How random is random?

English: German-born theoretical physicist Alb...
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What is a truly random event?

We are used to the idea that flipping a coin is likely to generate a random sequence of heads or tails but, of course, it is perfectly possible to predict, using the rules of classical mechanics, the outcome of a series of coin tosses if we know the values of a not very long list of parameters. In other words, the outcome of flipping a coin is entirely deterministic, it is just that humans are unlikely to be able to faithfully replicate the same flick over and over again.

Quantum events – such as the \alpha particle decay are, as far as our knowledge today tells us, truly random – in the sense they have a probability of occurring in a given time period but we have no way of knowing if a given nucleus will decay at any given time.

This is really a very profound finding – it implies that two physical objects, in this case atomic nuclei, behave in completely different ways despite all the physical parameters describing their existence being the same. That sounds like the exact opposite of everything that science has taught us about the nature of the universe.

Thinking about this, one can quickly come to agree with Einstein that it must be based on a flawed understanding of physical reality as “God does not play dice”. But it is also the best explanation we have for that physical reality.

But why would a nucleus decay in one time period and not another? Can this really be an event without specific cause? Just a ‘randomly‘ chosen moment? But chosen by what?

Of course, some will say by “God” but that really is metaphysics – a completely untestable and unverifiable proposition that merely kicks the physical puzzle in a domain beyond physics.