Physics simulators
Fields and the equations that move energy through space.
Electric & Magnetic Fields
Orbit a 3D scene of charges and currents, switching between electric field lines and the magnetic field around a wire.
Electromagnetic Waves
Drag charges through space and watch retarded E and B fields ripple outward. Build a dipole antenna and tune the medium to change wave speed and impedance.
Entropy
Count the arrangements behind what you can see. Entropy is a census, S = k ln Ω, and that counting alone is enough to make time run one way.
Heat Equation
Watch temperature diffuse across a room from a radiator and a cold window, and paint in your own heat.
Wave Equation
Pluck a string and watch the pulse travel and reflect. The contrast with heat: waves keep their shape and carry energy instead of smearing out.
Phonons
Every mass obeys Hooke’s law and pulls only on its neighbours. Out comes a pulse travelling at a speed nobody wrote down, and a shortest possible wavelength.
Wave Interference
Two sources of ripples cross and combine into bright and dark fringes. Drag the sources to see the pattern behind the double-slit experiment.
Ideal Gas
A few hundred molecules bouncing in a box. Pressure is the drumming of their impacts, temperature is how fast they are, and PV = NkT is what that adds up to.
Stationary Action
Bend the path a particle takes between two fixed events and watch its action get worse. Rolling that downhill turns out to be Newton in disguise.
Band Theory
Bring a line of atoms together and every level splits into a band. Which bands are full, and how wide the gap is, decides metal, semiconductor or rock.
Schrödinger Equation
Launch a quantum wave packet at a barrier taller than its energy and watch part of it tunnel through, the wave nature of matter in action.
Stern-Gerlach Experiment
A beam of atoms should smear into a band and arrives as two spots. Chain the analysers, turn the next one, and measuring x wipes out what was known about z.
Quantum Gates
Build a circuit on two qubits and watch the amplitudes, their phases and both Bloch arrows move together. Then build the one circuit whose arrows shrink to nothing.
Nuclear Fission
One neutron splits one nucleus and two more fly out. Turn the enrichment, the size and the control rods and watch the chain die, hold steady, or run away.
Nuclear Fusion
Slam light nuclei together hard enough to tunnel through their own repulsion, and chase the one line every star has to cross: power out beating power lost.
Special Relativity
Boost to a moving frame on a spacetime diagram and watch its axes skew: relativity of simultaneity, time dilation and length contraction, all at once.
Four-Vectors
One arrow in spacetime, read by many observers. Boost and both shadows change while the length refuses to: proper time, the speed of light, the rest mass.
General Relativity
Fall down the curved-space funnel of a black hole. Clocks run slow deep in the well and a proper meter swallows less coordinate distance near the horizon.