The Universe in a Nutshell by Stephen Hawking, Bantam, 拢20,
ISBN 0593 048156
IS THE end of theoretical physics still in sight? Have we yet peered into the
mind of God? It鈥檚 well over a decade since the astonishing success of A
Brief History of Time, with its suggestion that physics was close to
telling us why the Universe is the way it is. Since then there鈥檚 been a slump in
the fortunes of would-be theories of everything, but now something called
M-theory has put optimism in style again. In The Universe in a Nutshell,
Hawking paints an intriguing picture of the cosmos as he sees it now.
With his laconic, declarative style Hawking glides swiftly through vast areas
of physics. He has a deft sense of exactly how much to say, and can get from the
foundations of relativity to the implications of imaginary time by moving,
appropriately enough, along the most economical path. His words come with lavish
and numerous illustrations: photos, diagrams, sidebars, time lines, whimsical
cartoons, all luxuriously displayed against copious white space. This is an
extravagantly produced book, but I found myself frequently turning the page
without inspecting all the artwork, so as not to lose the thread of the
purposeful text.
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Hawking gets his narrative clarity by judiciously leaving things out, but
some omissions are misleading. He is terse, even acerbic about superstrings,
which were all the rage in the early 1990s, but then ran into trouble. Now
enthusiasm centers on M-theory鈥攖hough, like a dinosaur skeleton
inferred from a tooth and a left anklebone, it is not yet proved to exist. It
promises to enfold superstrings and supergravity under the same mathematical
roof. Its fundamental elements are branes, generalised geometric structures that
include strings, surfaces and higher-dimensional shapes. Hawking sees its
emergence as vindicating his abiding faith in supergravity. But in fact all the
earlier ideas now stand as differently flawed approximations to the
as-yet-unrevealed wonders of the M-world, and you cannot tell from Hawking鈥檚
account how much string theorists were behind the rise of M-theory.
It鈥檚 valuable, though, to see these ideas presented by a physicist who began
in relativity, not particle physics. Hawking has always emphasised the global
issues of space-time structure more than the local questions of particle
interactions, but as we are all coming to understand, harmonising local and
global concerns may be the toughest task.
In a short, strange chapter, Hawking recommends that we safeguard the future
of humanity by supersizing our brains through genetic engineering.
Unfortunately, the image of giant-headed babies growing in jars put me more in
mind of the cheery tackiness of the cartoon Futurama than of the pious
utopianism of Hawking鈥檚 favourite TV show, Star Trek.
Saving the best for last, however, Hawking offers a sweeping vision of the
brane-y Universe. This is speculative and mind-boggling, but in a good way. Our
Universe may be a brane embedded in a higher-dimensional space; it may even be a
sort of holographic projection of information from the larger space onto the
simpler surface that is all we poor creatures can perceive.
Has there perhaps been a little mellowing of earlier opinions? Hawking
repeatedly calls himself a positivist, meaning that he thinks theories can be
assessed only by the concrete results they produce. Whatever the final theory
turns out to be, Hawking suggests, it鈥檚 likely to offer a bewildering and
bizarre variety of possible universes. Many of these will be far too strange to
permit life to develop, which limits the options for the particular Universe we
find ourselves in. But that could still leave a lot of wiggle room.
So in the end, we won鈥檛 really know the mind of God. But The Universe in
a Nutshell offers a fascinating tour of the mind of Hawking.