What is PhysX and do I need it?

PhysX is essentially a physics engine. Simple, you can leave now. Although it’s more than just that. Still in development by Nvidia, the PhysX API gives game designers a cheaty, GPU accelerated way of simulating realistic, dynamic objects in 3D environments.

What does PhysX software do?

PhysX is a multi-threaded physics simulation SDK. It supports rigid body dynamics, soft body dynamics (like cloth simulation, including tearing and pressurized cloth), ragdolls and character controllers, vehicle dynamics, particles and volumetric fluid simulation.