  We introduce PhysGaussian, a new method that seamlessly integrates physically
grounded Newtonian dynamics within 3D Gaussians to achieve high-quality novel
motion synthesis. Employing a custom Material Point Method (MPM), our approach
enriches 3D Gaussian kernels with physically meaningful kinematic deformation
and mechanical stress attributes, all evolved in line with continuum mechanics
principles. A defining characteristic of our method is the seamless integration
between physical simulation and visual rendering: both components utilize the
same 3D Gaussian kernels as their discrete representations. This negates the
necessity for triangle/tetrahedron meshing, marching cubes, "cage meshes," or
any other geometry embedding, highlighting the principle of "what you see is
what you simulate (WS$^2$)." Our method demonstrates exceptional versatility
across a wide variety of materials--including elastic entities, metals,
non-Newtonian fluids, and granular materials--showcasing its strong
capabilities in creating diverse visual content with novel viewpoints and
movements. Our project page is at: https://xpandora.github.io/PhysGaussian/
