WHEN IT COMES TO its ability to formulate accurate explanations and make testable predictions, the science of quantum mechanics is one of the most successful theories of all time. Despite its astonishing successes, quantum mechanics has an unfortunate side effect – it can induce the cerebral equivalent of dropping a jellyfish into a blender and transform the human brain into a quivering mess of gelatinous denial.

Quantum mechanics is the theoretical construct that allows scientists to describe how matter behaves at the subatomic level. To say that it is weird is an understatement of galactic proportions and perhaps the weirdest of all its predictions is something called ‘Heisenberg’s uncertainty principle’.

Thought up by genius physicist Werner Heisenberg in 1927, the uncertainty principle states that, in the quantum world, it is impossible to simultaneously know where a particle is and where it is going – you can know its position, or you can know its momentum, but you can’t know both.

Ok, so perhaps that doesn’t sound so very strange, but the reason why you can’t know both quantities is very strange indeed.

If you were asked to describe a particle, chances are you would imagine it to be a discrete, spherical lump of matter (like a teeny tiny ball bearing), but you’d be wrong. In quantum mechanics a particle is more of a wavy smudge of spread out potential – a cloud of possibility where the particle exists in multiple states and in multiple positions.

The uncertainty principle allows you to only determine one of those possibilities by saying that as you zero in on a particle’s position, so your ability to measure its momentum slips away. It’s a bit like rolling a dice – as it scoots along the tabletop you can see where it’s going but the numbers are a blur (it could stop on anyone of them), only by stopping the dice can you ‘force’ it to choose a number.

This indeterminate nature of the stuff makes up the world around us didn’t well with scientists – after all, who wants to believe that the particles you are made of exist in a state of quantum flux? Even the physicists that created the science of quantum mechanics were uncomfortable with the predictions it made (which led Erwin Schrödinger to create his famous dead-and-alive cat in a box mind experiment).

For decades, some scientists have expected (and hoped) that uncertainly would one day be proved false and that predictability would be returned to the Universe. But it seems that their hopes might have been dashed by physicists at the University of York who believe they have proof that the limits imposed by uncertainty are just as Heisenberg described them.

By constructing a theoretical experiment in which measurements of particles with known values were compared with those of particles whose states were unknown, they found that the errors in their measurements matched with Heisenberg’s original predictions.

Ok, so it was a lot more complicated than that, but their conclusion could prove to be a boon for quantum cryptography – messages encoded in such a fashion would, in theory, be unbreakable because any attempt to ‘see’ the message would force the multiple-state quantum bits that make it up to ‘collapse’ to a single state (thus ruining the message).