This Book Will Blow Your Mind by New Scientist

Author:New Scientist [New Scientist]
Language: eng
Format: epub
Publisher: Quercus
Published: 2018-08-22T16:00:00+00:00

Spontaneous universe

If we accept quantum theory, that is. All the havoc quantum theory wreaks with cherished notions of reality, relativity and causality raises a natural question: is quantum theory itself the problem? For all its successes, perhaps all that randomness, uncertainty and spooky influence is just because quantum mechanics is incomplete. As currently formulated, at least, it might simply not supply all the information we need to explain why things are as they are. An analogy might be made with the laws of thermodynamics. They provide a foolproof, high-level description of how things work – heat always passes from the hotter to the cooler – while saying nothing about the underlying dynamics of individual atoms that makes that happen.

To investigate this possibility, Roger Colbeck and Renato Renner of the Swiss Federal Institute of Technology (ETH) in Zurich have taken a look at what would happen in those classic Alice-and-Bob-type experiments if an underlying theory were to provide an additional, arbitrary amount of information about the correlations between two entangled particles. Do the outcomes of the measurements look any less random and unpredictable?

The short answer is no. In any situation where both Alice and Bob can independently choose the type of measurement they make on their particle, additional information doesn’t make their predictions of what will happen in experiments any more accurate than if they use quantum theory. The mysterious unpredictability of quantum mechanics has nothing to do with incomplete information, it seems.

‘The randomness is intrinsic,’ says Colbeck. Deep down, the universe is spontaneous. Fundamentally, there is no reason why a quantum particle has the properties it does: there is no hidden influence, no cast-iron cause and effect, no missing information. Things are as they are; there is no explanation.

‘Some people find this very depressing,’ Colbeck says. So depressing, in fact, that it leads them to question an even more fundamental assumption about reality and our relation to it. It lies in a little clause in the way most investigations of quantum reality and quantum measurements, including Colbeck and Renner’s, are set up. Let’s go back to the first experiment, the one with the photons at the half-silvered mirror. To measure the direction of the photons’ spins, you must first choose something to measure them relative to – the lab, the wind, the fly on the ceiling. Your choice influences the outcome of the measurement. But what if it is not actually your choice? What if something else were forcing your hand, making you perform the experiments such that the correlations always appear?

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