Domain: Natural Science — Physics
Target concept: A cloud of smoke collapses inward under uniform suction in a transparent chamber.

Video generation prompt: A diffuse cloud of smoke is suspended in still air within a transparent sealed chamber, and then uniform suction is applied through the chamber walls.

Evaluation guide:
(i) Target concept: Isotropic pressure-gradient–driven collapse of a passive scalar field (smoke) in a sealed, quiescent environment.
Minimum mechanism: Smoke must behave as an advected tracer (not self-propelled or reactive); chamber must be sealed to prevent inflow/outflow imbalance; suction must be spatially uniform (equal velocity magnitude normal to each wall) and temporally synchronous; air viscosity and diffusion must be low enough to permit observable directed collapse over 10 seconds.
(ii)Storyline: Frame 0–2: Static scene: transparent sealed chamber fully in view; diffuse smoke cloud centered, motionless, and uniformly translucent. Frame 3–4: Suction onset cue appears identically at all six walls (e.g., synchronized particle streamlines or visible activation of wall-mounted suction ports), with the chamber walls themselves remaining rigid and undistorted. Frame 5–8: Smoke undergoes continuous, radially symmetric contraction (maintaining diffuseness and center-aligned geometry) with no drift, rotation, or asymmetry. Frame 9–10: Smoke contacts all six inner surfaces simultaneously, forming a continuous, conformal layer with no gaps, thickening, or rebound. Perspective: Fixed frontal orthographic or slight three-quarter view; full chamber always in frame; no occlusions; lighting diffuse and shadow-consistent.

Manual:
Experimental Procedure
1. Fill a transparent, sealed cubic chamber with still air.
2. Introduce a diffuse cloud of white-gray smoke at the geometric center.
3. Activate uniform suction through all six inner wall surfaces simultaneously.
Observation of Experimental Phenomena
A centrally suspended, evenly dispersed smoke cloud remains motionless until suction begins; then it collapses smoothly and symmetrically inward from all directions, contacting all inner chamber walls at the same instant.
Summary of Experimental Principles
Uniform negative pressure applied across all chamber boundaries creates isotropic inward flow, overcoming diffusion and buoyancy to drive radial convergence of smoke particles — demonstrating pressure-gradient–driven fluid motion in a confined, quiescent medium.

Prompt Grounding rubric:
level_1: No transparent sealed chamber is visible; no smoke cloud is present at any frame; no suction indication anywhere in the chamber (no visible airflow markers, no wall-mounted inlets, no pressure-gradient cues); the chamber is absent, opaque, or missing walls.
level_2: A transparent chamber is present but does not look sealed (an open top, visible gaps, or unsealed seams); the smoke cloud is present but is not diffuse (it appears as a concentrated plume, a sharp-edged column, or a stratified layer instead of an even haze); suction is implied only by unrelated motion (background blur, camera shake) with no visible connection to the chamber walls.
level_3: The transparent sealed chamber is fully visible and intact; a diffuse smoke cloud is present within the chamber at video onset, filling a substantial share of the interior rather than being confined to one corner; uniform suction is indicated by simultaneous inward motion of smoke toward all chamber walls, with no preferential collapse toward one side, bottom, or corner; no external tools, hands, or hoses are visible inside the chamber.
level_4: Everything required at the 3-point level is present, and beyond that: the smoke stays visibly suspended (neither settling toward the floor nor rising toward the ceiling) before suction begins; inward motion begins only after a suction onset cue appears at the walls (e.g., synchronized airflow tracers or visible activation of wall-mounted suction ports), not before; the chamber walls themselves show no warping, dimpling, or other distortion at any point; no extraneous objects (labels, supports, stands) intrude into the chamber's interior at any frame.
level_5: Everything required at the 4-point level is present, and beyond that: the smoke's starting extent is large enough that its inward contraction is unmistakable to a viewer (it visibly spans at least half the chamber's cross-section at frame 0); the chamber walls show no visual distortion, reflection artifacts, or transparency inconsistency and remain perfectly rigid throughout; a suction cue (e.g., faint particle streamlines or synchronized activation of wall-mounted suction ports) appears identically at all six inner wall surfaces simultaneously and continuously until the collapse completes.

Scientific and Causal Correctness rubric:
level_1: Smoke moves outward, upward, or disperses; collapses into a solid-like mass or disappears abruptly; exhibits buoyant rise instead of inward acceleration; no causal link between wall action and smoke motion; smoke behaves like liquid droplets or solid particles (e.g., bouncing, splattering, rolling).
level_2: Smoke shows partial inward motion but violates physics: e.g., collapses only toward one wall while expanding elsewhere; accelerates *before* suction cue; forms sharp vortices or turbulent eddies inconsistent with uniform suction; exhibits sudden discontinuous jumps (teleportation) in position without intermediate frames.
level_3: Smoke cloud is initially motionless and uniformly distributed; upon suction onset, it exhibits continuous, smooth inward motion toward all chamber boundaries; no buoyancy-driven ascent or gravitational settling observed during collapse; motion direction is radially inward from center toward walls; no net lateral or vertical drift.
level_4: All conditions for score 3 are satisfied; additionally: smoke density remains visually uniform during collapse (no darkening at center or thinning at edges); no phase change (e.g., no condensation, no evaporation signature, no opacity shift inconsistent with compression); collapse terminates with smoke contacting *all* inner wall surfaces simultaneously; no wall contacted earlier than others.
level_5: All conditions for score 4 are satisfied; additionally: smoke exhibits no rebound, oscillation, or residual motion after wall contact; final state shows smoke evenly adhered as a thin, continuous layer across *all six inner surfaces* (front, back, left, right, top, bottom); no localized thickening, pooling, or detachment anywhere.

Spatiotemporal Consistency rubric:
level_1: Chamber geometry distorts (e.g., walls warp, corners shear, perspective flips); smoke teleports between frames (e.g., disappears then reappears meters away); lighting changes abruptly (e.g., flash, flicker, or shadow jump unrelated to motion); camera viewpoint shifts (e.g., pan, zoom, tilt) or rotates mid-sequence.
level_2: Chamber maintains fixed rectangular prism shape but exhibits inconsistent transparency (e.g., alternating clear/opaque walls per frame); smoke motion is jerky (≥2 frames with zero displacement followed by large jump); light/shadow on smoke or walls changes discontinuously (e.g., specular highlight vanishes then reappears with different location/intensity).
level_3: Chamber remains rigid and stationary with constant aspect ratio and wall alignment; smoke moves with continuous, fluid trajectory; no teleportation, no frame skips, no stutter; lighting and shadows remain stable and consistent with fixed overhead/diffuse illumination; no structural breaks (e.g., smoke splitting into disconnected fragments that later rejoin).
level_4: All conditions for score 3 are satisfied; additionally: smoke maintains coherent boundary throughout; no fragmentation into isolated blobs that move independently; chamber walls cast consistent, soft-edged shadows on smoke that shift smoothly with inward motion; no inter-frame occlusion inconsistencies (e.g., smoke edge hiding wall then revealing it without transitional overlap).
level_5: All conditions for score 4 are satisfied; additionally: parallax between smoke and chamber walls remains physically consistent (e.g., foreground smoke elements shift relative to background walls at correct proportional rate); no motion blur inconsistent with speed (e.g., static smoke showing streaks, or fast-moving smoke appearing unnaturally sharp); depth cues (e.g., relative size, atmospheric perspective) remain stable and mutually reinforcing across all frames.