Genesis-World: Core Physics Engineer

United States Digital Space LLC; Paris (TX); On-site; USD 120,000 - 190,000; Full time

Job summary

United States Digital Space LLC is building a leading open-source style physics simulation platform for physical AI, focusing on multi-physics, scalable GPU-accelerated simulation. You will push the physics forward from algorithm to production-ready code, collaborating with researchers and engineers to deliver a versatile engine capable of simulating complex robotics tasks at scale.

The role emphasizes end-to-end research, from theory to validated, well-documented code, with an eye toward

Qualifications

• Strong background in physics-based simulation for robotics.
• Experience shipping simulation code in production or research.
• Proficient in HPC programming (CPU/GPU).
• Ability to validate models with analytical or real-world data.

Responsibilities

• Advance the company-World physics engine toward production-ready capabilities.
• Research end-to-end from algorithm to merged, tested code.
• Collaborate with academic partners on groundbreaking work.
• Improve speed, fidelity, and scalability across diverse physics.

Skills

Physics-based simulation

Robotics

Numerical optimization

HPC programming

Tools

XPBD

VBD

IPC

FEM

MPM

Job description

What we're buildingRobots will learn in simulation before they hit the factory. the company-World is our bet on that future.

the company-World is an open-source, general-purpose simulation platform for physical AI from the company AI. One unified multi-physics engine: rigid bodies, FEM, MPM, particles, cloth, fluids. A robot arm can pour water onto sand, grasp a deformable object, or cut a soft body, all in the same simulation. Nyx, our in-house renderer, may be the most promising renderer for robotics out there: real-time photo-realistic rendering, advanced features like depth of field, and state-of-the-art techniques never seen before. Sensors of every kind: cameras, lidar, IMU, contact forces, temperature, plus arguably the most advanced tactile simulation available (paper). And the engine keeps growing: we are developing internally the most comprehensive and fastest Incremental Potential Contact (paper) solver for deformable body dynamics we know of, soon to be open-sourced. It powers real business applications, from full-fledged box packaging with labelling machine and all, to wire harnessing and lab automation, without any physics hack or compromise.

Everything is Python-first and runs anywhere. Kernels are written once, and Quadrants, our in-house JIT compiler, lowers them to CUDA, AMD ROCm, Apple Metal, Vulkan, x86, and ARM64. A single laptop or a datacenter. Massively batched GPU simulation for learning at scale, and complex non-batched scenes where CPU wins outright.

This is at the core of the company AI's strategy. Evaluation is the bottleneck of scalable robotics: real hardware caps iteration at wall-clock time, but simulation turns it into a compute problem. Ours already runs two orders of magnitude faster than hardware (tens of thousands of episodes in half an hour instead of 200+ hours), while correlating with on-hardware rollouts at 89%. The north star: physical AI that improves at the speed of compute.

The roleYou push the physics of the company-World forward. The mandate is clear: ship production-ready simulation capabilities that matter for the company's internal needs. Research applied end-to-end, from algorithm to merged, tested, documented code that real robot-learning pipelines depend on. Occasional groundbreaking research happens, notably through academic collaborations. But the core of the job is making the engine measurably better along five axes:

• Speed. Algorithms that are not only faster but also smart enough to spend compute only where it matters across both time and space: larger stable timesteps, selective fidelity (adaptive across scales or simply hand-set), structure-aware solvers.

• Completeness. No physics off limits: water, human animation, air flow, gravel, tendons, even body organs. Whatever the next use-case needs, the engine grows to cover it.

• Fidelity. More realistic models: contact, friction, deformation, energy, actuation, materials…

• Versatility. Extensible multi-physics without compromise on realism: all solvers in the scene coupled together at once, two-way and constraint-based. Write your own solver and it joins the scene like a native one, growing into an open solver ecosystem.

• Scalability. From workstation to factory scale, and one day, city scale: thousands of interacting entities, batched across environments, without losing physical soundness.

Our ambition is to establish the company-World as the go-to simulator for physical AI, from companies and research labs to individuals.

The problems waiting for you Every fidelity for every physics. The same physics at every point of the speed-accuracy spectrum, from heavily batched training with XPBD or VBD to final validation with IPC. Same scene, same API, pick your tradeoff.

• Invent physics level-of-detail (LOD). Rendering has had LOD for decades, physics is still waiting. Simulate at full fidelity what agents interact with and see, coarsely what they do not.

• Heterogeneous environments. Every parallel world can hold a completely different model: different bodies, joints, and collision geometries.

• Adaptive timesteps per island. Error-based control with Runge-Kutta Dopri5, and Time-of-Impact stepping during collision detection, as done in Jiminy.

• Couple everything, exactly. Efficient and accurate two-way constraint-based coupling between heterogeneous grey-box solvers, using state-of-the-art methods like ADMM. Owning every solver in the stack is what makes it possible.

• More scalable constraint solvers. Push rigid constraint solving beyond its current scalability ceiling (reference).

• Unify contact resolution. Hydro-elastic compliance, unilateral constraints, and sequential impulses in the same framework, ideally under one generic formulation.

• Closed kinematic loops without constraints. Handle loops intrinsically for numerical stability and speed, in the spirit of Kamino.

Day to day: you write your physics in plain Python and Quadrants makes it fast on every backend. And you validate it the hard way: analytical closed forms, other engines, real-world data.

Who you areYou are a physicist and an engineer at once. You judge a method by whether it holds up in production at real scale, and you do not stop until it does. No blind spots: you relentlessly hunt down even the defect that looks insignificant, because it never is.

• A strong background in physics-based simulation, preferably related to robotics: RBD, FEM, MPM, SPH, IPC, XPBD, VBD, ABD, plus constrained optimization and numerical integration of stiff systems.

• A track record of shipping simulation code that others rely on, in an engine, in industry, or in a research codebase used beyond its authors.

• Solid HPC programming (CPU and/or GPU), and an instinct for what makes a numerical method fast in practice, beyond complexity classes.

• Rigor in validation: analytical closed forms, cross-engine consistency, real-world data.

Bonus points: publications in simulation, graphics, or robotics venues (SIGGRAPH, ICRA, IROS, CoRL, RSS). Contributions to an open-source physics engine.

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