&gt;It is that spacetime which is curved rather than just space.<p>This is the crucial point that many discussions overlook. The concept of &quot;curvature of space&quot; is obvious nonsense because curvature is measured with respect to space. For space itself to curve implies the existence of meta-space (and as many nested metaspaces as you like). But &quot;spacetime&quot; does not work like &quot;space&quot;, and there actually is no metaspace. Talking about &quot;space&quot; curving or expanding is unnecessarily confusing.