According to the principles of quantum mechanics, it is not possible to simultaneously observe both the wave-like and particle-like characteristics of a single object. This concept is often referred to as the wave-particle duality.
The behavior of objects at the quantum level, such as electrons or photons, can exhibit wave-like properties, such as interference and diffraction, as well as particle-like properties, such as localized position and momentum. However, when we perform a specific measurement or observation on a quantum system, it collapses into one of these characteristic behaviors.
For example, if we perform a measurement to determine the position of a particle, the wave function representing the probability distribution of its position collapses to a localized particle-like state, and we observe a definite position. Conversely, if we perform a measurement to determine the momentum of the particle, the wave function collapses to a state with a well-defined momentum, and we observe a particle-like behavior.
In essence, the act of measurement or observation forces a quantum system to manifest either wave-like or particle-like behavior, depending on the nature of the measurement being performed. This wave-particle duality is a fundamental feature of quantum mechanics and is often described as a complementarity, where the wave and particle aspects are two complementary descriptions that cannot be simultaneously observed or measured.
It is important to note that while we cannot observe both wave-like and particle-like properties simultaneously, experimental setups can be designed to demonstrate various phenomena that exhibit one or the other. These experiments provide evidence for the wave-particle duality and are fundamental to our understanding of quantum mechanics.