Parallel transport is a method in differential geometry for moving vectors along a curve on a manifold while keeping them parallel with respect to the manifold's connection. It is crucial for defining the notion of curvature and plays a fundamental role in general relativity and gauge theories.
Theorema Egregium, formulated by Carl Friedrich Gauss, states that the Gaussian curvature of a surface is an intrinsic property, meaning it is preserved under local isometric deformations. This implies that curvature can be determined entirely by the surface's metric, without reference to the surrounding space, highlighting a profound connection between geometry and topology.
Extrinsic curvature refers to how a surface is curved within a higher-dimensional space, describing how the surface bends relative to the surrounding space. It is crucial in fields like differential geometry and general relativity, where it helps in understanding the geometry of surfaces and spacetime curvature influenced by gravity.