4DSpacetime
4DSpacetime is the four-dimensional continuum that unifies three spatial dimensions with one temporal dimension into a single geometric structure. In special relativity it is modeled as flat Minkowski space, with coordinates x^μ = (ct, x, y, z). The spacetime interval between events is ds^2 = c^2 dt^2 − dx^2 − dy^2 − dz^2; this quantity is invariant under Lorentz transformations and determines causal relations: timelike intervals allow sub-light-speed influence, lightlike intervals lie on the light cone, and spacelike intervals cannot influence each other.
In general relativity spacetime is curved by matter and energy; the geometry is described by the metric
Historically, Hermann Minkowski introduced spacetime in 1908 as a geometric setting for special relativity, and Einstein
In modern physics, 4DSpacetime underpins classical field theories, quantum field theory in curved spacetime, and cosmology,