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Sandbox Physics

OPEN LABZH / ENNO INSTALL

Change one condition.See the law respond.

Every experiment is an independently runnable physical system. Adjust its initial state, interaction, or boundary conditions, then use equations to explain what you actually observe.

166
runnable experiments
4
physics domains
2
languages
Enter the black-hole light Lab

LATEST LAB / NEW RELEASE

Released

Motion & dynamical systems

Yo-Yo & Spool Direction Puzzle

Can the pull direction predict the motion direction?

Suggested time
22 min
Model depth
3 / 4

FIELD NOTE · 2026 FIELDS MEDAL

One box, three worlds

Yu Deng’s work did not discover that gas particles collide. It proved that Newton’s laws for individual hard spheres can reach Boltzmann’s statistical world over long times.

Understand the story, then run the model
01 / EXPERIMENT DOMAINS

Choose a system first.
Then ask what law it follows.

Motion, waves, fields, matter, and quantum states use different descriptive languages, but every entry point is the same: change a controllable quantity, read the response, and check what is conserved, propagated, or transformed.

01DYNAMICS

How a state evolves through time

Motion & dynamical systems

observe trajectories and invariantsdpdt=F\frac{d\mathbf p}{dt}=\mathbf F

Start from an initial state and let forces and constraints determine the next moment. Read orbits, oscillation, chaos, and many-body motion.

17 experiments
  1. 01

    M051 · Rotation / mass distribution

    Moment-of-Inertia Designer

    Which distances matter to rotational inertia?
    key concepts

    parallel axesmass distributionangular impulsework-energy balance

  2. 02

    M052 · Rolling / friction constraints

    Rolling Race Laboratory

    Is the sphere always the fastest?
    key concepts

    rolling constraintsCoulomb frictionfinish eventsenergy dissipation

  3. 03

    M053 · Contact / direction reversal

    Yo-Yo & Spool Direction Puzzle

    Can the pull direction predict the motion direction?
    key concepts

    string torquedirection reversalcontact lossfriction envelope

  4. 04

    M032 · Momentum / restitution

    One-Dimensional Collision Bench

    What survives an inelastic collision?
    key concepts

    impulserestitutioninertial framescamera measurement

  5. 05

    M033 · Scattering / vector momentum

    Two-Dimensional Collision Table

    What controls the scattering angle?
    key concepts

    oblique collisionvector momentumnormal impulsescattering angle

  6. 06

    M034 · Impact / inverse measurement

    Ballistic Pendulum Lab

    Can a height measurement identify launch speed?
    key concepts

    inelastic embeddingnonlinear penduluminverse measurementidentifiability

02WAVES

Superposition, propagation, and boundaries

Waves & optics

observe amplitude and phase∂2ψ∂t2=c2∇2ψ\frac{\partial^2\psi}{\partial t^2}=c^2\nabla^2\psi

Change wavelength, phase, apertures, or media and watch local oscillations propagate into interference, diffraction, and resonance.

115 experiments
  1. 01

    Waves · superposition

    When Two Waves Meet

    Why do passing waves leave a stable fringe pattern?
    key concepts

    superpositionphasepath difference

  2. 02

    Fourier series · rotating vectors

    Draw Any Wave with Circles

    How can steady rotations rebuild almost any periodic signal?
    key concepts

    Fourier seriesspectrumharmonics

  3. 03

    Waves · diffraction

    Light after a Narrow Slit

    Why does a narrower opening spread light farther?
    key concepts

    diffractionapertureintensity

  4. 04

    Optics · ray tracing

    How a Lens Redirects Light

    How do three principal rays locate and size an image?
    key concepts

    refractionfocal lengthimaging

  5. 05

    Gravitational waves · laser interferometry

    Listen to Spacetime with Light

    How can a sub-proton length change become a readable signal?
    key concepts

    interferometrygravitational wavesdark port

  6. 06

    Fluid dynamics · water-wave diffraction

    How One Opening Redraws a Water Wave

    Why does narrowing an opening spread the transmitted wave through a wider angle?
    key concepts

    water-wave diffractionwave equationboundaries

03FIELDS + MATTER

How local interactions create global structure

Fields, fluids & matter

observe fields and distributionsF=−∇U\mathbf F=-\nabla U

Begin with local interactions among charges, particles, and fluids, then read field lines, distributions, pressure, and macroscopic response.

23 experiments
  1. 01

    Fluid dynamics · airfoil pressure workbench

    How an Offset Circle Becomes a Lifting Airfoil

    How do geometry, angle of attack, and the Kutta condition select circulation and pressure difference?
    key concepts

    Joukowski mappingKutta conditioncirculation lift

  2. 02

    Fields · electrostatics

    Make an Electric Field Visible

    How does the shape of potential predict the next force?
    key concepts

    potentialgradientfield lines

  3. 03

    Thermodynamics · molecular motion

    Billions of Collisions in a Gas

    How do random collisions become stable macroscopic laws?
    key concepts

    kinetic theorydistributionpressure

  4. 04

    Electromagnetism · Lorentz force

    A Charge Bending through Fields

    How can a magnetic field turn motion without changing speed?
    key concepts

    Lorentz forcecross productdrift

  5. 05

    Fluid dynamics · spinning balls

    Why a Spinning Ball Curves

    How does spin rearrange flow and create a sideways force?
    key concepts

    Magnus forcecirculationfluids

  6. 06

    Fluid dynamics · CFD benchmark workbench

    How One Moving Wall Drives an Entire Fluid

    Why does a right-moving lid create one giant clockwise circulation inside a sealed cavity?
    key concepts

    Navier–Stokes equationsvorticity transportReynolds number

04QUANTUM

How amplitudes become measurable probabilities

Quantum & fields

observe probability and measurementiℏ∂ψ∂t=H^ψi\hbar\frac{\partial\psi}{\partial t}=\hat H\psi

Change state, phase, measurement basis, or occupation and watch continuous amplitudes produce discrete, repeatable statistics.

11 experiments
  1. 01

    Ultracold quantum gas · Cooper pairing

    How Cooper Pairs Condense

    How can a fermion pair evolve continuously from a cloud-wide correlation into a composite bosonic molecule that condenses?
    key concepts

    Cooper pairingBEC–BCS crossoversuperfluid coherence

  2. 02

    Quantum Lab 01 · amplitude and phase

    Rotate a Qubit

    Where does phase hide when Z-basis probabilities stay fixed?
    key concepts

    amplitudephasemeasurement basis

  3. 03

    Quantum Lab 02 · forbidden region and transmission

    Can a Particle Cross an Impossible Wall?

    When classical transmission is zero, why can a quantum detector still click beyond the barrier?
    key concepts

    quantum tunnelingpotential barriermeasurement probability

  4. 04

    Quantum Lab 03 · path amplitudes

    Can One Particle Interfere?

    How do unpredictable hits accumulate into stable fringes?
    key concepts

    path amplitudescoherenceprobability

  5. 05

    Quantum Lab 04 · entry to field theory

    How a Field Becomes Quantized

    How can a continuous field produce discrete particle excitations?
    key concepts

    field modesquantum oscillatoroccupation

  6. 06

    Topological Matter 01 · one-dimensional bulk–edge correspondence

    How One-Dimensional Bulk Topology Creates an Edge

    Why can exchanging two bond strengths pin a zero-energy state to the end of a chain?
    key concepts

    SSH modelwinding numberbulk–edge correspondence

STATE → LAW → EVOLUTION → OBSERVATION

A physical law is not decoration.
It has to move the system.

Animation only displays the result. An experiment begins when you change a condition, shift the prediction, and test whether the equation still explains what follows.

Enter the first system