What We Cannot Know: Explorations at the Edge of Knowledge

by Marcus du Sautoy

Things get even more uncertain as I zoom in closer on my particle. There is a point at which the energy uncertainty is so large that the corresponding mass becomes so great that it causes a black hole to materialize. As I shall explore in the Fifth Edge, a black hole by its very nature appears to trap any information within a certain radius of the centre of the hole and prevent it being released. This means that the uncertainty principle implies an in-built limit to how far I can probe nature. Beyond a certain scale I seem to be denied access to what’s going on. That scale is very small. It is of the order of 1.616 × 10–35 metres, a distance known as the Planck length. This is ridiculously tiny. If I scale up the full stop at the end of this sentence to be the size of the observable universe, then something the size of the Planck length would scale up to look like the full stop before I enlarged it.