What is the wave particle duality theory

Matter is both wave and particle.Although light is most commonly thought of as a wave, it may also be conceived of as a collection of tiny energy packets known as photons.The particle nature is more easily discerned using an object with a large mass.By looking at it, you force it to decide on a single trajectory, like going through the left or right slit, or like schrödinger's cat that ends up being either dead or alive;It stated that electrons could be ejected from a metal sheet through electromagnetic radiation which includes light.

( there is something which tells the matter when to behave as matter and and when to behave as wave) in 1805, thomas young demonstrated that light was a wave.More generally, the theory states that everything has both a particle nature and a wave nature, and various experiments can be done to bring out one or the other.This definition opposes classical mechanics or newtonian physics.Electrons are considered to be particles.