Just Six Numbers: The Deep Forces That Shape the Universe (Hardcover)

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.

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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!

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