Understanding the “multiverse”

Book review: In Search of the Multiverse by John Gribbin

Price: NZ$55
Hardcover: 240 pages
Publisher: Allen Lane (August 27, 2009)
Language: English
ISBN-10: 1846141133
ISBN-13: 978-1846141133

These days when people talk about the “multiverse” they usually mean the idea that our “universe” is just part of a larger, perhaps unending, collection of “universes.” And that these different universes may have different characteristics, different values of physical constants, for example.

So, I was a little surprised to find John Gribbin beginning his book with the “many worlds’ idea of Hugh Everett. The idea that the different possibilities inherent in quantum-mechanical descriptions leads to formation of many words as events lead to multiple quantum-mechanical choices. A little disappointing as I wanted to learn about the origin of multiple universes in inflationary “big bang” theory. He discussed this only in the second half of the book.

A global approach

However, the book does take a “global” approach – describing the history of concepts of multiple worlds or universes. It also provides a suitable coverage for most current “multiverse” and “multiple world ideas.” And, despite the mind-expanding nature of the subject, in the very readable style we have come to expect from Gribbin who has written many popular science books. These include Eyewitness: Time & Space; Get a Grip on Physics; Science: A History: 1534-2001; Deep Simplicity: Bringing Order to Chaos and Complexity; The Scientists: A History of Science Told Through the Lives of Its Greatest Inventors; In Search of Schrödinger’s Cat: Quantum Physics and Reality, and others.

In Search of the Multiverse covers quantum theory, the branching tree of history and the “many worlds” theory: cosmic coincidences or “fine-tuning” and its relevance to multiverse ideas, the nature of time and infinity of time and space; “big bang” theory, the role of quantum effects, inflation, eternal inflation, chaotic inflation and a new idea of steady state theory; string theory, landscapes and their meaning for Multiverse ideas; and finally speculations about the future investigation of multiple universes, their evolution and even “designer universes.”

It’s all very interesting and stimulating. However, it can be difficult working out where the boundaries are. Where does ‘what we know’ stop and ‘what we think’ start? Where does the speculation start? And how widely are all these concepts accepted by modern theoretical physicists and cosmologists?

I would have liked more presentation of the differing opinions of these scientists – of what schools of thought there are on these subjects. Gribbon, for example, appears enthusiastic about the “many worlds” explanation of quantum mechanics, saying “To my mind, the fact that quantum computation works proves the existence of the Multiverse” – here he is referring to the “many worlds” version. However, he does not describe the opinions of Jim Hartle and Murray Gell-Mann on this. In The Quark and the Jaguar Gell-Mann refers to descriptions of the “many worlds” as being “equally real” as confusing. He believes one should instead talk of “many histories, all treated alike by the theory except for different probabilities.”

Similarly, in a later discussion of string theory he refers to quantum loop gravity as an alternative approach – but does not describe or discuss it.

The human side of science

Gribbon often injects a human side to his history of science, and this contributes to the appeal of his books. I was amused, for example, of his description of how Everett came up with his “many worlds” idea – in the aftermath of “a party at which a considerable amount of sherry was consumed, Everett, his fellow student Charles Misner (who would later become a leading expert on relativity theory) and a visitor, Aage Petersen, amused themselves by dreaming up increasingly ridiculous implications of quantum puzzles like the parable of Schrödinger’s cat.” Everitt tossed in his idea more or less as a joke – but later, in the sober light of day, the idea didn’t seem so wild to him. So he developed further.

Gribbon includes many other ideas and speculations from modern physics and cosmology in this book because of their association with multiverse theories. Ideas like entropy and the effect of gravity, time and the possibilities of time travel, formation of stars and universes from “nothing,” Ideas about the origin of universes themselves.

I was interested to find the multiple universes or worlds ideas have a long history. Giordano Bruno, for example, held similar ideas. “In 1584, [he] outraged the established Church by suiggesting that ‘the excellence of God’ might be ‘magnified and the greatness of his kingdom made manifest [if] he is glorified not in one, but in countless suns; not in a single earth, but in a thousand, I say, in an infinity of worlds.’” The Roman Inquisition imprisoned (and probably tortured) Bruno for seven years and eventually burned him at the stake in 1600 for this and other heresies (including support for Copernican heliocentricism).

And science fiction stories have often included ideas of multiple universes and dimensions.

So, another interesting book by John Gribbin. If you are interested in popular science it will entertain and inform you. It will provide a far more stimulating introduction to the subject then that usually encountered in theological cosmology which limits itself to interpreting the multiverse as an atheist attempt to avoid belief in gods.

Be aware, though, this is an area where there is plenty of imaginative speculation. Don’t take all these ideas as “gospel.” But do enjoy thinking about them.

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