When Light Folds Into a Cusp
A smooth wavefront can focus into something sharp, bright, and almost impossible-looking... a Caustic.
This scene is built from the Pearcey diffraction integral,
P(a,b) = ∫ exp(i(t⁴ at² bt)) dt,
one of the canonical objects in Catastrophe Optics.
The variables a and b unfold a cusp catastrophe. As they change, the wave does not simply brighten smoothly, it folds into sharp luminous curves, then breaks into diffraction fringes around the cusp. The visible intensity is
I(a,b) = |P(a,b)|²,
and the colour carries the complex phase arg P.
This is the Mathematics behind the bright cusps you see in focused light, water caustics, optical lenses, and wavefields near singular focusing events.
#CatastropheTheory #Optics #WavePhysics #MathematicalPhysics #PhysicsVisualization #Caustics