Science ε = –dø/dt, Peter Calder

North Pole, South Pole: The Epic Quest to Solve the Great Mystery of Earth’s Magnetism
Gillian Turner
Awa Press, $40.00,
ISBN 9780958275002


Consider this passage about magnetism:

Cooling basalts, it turns out, contain small crystals of iron-oxide compounds … that are highly magnetic. During the molten, plastic phase of their cooling process, these crystals tend to act as miniature compasses, swinging hither and yon, in the still-viscous mix, in an elegant harmony that is extremely susceptible to the lines of magnetic force that radiate between the Earth’s North and South Poles.

Once the cooling has concluded … the alignment of the swarm of magnetite compasses becomes fixed, and is set for all time. And each, crucially, is then aligned to where the North and South Poles were at the time the rocks froze … The compasses are thus powerful forensic tools: they tell us where the poles were in relation to the rocks, or the rocks in relation to the poles, a long, long while ago.


It’s an exemplary piece of science writing, really, packed with information couched in easily digestible imagery (“act as miniature compasses”; “forensic tools”) and evocative language (“elegant harmony”; “still-viscous mix”). You can almost touch the words.

Unfortunately the passage is not to be found in Gillian Turner’s North Pole, South Pole, but in Simon Winchester’s terrific Krakatoa (2003). And even more unfortunately, precious few similarly stirring moments are to be found in Turner’s pages.

This is not simply a quibble but goes to the heart of this book’s failing: it’s the work of a scientist, not a writer. Winchester was a Fleet Street veteran with a long journalistic pedigree before he wrote his first book. Turner is a geophysicist, garlanded for the excellence of her undergraduate teaching methods, but, according to her own “About the Author” note, her list of publications amounts to 50 articles in scientific journals.

The difference between the two consists in the ability to frame a sentence that invites the lay reader in. “Astronomers had observed two separate effects [of the gravitational pull of the sun and the moon] which they called precession and nutation,” she writes, without troubling to explain what these are. Yet mentioning technical terms without elucidating them is the worst fault of the specialist: if the term is not worth explaining, it’s not worth using, it seems to me. And telling us in passing that Faraday’s law of electromagnetic induction is rendered as ε = –dø/dt looks suspiciously like showing off, particularly when it is followed by the observation that Faraday wasn’t big on equations but rather that “his genius was in conceptualising physical phenomena and explaining them in words.”

I can still remember the day when my fourth-form eyes glazed over in physics class. We had just got on to magnetism and electricity when some mental circuit or other blew out. The arcane language of the science lab had already defeated me; I was more excited by the ablative absolutes of Latin class and the work of an old, dead playwright called William Shakespeare.

It may seem unfair that this journal lets loose a person of my scientific dim-wittedness on this book. But I am presumably the target audience. This is not an academic work but a compact book for a general audience. And not to put too fine a point on it, I found it pretty hard work.

Indeed, I found myself nodding in agreement with a citation Turner makes from the Edinburgh Courier. Addressing the question of why one James Clerk Maxwell had narrowly missed out on a chair at the university in 1860, the newspaper’s writer observed that Maxwell “is already acknowledged to be one of the most remarkable men known to the scientific world”, but added that he lacked “the power of oral exposition proceeding on the supposition of imperfect knowledge or even total ignorance on the part of pupils”.

Deleting the word “oral” and replacing “pupils” with “readers” turns that sentence into a more eloquent summary than I might manage of the failings of North Pole, South Pole.

The story the book tells is a fascinating one because it goes to the essence of the Earth on which we stand. As a species we have become uncomfortably aware of the thin coating of atmosphere that creates an environment in which we can live. But, it turns out, “interplanetary space … [teems] with charged particles and radiation that are harmful to human health.” Meanwhile the sun batters us with energy and outer space bombards the solar system.

“This solar wind and these cosmic rays,” Turner writes, in an uncharacteristically evocative passage, “would make Earth quite uninhabitable were it not for the fact that we sit in the middle of an enormous magnetic shield that arrests and diverts the onslaught way above our heads.”

The task Turner has set herself is to explore the history of human understanding of the nature of this magnetic field. It’s a story littered with the names of scientists that have entered the language as nouns: Ampère, Joule, Volta, Hertz. But time and again, Turner is defeated by the boffin’s biggest handicap: knowing too much about her subject.

Thus a few pages in she refers to the distinction between true north and magnetic north without having explained what they are, why they are distinct and what difference it makes. I for one find it hard to grasp why there would be any north that is not magnetic north, since the Earth seen from space doesn’t seem to have a top or a bottom. Likewise, it seems to me that the Earth’s tilted axis could do with a little explanation.

This preoccupation with the niceties while losing sight of the big picture can lead to unconscious absurdities. In explaining the concept of “inclination” – the tilting of a compass needle which varies according to latitude – Turner tells us that by the year 1600, it had been measured “at many locations around the globe, and a pattern was emerging”: the needle was horizontal at the equator but pointed vertically downwards at the north (magnetic) pole and upwards at the south (magnetic).

But at this point, we have not been told that the magnetic poles are nothing to do with the geographic poles; that they are not “antipodal” – directly opposite each other on the globe; and that they are moving all the time, by as much as 50km or so a year.

The book is also hampered by its chronological approach to its subject. For a scientist, it’s the obvious way of dealing with things: the truth emerges by starting with simple concepts and getting more complex as you go on. But the best stories don’t get told that way. Plainly the book’s most exciting part is its climax: the work done on the Cray supercomputer at Pittsburgh University in 1995 to produce a simulation of Earth’s magnetic field: it would mimic all the processes that had been documented over 400 years and, more importantly, those that had been inferred either from theoretical principles or the palaeontological record.

Apart from anything else, the results, which were a sensation in the community of geophysicists, created a picture of astonishing beauty: a computer-generated image that looks like a Len Lye light sculpture exploding from a tangled ball of neon wool. It also gave form to what had until then been only deduced reality – the process by which the Earth’s magnetic field reverses, so that magnetic north becomes magnetic south and vice versa.

What kind of book this might have been if it had opened with the high point and explained in flashback is hard to say. But it’s tempting to think it might have been a better – and an easier – read.

It’s fair to observe that jacket endorsements describe the book as “clearly written” and “highly readable”, and promise that it will “enthuse anyone, young or old, about the physics of the world around them”. Fairer still to add that the endorsements are from geologists and other academics. Quite what you get out of it may depend on the company you keep.


Peter Calder is an Auckland writer and critic.


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