In quantum theory, particles and phenomena are described by wave-particle duality, which means that they exhibit properties of both waves and particles. However, it is important to note that the behavior of subatomic particles in quantum mechanics cannot be precisely described by classical notions of waves or particles that we encounter in everyday life.
Instead, the fundamental entities in quantum mechanics are described by mathematical objects called wavefunctions. A wavefunction represents the quantum state of a particle or a system of particles. It contains information about the probabilities of various outcomes when measurements are made on the system.
The behavior of particles in quantum mechanics is often described in terms of probability waves or probability distributions associated with the wavefunction. These waves can exhibit interference and superposition, which are distinctly quantum phenomena. Interference refers to the phenomenon where waves can reinforce or cancel each other out, similar to what we observe in waves such as water waves or light waves. Superposition refers to the ability of quantum particles to exist in multiple states simultaneously.
So, while we often use the terms "wave" and "particle" as shorthand to describe certain aspects of quantum behavior, it is more accurate to say that the entities in quantum theory are described by wavefunctions, and their behavior is characterized by wave-particle duality and the principles of quantum mechanics.