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Wave Particle Duality

      The study of objects such as light or electrons have been a topic of discussion for many scientists. Many have attempted to discern the behavioral patterns of light as particle or wave behavior. Albert Einstein, in 1905, confirmed that light could behave as both a wave and a particle. Back then, his discovery was revolutionary because of the previously held belief that light could only portray wave behavior. But in 1923, French physicist Louis de Broglie was able to expand on that idea and theorized that this behavior could be seen and exhibited in mass, such as electrons.


     To understand why this was so significant, it is important to understand the difference between particle and wave behavior. Particle behavior consists of the movement of energy concentrated on a single point in space. An example would be when two objects collide with each other. Instead of dispersing and having points of contact across the space, the energy is concentrated onto the point that the two objects collide at. Wave behavior contrasts with particle behavior because the energy is spread out over a large space. An example of this would be the collision of two ripples in water. The points of contact aren’t focused on a singular point, but are spread out across the entire area of effect. The contrasting characteristics between these two behaviors couldn’t possibly be present in a singular mass such as an electron. Yet, it was still proven by Louis de Broglie in his theory of wave particle duality.


    The theory of wave particle duality was an extension of Albert Einstein’s theory of the photoelectric effect back in 1905. It stated that electrons could be ejected from a metal sheet through electromagnetic radiation which includes light. This theory proved that light was also capable of particle behavior, which contradicted the then-current belief of light having wave behavior. Soon after, Louis de Broglie was able to propose that this behavior is present in mass (notably electrons) by applying Einstein’s energy-mass equivalence equation (E=mc^2) to Planck’s equation (E = hf) . 


    The idea of wave particle duality was further solidified experimentally when multiple experiments by Clinton Davisson, Lester Germer, and George Paget Thomson in 1927 confirmed the fact that mass was indeed capable of wave and particle behavior when observing these behaviors in electrons. This confirmation of such a theory had earned Louis de Broglie a Nobel prize 2 years later in 1929. With the verification of wave particle duality, it became possible to express matter through the wave function, or Schrodinger’s equation. Not only that, but with the expression of matter through Schrodinger’s equation, it gave rise to the development of quantum mechanics.


“Wave-Particle Duality.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.,

Tim Davis Principle Research Scientist Materials Science and Engineering. “Explainer: What Is Wave-Particle Duality.” The Conversation, 15 Apr. 2020,

Jones, Andrew Zimmerman. “What You Need to Know About Wave Particle Duality.” ThoughtCo,

YouTube, YouTube, 4 Aug. 2015,

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