<p align="right">Last Update: <font color="#4f81bd">November 29, 2024</font></p> ## BIG IDEAS - particle-wave duality is [[Electromagnetic radiation|electromagnetic radiation]] has properties of both [[Particle Model|particles]] and [[Waves|waves]]. - Waves and particles are two very different [[Models|models]] for physical systems. - [[Electromagnetic radiation]] is a wave that describes the propagation of energy across space. - [[Photon|Photons]] are the individual quanta, or packets, of that energy, which you can think of as how that wave **interacts** with things at the quantum level. >[!note] Light is simultaneously a wave in the electromagnetic field and a stream of particles called photons. -- CERN > >- When we're describing the **propagation** of light, we think of it as a wave. >- When we're describing how light **interacts** with matter, we think of it as photons. ### Key Experiments - **Double-slit experiment**: Demonstrated that particles like electrons create an interference pattern, a characteristic of waves, when not observed, but act like particles when observed. - **Photoelectric Effect**: Showed that light can eject electrons from a material, supporting the idea that light has particle-like properties (photons). ### Timeline - [[Notes Vault/Physics Notes Vault/Physicists/Classical Physics/Isaac Newton|Newton]], Descartes, and others suggested light is a particle. - Thomas Young (1801) showed light can behave as a wave. - [[Max Planck]] (1901) suggested (See [[Notes Vault/Physics Notes Vault/Quantity of Motion/Quantum Mechanics/Blackbody Radiation|Blackbody Radiation]]) - [[Albert Einstein]] (1905) showed light consists of localized packets. (See [[Photoelectric Effect]]) - Louis de Broglie (1924) ### Related Topics --- [[Home|Home]] | [[Quantum mechanics]] | [[Notes Vault/Physics Notes Vault/Quantity of Motion/Quantum Mechanics/Blackbody Radiation|Blackbody Radiation]] | [[Photoelectric Effect]] | [[Atomic Theory]]