PERFECT COSMOLOGICAL PRINCIPLE

The 'Perfect Cosmological Principle' states that the Universe is homogenous and isotropic in space ''and'' time. In this view the universe looks the same everywhere (on the large scale) as it always has and always will. It is the principle underpinning steady-state theory.
The Perfect Cosmological Principle is an extension of the Cosmological Principle, which accepts that the universe changes its gross feature with time, but not in space.