Gen-4.5 by Runway: status and timeline

Milestones

Next · Integration with major creative software platforms

Gen-4.5 releasedDec 2025Complete.
Ranks at top of AI video generators at launchDec 2025Complete.
Becomes foundation for GWM-1 world modelsDec 2025Complete.

Most important updates

Runway releases Gen-4.5 video generation model with improved physics simulation1 Dec 2025

Upcoming

2026Integration with major creative software platforms (next)
Q4 2026Enterprise adoption for media production

Current obstacles

Long-horizon physical consistencyPhysics errors compound over many frames; maintaining accuracy over minutes of video is harder than seconds.
Rare or complex physical scenariosTraining data bias means uncommon physical phenomena (specific collision types, material interactions) are underrepresented.

Physics limits

Video generation is high-entropy synthesisEach frame has combinatorial variation; as sequences grow longer, the number of plausible continuations explodes exponentially, making perfect physics impossible.
Generalization beyond training distributionModels learn statistical patterns from training video; novel scenarios not well-represented in training will be hallucinated or oversimplified.

How it works

3 parts

Physics-aware diffusion

Models momentum and conservation laws

Reasons about physics conservation to maintain momentum and object continuity.

Fluid dynamics simulation

Accurate liquid and gas behavior

The model has learned to simulate fluid flow, turbulence and interactions with objects, key to photorealistic video of natural phenomena.

Multi-object tracking

Consistent object identity across frames

Gen-4.5 maintains object identity and trajectories across generated sequences, preventing the pop-in/pop-out artifacts of earlier models.

Spec sheet

Spec	Gen-4.5
Quality ranking	Top of AI video generators at launch^R (reported)
Physics simulation capability	Momentum, fluid dynamics, object interactions^R (reported)

^R reported by the company

Papers & demos

1 item

Dec 2025demo
Gen-4.5 video generation model launch (opens runway.com)Leading video generation model excelling at physical phenomena simulation; ranked at top of AI video generators at launch.

Update log

1 update

Mon 1 Dec 2025

Major: Runway releases Gen-4.5 video generation model with improved physics simulationPressSoftware

About Runway

The team behind Gen-4.5

Runway

Gen-4.5 video generation, GWM-1 world model, generative media

New York-based company founded 2018 by Cristóbal Valenzuela, Anastasis Germanidis, Alejandro Matamala. Develops Gen-4.5 video generation and GWM-1 world model for robotics and avatars.

Raised $315M Series E Feb 2026 at $5.3B valuation; led by General Atlantic, Nvidia, AMD.
Gen-4.5 (Dec 2025): top-ranked video generator; excels at physics (momentum, fluids).
GWM-1 (Dec 2025): world model for robot simulation, avatar generation, virtual test environments.

runwayml.com (opens runwayml.com)Company profile →

Founded: 20188 yrs
Headquarters: United States
Status: Private
Valuation: $5.3BprivateFeb 2026
Raised: $858M6 rounds
Last round: Series E · $315MFeb 2026$5.3B post
Works in: AIImage & voice generation
Coverage: 2 programs · 3 updateslatest 10 Feb 2026checked 10 Oct
Lead investors: General AtlanticGoogleFelicisCoatueAmplify Partners
Investors: Nvidia (opens nvidia.com)General Atlantic (opens generalatlantic.com)AMD Ventures (opens amd.com)
People: Cristóbal Valenzuela (opens twitter.com)Co-founder & CEOAnastasis Germanidis (opens twitter.com)Co-founder & CTOAlejandro Matamala (opens twitter.com)Co-founder

Spec

Gen-4.5

Quality ranking

Top of AI video generators at launch^R (reported)

Physics simulation capability

Momentum, fluid dynamics, object interactions^R (reported)