The Edge of Infinity by Fulvio Melia, Cambridge University Press, £18.95, ISBN 0521814057 Reviewed by Marcus Chown
HOW can a region of space no bigger than the solar system shine as brightly as 10 trillion suns? This was the pressing question facing astronomers after Martin Schmidt and Cyril Hazard discovered quasars in 1963. The only possibility – at least within the bounds of known science – was that matter is heated to incandescence as it spirals down into a black hole with a mass of a billion or so suns.
For several decades it was possible to think of such “supermassive” black holes merely as anomalous sports of nature. But with the discovery that quasars live in the nuclei of galaxies and that most galaxies, including our own Milky Way, contain quiescent or at least toned-down quasars, supermassive black holes began to creep in from the periphery of astrophysicists’ radar screens.
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Recently, astronomers have found a striking connection between the mass of a galaxy’s supermassive black hole and the orbital speed of the stars in its outermost regions. Since such stars are way beyond the gravitational reach of the central black hole, the discovery can only mean that the stars and black hole somehow influenced each other in the past. Suddenly, we realised that the birth of galaxies was intimately connected with the birth of supermassive black holes.
No one knows what came first – whether galaxies “seeded” supermassive black holes or vice versa, or whether the relationship was more symbiotic than either scenario. But there can be little doubt now that supermassive black holes, far from being at the periphery of those radar screens, are now at the dead centre.
In The Edge of Infinity, University of Arizona astronomer Fulvio Melia tells the fascinating story of supermassive black holes, beautifully illustrated with stunning colour plates. Melia is great on the science, but when it comes to the writing, he tries a little too hard. The material he covers is extraordinary enough to speak for itself, yet Melia insists on writing things like: “This tessellation of historical markers stirring the world in 1963 formed quite a backdrop for two minor events that would lead, over time, to the eventual uncloaking of the most powerful objects in the universe.” Pretentious? Lui?