n=e
ψ
c
1
=e
−ψ
ṙ=c
1
v
ṽ=c
1
(I−vvᵀ)∇ψ
a=(c²/2)∇ψ
Exact DFD ray law. Yellow=ψ contours; cyan=photons; green=tests. Toggle ∇ψ vectors to see inward gradient.
ψ contour
photon
test mass
DFD Controls
Point mass outside a finite core (optional). ψ=2GM/r with inward ∇ψ. Numerics use c=1.
Presets
Baseline
Stronger
Zoom-in
Field
GM (strength)
Contours
show ψ‑contours
show ∇ψ vectors
finite radius core
R
core
Launch
Photon →
Test mass →
Burst
Clear
stream photons
periodic masses
Integrator
Ray time step (dt)
Matter time step (dt)