BookendsThe word

A fine fightThe Poincaré Conjectureby Donal O’Shea, Allen Lane/Walker Books, £17.99/$25.95, ISBN 9781846140129/ 9780802715326Reviewed by Ben Longstaff

“PROBLEMS worthy of attack prove their worth by fighting back.” Anyone doubting the truth of this aphorism should read Donal

O’Shea’s account of a problem left to the world by the French genius Henri Poincaré. His famous conjecture fought back for almost a century, swallowing large chunks of careers and ending up with a million-dollar bounty on its head. Amazingly, the apparent victor seems reluctant to claim any glory. O’Shea’s approach is more narrative than technical, but he conveys the gist of topology’s mind-bending contortions with great flair.

Life unpluggedHow to Live Off-Gridby Nick Rosen, Transworld, £12.99, ISBN 9780385611275Reviewed by Michael Bond

SOME 25,000 households in the UK live free of mains water and energy supplies. Nick Rosen spent months in a camper van

visiting some of them. A fan of the off-grid lifestyle, his book gives good tips for those aspiring to it, such as how to install a sewerage system. But it left me wondering: why do it? Rosen lists many reasons – from saving money to sustainable living – but the only one that rings true is his desire to be self-sufficient. Even that is contradictory, since he was utterly dependent on his cellphone network, perhaps the most pervasive grid of all.

Enigma

STARE into the night sky and you can’t

help being amazed by the sheer scale

of the universe. Look for Sirius, the

brightest star in the sky. That’s 8.6

light years away. Polaris, the North

Star, sits 431 light years from us, and

the faintly visible Andromeda galaxy

lies 2.6 million light years from Earth.

These are distances that boggle the

mind, yet we’re only talking about

the scenery in our cosmic backyard.

Is this magnificent view typical,

the sort of spectacle you’d see from

anywhere in the universe? Not at all.

From the middle of the Boötes Void, for

instance, the universe appears a very

different, and much darker, place.

The Boötes Void is a giant hole in

the universe some 350 million light

years across, a place where galaxies,

for the most part, never formed. It lies

about a billion light years from Earth

in the direction of the constellation

Boötes, after which it was named when

it was discovered in 1981 by Robert

Kirshner of the Harvard-Smithsonian

Center for Astrophysics in Cambridge,

Massachusetts, and colleagues.

What makes this expanse of

nothingness so interesting? The very

existence of the Boötes Void is a

mystery, one that is challenging our

standard story of the universe’s past.

The pattern of galaxies and voids is

thought to arise from tiny quantum

fluctuations in the fabric of space-time

at nearly the beginning of time that

have been stretched to galactic

proportions as the universe expanded.

These fluctuations corresponded

to variations in the density of matter

throughout space, and led to the

formation of clusters of galaxies as

well as voids between them. Yet given

the age of the universe and its rate of

expansion, there has only been

enough time for galaxies and voids

to form on a scale of tens of millions

of light years – not hundreds (New Scientist, 10 March, p 30). Boötes is

just too big to fit this picture.

So how did this so-called supervoid

come to be? One theory, which recent

evidence may back up, is that it formed

when two or more ordinary voids

collided. Boötes is not quite empty:

it turns out to contain a sprinkling

of galaxies arranged in a tubular

shape. This could be the remains of

the shared edge of two smaller voids

before they combined.

Another possibility is that our

existing theory of the big bang will

have to be modified to accommodate

Boötes’s existence. Both gravity and

quantum mechanics played a role in

forming the supervoid, but no one

has figured out how to combine them

into a “theory of everything”. Perhaps

when we have a theory of everything,

we will understand this piece of

nothing, too. ●

The Boötes Void

“Our current theory of the big bang may have to be modified to explain Boötes”

Fantasy centuryNo. 1443 Richard England

IT PAINS me that the two fastest cricket test

match centuries (by Viv Richards in 1986 off

56 balls and by Adam Gilchrist in 2006 off

57 balls) have both been scored against my

namesake team. I retaliated by scoring a

century off even fewer balls against the

bowling of Shane Warne and Glenn McGrath

and thus forced them both into retirement.

In reaching my century I faced balls off

which I had scores of 0, 1, 2, 4 and 6 runs, a

different perfect square number of balls for

each of those scores.

Exactly how many runs had I scored in

total after completing the runs from the ball

that brought me to my century?

£15 will be awarded to the sender of the first

correct answer opened on Wednesday

20 June. The Editor’s decision is final.

Please send entries to Enigma 1443, New

Scientist, Lacon House, 84 Theobald’s Road,

London WC1X 8NS, or to enigma@

newscientist.com (please include your

postal address). The winner of Enigma 1437

is Steve Pretty of Stowmarket, Suffolk, UK.

Answer to 1437 Two squared

The three 3-digit squares that neither of

them used were 324, 729, 784.

SCIE

NCE

FA

CTIO

N/G

ETTY

58 | NewScientist | 19 May 2007 www.newscientist.com

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