With more understanding, more mystery

Beatrice Tinsley

Sometimes explanations of science simply outlay the developments in theories, but science, much like other pursuits, is influenced by the personalities involved, and the arc of scientific discovery is guided as much by the quirks of individuals as by some sort of natural progression of overall knowledge. The authors of Heart of Darkness: Unraveling the Mysteries of the Invisible Universe (Jeremiah Ostriker and Simon Mitton) understand this, thankfully. Their book is an excellent introduction to the history of cosmology, eventually ending up – as the book’s title suggests, with the profound mysteries of dark matter and dark energy. And while there is plenty of theory, there is also much about the individual theorists, including Beatrice Tinsley (above), who was the first to realise what may now be obvious – that galaxies, rather than just the stars within them, are also changing and growing (and therefore can’t be regarded as some sort of yardstick, as they had been). The precocious Tinsley is also partly responsible for the reintroduction of Einstein’s cosmological constant.

With the incredible progress in understanding the universe it is easy to forget just how much is mysterious, and how much more mysterious things are becoming as understanding progresses. Dark matter and dark energy, for example, are not just oddities for specialist interest. They make up 90% of stuff in the universe. While their existence is fairly certain, having been proven by, amongst other things, the observation of colliding galaxies and the way gravity seems to operate in the collision, dark matter and dark energy are not observable in any conventional sense. Intriguingly, their existence has brought back Einstein’s cosmological constant, his fudge in his theory of general relativity, and what he supposedly called his greatest blunder. (This posthumous attribution is now questioned, as the evidence points to Einstein sensibly suggesting that it was something that simply needed to be further investigated.) The cosmological constant countered the force of gravity pulling, and this is exactly what dark energy is thought to do. While gravity is trying to pull galaxies together, dark energy seems to repelling them, and weirdly, working harder as the distances between matter increase (the opposite of how gravity works). No wonder Ostriker and Mitton more than once mention Alice in Wonderland. The expansion of the universe, due to dark energy, is not only fast, it is accelerating. The authors call this the “most surprising discovery of science in the last half-century”.

The book is a beautiful package, with glossy pages of (one assumes) high china clay content, and colour photos of theorists, images of the cosmos, and graphs and diagrams. Apart from sections of mathematics that are clearly delineated and can be skimmed over if one’s high school maths has become fuzzy, the writing is clear and enthusiastic.

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