. Elements such as helium would never form.

If E was larger (say 0.008) no hyrdogen (which has one proton, no nuetron) would have survived from the big bang. Two protons would have been able to bind as they would have easily overcome the electrical repulsion to each other. This would have happened in the early universe so that all hydrogen would quickly be gone. No hydrogen, amongst other things means no water.

3. Omega.
The universe is quite empty. Omega is the ratio of actual density to critical density. If the universe were closer to critical density, gravitational force would over come explosive energy and the universe could collapse. If the actual density was too small, no stars or galaxies would have formed because gravitational energy would not be strong enough.

4. Lambda. This controls the expansion of the universe. It relates to the anti gravitational force (a new force and recent discovery) which determines the speed of expansions of the universe. I gathered that not a lot is known about this other than it is a small number. Had it not have been galaxies etc would not have formed.

5. Q: 10 pow -5. This ratio of ratio of energy required to break up stars and galaxies to their rest mass energy (i.e. E = mC pow2). This is 10 pow -5. If Q were less the universe would be structureless. If Q were too large no stars or solar systems would survive.

6. D: Number of spatial dimensions which is 3. If D was 2 or 4 life could not exist.

Although this book is well written some of the concepts in it are difficult to grasp. There is a lot more in this book than just simple numbers. There are some very sophisticated concepts in this book. If you are doing a PhD in Theoritical Physics its probably quite easy, but I found myself having to re-read several passages to grasp the ideas. Other Universe-esque books such Stephen Hawkings' 'Brief History of Time' or Simon Singh's 'The Big Bang', I found a lot easier to understand and arguably better.

That said, the overall hypotheisis that just 6 numbers play a critical role in shaping our universe is fascinating, mind boggling and well presented.

One universe or many? *****
What an excellent book! Martin Rees looks at six facets of the universe, and considers how changing any one of these parameters would lead to a very different type of universe to the we can see (and infer) all around us. He explains complex ideas beautifully and elegantly. He helps the reader wonder if this universe was designed for our purposes (sorry chaps, we're not that important), or whether we evolved to take advantage of the conditions that were available. And the logical extensions to his thinking and writing are really quite breathtaking. Has our universe expanded and crashed many times? Or is our view of just one universe simply limited and parochial? And if there are many universes, how would they form and what would they look like? Rees using mathematics, physics and some creative and highly enjoyable thinking to talk us through these ideas. And the idea that there is no chance of us being here? Well ...you're almost right. But there's at least one universe full of difference between no chance and almost no chance ... Makes you think, doesn't it?

One universe or many? *****

What an excellent book!

Martin Rees looks at six facets of the universe, and considers how changing any one of these parameters would lead to a very different type of universe to the we can see (and infer) all around us.

He explains complex ideas beautifully and elegantly. He helps the reader wonder if this universe was designed for our purposes (sorry chaps, we're not that important), or whether we evolved to take advantage of the conditions that were available.

And the logical extensions to his thinking and writing are really quite breathtaking. Has our universe expanded and crashed many times? Or is our view of just one universe simply limited and parochial? And if there are many universes, how would they form and what would they look like?

Rees using mathematics, physics and some creative and highly enjoyable thinking to talk us through these ideas.

And the idea that there is no chance of us being here?

Well ...you're almost right. But there's at least one universe full of difference between no chance and almost no chance ...

Makes you think, doesn't it?

A problem of Prejudice ****
You can lead a horse to water, but you cannot make it drink. It appears that you can also lead a Scientist to the evidence that there is a reason for the Cosmos, but you cannot make him think, particularly if the evidence points to an intelligent Creator. The evidence that Martin Rees presents provides substantial support for my Thesis, "The Process of the Cosmos", also published in 1999. This Thesis is freely available on my Website. The New Jersey City University Library refers to my Website:"Big Questions of Philosophy and the Answers" - in the following terms:- "Dr. Anthony Kelly's thesis is to examine nothing less than the relationship between God, humanity and the history of the universe, exploring unresolved philosophical questions about the cosmos and human nature which go back to Aristotle." Martin Rees is prepared to go to absurd lengths to avoid the conclusion his evidence leads to, that there is a God. He proposes the existence of multiple universes as an alternative to an intelligent Creator, our universe only becoming fine tuned "by accident". He admits not only that there is no evidence for such multiple universes, saying "it is only a hunch" (page 174). He then admits that if there were such universes we could never know anything about them. He finds this approach more comforting than accepting the existence of a God. Perhaps Ree's real problem is the fanciful religious notion that God intervenes in the world, rather than the perception that God is necessarily "hands-off" the Cosmos, the world being humanity's "Do-it-yourself kit".

