Once again, it will soon be time for many of us to take a well-earned break with friends and family, probably after a few hectic hours searching for presents in this festive season. To help with the shopping – whether for others or for yourself – this end-of-year Bookshelf presents some suggestions for more relaxed reading.
Madam Wu Chien-Shiung: The First Lady of Physics Research
By Chiang Tsai-Chien (translated by Wong Tang-Fong)
The discovery of parity non-conservation was honoured with a Nobel Prize in Physics awarded to Chen-Ning Yang and Tsung-Dao Lee who raised the “question of parity conservation in weak interactions” in 1956 (Phys. Rev. 104 254). Originally the preprint contained a question mark – “Is parity conserved in weak interactions?” – but the editors of Physical Review at that time discouraged question marks in the titles of regular articles. The crucial question mark was eliminated forever the same year by the valiant effort of Chien-Shiung Wu and her collaborators – Ernest Ambler, Raymond Hayward, Dale Hoppes and Ralph Hudson. They conducted a memorable experiment at the National Bureau of Standards and the results were published in the first few months of 1957 (Phys. Rev. 105 1413). The concept of their experiment was remarkably simple: take a β-decay source (cobalt-60) and magnetize it with a circular current flowing first in one direction and then in the opposite sense, so that the initial states are the mirror images of each other. The β decays of the mirror-symmetric initial states turned out to be non-mirror-symmetric. Immediately afterwards, two other groups published similar evidence for parity non-conservation – Richard Garwin, Leon Lederman and Marcel Weinrich in Columbia University and Jerome Friedman and Valentine Telegdi in Chicago.
Weak interactions are at the heart of this interesting biography. Of course, Wu was not the first lady working in physics – other remarkable women preceded her in the path to great discoveries. However, as the author argues, she was a person of many “firsts”, such as the first recipient of the Wolf prize and the first female president of the American Physical Society.
The biography tells the exciting story of a young woman who left the rural China vividly described in the novels of Pearl S Buck and became one of the recognized authorities in the physics of β decay. Wu joined the Manhattan Project and later worked on several other topics, ranging from the Mossbauer effect to exotic atoms. However, her main contributions remain connected to weak interactions. In collaboration with her group in Columbia she also tested the conserved vector-current hypothesis and the universality of Fermi interaction proposed by Richard Feynman and Murray Gell-Mann – a discovery that was essential for the subsequent development of the Standard Model of electroweak interactions.
Wu was above all a scientist who did not like much exposure and dramatic headlines. She also had a wonderful family and various interests, including the rights of women in science. After leaving Shanghai in 1936, she was not allowed back into mainland China for 37 years and so never again saw family members who had died in the meantime. The Cultural Revolution threatened Chinese science but did not succeed. A number of remarkable Chinese scientists, including Wu, contributed enormously to the current success of the standard electroweak theory.
• Massimo Giovannini, CERN and INFN Milan-Bicocca.
Time Reborn: From the Crisis of Physics to the Future of the Universe
By Lee Smolin
This is a fascinating and thought-provoking book about the nature of time and its role in explaining the universe. Smolin is an original thinker who is unafraid to challenge established orthodoxy. He argues that modern attempts to understand the universe have reached an impasse as a result of the extraction of time from our concept of reality.
The book is presented in two parts. The first offers an historical and philosophical account of how we have arrived at a timeless view of the world. The second develops ideas for a new approach to physics, which incorporates time as a central and fundamental theme. While both parts are interesting and relevant, physicists might find it more satisfying to read the second part first. There is also an epilogue where Smolin discusses some of the implications of redefining our concept of time and reality and how we might meet the challenges of the future, such as climate change and market economics. Finally, he considers the nature of consciousness.
Smolin begins by illustrating, with the simple example of projectile motion, how time can be excluded from our understanding of a physical system by using mathematical constructs. The role of mathematics is to make a physical system abstract, rendering it eternal and timeless. Here Smolin gives an excellent account of the history of the Copernican Revolution, Johannes Kepler and Galileo Galilei. His unique perspective gives new insight into how each world view might have developed and persisted. At each stage the concept of time becomes increasingly obsolete, culminating in the determinism of the Newtonian paradigm. Relativity is no less deterministic, leading us to a timeless “block universe” picture where reality is the whole history of the universe at once.
In what he calls “doing physics in a box”, Smolin examines the applicability of the Newtonian paradigm to cosmology. A physical system can never be isolated from external influences, so the solutions are an approximation to reality. The approximation can be removed by taking the universe as a whole into consideration but such a step cannot be justified because the Newtonian paradigm necessarily applies to a system that is part of a whole. Smolin calls the inappropriate application of physical laws to the universe a “cosmological fallacy”. His reasoning draws attention to the distinction between physics-in-a-box and cosmology. “The universe is an entity different in kind from any of its parts.”
Smolin is a strong proponent of Leibnitz and the principle of sufficient reason, which states that if there is more than one possibility for things to be as they are, then there must be a sufficient reason for the actual outcome being the case. He uses this to great effect in defining his principles for a new cosmology. In particular, “there should be nothing in the universe that acts on other things without itself being acted upon.” This expresses the philosophy of relationism, where every entity in the universe evolves dynamically, including the physical laws governing the universe. These laws then “become explicable only when they participate in the dance of change and mutual influence that makes the world a whole”. A consequence of relationism, Smolin argues, is that symmetries and conservation laws can only be approximations to reality.
