Sandbox.PhysicsWorld

// From scene
PhysicsWorld physics = Scene.PhysicsWorld;

// Get/set gravity
Vector3 gravity = physics.Gravity;
physics.Gravity = new Vector3(0, 0, -800);

// Physics simulation rate
float step = physics.TimeStep; // Usually 0.02 (50Hz)

// All physics bodies
foreach (var body in physics.Bodies)
{
    Log.Info($"Body: {body.GameObject}");
}

// AABB query
var inBox = physics.GetBodiesInBox(box);

// Sphere query
var inSphere = physics.GetBodiesInSphere(center, radius);

// Raycast (use Scene.Trace for this)

// Layer mask for queries
int mask = physics.GetLayerMask("solid", "debris");

// Pause physics
physics.SimulationEnabled = false;

// Resume
physics.SimulationEnabled = true;

// Global collision events
physics.OnCollisionStart += (body1, body2, collision) =>
{
    Log.Info($"Collision: {body1} vs {body2}");
};