Interactive physics simulations

Umbra is a free collection of 40 interactive 3D physics simulations that run in your browser. Each one shows the governing equation, a short lesson, predict-first questions and an AI tutor that can see what is on screen. The topics are mapped to A-level and IB physics, and everything works on a laptop or a classroom projector with no account or install.

Special Relativity

Interactive special relativity: drag events across a 3D light cone and watch light clocks slow and spaceships contract near the speed of light.

• Light cone
• Time dilation
• Length contraction

Quantum Mechanics

Interactive quantum mechanics: Bloch sphere qubits, particle in a box, the double-slit experiment, entanglement and tunnelling, visualised live in 3D.

• Bloch sphere
• Particle in a box
• Double slit experiment
• Quantum entanglement
• Quantum tunnelling

General Relativity

Interactive general relativity: curved spacetime, precessing orbits around a black hole, bent light and the chirp of a black hole merger, computed live.

• Spacetime curvature
• Geodesics and orbit precession
• Gravitational waves

Wave Mechanics

Interactive wave simulator: a 3D ripple tank you click to add sources, Young’s double slit with a fringe screen, and vibrating drum normal modes.

• Ripple tank
• Young’s double slit
• Normal modes

Optics

Interactive optics: white light splitting in a prism, a lens bench with real and virtual images and principal rays, and a diffraction grating spectroscope.

• Prism dispersion
• Lens ray diagram
• Diffraction grating

Dynamical Systems

Interactive chaos theory: Lorenz, Rössler, Thomas and Aizawa strange attractors in 3D, a Van der Pol phase portrait and a chaotic double pendulum.

• Lorenz attractor
• Rössler attractor
• Thomas attractor
• Aizawa attractor
• Van der Pol phase space
• Double pendulum

Electromagnetism

Interactive electromagnetism: 3D field lines and iron filings for bar magnets, solenoids and Halbach arrays, plus charged particles in B fields.

• Magnetic field lines
• Lorentz force

Thermodynamics

Interactive thermodynamics: an ideal gas with the Maxwell–Boltzmann distribution, entropy increasing, a Carnot engine on a p–V diagram and the Ising model.

• Ideal gas
• Entropy
• Carnot heat engine
• Ising model

Fluid Dynamics

Interactive fluid dynamics: streamlines and pressure around an obstacle, a Kármán vortex street, and a smoothed-particle hydrodynamics dam break.

• Streamlines and pressure
• Kármán vortex street
• SPH dam break

Acoustic Physics

Interactive acoustics: sand forming Chladni figures, the harmonic series on strings you can pluck, and Lissajous figures of musical intervals.

• Chladni plate
• Harmonics
• Lissajous figures

Frontier Physics

Interactive astrophysics: a ray-traced black hole, galaxy rotation curves and dark matter, Hubble expansion of the universe and an N-body simulation.

• Black hole
• Galaxy rotation curves
• Hubble expansion
• N-body gravity

Physics Sandbox

A free physics sandbox: place attractors, repulsors and vortices and watch 5,000 tracer particles respond, with the potential and streamlines drawn live.