Smolin is keen to emphasize a new approach to a theory of the universe that is not constrained by the Newtonian paradigm. He attempts to provide a framework for a new theory, insisting that it must be able to provide falsifiable predictions. In this sense he is less speculative than those who opt for a multiverse of universes that are not causally connected to our own. He proposes the existence of many universes but with causal connections, which in principle allow their existence to be detected. A possible candidate for the new theory is cosmological natural selection – the subject of his earlier book The Life of the Cosmos – in which universes reproduce through the creation of new universes within black holes. The presence of a large number of black holes in a universe is a measure of its fitness in evolutionary terms. The analogy with Darwinian evolution raises the fascinating possibility of novel outcomes, similar to the emergence of new species through natural selection.
This book is great for providing numerous thought-provoking ideas. The reader does not have to agree with all of them to be stimulated into pondering the nature of time. Unsettling and controversial in places, it offers a much needed re-examination of some of our most cherished views.
• Theresa Harrison, Warwick University.
The Adventurous Life of Friedrich Georg Houtermans, Physicist (1903–1966)
By Edoardo Amaldi (Saverio Braccini, Antonio Ereditato and Paola Scampoli eds.)
Paperback: £44.99 €52.70 $49.95
E-book: £35.99 €41.64 $39.95
Before visiting a university or physics laboratory, most people imagine today’s physicists as peaceful men or women wearing white lab coats and dealing with test tubes, clouds of coloured smoke and mathematical equations. Although the description would be more appropriate for ancient alchemists rather than modern physicists, one word should still stand out – peaceful. However, there was a time when physicists were investigating dangerous radiation, fissile nuclei and particles to trigger a nuclear-reaction chain. These were also the times when Europe was a battlefield and scientific results were regarded as potential material for spies and the tellers of spy stories. In those days, almost every scientist could have made a good subject for writers and Hollywood.
Friedrich “Fritz” Houtermans is no exception. Indeed, his private and professional lives make a good subject for a book. However, in my opinion, the most intriguing aspect of this book is the author – Edoardo Amaldi – and the reason why he decided to write about Fritz, a man who was married four times, spent a few years in Lubianka and other prisons and published several important physics results along the way. Amaldi had seen L’Aveu – the film by Costa Gravas about Artur London, the Czechoslovakian communist minister falsely arrested and tried for treason and espionage – and was struck by similarities with the story of Houtermans. Amaldi began to write about Houtermans but died in 1989. Twenty years later, Edoardo Amaldi’s son Ugo gave his father’s unpublished manuscript to the Laboratory for High Energy Physics at the University of Bern, where Fritz had done much to initiate research on particle physics. I share the fascination of the editors when they describe how grateful they were to have the opportunity to “meet two outstanding physicists” – Fritz and Edoardo.
The result is a detailed description of both the life of Houtermans and the lives of other friends of Amaldi. It is a beautiful description of Europe and science during the years before, during and after the Second World War. The words Amaldi uses – which are well edited – are not those of a storyteller. Instead, he provides a detailed – almost scientific – report of this almost unknown physicist.
Although Houtermans is an interesting subject, more interesting to me are the chapters where Amaldi explains the “making of” the book and his research into accurate information sources about its subject. I think that soon I will be looking for an equivalent book about Amaldi’s life.
• Antonella Del Rosso, CERN.
Allegro Neutrino ou L’attrape-temps
De François Vannucci
Paris, dans les années 1950. Michel a 11 ans et voit des bulles, ce dont il est très fier. Terme résolument non scientifique, le mot ” bulle ” désigne pour le narrateur – Michel – ” une myriade de points lumineux dansant dans tous les sens “, points lumineux qui se révèleront être, au fil des pages, des ” neutrinos “. Nous y voilà.
Vous l’aurez compris, bien qu’écrit par un physicien des particules spécialisé en physique des neutrinos, ce livre est un roman. L’objectif n’étant pas de vous en apprendre des kilomètres sur ces fameux neutrinos, mais de vous embarquer dans une histoire dont ils sont les protagonistes. Et si l’histoire est contée par un jeune narrateur passionné de physique, il n’en reste pas moins qu’il s’agit d’un enfant, et non pas (encore) d’un physicien des particules.
L’intrigue, si je puis donner à l’histoire cette connotation très romanesque, est somme toute assez simple. Michel, écolier plutôt mauvais en maths mais bon en imagination, vit dans un minuscule appartement parisien avec ses parents. Il va à l’école à pied, troue ses chaussettes, accompagne sa mère au marché le jeudi et à la messe le dimanche, passe ses vacances d’été à la campagne, collectionne les timbres, adore les truffes au chocolat, et se délecte des histoires de science de son oncle Albert, fonctionnaire tire-au-flanc et lecteur assidu de magazines de vulgarisation scientifique. Mais ce qui anime surtout Michel, moins son histoire, c’est cette étrange capacité à voir des neutrinos.
Mais ne vous méprenez pas, les neutrinos de Michel sont loin de coller à l’idée que l’on s’en fait au CERN. Pour Michel, ce ne sont en effet ni plus ni moins que les constituants de l’âme des êtres vivants, ou, comme les décrit encore le narrateur, ” notre carburant spirituel “. Ce qui explique d’ailleurs que les jeunes en émettent plus que les vieux, et que ceux qui n’en émettent plus sont morts. CQFD.
Au final, ce livre est un long voyage dans la tête d’un gamin de 11 ans, à la rencontre de ses idées farfelues, de ses expérimentations et déductions scientifiques, de ses découvertes triomphantes et de ses confrontations au monde des adultes. Certains passages sont franchement réjouissants, et l’on finit par se prendre d’affection pour le jeune Michel, qui garde précieusement au fond de sa poche, un marron, une bille et une boîte pleine de neutrinos.
• Anaïs Schaeffer, CERN.