The intellectual adventure story of the"'double-slit" experiment, showing how a sunbeam split into two paths first challenged our understanding of light and the nature of reality itself and continues to do so almost 200 years later.
Experimentalists...have entered territory truly hard for nonexperts to comprehend, and it’s extraordinary that they’ve been able to push things to this edge. Nothing like these experiments happens in the natural world. These are products of hand-made human craft. At a time when popular physics writing so valorizes theory, a quietly welcome strength of Ananthaswamy’s book is how much human construction comes into focus here. This is not 'nature' showing us, but us pressing 'nature' for answers to our increasingly obsessional questions ... is the wavefunction a part of objective reality, or is it a subjective tool that we see and use, but ultimately just a descriptive device? Ananthaswamy ends his book without resolving these issues. And when so many people are so assuredly proffering answers, this is an honest, courageous move. Rather, he suggests, the double-slit experiment will continue to deliver surprises.
If you find it hard to think about half-silvered mirrors, then be warned that there are a great many of them in this book. Suitably arranged, they can be used to create a variety of photon mazes rich in theory-testing possibilities. Mr. Ananthaswamy helpfully supplies schematic diagrams, though the actual mirrors are unlike the ordinary kind ... Mr. Ananthaswamy interviewed many leading theoreticians and experimentalists in the course of writing this book, and he covers a large and complex field in an admirably accessible way. Historical or biographical details are mostly subordinated to scientific and philosophical issues, though we glimpse a few colorful characters.
Ananthaswamy...is mostly using the 'double slit' as a means of exploring the various possible interpretations of quantum physics, in much the same way that Adam Becker's book from my last group of book reviews does. Along the way, he hits a pretty good range of stuff—the obvious Copenhagen and Many-Worlds discussion, but also a nice and detailed discussion of Bohmian mechanics and a couple different varieties of spontaneous-collapse theories, and even a section devoted to the epistemic new-kid-on-the-block, 'quantum Bayesianism' (usually shortened to 'QBism') ... Ananthaswamy explores the variations on the double-slit formula through interviews with a variety of physicists ... This provides some diversity of viewpoints that helps the book feel less narrow than the focus on a single experiment would suggest. Ananthaswamy's own voice is not terribly intrusive, making for a very balanced treatment of all the various interpretations considered: each interpretation is described by its own proponents, with a minimum of editorializing.