By **Lewis Dartnell**

In a short story by the science fiction writer Alastair Reynolds, a man accepts the offer from an alien species to further extend the cognitive capabilities of his brain so that he may come to understand the true nature of the universe. The absolute truth of reality is compared to the patterned floor of a room, buried beneath layer upon layer of carpets. The process of coming to know the fundamental nature of the cosmos is a process of finding a flaw in the uppermost carpet, then tugging at this loose thread to remove the flawed rug and reveal the underlying layer, and so on down through the layers of description until you reach the floor.

Frank Wilczek’s A Beautiful Question is the first book I’ve read in which I’ve felt that almost vertiginous sensation of peering through layers of theories down to the true nature of the universe. Wilczek, a Nobel Prize-winning theoretical physicist, sets out to answer a deceptively simple question: “Does the world embody beautiful ideas?” Or to rephrase this in a slightly more useful way: “Is the physical universe, and the equations that physicists have derived to explain it, beautiful?”

The author’s contention is that the standard model of particle physics (or the “Core Theory”, as Wilczek calls it) is indeed beautiful, but to appreciate this the reader must first understand what the standard model actually is. So the bulk of this book is a summary of the development of key notions in the history of physics, and how we have come to uncover the “fundamental operating system” of nature.

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Wilczek starts his “meditation” with Pythagoras and his theorem on right-angled triangles that revealed a deep relationship between geometry and number, and his investigations into music and the link between harmony and number. These, Wilczek argues, were the first inklings towards the deep numerical order underlying the world, and he returns throughout the book to these themes of order, pattern, symmetry and simplicity in the laws governing the universe.

The sense of these layers of understanding is perhaps clearest in the story of light. Isaac Newton’s experiments with prisms showed that white light was made up of a blending of all colours, and that colour was something intrinsic to the light ray itself. But it was not for another century that we came to understand the substance of light.

While working on the seemingly related phenomena of electricity and magnetism, James Clerk Maxwell derived a set of equations to describe how the two interrelated. His equations showed that since an electric field that changed over time generated a magnetic field, and conversely a varying magnetic field induced an electric field, then the two ought to self-support and produce an electromagnetic wave that rippled through empty space. As Wilczek so poetically describes, the situation “takes on a life of its own, with the fields dancing as a pair, each inspiring the other”. Maxwell could also use his equations to calculate how fast such an electromagnetic undulation would travel, and he found that it matched what had already been measured for the speed of light. For Maxwell, it was obvious that this correspondence was no coincidence; that, in fact, the underlying agent of light, a mystery that had foxed Newton, was no more than a mutually supporting disturbance in magnetic and electric fields. To use the parlance of modern physics, this was a monumental feat of reductionism, as Maxwell had achieved in one go the unification of the theories of electricity, magnetism and light.

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More recently, Maxwell’s equations have been incorporated with quantum mechanics to produce the theory of quantum electrodynamics (QED), and we’ve realised that this electromagnetic force is one of four fundamental forces of the universe; alongside gravity there is also the strong force holding together quarks in subatomic particles (accurately described by the theory of quantum chromodynamics, QCD) and the weak force. And these forces act on a range of different particles of matter, which can themselves be organised into related families. So the essence of the standard model is of a number of forces directing how particles of matter behave, and this overarching mathematical framework contains an astonishing degree of pattern and symmetry.

As Wilczek explains, physicists have become so accustomed to finding that the laws of nature they infer from experiments possess deep symmetries that the reverse process is now attempted – the proposition of equations containing lots of symmetry, followed by the study of whether nature uses them. The theory of supersymmetry, or SUSY, has been developed to resolve the apparent duality in the universe between forces and matter by explaining the two as simply manifestations of the same underlying structure.

At times this is a challenging text, but it is well worth the effort. Wilczek is admirably clear in his explanations. But the book falls short of answering whether the world embodies beautiful ideas. Despite the fact that Wilczek says the answer is a resounding “yes!”, he fails to provide a convincing discussion of the meaning of “beauty” and whether the physical laws satisfy this.

The links between seemingly disparate phenomena and the symmetries inherent in the equations are profound, and the scientists who devise and confirm these mathematical descriptions are extraordinarily creative, but is this necessarily beauty? Nature is undeniably economical in the rules she uses to mould the universe, but is this minimalism necessarily beautiful? Does Wilczek think that beauty is something beyond order, symmetry, simplicity? If not, why not just use these terms to relate to the laws of the universe? But if so, the onus is upon him to clearly lay out why he feels this may be.