# Black Hole spacetime geometries

**URL:** <https://boards.straightdope.com/t/black-hole-spacetime-geometries/853993>\
**Category:** Factual Questions\
**Created:** [May 17, 2020, 7:28pm UTC](https://boards.straightdope.com/t/black-hole-spacetime-geometries/853993 "2020-05-17T19:28:26Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\
**Post date:** [May 17, 2020, 7:28pm UTC](https://boards.straightdope.com/t/black-hole-spacetime-geometries/853993/1 "2020-05-17T19:28:26Z")

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In what ways are Penrose Diagrams  
[https://www.researchgate.net/profile/Daniel\_Pollack2/publication/45910536/figure/fig3/AS:667041270861828@1536046440330/The-Carter-Penrose-diagram-6-for-the-KruskalSzekeres-space-time-with-mass-M-There-are.png](https://www.researchgate.net/profile/Daniel_Pollack2/publication/45910536/figure/fig3/AS:667041270861828@1536046440330/The-Carter-Penrose-diagram-6-for-the-KruskalSzekeres-space-time-with-mass-M-There-are.png)

and Kruskal-Szekeres coordinates  
[![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Kruskal_diagram_of_Schwarzschild_chart.svg/2000px-Kruskal_diagram_of_Schwarzschild_chart.svg.png) ](https://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Kruskal_diagram_of_Schwarzschild_chart.svg/2000px-Kruskal_diagram_of_Schwarzschild_chart.svg.png)  
alike/different?

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**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\
**Post date:** [May 18, 2020, 7:00am UTC](https://boards.straightdope.com/t/black-hole-spacetime-geometries/853993/2 "2020-05-18T07:00:25Z")

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Obviously Kruskal-Szerkeres cooridnates are a coordinate system for a certain spacetime and a Penrose diagram is a pictorial representation of a spacetime. The two pictures obviously look similiar, the difference being that the Penrose diagram is compactified to include the whole spacetime (notice the “boundaries” at infinity are included in the Penrose diagram).