MAJORFailure Reference

Runway ML Physics Collapse — Fluid, Gravity & Simulation Failures

Technical Classification

Physics Simulation Constraint Violation

Physics Simulation Constraint Violation occurs when Runway's model violates fundamental Newtonian mechanics in the generated video. Unlike CGI physics engines, video diffusion models have no explicit physics simulator — they learn physical behaviour statistically from training data. When the prompt includes complex fluid dynamics, gravity interactions, or multi-body physics over longer durations, the model often produces outputs that defy the laws of physics. The failure is most severe after the 5-second mark, where temporal coherence degrades significantly.

How to identify this failure

✕Water, lava, or smoke flowing upward against gravity
✕Objects falling or moving in the wrong direction
✕Fluid not splashing or dispersing upon impact
✕Steam rising downward or remaining static
✕Collision between objects producing no physical response

Real generation examples

Prompt used

"Molten lava flowing down a volcanic mountain into the ocean"

Failure observed @ 0.9s

Lava flow vectors inverted — fluid moves upward against gravity

Prompt used

"Water fountain exploding upward, slow motion, 120fps"

Failure observed @ 0:04

Fluid inversion at 0:04 — water falls upward instead of arcing

Documentation strength

If you need to escalate

HIGH — Physics violations are objectively verifiable and clearly attributable to model failure, not user error.

AVA is a pre-purchase prevention tool, not a post-purchase recovery tool. Platforms generally do not guarantee credit refunds for output-quality failures; goodwill credits are at each platform's discretion. The strength rating reflects how well-formed your support ticket can be, not a promised outcome.

Prevention + documentation steps

01
Score your prompt before you generate
Run your prompt through AVA's pre-flight scoring against the Physics Simulation Constraint Violation pattern. Green light = generate. Yellow/red = rewrite using the suggested fix before you commit credits.
02
Capture Generation ID + timestamp if it failed anyway
Find the Generation ID in the URL or share link. Note the exact time when the Physics Simulation Constraint Violation first appears (e.g. "failure first visible at 1.2s"). Timestamped evidence is significantly stronger than a general complaint.
03
Use the correct technical term in your support ticket
Describe this failure as "Physics Simulation Constraint Violation". This term maps to a recognised internal workflow in the support system and routes the ticket to the right team.
04
Submit via the correct support channel
Runway has no direct email intake. Pro+ plan: open the in-app AI Assistant (help widget bottom-right of app.runwayml.com), describe the failure with the technical term, attach evidence. Free/Standard plan: human support isn't available — your channel is Discord #community-help with @On Call - Moderators.

Frequently asked questions

How does Runway support handle credits for physics simulation failures?

Yes, particularly when the failure is objectively verifiable (e.g., fluid moving upward against gravity). Include your Generation ID, timestamp of the failure, and describe it as "Physics Simulation Constraint Violation" to trigger the correct support workflow.

Why does Runway fail at complex physics?

Video diffusion models learn physics statistically rather than using a simulation engine. Complex fluid dynamics, especially over longer clips (5s+), exceed what the model can consistently reproduce from training data alone.

How can I avoid physics failures in Runway?

Keep clips under 5 seconds for physics-heavy content. Split complex scenes into separate generations. Avoid combining fluid dynamics with camera movement. AVA's L1 scanner warns you before you generate.

Catch it before you generate

AVA scores this failure mode against your prompt in real time

Free Chrome extension. Analyzes your prompt as you type, flags failure-prone patterns specific to this model, and tells you what to rewrite — before you commit credits to a generation that will fail.

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