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'''Spacetime''' is the 4-dimensional [[vector space]] or [[manifold]]<ref>Often treated as a vector space when working examples, but that isn't really correct because it has no origin.  The more sophisticated term "manifold" is correct.</ref> that simultaneously embodies the concepts of time and 3-dimensional space.  Whether one considers space and time to be real constructs or just theoretical ones, or whether one can ascribe a separate existence to them, or whether one can ascribe a separate existence to spacetime itself, depends on one's physical intuition.  But that doesn't matter&mdash;"separate existence" or not, physicists working in the field understand spacetime as a useful concept.

'''Spacetime''' is the 4-dimensional [[vector space]] or [[manifold]]<ref>Often treated as a vector space when working examples, but that isn't really correct because it has no origin.  The more sophisticated term "manifold" is correct.</ref> that, by hypothesis, simultaneously embodies the concepts of time and 3-dimensional space.  Whether one can ascribe a separate existence to spacetime itself, depends on one's physical intuition.  But that doesn't matter&mdash;"separate existence" or not, physicists working in the field understand spacetime as a useful concept.

Under Newtonian/Galilean physics or Newtonian/Galilean relativity at the high-school and general undergraduate level, one typically thinks of time, and the 3 dimensions of space, completely separately.  One can solve many problems of physics with this formulation.

Under Newtonian/Galilean physics or Newtonian/Galilean relativity at the high-school and general undergraduate level, one typically thinks of time, and the 3 dimensions of space, completely separately.  One can solve many problems of physics with this formulation.