When struck by light, the electrons in an atom of silver vibrate in a way that causes them to radiate small amounts of light themselves.

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The principle behind these experiments is that particles hitting the xenon cause the nucleus of the atom to give off a little bit of light.

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"As humans we can identify galaxies light years away, we can study particles smaller than the atom, but we still haven't unlocked the mystery of the 3lb of matter that sits between our ears, " he said.

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That means its nucleus has a stronger positive charge and that, in turn, means the electrons orbiting the nucleus are more attracted to it and travel faster, at roughly 60% of the speed of light, compared with 35% for the electrons orbiting a tin atom.

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