25 November, 2015Issue 29.3Science

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Superstars and Supermassive Black Holes

Kanta Dihal

Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled on by Hawking Became Loved
Marcia Bartusiak
Yale University Press, 2015
256 pages
ISBN: 9780300210859






We will never be able to see black holes. The very concept of a black hole—a dense point in space from which light can never escape—implies that direct observation is impossible. It is only within the last few decades that we have finally been able to infer their presence from the effects they have on their surroundings, as they draw in visible matter and emit x-ray radiation. It is no wonder, then, that from the moment of their first conception, the idea of such a thing as a black hole was met with scepticism and even scorn within the scientific community. And yet their conception dates back centuries, and their modern debut arose as a direct consequence of the most famous scientific theory of the twentieth century: Einstein’s General Theory of Relativity. In other words, the kind of history that would be an ideal topic for a popular science book.

Black Hole, by science journalist and science writing professor Marcia Bartusiak, therefore seems long overdue. Bartusiak presents a comprehensive overview of both the history and the science behind the black hole. A black hole is not a hole, nor is it black. It is the remnant of what once was a huge star, which collapsed at the end of its lifetime in a supernova. If the remnant that is not blown away is substantial enough, at least three to four times the mass of our sun, the gravitational attraction will be so intense that the entire star will collapse in onto itself into a singularity, a dimensionless point with infinite density. Its name, Bartusiak points out, comes from a very inappropriate comparison between these phenomena and the Black Hole of Calcutta.

Bartusiak starts off her history with Newton and his development of the laws of gravitation. She shows how it in fact did not take very long before the first idea of a black hole emerged in the eighteenth century. What emerges is a surprising history with which not many casual readers will be familiar. As she engagingly describes, the Englishman John Michell extrapolated the idea that larger stars, which would have a larger gravitational attraction, would slow down the light emitted from them. Using Newton’s laws of gravitation, published only a century earlier, he calculated how big a star would have to be to ensure that no light would be able to escape from the star at all. He concluded that star would have a diameter larger than the orbit of Mars, would be just as dense as our Sun, and would be entirely invisible.

Bartusiak soon leaves this brief historical survey, however, and brings up Einstein in her second chapter already. Although Einstein himself believed black holes could not actually exist, he did explain how they might be theoretically possible. His 1915 paper on general relativity explained how gravity curves the spacetime paths that light must follow. Therefore, an immensely heavy body could curve spacetime back onto itself so that light would never be able to escape from it. In the remaining eleven chapters, the book covers the period from Einstein’s papers on relativity to Hawking in the 1970s, with the epilogue covering the most recent research concerning attempts to detect gravitational waves.

The book traces the journey of the black hole becoming an accepted concept in science in a linear fashion, which is of course only natural for a historical overview, but also in a way that suggests an absolute, linear development which has a well-defined climax in the present. The past was filled with conflict, the present is more peaceful. Bartusiak thus risks presenting the reader with an unduly one-dimensional view of scientists in the past, which becomes clear in her discussion of Einstein. Readers deriving all their knowledge about Einstein from Black Hole may well end up thinking that by the time of his death, Einstein was ridiculed by his younger, more modern scientific peers, and that he had not contributed anything useful since the General Theory of Relativity. The timeline at the end of the book gives only the information that this is what Einstein thought of himself at the end of his life. In fact, Einstein’s scepticism about—and strong criticism of—quantum theory, especially the 1935 Einstein-Podolsky-Rosen paradox, proved to have been extremely helpful for the further development of quantum physics. Einstein may have adhered to the wrong viewpoints, but even his mistakes led to new scientific breakthroughs.

Bartusiak has illustrated her work, and several of the illustrations are taken from Wikimedia Commons, an intriguing choice for a Yale University Press work. Though it may be difficult to illustrate a book on a phenomenon that cannot be seen, the visual simply cannot be left out from an astrophysics popularisation, especially not since the Hubble telescope inundated the world with astounding images of distant galaxies. Bartusiak has chosen to alternate such galaxy photographs with illustrations that are used as a visual aid to support Bartusiak’s scientific explanations. However, many illustrations are simply photographs of the key players in the history of the black hole. They helpfully provide readers with faces to match up with the many names that are mentioned as the history of the black hole unwinds across eras and disciplines but unfortunately, the photographs are all of men.

Last year saw the publication of a rather similar book. Pedro Ferreira’s The Perfect Theory, which is acknowledged in Bartusiak’s bibliography, is a history of gravity, and is therefore equally concerned with black holes. His book similarly relies on biographical oddities, and it must be said that he comes up with more startlingly original biographical details than Bartusiak, many of which he seems to have found through personal interviews with the people involved. Bartusiak, on the other hand, narrates a conversation with Arthur Eddington which is by now really something of an old hat: Eddington, being told that he is apparently one of three people who understands relativity, replies that he wonders who the third person is.

Bartusiak’s work concludes with an all’s-well-that-ends-well conclusion that ties in with her model of linear development: after all the fights and disputes described in the previous chapters, by 2013 the black hole is a commonly accepted phenomenon which has outgrown science fiction. This “happy ending” glosses over the fact that black holes are still the subject of heated debate. Though their existence is agreed upon, the way black holes function is still largely a mystery to which various solutions have been proposed over the recent years. Bartusiak focuses mainly on developments up to the 1980s, and limits her discussion of more recent findings to the attempts to detect gravity waves. This means that she leaves out the conflicts that have arisen in the twenty-first century, such as the black hole information paradox and the firewall paradox. The latter is mentioned in passing in the final chapter, but the suggestion is made that this is only a minor hypothesis among many, rather than a source of conflict comparable to the ones she covered in the rest of her book. Bartusiak’s conclusion is complacent, whereas contemporary black hole astrophysics contains at least as much excitement as the twentieth-century history she so vividly describes.

Black Hole is a thin book, just over two hundred pages, which includes a timeline, notes, and an extensive and interesting bibliography. Fortunately, Bartusiak manages to avoid the pitfall of condensing a book so strongly that the scientific concepts are thrown at the reader at a pace too quick to follow—a mistake previously made by, for instance, Stephen Hawking. Her language is colloquial, immensely so at times, but it fits in well with the type of narrative she is presenting to the reader: a mix of quirky personal narratives and reports of fierce conflicts. This work comes highly recommended as a timely tie-in for those who have seen the spellbinding visual depictions of black holes in Interstellar (2014): this book is able to comprehensively explain exactly why viewers were so spellbound.

Kanta Dihal is a second-year DPhil candidate in English at St Anne’s college, Oxford.