Talk:Cauchy surface

Bad definition

I think the definition you give here of $D^{+}({\mathcal {S}})$ is wrong. Def: given ${\mathcal {M}}$ Lorentzian manifold, $D^{+}({\mathcal {S}}):=\{p\in {\mathcal {M}}{\text{ such that }}\forall {\text{ past directed, non-spacelike curve from }}p{\text{ intersects }}{\mathcal {S}}\}$.

151.49.212.151 (talk) 16:12, 4 December 2014 (UTC)

I think what you wrote is correct and what the article says is correct. What you wrote is better and clearer than the article, which is unclear and garbled. Someone should fix this. The article is also garbled about "inextensible"; that needs fixing too. So it goes. 67.198.37.16 (talk) 07:50, 18 November 2023 (UTC)

informal version

Maybe start with uninteresting(?) example: first 'everywhere at 1PM', next 'everywhere at local noon', then get more technical. (or, 1PM -> 7AM and local noon -> sunrise, since 'local noon' is less familiar) --2607:FEA8:86DC:80E0:0:0:0:D2E4 (talk) 17:10, 10 September 2023 (UTC)