Answer:

The Heisenberg uncertainty principle is a rule in quantum mechanics. It states that there is a fundamental limit to how well you can simultaneously know the position and momentum (where momentum is classically mass times velocity) of a particle. This means if you know the position very precisely, you can only have limited information about its momentum and vice-versa.

Furthermore this is a mathematical inequality that does not depend on measurement technique or how you find the position and momentum. In fact, it has recently been shown experimentally that even if you have an instrument that is so precise that it should (theoretically) be capable of measuring the position and momentum of the particle below the Heisenberg uncertainty limit, the spread in measured values leads to an uncertainty that is still above this limit.

Introduced first in 1927, by the German physicist Werner Heisenberg, it states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa.