1. Wave-Particle Duality

2. Wave-Particle Duality:
The property of electromagnetic radiation (light) that defines its dual nature of displaying both wave-like and particle-like characteristics.
The best way to think of wp duality for a photon is that the electromagnetic wave relates the probability that a photon is in a certain spot

3. Principle of Complementarity:
One must use either the wave theory or photon theory, but not both at the same time when trying to understand a specific experiment.
Generally, when light travels through space it tends to behave like a wave. When it interacts with matter, it tends to behave like a particle

4. Alexander de Broglie 1924 - PhD thesis
Wanted to apply the concept of wave-particle duality of light to all particles
His professors didn’t know whether he was right or wrong so they sent the paper to Einstein for comment:
“I believe it is a first feeble ray of light on this worst of our physics enigmas".

5. (for particles with non-zero mass)
De Broglie Wavelength
 = h =h
p mv
(for particles with non-zero mass)
where  is the de Broglie wavelength
These waves are called matter waves
Matter waves do not carry energy but they predict location!

6. Double Slit Experiment
Video

7. In 2012… DeBroglie continued
Thomas Juffman and associates conducted the experiment on molecules of up to 100 atoms

8. In 1927, experimenters demonstrated that an electron showed diffraction effects (commonly only seen in waves)
This was backed up by the mathematics which used the de Broglie wavelength to predict the diffraction effects perfectly

9. For a bowling ball,
h is very small, momentum is big
When divided, the wavelength is very, very, very small so we don’t see the wave length effects when we go bowling
When dealing with electrons and other subatomic particles, we can see the wave effects

10. Wave Mechanics Was Born!!!
The mathematical interpretation of the structure and interactions of matter based on the concept that particles have a wave nature