A problem of Prejudice ****

You can lead a horse to water, but you cannot make it drink. It appears that you can also lead a Scientist to the evidence that there is a reason for the Cosmos, but you cannot make him think, particularly if the evidence points to an intelligent Creator.

The evidence that Martin Rees presents provides substantial support for my Thesis, "The Process of the Cosmos", also published in 1999. This Thesis is freely available on my Website. The New Jersey City University Library refers to my Website:"Big Questions of Philosophy and the Answers" - in the following terms:-
"Dr. Anthony Kelly's thesis is to examine nothing less than the relationship between God, humanity and the history of the universe, exploring unresolved philosophical questions about the cosmos and human nature which go back to Aristotle."

Martin Rees is prepared to go to absurd lengths to avoid the conclusion his evidence leads to, that there is a God. He proposes the existence of multiple universes as an alternative to an intelligent Creator, our universe only becoming fine tuned "by accident". He admits not only that there is no evidence for such multiple universes, saying "it is only a hunch" (page 174). He then admits that if there were such universes we could never know anything about them. He finds this approach more comforting than accepting the existence of a God. Perhaps Ree's real problem is the fanciful religious notion that God intervenes in the world, rather than the perception that God is necessarily "hands-off" the Cosmos, the world being humanity's "Do-it-yourself kit".

Is this "just the way things are?" ****
This book is about cosmology, and specifically the manner in which our universe is constructed. The basic premise is that six dimensionless numbers govern the state of our universe so precisely that if any of them changed by even a tiny amount the result would be the impossibility of life, as we know it. The term "number" here is important, as these are all dimensionless ratios and fractions. According to Rees the numbers are: 1) Ratio of electrical force to gravitational force (10^36) 2) Fraction of rest mass converted to energy when hydrogen fuses (0.007) 3) Ratio of actual density to critical density in universe (close to 1.0) 4) Ratio of gravity to antigravity (very small) 5) Ratio of gravitational binding energy of galaxies to their rest-mass energy (10^-5) 6) Number of spatial dimensions in our universe (3) Rees argues that if any of these numbers were slightly different from what they really are, the universe as we know it would not exist. For example, if the ratio of electrical force to gravitational force was larger (by just a "few zeros") the universe would exist for only a short time and there would be no time for the biological evolution that led to animals such as us. Similarly, if the fusion of hydrogen to helium released much more energy than it does, stars would burn out more quickly, again leading to a universe in which animals like us would not have time to evolve. Punctuated throughout the book are references (sometimes abbreviated) to the larger question of why these six numbers, and why the values they have. There's a natural sense of awe and amazement that these numbers all just happened to have precisely the values needed to make life, as we know it, possible. Such amazement leads, naturally enough, to various attempts to explain the apparent coincidence. Perhaps the first question is whether it's a coincidence at all. That is, perhaps the universe was "designed" by a "god" who picked the numbers, knowing before hand exactly what values were needed. Of course this explanation leaves us asking why there is a "god," which seems like as big (or bigger) question than why a half-dozen ratios have the values they do. So this line of reasoning doesn't seem to take us very far. Another approach is to invoke the anthropic principle (I think this is the one Rees prefers). In other words, we see the universe the way it is because if it were any other way we would not exist to wonder about it. Okay, so that doesn't really "explain" anything, either - or, at the very least, it seems just a little too convenient. After all, couldn't we invoke the anthropic principle for just about anything? And if we did, what would happen to our sense of wonder and our desire to learn more - to push back the string of "why?" questions at least one more level? On the other hand, suppose the apparent coincidence is just that; apparent? Suppose these numbers are all somehow related. Suppose that if any one of them is in the right range, all the others will be in the right range, too. That might be the case, but as Rees explains, "At the moment ... we cannot predict any one of them from the values of the others." Although we don't know for sure, it's possible that physics will eventually uncover the "theory of everything" and the ratios will all be in there, in a very nateral and logical way. Or, perhaps the answer is simply "because that's the way things are." Anyone who's been around children (or been a child themselves) knows about the "why?" game. It starts out with something like this: "Daddy (or Mommy), why is the sky blue?" So you explain about Rayleigh scattering and the fact that molecules in the atmosphere scatter photons with an efficiency that's inversely proportional to the fourth power of the wavelength. You are hardly finished when the next question shoots across your bow: Daddy (or Mommy) why is there an atmosphere?" So you dutifully explain planetary evolution, the expulsion of vast quantities of carbon dioxide that facilitated the evolution of life forms that exploit photosynthesis, producing oxygen, etc. Then the third question comes "Daddy (or Mommy) why do planets form?" You follow this question with a short lecture on the planetary nebular hypothesis. But the questions don't stop; they just keep coming and coming and coming. There is, it seems, never an answer that cannot be followed with "why?" If we did have a "theory of everything," and if it did explain these six ratios, there would still be the question "why this theory of everything?" And if we answer that, there undoubtedly will be another "why" question after it. Is there ever an answer that cannot be followed with "why?" That's the real question, for me, in Rees' book. Would the string of questions stop if we could answer why there are just "six numbers," and why they have the values they have? Or, could it be that we might answer that question simply to discover a new "why" question? And if not, how would we know if or when we've arrived at the final answer: "Because that's just the way things are?" This book covers a lot of ground, and does so in abbreviated style in many instances. It's something of a quick cosmic tour. I liked it best for the way it helped me think a little more deeply about the bigger picture. It's a fun book to read, and definitely well worth the time.

