Louis **de Broglie** (de br-oye) did his dissertation contemplating that if light can be both a wave and a particle, can matter also be a particle and a wave? He related the momentum (a unit dependent on mass) to Planck’s quantization constant: $p=\frac{h}{\lambda}=\frac{2\pi \hbar}{\lambda}$ **Heisenberg** later derived the uncertainty principle which can be intuitively understood in the figure below. A wave can varying preciseness on its wavelength and location. Formally: $\sigma_x\sigma_p \ge \frac{\hbar}{2}$ ![[4 - Attachments/image 4.png|image 4.png]] ### Resources: - [https://www.youtube.com/watch?v=qJZ1Ez28C-A&t=407s&ab_channel=Veritasium](https://www.youtube.com/watch?v=qJZ1Ez28C-A&t=407s&ab_channel=Veritasium) - Griffiths, D.J. & Schroeter, D.F. — Introduction to Quantum Mechanics, 3rd edition, Cambridge University Press ![[Connect#Connect]]