The Heisenberg uncertainty principle, introduced by German physicist Werner Heisenberg in 1927, puts forward the concept of a certain fuzziness in physics. It says that if one characteristic of a quantum particle can be predicted with precision, a paired characteristic becomes less certain.

Position and momentum are the most often-mentioned of these pairs, known as non-commuting variables. Being able to ascertain where a quantum particle is makes it harder to judge its movement, and vice versa.

That fuzziness makes it more difficult to take accurate measurements of weaker signals in physics – in everything from the LIGO gravitational wave detector to the atomic clocks that underpin systems like GPS.