Is this "just the way things are?" ****

This book is about cosmology, and specifically the manner in which our universe is constructed. The basic premise is that six dimensionless numbers govern the state of our universe so precisely that if any of them changed by even a tiny amount the result would be the impossibility of life, as we know it.

The term "number" here is important, as these are all dimensionless ratios and fractions. According to Rees the numbers are:
1) Ratio of electrical force to gravitational force (10^36)
2) Fraction of rest mass converted to energy when hydrogen fuses (0.007)
3) Ratio of actual density to critical density in universe (close to 1.0)
4) Ratio of gravity to antigravity (very small)
5) Ratio of gravitational binding energy of galaxies to their rest-mass energy (10^-5)
6) Number of spatial dimensions in our universe (3)

Rees argues that if any of these numbers were slightly different from what they really are, the universe as we know it would not exist. For example, if the ratio of electrical force to gravitational force was larger (by just a "few zeros") the universe would exist for only a short time and there would be no time for the biological evolution that led to animals such as us. Similarly, if the fusion of hydrogen to helium released much more energy than it does, stars would burn out more quickly, again leading to a universe in which animals like us would not have time to evolve.

Punctuated throughout the book are references (sometimes abbreviated) to the larger question of why these six numbers, and why the values they have. There's a natural sense of awe and amazement that these numbers all just happened to have precisely the values needed to make life, as we know it, possible. Such amazement leads, naturally enough, to various attempts to explain the apparent coincidence.

Perhaps the first question is whether it's a coincidence at all. That is, perhaps the universe was "designed" by a "god" who picked the numbers, knowing before hand exactly what values were needed. Of course this explanation leaves us asking why there is a "god," which seems like as big (or bigger) question than why a half-dozen ratios have the values they do. So this line of reasoning doesn't seem to take us very far.

Another approach is to invoke the anthropic principle (I think this is the one Rees prefers). In other words, we see the universe the way it is because if it were any other way we would not exist to wonder about it. Okay, so that doesn't really "explain" anything, either - or, at the very least, it seems just a little too convenient. After all, couldn't we invoke the anthropic principle for just about anything? And if we did, what would happen to our sense of wonder and our desire to learn more - to push back the string of "why?" questions at least one more level?

