“The Irresistible Attraction of Gravity” by Luciano Razzola

sBlack holes are mysterious objects. Predicted by Einstein’s theory of relativity, their gravity is so strong that nothing, not even light, can escape from them. Astrophysicist Luciano Razzola’s book is devoted to this irresistible attraction of gravity. In general, black holes can arise when massive objects collapse under the influence of their own gravity—an insight we owe to a work from 1965 by Roger Penrose, who won the Nobel Prize in Physics 55 years later. had won the award. We now know that our universe is populated by many black holes, whose masses are either in the range of three to a few dozen solar masses (stellar black holes) or millions and billions of solar masses (supermassive black holes). The latter is at the center of almost all galaxies, including our own Milky Way.

The author, who has been a professor at Goethe University in Frankfurt since 2013, has been involved in researching black holes himself. In particular, he is a member of the Event Horizon Telescope (EHT) project, a joint project of international institutions that aims to image the “shadow” of a black hole that forms when radiation is swallowed by an object or When it’s bizarre it’s distracting. In fact, it is radio radiation that is observed by eight radio telescopes distributed around the Earth to achieve the highest possible angular resolution. The first image of its kind – the shadow of the black hole at the center of the elliptical galaxy Messier 87 (M87) – was released in April 2019 and has achieved cult status on social media. Financial support from the European Research Council, which Rezzola was able to win in 2013 together with his colleagues Heino Falke (Nijmegen) and Michael Kremer (Bonn), was decisive for the project.

He who runs cannot escape

The author of a non-fiction book on such subjects usually faces a dilemma. If it’s too easy to read, there’s a risk that the material will be more about the general anecdotes surrounding the researchers involved than it is about real science. If he places too much emphasis on accuracy and completeness, there is a risk of getting bogged down in technical jargon. Fortunately for the reader, Rezzola has managed to strike a balance between these extremes. He’s written a book that’s easy to read, but doesn’t shy away from mathematical formulas either, which is where they really help. The author not only provides a competent introduction to the fundamentals of the field, but also provides a feel for how scientific work on these highly complex topics is carried out in practice.

According to Einstein’s theory, gravity is nothing more than the geometry of four-dimensional space-time. Rarely is it as clear as a black hole. This corresponds to a matter-free region of space-time, which is reasonably separated from the regions of external observers. If such an observer is daring enough to plunge into the black hole, there is no more escape, for the simple reason that the inside of space behaves like time and reversal in time is impossible. Behind the irresistible attraction of gravity lie the unique properties of space and time.