Australasian Science: Australia's authority on science since 1938

How much free will do we have?

By Tim Wetherell

Quantum mechanics may be even spookier than we thought.

Source: ANU

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Quantum mechanics is inherently statistical in that it can tell you the probability of something like a nucleus emitting an alpha particle in a given time, but it can’t tell you exactly when or how. In the early days of quantum mechanics this caused great consternation for many scientists, including Einstein whose dislike of this apparent randomness prompted him to protest “God does not play dice!”

Einstein and others, proposed what’s now known as hidden variable theory, to get some causality back into the quantum world. In essence this says that there are mechanisms within the nucleus that lead to the emission of the alpha particle in a deterministic way, but we can’t see them so they appear random to us. However in 1964, the physicist John Bell published a famous paper in which he argued that no hidden variable theory can reproduce all of the observed quantum phenomena.

A well-known and intriguing aspect of Bell’s work are what’s known as Bell inequalities. Bell proposed a situation in which something like the decay of a nucleus emits two particles simultaneously that move in opposite directions.

One of the key features of quantum mechanics is that each such emitted particle exists in a superposition of every possible state until a measurement is made, at which point they condense into a single real state. In this way, it’s the actual process of...

The full text of this article can be purchased from Informit.