Hunting down the Universe by Michael Hawkins,
Little Brown, 拢18.99 hbk, ISBN 0316883336
HE IS AN astronomer with an extraordinary idea: Mike Hawkins believes that 99
per cent of the mass of the Universe is in the form of mini black holes, each
鈥渢he size of a double bed鈥�. Hawkins is no head-in-the-clouds theorist, positing
the existence of a new exotic component of the cosmos on the basis of an
esoteric, untested and probably untestable theory of particle physics. No, he is
a hard-bitten observer, and his evidence comes from a long-term monitoring
programme of a thousand or so quasars.
He has found that the observed brightness of every quasar in his sample
fluctuates, on timescales ranging from months to years and believes these
fluctuations are caused by 鈥済ravitational microlensing鈥�, the temporary
magnification of a distant quasar鈥檚 light by the gravity of a body which moves
between the quasar and the Earth.
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Hawkins believes these 鈥渓ensing bodies鈥� are primordial black
holes鈥攕pawned by the turbulent 鈥渜uark-hadron phase transition鈥�, when the
Universe was a mere millionth of a second old. Assuming that the bodies are in
the most probable positions, he deduces that these black holes have masses close
to that of Jupiter鈥攁nd so calculates the homely size.
Theoretical argument by two other astronomers indicates that, if such
mini-black-holes exist, their total mass is almost exactly enough to 鈥渃lose鈥� the
Universe鈥攖o put a brake on its expansion. This (previously) 鈥渕issing mass鈥�
is a hundred times the mass of the visible stars and galaxies.
As you might guess, Hawkins鈥� claim is controversial. Most astronomers
maintain that the long-term fluctuations in quasars鈥� brightness happen in the
quasars, not between us and them. But nobody can put their finger on exactly
what is going on in the quasars. Few worry about this because, even a quarter of
a century after their discovery, most things about quasars are mysterious.
One prominent astronomer has publicly dismissed Hawkins鈥檚 idea as 鈥渞ubbish鈥�.
In truth, the source of the irritation was not Hawkins himself. He just happened
to be in the firing line. What upset some was a wider issue: the way ideas that
the astronomical community sees as off-the-wall so often excite the media, while
more generally accepted ideas are ignored.
The story of the reaction of the astronomical community to the black hole
claim, and that of the genesis of the whole idea, is recounted by Hawkins in
Hunting down the Universe. It鈥檚 a complex and fascinating tale, which
tackles just about every hot topic in cosmology, from inflation to dark matter.
It also contains Hawkins鈥檚 strong views on the shortcomings of the
scientific process with an impassioned attack on the scientific community for
its treatment of Fred Hoyle.
If I have a criticism, it is that Hawkins spends a lot of time on
generalities, interesting though they are, and comparatively little on the
specifics of his quasar discovery. This could make the book a little difficult
for the general reader to follow.
Time will tell whether Hawkins is right. But there is no doubt he has come up
with an immensely stimulating idea. This has a bearing on the whole controversy
over the publicity attracted by his claim. Although his idea is not generally
accepted by the scientific community, it still excites the public鈥檚 imagination,
while a 40-year dispute over the value of the Hubble constant manifestly
诲辞别蝉苍鈥檛.
This is important not only because the public ultimately foots the bill for
much science, but because young people exposed to scientific speculation at its
most mind-blowing may actually consider science as a career. On balance, I
believe the danger of distorting the public鈥檚 idea of scientific progress is far
outweighed by the benefit of sparking interest in an endeavour that the public
increasingly sees as irrelevant to them.