Robert Crease in Physics World:
Its name is Quantum Cloud. Visitors to London cannot miss it when visiting the park next to the Millennium Dome or taking a cruise along the Thames. It rises 30 m above a platform on the banks of the river, and from a distance looks like a huge pile of steel wool. As you draw closer, you can make out the hazy, ghost-like shape of a human being in its centre. It is a sculpture, by the British artist Antony Gormley, made from steel rods about a metre and a half long that are attached to each other in seemingly haphazard ways. Framed by the habitually grey London sky, it does indeed look cloud-like. But “quantum”?
The word quantum has a familiar and well-documented scientific history. Max Planck introduced it into modern discourse in 1900 to describe how light is absorbed and emitted by black bodies. Such bodies seemed to do so only at specific energies equal to multiples of the product of a particular frequency and a number called h, which he called a quantum, the Latin for “how much”. Planck and others assumed that this odd, non-Newtonian idea would soon be replaced by a better explanation of the behaviour of light.
No such luck. Instead, quantum’s presence in science grew. Einstein showed that light acted as if it were “grainy”, while Bohr incorporated the quantum into his account of how atomic electrons made unpredictable leaps from one state to another. The quantum began cropping up in different areas of physics, then in chemistry and other sciences. A fully fleshed out theory, called quantum mechanics, was developed by 1927.
Less familiar and well documented, though, is quantum’s cultural history. Soon after 1927 the word, and affiliated terms such as “complementarity” and “uncertainty principle”, began appearing in academic disciplines outside the sciences. Even the founders of quantum mechanics, including Bohr and Heisenberg, applied such terms to justice, free will and love. Quantum has made unpredictable leaps to unexpected places ever since. The next James Bond film, for example, is to be called Quantum of Solace.