The Heisenberg uncertainty principle is a fundamental principle of quantum mechanics, which states that certain pairs of physical properties of particles, such as position and momentum, cannot both be accurately measured or known at the same time.
The principle, formulated by the German physicist Werner Heisenberg in 1927, states that the more accurately we know the position of a particle, the less accurately we can know its momentum, and vice versa. In other words, the more precise we attempt to make a measurement of one property, the less precise the measurement of the other property becomes.
This principle applies not only to position and momentum, but also to other pairs of complementary properties, such as energy and time. The Heisenberg uncertainty principle is important in understanding the behavior of subatomic particles and plays a role in the foundations of modern physics.