Just Six Numbers: The Deep Forces That Shape the Universe [Paperback]

Rees's book is another addition to much maligned but (in this reader's humble opinion) highly valuable genre of popular science, in this case dealing with the amazing fact that just six surprisingly basic numbers effectively govern the fundamental forces operating throughout the entire cosmos. In the simplest language, Rees demonstrates how these six quantities shape the whole Universe as we know it by governing the worlds of the very large and the very small---the forces that operate within and between atoms and, by extension, all the matter within our Universe, explaining how if these values had been even very slightly different by the minutest degree, the Universe would not have developed as it is, even to the extent that life may not have arisen at all in the first place (the well-known Anthropic Principle). Blessedly free of equations and jargon, like Rees's other popular science works (especially 'Before the Beginning') 'Just Six Numbers is a model of clarity and concision---the sort of popular science writing that allows the lay reader to partake, albeit in a humble way, in the mysteries of the cosmos and can make even the most scientifically illiterate reader feel like something approaching a genius, which to my mind Rees (Britain's Astronomer Royal) undoubtedly is. Very, very highly recommended.

The answer? You're sitting here reading this. Instead of not existing at all. In this delightful study, Martin Rees describes the six fundamental cosmic forces with refreshing clarity. One of these, nuclear efficiency has a value of .007. A lower value would result the entire cosmos consisting only of hydrogen: no carbon to build your body and brain, no oxygen to breathe. A higher level would have resulted in rapid stellar evolution and decay leaving no time for life to evolve.

The image of the astronomer, especially the Astronomer Royal, locked away in an observatory, immune to human feelings and capacities is dashed forever by this book. Rees portrays the "deep forces that shaped the universe" without sinking into a pedantic morass. No arcane mathematics or arcane cosmology in this book. Rees takes us on a journey through space and time with examples of atomic forces, gravity, cosmic structure and why we live in a three dimensional universe. He shows how these forces interact and why they are important to us.

The human value of the study of cosmology permeates this excellent presentation. Cosmology is "stellar paleontology." As telescopes have improved we are observing the radiation of light and other forces that was emitted from shining object many billions of years ago. Recording and analyzing these forces has built up an image allowing us to assess how the cosmos began. Rees takes us through the instruments and techniques what the images tell us. He builds an enthralling picture, never failing to demonstrate why it's important that we all understand it. Where it's confusing or indistinct, he manages to bring clarity and wit. Most importantly, he asserts why these are physical quantities and not the result of divine interaction. The "creator" thesis has esthetic appeal, he admits, but divinities reduce the study of physics to an absurdity. Why learn about these forces and their origins if it's only to result in a "divine plan?" It's too easy an answer, in Rees' view. The fine balance of cosmic forces should lead us to learn more, not be satisfied with metaphysical platitudes.

He also engages in some speculation about what else the cosmos might reveal. His conclusion, that there might be "multiverses" instead of the solitary one we inhabit is based on good logic results from his discussion of the Big Bang. We can see only so far back in time. We can't "see" either the Big Bang nor objects such as black holes. Both these phenomena stretch the limits of today's physics. Yet we can infer their existence from what we can see and extrapolate from other evidence. Since a single cosmos is likely illogical, the concept of multiple universes must be given serious thought. Bigger and more sensitive telescopes may someday allow us to perceive these entities. It's not a subject we should dismiss out of hand.

In short, this is a book for anyone wishing to understand how the universe came to be and our place in its existence. Rees carries his theme with precision in a deftly structured framework. He brings many years of experience to present this summation to us. He's to be applauded for a vivid portrayal of what might otherwise be a daunting topic. [stephen a. haines - Ottawa, Canada]

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.