ABSTRACT
In the particle-wave duality interpretation of matter and radiation (Topic G3) a particle moving in space can also be described as a wave in space with a wavelength related to the particle momentum by de Broglie’s equation, λ=h/p. In quantum mechanics, the notion of a particle moving in defined trajectories in a system is replaced entirely by this description of the system in terms of its wavefunctions, ψ. The wavefunction simultaneously describes all regions of space in which the particle it represents can be found. This, in turn, introduces the idea of uncertainty into quantum mechanics because the exact position of the particle at each point in time is not defined, only the region of space of all its possible positions. The exact shape of the wavefunction is important because the probability of finding the particle at each point is proportional to ψ2 at that point; a greater amplitude in the wavefunction corresponds to a greater probability density in the particle’s distribution.
