# Heisenberg's instinct was accurate

## Scientists develop mathematical proof of quantum physics feature

In 1927, Werner Heisenberg reasoned that scientists couldn’t take a measurement of a physical object without changing it in some way. The idea, which has persisted in physics, was based on intuition and has implications for quantum cryptography.

Now, Paul Busch of the University of York and his colleagues have developed a more precise mathematical description of Heisenberg’s idea, which laid out a reciprocal relationship between the accuracy of a position measurement of an object and the associated disturbance in the object’s momentum.

The scientists offer the proof, published October 17 in *Physical Review Letters, *as a counter to experiments described in 2012 that found fault with Heisenberg's idea.