On the other hand, suppose the apparent coincidence is just that; apparent? Suppose these numbers are all somehow related. Suppose that if any one of them is in the right range, all the others will be in the right range, too. That might be the case, but as Rees explains, "At the moment ... we cannot predict any one of them from the values of the others." Although we don't know for sure, it's possible that physics will eventually uncover the "theory of everything" and the ratios will all be in there, in a very nateral and logical way.

Or, perhaps the answer is simply "because that's the way things are."

Anyone who's been around children (or been a child themselves) knows about the "why?" game. It starts out with something like this: "Daddy (or Mommy), why is the sky blue?" So you explain about Rayleigh scattering and the fact that molecules in the atmosphere scatter photons with an efficiency that's inversely proportional to the fourth power of the wavelength. You are hardly finished when the next question shoots across your bow: Daddy (or Mommy) why is there an atmosphere?" So you dutifully explain planetary evolution, the expulsion of vast quantities of carbon dioxide that facilitated the evolution of life forms that exploit photosynthesis, producing oxygen, etc. Then the third question comes "Daddy (or Mommy) why do planets form?" You follow this question with a short lecture on the planetary nebular hypothesis. But the questions don't stop; they just keep coming and coming and coming. There is, it seems, never an answer that cannot be followed with "why?"

If we did have a "theory of everything," and if it did explain these six ratios, there would still be the question "why this theory of everything?" And if we answer that, there undoubtedly will be another "why" question after it. Is there ever an answer that cannot be followed with "why?" That's the real question, for me, in Rees' book. Would the string of questions stop if we could answer why there are just "six numbers," and why they have the values they have? Or, could it be that we might answer that question simply to discover a new "why" question? And if not, how would we know if or when we've arrived at the final answer: "Because that's just the way things are?"

This book covers a lot of ground, and does so in abbreviated style in many instances. It's something of a quick cosmic tour. I liked it best for the way it helped me think a little more deeply about the bigger picture. It's a fun book to read, and definitely well worth the time.

Just 6 words...? *****
6 words: This book blew my bloody mind!

Just 6 words...? *****

6 words: This book blew my bloody mind!

JUST a little book that explains A BIG TOPIC!! *****
=====> This eleven chapter book (with seven excellent illustrations) by U.K. Astronomer Royal (a title bestowed upon a distinguished astronomer) Sir Martin Rees is about the following: (1) Cosmology (branch of astronomy concerned with the origin, properties, and evolution of the universe) (2) Theoretical cosmology (that establishes models which attempt to describe the universe's observed properties) (3) Speculative cosmology (which is based on hypotheses). These are large topics that can be incredibly complex and detailed but Rees manages to explain these topics in only 160 pages! As well, the language involved in explaining these topics can be very technical but Rees manages to reduce the technicality resulting in a book that's easy to follow and thus that's "intended for general readers." I agree that this deceptively concise book is written for the general reader. However, for those not used to this kind of material, I suggest reading this book slowly since Rees cuts out extraneous detail. Whether you are used to this kind of material or not, you'll find that this book offers a stimulating and accessible account of new discoveries, and perceptive insights into cosmology. In fact, this book is so well-written, that according to Rees' internet site, this book is being considered for translation into twenty languages! Rees, in the last paragraph of this book, summarizes its contents: "A theme of this book has been the intimate links between the microworld and the cosmos...Our everyday world...[shaped] by subatomic forces...owes its existence to our universe's well-tuned expansion rate, the processes of galaxy formation, the forging of carbon and oxygen in ancient stars, and so forth. A few basic physical laws set the 'rules'; our [universe's] emergence from a simple Big Bang was sensitive to six 'cosmic numbers.' Had [any one of] these numbers not been 'well-tuned' [or precise enough], the gradual unfolding of layer upon layer of [the universe's] complexity would have been [suppressed]." That is, "there would have been no stars and no life." This book has a framework that is centered around the above six cosmic numbers or as Rees states: "[T]his book is the story of six [numbers] that are crucial for our universe, and our [that is, biological life's] place in it." What are these six numbers? Three of them relate to forces in the universe (two of these numbers are basic forces while one of them deals with an "unsuspected new force"); one number is concerned with the basic "texture" of the universe; and two deal with the properties of space itself. As already mentioned, all these numbers have a precise value that allow our universe (and us) to exist. Rees asks: "Is this [precision] just...a coincedence? Or is it providence of a benign Creator?" Besides learning about these six critical numbers, the reader will learn much more. Some other things you'll learn about are antimatter, atomic structure, atoms, neutrinos, quarks, the periodoc table, the importance of hydrogen, deuterium, and helium, biological evolution, dark matter, black holes, cosmic background radiation, protoplanets and planets, galactic clusters, the strong nuclear force, extraterrestrial intelligence, particle physics, quantum theory, relativity theory, supernovae, and superstring theory. You'll read about such people as Einstein, Arthur Eddington, Michael Faraday, Richard Feynman, Galileo, Newton, Stephen Hawking, Fred Hoyle, and Edwin Hubble. At the end of the book, Rees asks more questions: "Are there an infinity of other universes [called collectively the 'multiverse'] that are "badly tuned," and therefore sterile? Is our universe an "oasis" in a mutiverse? Should we seek out other reasons for the...values of our six [cosmic] numbers?" My only minor complaint (and I'm nit-picking here) is that in chapter one Rees states the value of one of these six cosmic numbers. (It is a one followed by 36 zeros.) Instead of expressing this number in scientific notation, he actually writes out all the zeros. I reasoned that by doing this he was attempting to convey a sense of the immensity of this number. However, in chapter three he does the same thing. Why? Writing this long number out once was quite sufficient. In conclusion, this book offers an accessible account of the forces that shape -- everything. You'll find this book to be an enjoyable and provocative intellectual adventure! <=====>

