View source for Quantum: Einstein, Bohr and the Great Debate About the Nature of Reality by Manjit Kumar

{{infobox1
|title= Quantum: Einstein, Bohr and the Great Debate About the Nature of Reality
|author= Manjit Kumar
|reviewer= Magda Healey
|genre=Popular Science 
|summary= A fascinating, powerful and brilliantly written book that shows one of the most important theories of modern science in the making and discusses its implications for our ideas about the fundamental nature of the world and human knowledge, while presenting intimate and insightful portraits of people who made the science. Highly recommended. 
|rating=4.5 
|buy= Yes
|borrow= Yes
|pages=464 
|publisher= Icon Books Ltd
|date= April 2009
|isbn=978-1848310353
|cover=1848310358
|aznuk=1848310358
|aznus=1848310293
}}

Two theories have shaped modern physics and thus our understanding of the world: quantum mechanics and general relativity. The relativity deals with huge scale systems and gravity - and works, while in the process creating its own well know paradoxes. Quantum mechanics applies at the atomic (and lower) levels. Of the two, it's the quantum mechanics that is - and has been - the most mind boggling for scientists and laymen alike.

Niels Bohr said that if anybody says that they understand quantum mechanics that means they don't really understand it. Richard Feynman suggested that one should try, if at all possible, just to accept that it is like that instead of wondering how it could possibly be like that. Albert Einstein struggled with the ''quantum demon'' for many years, and his famous quote about God not playing dice is connected to those struggles.

And yet quantum mechanics is an incredibly fruitful theory, which successfully explains and describes most fundamental phenomena of our whole world: it allows us to peek into the very core of matter, at the forces creating and governing the infinitesimal particles constituting the atoms of which constitute everything in the Universe.

Kumar's ''Quantum'' is a historical narrative of the development of the quantum theory, from the first reluctant introduction of the term ''quantum'' (and its implications) by Max Planck to the development of the whole theory by Niels Bohr and his troop of Young Turks of theoretical physics which included Heisenberg, Dirac and Pauli and its solidification in so-called Copenhagen interpretation; and beyond, to the most recent attempts at testing the same interpretation.

This narrative is presented on a rich historical and political background and a lot of biographical and personal information about all the major players is provided.

Throughout the book, Kumar repeatedly focuses on philosophical antecedents and consequences of what he calls in the subtitle the Great Debate About the Nature of Reality. The figure of Einstein is fundamental to Kumar's argument, and especially in the second half of ''Quantum'' he shows how Einstein's doubts kept the philosophical debate - and the search for new interpretations - of quantum theory alive even when the great majority of the scientists subscribed to the orthodox Copenhagen version.

I found ''Quantum'' a fascinating, riveting read. I have not read individual biographies of the scientists concerned beyond what can be found in customary introductory sections of popular science books, and I normally dislike the biographical approach to popular science, but in this case the interweaving of the stories of the scientists and of the science worked brilliantly. ''Quantum'' shows not only the body of science, but also its human face. I had a real feeling of observing one of the greatest revolutions of human understanding of the world as it happened; from the personalities of people involved to the administrative details of their employment to the grand sweeps of history that engulfed them. Particularly compelling was how essential for the development of ideas was the communication, co-operation and competition between the scientists: how ideas were bounced between them, reused and refashioned, and how astonishingly creative this cohort of incredibly young men became in the process.

If I have one criticism of Kumar's book it is that the presentation of the science itself was a bit uneven: parts of ''Quantum'' read like a physics textbook, including some perhaps unnecessary equations and diagrams. I felt he couldn't decide whether he was writing for those who have more than a very basic understanding of physics, or whether he felt he had to explain everything from scratch and it resulted in some rather technical sections that could have been skipped or truncated.

One probably needs to have some basic idea of molecular physics to be able to appreciate the story told in ''Quantum'', although a very rough, general knowledge (mine is limited to secondary school physics and chemistry 20 years ago) is likely to be enough as long as the reader doesn't feel a compulsion to understand every paragraph in depth.

But ''Quantum'' is not really a popular science introduction to the subject, and it doesn't really attempts to be: there are better books out there which present the ideas themselves. It is a narrative account that combines chunks of popular science with individual biographies, social history of science and rather fundamental questions of philosophy.

At the centre of this narrative is the title debate between Albert Einstein and Niels Bohr and his cohort of followers about nothing less then the nature of reality itself.

Einstein himself started the quantum ball rolling, but could never come to terms with what became the dogma of quantum mechanics - the so called Copenhagen interpretation derived by Bohr, Pauli and Heisenberg.

Many are familiar with the famous Einstein's claim of ''God not playing dice'', which is normally taken to indicate Einstein's unshakable belief in causality in a deterministic world. This belief is profoundly shaken by the quantum theory, according to which atomic world is probabilistic in its essence. But there was something in quantum mechanics that troubled Einstein (and Schrödinger: his famous thought experiment intended to show the absurd implications of the Copenhagen interpretation of quantum mechanics, not to support it) even more than the loss of causality and its replacement by statistical models only.

According to the Copenhagen interpretation, at the atomic level, light is either a particle or a wave, depending on the experiment performed: there is no independent reality, no separation is possible between observers and and the objects of observation. In the absence of an observer, a particle does NOT exist in an unknown but real state. We ourselves produce the results of measurements. The electron has NO position. The cat is neither dead nor alive, or rather it's both dead and alive.

According to Bohr, the task of physics was not to describe how nature is, but to find out what we can say about it. Theory is only a model. Einstein believed that there is a reality behind it, even if it's to remain forever unknown to humans. Bohr argued that there is no reality, or that it's meaningless to claim it exists.

Is it important? Are we arguing here about the number of angels that can dance on the point of the pin? Does it matter whether the theory is only a model or whether there is some reality behind it and whether electrons exist in the same manner that rocks and trees exist?

It's important to anybody who cares about the nature of science and its ability to describe and explain the world. It's also an interesting question to everybody who has ever been attracted by solipsist ideas and doubted whether a branch falling in a forest when nobody can sea or hear it makes a sound.

''Quantum'' is a fascinating, powerful and brilliantly written book that shows one of the most important theories of modern science in the making and discusses its implications for our ideas about the fundamental nature of the world and human knowledge, while presenting intimate and insightful portraits of people who made the science. Highly recommended.

The review copy was sent to the Bookbag by the publisher - thank you!

Those interested in how history, politics, lives of individual scientists and ground breaking discoveries intertwine would enjoy Eric Kendal's [[In Search of Memory: The Emergence of a New Science of Mind by Eric R Kandel|In Search of Memory]].  [[The Canon by Natalie Angier]] 
provides a back-to-basics introduction to several areas of modern science and [[The Oxford Book of Modern Science Writing by Richard Dawkins]] is an anthology of classic 20th century science writing.

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[[Category:History]]