New Scientist - The Essential Guides

The Essential Guide series brings together the best recent coverage from New Scientist specially curated into beautiful compendiums about the most exciting themes in science and technology today. Written and edited by some of the world’s best science writers, these guides will leave you with everything you need to know about subjects from nutrition to the solar system and more.

QUANTUM PHYSICS

New Scientist - The Essential Guides

INTO THE QUANTUM WORLD

THE ORIGINS OF QUANTUM MECHANICS • In 1894, physicist Max Planck was warming to a new challenge. A consortium of electric companies had commissioned Planck to make a light-bulb filament generate maximum light for the least amount of energy. It was a mundane start to perhaps the most extraordinary voyage of intellectual discovery science has ever taken us on.

QUANTUM UNCERTAINTY • The strange predictions swirling round the new quantum theory didn’t stop with de Broglie’s wave-particle duality. In 1927, another young researcher came up with a statement about the reality it depicted that more than any has come to define popular perceptions of the quantum world. It also, you might say, is the determining factor in material reality existing at all.

UNCERTAIN GENIUS

THE EXPERIMENT THAT DEFIED REALITY • One experiment, in various iterations, did more than any other to establish that quantum theory’s weird predictions do indeed reflect reality: the infamous double-slit experiment, which sends one thing two ways at once

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A TIMELINE OF QUANTUM PHYSICS • Although its origins at the turn of the 20th century, a frenzied burst of discoveries in the mid 1920s really established the outline of quantum theory. Its application to the world of particles and forces has slowly developed in the decades since

QUANTUM WEIRDNESS

“SPOOKY ACTION AT A DISTANCE” • Spukhafte Fernwirkung – that was the original German version of Einstein’s disparaging characterisation of quantum entanglement. In the end, though, it was those who thought it couldn’t be real who got spooked.

QUANTUM DUELLISTS • The fight over the nature of quantum reality was fought, decorously and over many decades, between two great contemporaries – Niels Bohr, the helmsman of the “Copenhagen” school of researchers that dominated early quantum thinking, and arch quantum sceptic Albert Einstein

LOOPHOLES IN REALITY • Entanglement is easy to define, but difficult to pin down. The inequalities derived by John Stewart Bell in 1964 provided a way of testing whether it was a real phenomenon, and so if quantum mechanics was “correct”. At least they did in theory. Establishing the reality of Einstein’s nemesis has pushed experimental physics to its limits – and pushed many physicists to theirs.

CAN EFFECT PRECEDE CAUSE? • If you were to break your arm tomorrow afternoon, would you suddenly find it hanging useless in a sling this morning? Of course not – the question makes no sense. Cause always precedes effect. But maybe life isn’t quite so straightforward for a photon. In the quantum realm, the one thing that we always considered beyond the pale might just be true.

QUANTUM AND REALITY

THE MYSTERY OF SCHRÖDINGER’S CAT • WANTED: DEAD AND ALIVE! When it comes to Schrödinger’s cat, the hipster T-shirts write themselves. The zombie feline in an ambiguous state of animation fascinates the wider world. For quantum physicists, it is more of a tormentor, clawing at their belief in a treasured theory and coughing up hairballs over its claim to provide true enlightenment about the workings of reality.

THE CAT KILLER

THE DE BROGLIE-BOHM INTERPRETATION • The roots of one rival to the standard “Copenhagen” interpretation of quantum theory stretch back right to the beginnings of the...