Learn Quantum Electrodynamics (QED) with interactive simulations. Understand photon-electron interactions, Feynman diagrams, vacuum polarization, and renormalization through step-by-step visualizations and real-world quantum phenomena.
Quantum Electrodynamics (QED) is the quantum field theory that describes how light and matter interact. It is the first theory where full agreement between quantum mechanics, special relativity, and electromagnetism is achieved. QED mathematically describes all phenomena involving electrically charged particles interacting by means of exchange of photons.
Developed in the late 1940s by Richard Feynman, Julian Schwinger, and Sin-Itiro Tomonaga, QED has been called "the jewel of physics" due to its extremely accurate predictions. For example, the anomalous magnetic moment of the electron and the Lamb shift in hydrogen levels have been predicted with remarkable precision.
The core concepts that form the foundation of Quantum Electrodynamics
Graphical representations of particle interactions that visualize the mathematical expressions governing the behavior of subatomic particles.
Probability Amplitude = Σ(all possible diagrams)
Electromagnetic forces arise from the exchange of virtual photons between charged particles.
F = (k × q₁ × q₂) / r²
The quantum vacuum is not empty but filled with virtual particle pairs that affect electromagnetic interactions.
α(μ) = α(0) / (1 - (α(0)/(3π)) ln(μ/mₑ))
A systematic procedure for dealing with infinities that arise in quantum field theory calculations.
m_{renormalized} = m_{bare} + δm
How Quantum Electrodynamics influences modern science and technology
QED predictions for the electron's magnetic moment agree with experiments to 12 decimal places, making it the most accurately verified theory in physics.
The stimulated emission process underlying lasers is fundamentally a QED phenomenon involving photon interactions with atoms.
Transistors and diodes rely on quantum mechanical effects that are described by QED principles in solid-state physics.
Both relativistic and quantum corrections are necessary for the precise timing required by GPS satellites.
QED explains phenomena such as synchrotron radiation from pulsars and the behavior of cosmic rays in magnetic fields.
The study of light-matter interactions at the quantum level, crucial for developing quantum computers and secure communication.
Perform calculations for various quantum electrodynamics phenomena
Calculate the dimensionless coupling constant of electromagnetism
Fine-Structure Constant (α): 1/137.036
Approximate Value: ≈ 1/137
Formula: α = e²/(4πε₀ℏc)
Calculate the anomalous magnetic moment of the electron
Anomalous Moment (aₑ): 0.001159652181
Parts Per Billion: 1159.652181 ppb
Formula: aₑ = (g-2)/2
Calculate the quantum wavelength of particles
Compton Wavelength (λ_C): 2.426 × 10⁻¹² m
Energy Equivalent: 511 keV
Formula: λ_C = h/(m₀c)
Calculate the classical size of an electron based on its energy
Classical Radius (rₑ): 2.818 × 10⁻¹⁵ m
Alternative Formula: rₑ = e²/(4πε₀mₑc²)
Energy Equivalent: 2.587 × 10⁻⁴ MeV
Convert between different units used in quantum electrodynamics
Explore quantum electrodynamics phenomena through hands-on visualizations
Visualize Compton scattering where photons collide with electrons
Step 1: Incident photon approaches stationary electron.
Observe how virtual electron-positron pairs affect electromagnetic fields
Step 1: Strong electric field creates virtual electron-positron pairs.
Create and analyze particle interaction diagrams
Diagram Type: None
Conservation Laws: Not checked
Probability Amplitude: 0
Interactive three-dimensional visualization of quantum electromagnetic fields
3D Quantum Field Visualization
Interactive 3D model showing quantum electromagnetic field fluctuations
3D representation of propagating electromagnetic radiation
Animated visualization of photon-particle interactions
Adjust parameters like field strength, frequency, and polarization
How Quantum Electrodynamics relates to and differs from other areas of physics
| Aspect | Classical | Quantum |
|---|---|---|
| Field Description | Continuous fields | Quantized photons |
| Particle Nature | Point particles | Wave-particle duality |
| Interactions | Deterministic forces | Probabilistic exchanges |
| Vacuum State | Empty space | Virtual particles |
| Predictions | Macroscopic behavior | Precision measurements |
| Theory | Force | Mediator | Strength |
|---|---|---|---|
| QED | Electromagnetic | Photon (γ) | 10⁻² |
| QCD | Strong | Gluon (g) | 1 |
| EW | Weak | W/Z bosons | 10⁻⁶ |
| Gravity | Gravitational | Graviton (G?) | 10⁻³⁹ |