Heisenberg uncertainty principle is a famous quantum mechanics
principle made by the Nobel Price winning physicist Werner Heisenberg.
Written as a mathematics equation, the most common word translation
is that it is impossible to determine both the position and the
momentum of a subatomic particle (an atom's electron, proton
or neutron). The more accurately you measure one quality, the
less accurate becomes the measurement of the other quality.
This happens because to measure the position of a subatomic
particle you must shine light on it. The scientist needs to shine
light to 'see' the particle, just as you or I need light to locate
an apple or chair. While necessary to identify the position,
the added light energy speeds up the tiny particle. The mere
act of observing the particle changes it.