Wave–particle duality

In physics and chemistry, wave–particle duality is a conceptualization that all objects in our universe exhibit properties of both waves (such as non-locality) and of particles (such as quantization of some of their properties). A central concept of quantum mechanics, duality addresses the inadequacy of conventional concepts like "particle" and "wave" to fully describe the behaviour of quantum objects. The idea of duality is rooted in a debate over the nature of light and matter dating back to the 1600s, when competing theories of light were proposed by Christiaan Huygens and Isaac Newton. Through the work of Albert Einstein, Louis de Broglie and many others, current scientific theory holds that all particles also have a wave nature. This phenomenon has been verified not only for elementary particles, but for compound particles like atoms and even molecules. Various interpretations of quantum mechanics attempt to explain this ostensible paradox.

Because waves are non-local, all objects are, in theory, non-local, too (exist in many places at once) — see non-locality. The reason we can't detect wave properties of macroscopic particles is their small wavelength.