It’s easy to forget that we’re all living on a giant magnet, with all the advantages that entails. Where would we be without the entire concept of compasses, for example? How would animals achieve their vast migrations? But there’s much more to consider, not least that north and south are prone to switching at any moment, known as a ‘magnetic reversal’. A switch now, with all our delicate infrastructure in place, could be apocalyptic, Mitchell reminds us.
As is necessary for a book on magnetism, there is a leap into complex physics. Happily, Mitchell explains these in simple and compelling terms. Interlaced are historical lessons about key figures – including Ørsted, Gilbert, Curie and Faraday – as well as travels to important sites from the evolving story of humanity’s understanding of magnetism (such as Port Farin in rural France, where Bernard Brunhes discovered that magnetic reversals can occur).
The crux of the book revolves around it being 780,000 years since Earth’s last magnetic reversal, and that we’re long overdue. Unfortunately, there is evidence of a weakening magnetic field in the southern hemisphere – the South Atlantic Anomaly – which may or may not be the start of such a reversal. One of the most damaging impacts this could have is to the magnetic shield that protects the planet from dramatic phenomena such as solar ejections. In July 2012, an especially powerful ejection could have had ‘catastrophic’ consequences had it not occurred on the side of the sun facing away from the Earth. A week earlier and it would have apparently reduced civilisation to ‘a pre-electricity Victorian era’.
By the end, there’s a seeming inevitably to the coming apocalypse that leaves the reader wondering whether they were perhaps better off not knowing the details of our impending doom. For those who prefer to be informed about their fates, you could do no better than read this.
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