There are a number of physical concepts that are often treated as laws, when in fact they have not been rigorously proven. Among these is the Heisenberg uncertainty principle, which states that you cannot measure both the position and momentum of a particle with perfect precision. Some 80 years after this idea was first suggested, researchers at the University of York, University of Turku, and Leibniz Universität Hannover have successfully proven it.
The reason it is impossible to measure both the position and momentum of a quantum particle with perfect precision is because measuring a particle affects it. Measuring one value causes unavoidable measurement error in the other. To prove this idea, the researchers considered how one measures position and momentum simultaneously. They then defined the measurement error as the spreads of the distributions of possible outcomes. Combining the errors revealed that they obey Heisenberg's original intuition.
While this work may seem the kind of stuff to remain in theoretical physics, it could have implications in quantum computing, especially quantum communication. It is the effect a measurement has on a particle that secures quantum encryption against eavesdropping, and that is defined by the Heisenberg principle.
Source: University of York