The spacetime continuum is the fundamental concept in General Relativity that unifies space and time into a single entity, where events occur and physical laws apply.

Riemannian Geometry is used to describe the geometry of spacetime in General Relativity, as it allows for the curvature of space and time.

The curvature of spacetime is the bending or warping of spacetime caused by the presence of mass and energy, as described by General Relativity.

Black holes are known for their extreme curvature of spacetime, leading to the formation of an event horizon, beyond which nothing, not even light, can escape.

A singularity is the hypothetical boundary in spacetime where time and space become infinitely curved, as predicted by General Relativity, often associated with the center of black holes.

The Big Bang Model is the prevailing cosmological model that describes the universe as expanding from a hot, dense state and cooling over time.

A spacetime wormhole is a hypothetical connection between two distant points in spacetime, allowing for faster-than-light travel, as predicted by certain solutions to Einstein's field equations.

The Principle of Relativity states that the laws of physics are the same for all observers in uniform motion, forming the foundation of Einstein's theory of Special Relativity.

The Lorentz Transformation is the mathematical transformation used to convert between different inertial reference frames in Special Relativity, accounting for the effects of time dilation and length contraction.

Geodesics in General Relativity describe the paths that objects with mass or energy follow in curved spacetime, influenced by the curvature caused by the distribution of mass and energy.

Gravitational waves are ripples in spacetime caused by the acceleration of massive objects, predicted by General Relativity and recently detected through various experiments.

The Cyclic Model proposes that the universe undergoes a cycle of expansion and contraction, repeating itself infinitely, with each cycle starting from a Big Bang and ending in a Big Crunch.

A singularity is the hypothetical region of spacetime where the laws of physics break down, often associated with the center of black holes, where matter is compressed to an infinitely small point.

The Multiverse Model proposes that the universe is composed of multiple, parallel universes, each with its own set of physical laws and constants, existing alongside our own universe.

Gravitational lensing is the phenomenon where light bends as it passes through a gravitational field, predicted by General Relativity, causing the apparent position of objects to be distorted.