JUST a little book that explains A BIG TOPIC!! *****

=====>

This eleven chapter book (with seven excellent illustrations) by U.K. Astronomer Royal (a title bestowed upon a distinguished astronomer) Sir Martin Rees is about the following:

(1) Cosmology (branch of astronomy concerned with the origin, properties, and evolution of the universe)
(2) Theoretical cosmology (that establishes models which attempt to describe the universe's observed properties)
(3) Speculative cosmology (which is based on hypotheses).

These are large topics that can be incredibly complex and detailed but Rees manages to explain these topics in only 160 pages! As well, the language involved in explaining these topics can be very technical but Rees manages to reduce the technicality resulting in a book that's easy to follow and thus that's "intended for general readers."

I agree that this deceptively concise book is written for the general reader. However, for those not used to this kind of material, I suggest reading this book slowly since Rees cuts out extraneous detail. Whether you are used to this kind of material or not, you'll find that this book offers a stimulating and accessible account of new discoveries, and perceptive insights into cosmology. In fact, this book is so well-written, that according to Rees' internet site, this book is being considered for translation into twenty languages!

Rees, in the last paragraph of this book, summarizes its contents: "A theme of this book has been the intimate links between the microworld and the cosmos...Our everyday world...[shaped] by subatomic forces...owes its existence to our universe's well-tuned expansion rate, the processes of galaxy formation, the forging of carbon and oxygen in ancient stars, and so forth. A few basic physical laws set the 'rules'; our [universe's] emergence from a simple Big Bang was sensitive to six 'cosmic numbers.' Had [any one of] these numbers not been 'well-tuned' [or precise enough], the gradual unfolding of layer upon layer of [the universe's] complexity would have been [suppressed]." That is, "there would have been no stars and no life."

This book has a framework that is centered around the above six cosmic numbers or as Rees states: "[T]his book is the story of six [numbers] that are crucial for our universe, and our [that is, biological life's] place in it." What are these six numbers? Three of them relate to forces in the universe (two of these numbers are basic forces while one of them deals with an "unsuspected new force"); one number is concerned with the basic "texture" of the universe; and two deal with the properties of space itself. As already mentioned, all these numbers have a precise value that allow our universe (and us) to exist. Rees asks: "Is this [precision] just...a coincedence? Or is it providence of a benign Creator?"

Besides learning about these six critical numbers, the reader will learn much more. Some other things you'll learn about are antimatter, atomic structure, atoms, neutrinos, quarks, the periodoc table, the importance of hydrogen, deuterium, and helium, biological evolution, dark matter, black holes, cosmic background radiation, protoplanets and planets, galactic clusters, the strong nuclear force, extraterrestrial intelligence, particle physics, quantum theory, relativity theory, supernovae, and superstring theory. You'll read about such people as Einstein, Arthur Eddington, Michael Faraday, Richard Feynman, Galileo, Newton, Stephen Hawking, Fred Hoyle, and Edwin Hubble.

