How do you understand:
Electrons (as particles) sometimes behaviour like wave?
Light (as EM wave) sometimes behaviours like a particle?
Video 1: Wave-Particle Duality Animation
Animation of the Wave-Particle Duality through the double slit experiment with and without an observer.
Video 2: Single Photon Interference
What happens when single photons of light pass through a double slit and are detected by a photomultiplier tube?
In 1801 Thomas Young seemed to settle a long-running debate about the nature of light with his double slit experiment. He demonstrated that light passing through two slits creates patterns like water waves, with the implication that it must be a wave phenomenon.
However, experimental results (e.g. photoelectric effect) in the early 1900s found that light energy is not smoothly distributed as in a classical wave, rather it comes in discrete packets, called quanta and later photons. These are indivisible particles of light. So what would happen if individual photons passed through a double slit? Would they make a pattern like waves or like particles?
Video 3: Wave-Particle Duality and the Photoelectric Effect
Check out how the concept of Duality led to the understand of the Model of Atom.
The Heisenberg Uncertainty Principle states that you can never simultaneously know the exact position and the exact speed of an object. Why not? Because everything in the universe behaves like both a particle and a wave at the same time. Chad Orzel navigates this complex concept of quantum physics.