Uncertainty
Heisenberg’s Uncertainty Principle:
In quantum mechanics, the Heisenberg uncertainty principle states by precise inequalities that certain pairs of physical properties, like position and momentum, cannot simultaneously be known to arbitrary precision. That is, the more precisely one property is known, the less precisely the other can be known. In other words, the more you know the position of a particle, the less you know about its velocity, and the more you know about the velocity of a particle, the less you know about its instantaneous position.