Near-c flight

The environment is stationary in one inertial laboratory. The observer moves forward along −z at βc. Choose laboratory time t in ns: distance is βct and traveler proper time is τ=t/γ. The scene is computed explicitly; optional playback advances 80 ns of model time per screen second and ends at 1000 ns. Changing β clears the result. Typed time retains its precision when showing and resizing the view. Manual time works without animation. Reduced motion keeps manual controls.

The optical view transforms the incoming light direction for each sampled point. If μ is the laboratory direction cosine toward the source along the forward axis, μ′=(μ+β)/(1+βμ) and D=ν′/ν=γ(1+βμ). This includes the light-arrival geometry of a static environment; no arbitrary rotation or extra contraction is applied to the optical image. For β=0.6, γ=1.25, the forward Doppler factor is 2 and a sideways source is seen at arccos(0.6). At β=0 both views coincide.

The simultaneous view is a different measurement: transverse coordinates remain unchanged and forward separations contract by 1/γ on the observer’s simultaneous spatial slice. It is not a photograph. Distant sky markers are hidden in this comparison. The optical scene remains a transparent wire model; sampled edges are short straight chords approximating curved apparent edges. It does not compute opaque-surface occlusion.

Colors are false-color codes for log₂D, with red below 1, white at 1 and blue above 1, saturated at factors 1/4 and 4. They are not a visible spectrum or physical stellar colors. Optional brightness codes the bolometric radiance factor D⁴ with fixed tone curve 2D⁴/(1+D⁴), without changing camera FOV. Point sizes aid visibility, not resolved stellar photometry. The deterministic sky is a reference pattern, not an astronomical catalogue. No illumination transport, spectra, gravity or acceleration is simulated.

Drag or arrow keys change viewing direction without moving the observer off its worldline. Home or Reset view restores forward direction and 60° FOV. Ctrl/Meta+wheel changes FOV 25°…100°; plain scrolling moves the page. Inputs β0…0.995 and t 0…1000 ns are strict; no silent clamping. Valid settings survive navigation; reload waits for Show. Hidden tabs pause playback and GPU drawing. WebGL failure leaves an explicit shared fallback with the numeric results.

Kraus: aberration; wire-frame method.