A strong candidate for “word of the year” would be “quantum”. The 16 October 2018 edition of the Financial Times featured an article by Ilyas Khan with the headline: “Why you need to quantum-proof your cyber security now”. Five days later the New York Times published an article by Cade Metz on “The next tech talent shortage: quantum computing researchers”, describing competition between firms in the US, London, Paris, Montreal and Beijing for scientists experienced in quantum computing. The broad interest in this topic stems from the expectation that future computers will exploit aspects of quantum mechanics, in particular entanglement of quantum states, to solve problems that are too difficult or impossible for machines operating on classical physics. Modern quantum mechanics, developed by Werner Heisenberg, Erwin Schrödinger, Wolfgang Pauli, Paul Dirac and others in the mid-1920s is the most successful and accurate theory we have. And yet, despite being the foundation of nuclear, solid-state and semiconductor physics, enabling the invention of the transistor, the laser and magnetic resonance imaging, fundamental questions about the interpretation of quantum mechanics persist to this day. To address this, Jeffrey Bub, a physicist and philosopher at the University of Maryland, and his artist daughter Tanya Bub have created Totally Random – Why Nobody Understands Quantum Mechanics, a non-fiction graphic novel that is subtitled “a serious comic on entanglement”. A serious comic: Tanya Bub and Jeffrey Bub use graphic art and a sense of humour to explain the complexities of quantum physics. (Courtesy: Tanya Bub and Jeffrey Bub/Princeton University Press) Jeff and Tanya (represented as J and T, respectively) are heard but not seen in the comic, appearing as disembodied voices, with J explaining the “curious correlation” at the heart of quantum mechanics. While real experiments on entanglement involve photon polarizations, Totally Random considers the results of flipping two identical coins. For two ordinary US quarters, these would be two heads, two tails, one head and one tail, or one tail and one head, with each result being equally likely, regardless of the coins configuration prior to flipping. The Bubs introduce an imaginary “Superquantum Entangler Pr-01”, which looks very much like a two-slot toaster, that “entangles” the two quarters, so that when flipped they now behave like quantum particles – the modified quarters being dubbed “Quoins”. Now when the Quoins are flipped, how they land (heads or tails) will depend on their initial orientation on the thumb. If both Quoins are flipped starting with heads up, then one will land heads up, and the other with the tail facing up. If the Quoins are flipped with one head and one tail facing up, they will land with either both heads or both tails facing. No matter whether they are flipped simultaneously or one at a time, either adjacent to each other or separated by a great distance, this correlation between how they are situated before being flipped and the result of flipping persists. Clearly, the Superquantum Entangler Pr-01 is doing something to the quarters, but what? Maybe the Entangler rigs the quarters somehow, changing some inner state of the coin, so that the way they land is dependent on how they are flipped. Totally Random presents one of the clearest explanations I’ve seen of Bell’s theorem, demonstrating without mathematics that no internal rigging (or “hidden variables”, if you will) would yield the observed correlations of the Quoins for all four starting configurations. It then shows that if the Quoins were somehow communicating their orientation information to each other, they would have to send signals faster than the speed of light in order to maintain the correlations. Having stated the central mystery, the Bubs then consider physicists’ various attempts to interpret these correlations. The story opens up, and caricatures of many of the pioneers of quantum mechanics appear, each promising to account for what happens at the moment when the flipped Quoins are examined. Schrödinger’s cat makes an obligatory appearance, as does Hugh Everett’s many-worlds interpretation (when one of the narrators protests “You can’t prove that the world split off into two branches!” Everett, portrayed as a carnival worker, nonchalantly replies “Can’t prove it didn’t.”) and David Bohm’s pilot waves (which are written on a paper aeroplane that literally pokes Albert Einstein in the eye). Any anxiety “from uncontrollable urges to picture an underlying reality” can be resolved by calling Dr Bohr at 1-800-Let-It-Go (which actually turns out to be the number for a medical alert company). The Bubs give each their due, though a preference for the Copenhagen Interpretation comes through. The final third of the book illustrates the various ways that, even without understanding their origin, these correlations can be useful, such as for quantum encryption and the teleportation of information. Here we see the potential applications for entanglement that are driving much of the current interest in this subject. Tanya Bub’s artwork at times invokes the stippling photo-realism of American cartoonist Drew Friedman. However, I would have liked a bit more of an introduction to the underlying correlations of the flipped Quoins, and some scenes are unnecessarily drawn out. I also found the arguments in the Quantum Casino (where a couple are able to exploit the correlations of Quoins to beat a complex game of chance) a bit hard to follow. There is an extensive notes section at the back of the book that will be useful for those who want to delve deeper into the material presented, and like all good comic books, there are ads for sea monkeys and X-ray specs at the very end. Totally Random provides an accessible introduction to questions of nonlocality, superposition and entanglement, topics that have relevancy for applications such as Bitcoin and cryptocurrency. In some ways a graphic novel is the ideal method to engage with such concepts. As Clifford Johnson, author of his own non-fiction graphic novel about modern concepts in theoretical physics The Dialogues (May 2018) has argued, there is a natural connection between physics and comics, in that both involve constructions of space and time. 2018 Princeton University Press £17.99pb 272 pp