Physics Simulation in Isaac Sim

Targets Isaac Sim 6.0+ / Kit 110. Both backends share UsdPhysics.*; backend-specific behavior is called out per section.

Backend selection (Kit 110)

isaacsim.core.simulation_manager registers physics engines and picks the active one. default_engine in its extension.toml is "physx", but the isaacsim.physics.newton extension defaults auto_switch_on_startup = true, so any app that enables isaacsim.physics.newton (the standard isaacsim.exp.full.kit does) ends up with Newton active at startup.

from isaacsim.core.simulation_manager import SimulationManager

SimulationManager.switch_physics_engine("newton")   # or "physx"
print(SimulationManager.get_active_physics_engine())

# Inspect what is available
from isaacsim.physics.newton import get_available_physics_engines, get_active_physics_engine
print(get_available_physics_engines())