&gt;&gt; It is that spacetime which is curved rather than just space.<p>&gt; This is the crucial point that many discussions overlook<p>I agree completely with this (and have said as much in the past --<a href="https:&#x2F;&#x2F;www.reddit.com&#x2F;r&#x2F;cosmology&#x2F;comments&#x2F;2zy19s&#x2F;bowling_ball_on_a_mattress&#x2F;cpnf7ck" rel="nofollow">https:&#x2F;&#x2F;www.reddit.com&#x2F;r&#x2F;cosmology&#x2F;comments&#x2F;2zy19s&#x2F;bowling_b...</a>) but<p>&gt; The concept of &quot;curvature of space&quot; is obvious nonsense<p>This is emphatically <i>not</i> correct. Space can be curved without being embedded in a higher &quot;meta-space&quot;. You can have a 2D surface that is curved <i>as if</i> it were the surface of a sphere without it actually being on an actual 3D sphere -- it just has to &quot;connect up&quot; the right way and have &quot;parallel&quot; lines bend towards each other and so on. Ditto in more dimensions.