We don't know it all, but what we do know is all here

Origins

May 27, 2005

Historians of knowledge sometimes claim that the mid-19th century was the last time anyone could reasonably know everything that was known. Since then, science has erupted at such a rate that no individual could keep up.

But here, Neil deGrasse Tyson and Donald Goldsmith promise to reverse this trend. As they see it, our knowledge of the key processes that have brought our species where it is today - the origin of the universe, the formation of the atoms in it and the major objects it contains, and the nature of life - is now converging to a point at which we can grasp it in a single view. And we are not just passive observers. As they say: "We are not simply in the universe, we are part of it. One might even say that the universe has empowered us, here in our small corner of the cosmos, to figure itself out."

The story that ensues is written well, with jokes and irony to the fore, as befits the book of a blockbuster TV series. One interesting message is that our detailed knowledge of the key passages in the history of the universe is balanced by ignorance elsewhere. We know a great deal about the first second of the universe, when the forces and particles that still shape the way it works emerged. But we know nothing about the "dark" matter and energy that make up most of the universe and dominate its development today. We know dark matter exists because we can feel its gravitation, and we know dark energy exists because of the way it affects the expansion of the universe. But it is almost impossible to devise an experiment to discover anything else about them.

However, the authors' focus is on what we are finding out, not on our ignorance. They describe in detail the use of a specific tool - the measurement of the brightness of supernova explosions - to find out about the expansion of the universe. It shows that dark energy, originally dreamt up by Einstein to balance a tricky equation, is real. It has a definite effect, too, because the push it gives to the universe means that it will expand for ever at a gradually increasing pace. Come back in 100 billion years, and all but the nearest galaxies will have retreated into invisibility.

Another challenge well dealt with is just how we happen to be here in a universe whose grand architecture and detailed structure combine to allow us to exist. The odds are heavily against this happening, but there is no doubt that it has. For some observers, this is just a coincidence, for others, it shows the hand of God in action. For yet others, the fact that many other universes can be created as ours has been means that this result was bound to come up at some point. DeGrasse Tyson and Goldsmith point out that like many supposed big problems of the past, it may just evaporate as we learn more.

Even after the origin and structure of the universe have been sorted out, Origins goes on confronting big topics. One is the formation of the chemical elements. All the heavy elements are made inside stars; of these, the heaviest can be made only in supernovae, which then scatter them to the stellar winds so that billions of years later we can have gold rings and silver spoons. This story is one of the most complete and satisfying in modern knowledge, and the authors tell it with style.

When it comes to the origin of life on Earth, the authors remain sure-footed despite their shared background in astronomy. They play to their strengths by avoiding issues such as the development of humans and human cultures. Instead, they speculate usefully on the scope for life elsewhere in the universe and the reasons why we have yet to find evidence of it. Here, too, they warn against complacency. There could be astounding news just around the corner.

This is the book for anyone who wants to see how much we know about our surroundings and how we got here. But it is even more worthwhile for its sense of adventure and for showing just what science - imagination constrained by evidence - can tell us.

Martin Ince is contributing editor, The Times Higher .

Origins: Fourteen Billion Years of Cosmic Evolution

Author - Neil deGrasse Tyson and Donald Goldsmith
Publisher - Norton
Pages - 345
Price - £18.99
ISBN - 0 393 05992 8

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