One of the blogs I frequently post comments on is HLSWatch.com!
Today’s post on that blog invites readers to submit essays to a contest that requests new terms or concepts that might have application to HS. I don’t plan to submit an essay but came up with the Heisenberg Uncertainty Principle as a possibility. Can you guess why?
In quantum mechanics, the Heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, cannot be simultaneously known. In other words, the more precisely one property is measured, the less precisely the other can be controlled, determined, or known.
Max Born states, in his Nobel Laureate speech:
- To measure space coordinates and instants of time, rigid measuring rods and clocks are required. On the other hand, to measure momenta and energies, devices are necessary with movable parts to absorb the impact of the test object and to indicate the size of its momentum. Paying regard to the fact that quantum mechanics is competent for dealing with the interaction of object and apparatus, it is seen that no arrangement is possible that will fulfill both requirements simultaneously.” 
Published by Werner Heisenberg in 1927, the uncertainty principle was a key discovery in the early development of quantum theory. It implies that it is impossible to simultaneously measure the present position while also determining the future motion of a particle, or of any system small enough to require quantum mechanical treatment. Intuitively, the principle can be understood by considering a typical measurement of a particle’s position, which involves the scattering of light or other particles off of the target, and this involves the probabilistic exchange of energy. The uncertainty principle is a fundamental property of quantum systems, not a statement about the observational strength of current technology. Some uncertainty about such particles is unavoidable. One can at least, however, identify the average momentum and position of particles (using weak measurements).
The principle states specifically that the product of the uncertainties in position and momentum is always equal to or greater than one half of ħ, the reduced Planck constant (ħ = h/2π).
Mathematically, the uncertainty relation between position and momentum arises because the expressions of the wavefunction in the two corresponding bases are Fourier transforms of one another. In the mathematical formulation of quantum mechanics, any non-commuting operators are subject to similar uncertainty limits.