At the end of the book, Rees asks more questions: "Are there an infinity of other universes [called collectively the 'multiverse'] that are "badly tuned," and therefore sterile? Is our universe an "oasis" in a mutiverse? Should we seek out other reasons for the...values of our six [cosmic] numbers?"

My only minor complaint (and I'm nit-picking here) is that in chapter one Rees states the value of one of these six cosmic numbers. (It is a one followed by 36 zeros.) Instead of expressing this number in scientific notation, he actually writes out all the zeros. I reasoned that by doing this he was attempting to convey a sense of the immensity of this number. However, in chapter three he does the same thing. Why? Writing this long number out once was quite sufficient.

In conclusion, this book offers an accessible account of the forces that shape -- everything. You'll find this book to be an enjoyable and provocative intellectual adventure!

<=====>

a Cosmological " What If" book ****
For the universe to be as the universe is, the author traces this fact to the happenstance of six numbers or ratios, of forces. Examples of this forces are, gravity, nuclear binding force, weak and strong force, density of the universe etc. The author's thinking is something like this, If gravity was stronger the big bang would have spent its outward force already and be contracting. A two-billion year cyclical universe would not have the time to form planets, or for life to form. If gravity was less strong then planets would not have appeared. The author proceeds through each ratio, considering the min and max values. Vary too much from the present ratio and we would not exist, or life, the earth or the universe would not exist. Interesting concept. The surprising thing is the narrow range of some of the values. It shows that we exist from a combination of these numbers within such a narrow range that it borders on the miraculous that we exist at all. Is this. an argument for infinite universes with infinite chances to form or a universe built upon a master plan ?

a Cosmological " What If" book ****

For the universe to be as the universe is, the author traces this fact to the happenstance of six numbers or ratios, of forces. Examples of this forces are, gravity, nuclear binding force, weak and strong force, density of the universe etc. The author's thinking is something like this, If gravity was stronger the big bang would have spent its outward force already and be contracting. A two-billion year cyclical universe would not have the time to form planets, or for life to form. If gravity was less strong then planets would not have appeared. The author proceeds through each ratio, considering the min and max values. Vary too much from the present ratio and we would not exist, or life, the earth or the universe would not exist. Interesting concept. The surprising thing is the narrow range of some of the values. It shows that we exist from a combination of these numbers within such a narrow range that it borders on the miraculous that we exist at all. Is this. an argument for infinite universes with infinite chances to form or a universe built upon a master plan ?

Very Interesting *****
The Astronomer Royal (the Queen's own?) seems to take seriously Linde's chaotic inflation and the idea that our universe is just one among countless others in a "multiverse." I find it significant that even so great an authority as Steve Weinberg does not dismiss it out of hand. The notion that our universe is finite and has a beginning in time is of course no longer speculation. But the idea that there are other universes out there with totally different fundamental constants and probably different number (some many more than ours) of dimensions as well is just so hard to fathom. It's mind-boggling to me how anyone can prove or disprove it; yet here it is and it's not a crackpot idea from some harebrained science-fiction writers. Sir Martin is a very eminent astronomer - far more credible than Carl Sagan even. But if you look back on the astronomical discoveries in the past two millennia, clearly our place in the universe/multiverse has been found to be less and less unique. First we were found to be no longer the only planet, then no longer the planet in the center of the solar system, then no longer the only solar system, then no longer the solar system in the center, then no longer the only galaxy, then no longer the galaxy in the center (because the universe has no center).....and now, perhaps, no longer the only universe. It's all so logical. Sir Martin seems to think, surprisingly given what he now believes, that intelligent life may be rare in the universe. I for one cannot believe that life, intelligent or not, is rare in our universe, and if there are other universes out there, the odds are considerably higher still. (The Drake Equation suggests there are billions of planets in our universe alone with intelligent lifeforms, and many millions in our galaxy alone.) Perhaps he doesn't want to be taken for a mad scientist encouraging "raelians", ufologists, X-file enthusiasts, "abductees" and other such idiots. The damage it can do to his career is all too real. But all he has to do is to draw a clear distinction between the odds for life, and in particular intelligent life, in other worlds on the one hand, and the odds that any of them have visited us on the other. Again, I think the odds are very high for the former, but almost certainly nil for the latter. In any case, the possibility of our finding these lifeforms is not very high, since considering the distances involved our space technology is still in the Stone Age. Interestingly, the religious implications are profound if we are indeed living in a multiverse in which our own universe is merely one among countless others, all very different from one another. It may be impossible to prove the origin of such a multiverse, if in fact it even has a beginning. Perhaps the multiverse has always been there, more or less unchanging except at local levels. Or perhaps the multiverse itself has a beginning, and is again only one among countless others. Either way, the role of a Creator cannot be proven - perhaps never can be. No math is needed to read this book, but it can still be heavy going for the uninitiated, despite its deceptive shortness. Have an astronomy dictionary handy, or else be very patient and careful when following his arguments. Referring back to his earlier book "Before the Beginning" may be a good idea, as is looking things up in an introductory astronomy textbook. If you're still stuck, skip & move on to other interesting topics. Eventually the pieces will fall into place. If not, it may not be your fault, but you're out of luck because Martin John Rees is one of the clearest & most admired educators in astronomy and astrophysics for laypeople.

