# Bookshelf

27 April 2012

L’enigma dei raggi cosmici. Le più grandi energie dell’ universo • Books received

L’enigma dei raggi cosmici. Le più grandi energie dell’ universo
By Alessandro De Angelis
Springer
Paperback: £19.99 €24.44

In telling the story of “the enigma of cosmic rays”, physicist and enthusiastic communicator Alessandro De Angelis traces the fascinating adventure of cosmic rays since their discovery a century ago. Today, the exploration of the mysteries of cosmic rays continues with even more powerful tools in a range of energies that extends 20 orders of magnitude.

Cosmic rays have always been puzzling. In the first decade of the 20th century, physicists were seeking a solution to the problem of why gold-leaf electroscopes – instruments that are still common in laboratories in schools today – discharge spontaneously. Many scientists faced this problem, including an Italian, Domenico Pacini, who made some important measurements by immersing his instruments under water at different depths and observing a marked decrease in the discharge rate. Indeed, Pacini was the first to give a clear indication that part of the natural radiation he detected came from the atmosphere and from the cosmos. However, his results were published only in Italian and had no great prominence – although Viktor Hess did mention Pacini several times in his speech when he obtained the Nobel Prize in Physics for the discovery of cosmic rays. Pacini’s work is yet another glaring example of a discovery that has not obtained the international recognition it deserves.

The riddles of cosmic rays do not end there. We still do not know for sure where they come from. They are deflected by the interstellar magnetic field so their direction of arrival cannot be connected to their starting point. Above all, we still struggle to understand what mechanism provides them with an energy that can in extreme cases reach the energy of a tennis ball concentrated in a single atomic nucleus. Enrico Fermi proposed a theory for the acceleration of cosmic rays that explains in part what is observed. However, there is still much to understand and we hope that recent and future results in high-energy astrophysics will be able to answer this fundamental question.

What is sure is that cosmic rays bring to the Earth pieces of the far-away universe. Furthermore, their high energy makes them interact with the atmosphere, producing secondary particles – as in powerful particle accelerators. For this reason, in the first half of the past century cosmic rays revealed the first particle of antimatter – the positron – and many new particles that led to the birth of elementary particle physics before accelerators made by humans turned it into a mature science. Even today, in the LHC era, the study of high-energy cosmic rays and the precision testing of their composition at intermediate energies are active fields of research, with experiments on Earth and in space. In particular the first evidence of neutrino oscillations – and thus of their mass – was observed by studying the secondary neutrinos produced by cosmic rays in the atmosphere.

This book by De Angelis traces the history of the study of cosmic rays in a documented, comprehensive way, often providing details both interesting and little known. It is easily readable and an excellent reference for anyone interested in fundamental physics and contemporary astrophysics.

Roberto Battiston, University of Perugia.

### Books received

The Universe: A Challenge to the Mind
By Jacques Vanier
Imperial College Press
Hardback: £74 $120 Paperback: £33$54

In this book, Jacques Vanier gives a comprehensive picture of the physical laws that appear to regulate the functioning of the universe, from the atomic to the cosmic world. It offers a description of the main fields of physics as applied to the atomic world and the cosmos, to describe how the universe evolved to its present state. This is done without equations, except for a few, although there is a short annexe for readers who wish to see how the principles and laws expressed in words can be visualized in the language of mathematics. The author also occasionally uses two young people placed in various situations to explain aspects of physics through their observations.

An Introduction to String Theory and D-Brane Dynamics: With Problems and Solutions (2nd Edition)
By Richard J Szabo
Imperial College Press
Hardback: £42 $68 E-book:$88

Originally published in 2004, this book provides a quick introduction to the rudiments of perturbative string theory and a detailed introduction to the more current topic of D-brane dynamics. The presentation is pedagogical, with much of the technical detail streamlined. The rapid but coherent introduction to the subject is perhaps what distinguishes this book from other string-theory or D-brane books. This second edition includes an additional appendix with solutions to the exercises, thus expanding the technical material and making the book more appealing for use in lecture courses. The material is based on mini-courses in theoretical high-energy physics delivered by the author at various summer schools, so its level has been appropriately tested.

Adventures in Cosmology
By David Goodstein (eds.)
World Scientific
Hardback: £57 $86 E-book:$112

This up-to-date collection of review articles offers a general introduction to cosmology by experts in various fields. It starts with “Galaxy Formation from Start to Finish” and ends with “The First Supermassive Black Holes in the Universe”, exploring in between the grand themes of galaxies, the early universe, the expansion of the universe, neutrino masses, dark matter and dark energy. Together the chapters provide a detailed view of what is known about the universe as well as what remains unknown. Students, researchers and academics interested in cosmology should find this book useful.