Very Interesting *****

The Astronomer Royal (the Queen's own?) seems to take seriously Linde's chaotic inflation and the idea that our universe is just one among countless others in a "multiverse." I find it significant that even so great an authority as Steve Weinberg does not dismiss it out of hand.

The notion that our universe is finite and has a beginning in time is of course no longer speculation. But the idea that there are other universes out there with totally different fundamental constants and probably different number (some many more than ours) of dimensions as well is just so hard to fathom. It's mind-boggling to me how anyone can prove or disprove it; yet here it is and it's not a crackpot idea from some harebrained science-fiction writers. Sir Martin is a very eminent astronomer - far more credible than Carl Sagan even.

But if you look back on the astronomical discoveries in the past two millennia, clearly our place in the universe/multiverse has been found to be less and less unique. First we were found to be no longer the only planet, then no longer the planet in the center of the solar system, then no longer the only solar system, then no longer the solar system in the center, then no longer the only galaxy, then no longer the galaxy in the center (because the universe has no center).....and now, perhaps, no longer the only universe. It's all so logical.

Sir Martin seems to think, surprisingly given what he now believes, that intelligent life may be rare in the universe. I for one cannot believe that life, intelligent or not, is rare in our universe, and if there are other universes out there, the odds are considerably higher still. (The Drake Equation suggests there are billions of planets in our universe alone with intelligent lifeforms, and many millions in our galaxy alone.) Perhaps he doesn't want to be taken for a mad scientist encouraging "raelians", ufologists, X-file enthusiasts, "abductees" and other such idiots. The damage it can do to his career is all too real. But all he has to do is to draw a clear distinction between the odds for life, and in particular intelligent life, in other worlds on the one hand, and the odds that any of them have visited us on the other. Again, I think the odds are very high for the former, but almost certainly nil for the latter. In any case, the possibility of our finding these lifeforms is not very high, since considering the distances involved our space technology is still in the Stone Age.

Interestingly, the religious implications are profound if we are indeed living in a multiverse in which our own universe is merely one among countless others, all very different from one another. It may be impossible to prove the origin of such a multiverse, if in fact it even has a beginning. Perhaps the multiverse has always been there, more or less unchanging except at local levels. Or perhaps the multiverse itself has a beginning, and is again only one among countless others. Either way, the role of a Creator cannot be proven - perhaps never can be.

No math is needed to read this book, but it can still be heavy going for the uninitiated, despite its deceptive shortness. Have an astronomy dictionary handy, or else be very patient and careful when following his arguments. Referring back to his earlier book "Before the Beginning" may be a good idea, as is looking things up in an introductory astronomy textbook. If you're still stuck, skip & move on to other interesting topics. Eventually the pieces will fall into place. If not, it may not be your fault, but you're out of luck because Martin John Rees is one of the clearest & most admired educators in astronomy and astrophysics for laypeople.