How Does Curved Space Around Black Holes Compare to L2 and LP Spaces?

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Discussion Overview

The discussion explores the nature of curved space around black holes in comparison to L2 and LP spaces, focusing on the implications of curvature and local flatness in different mathematical contexts. Participants examine whether small regions near black holes behave like flat L2 space or exhibit characteristics of LP spaces.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant notes that in L2 space, the Pythagorean theorem holds true for small triangles, while in LP space with p ≠ 2, it does not, even for small triangles.
  • Another participant suggests that the behavior of space near a black hole depends on whether one is past the event horizon, indicating that the singularity presents infinite mass and curvature.
  • A later reply posits that anywhere in spacetime behaves locally like the curved surface of the Earth, rather than like LP space, due to the equivalence principle, which suggests that spacetime appears flat when examined closely.
  • It is mentioned that Lp spaces lack a notion of angle, which differentiates them from the spacetime context being discussed.

Areas of Agreement / Disagreement

Participants express differing views on the nature of curvature in black hole space compared to L2 and LP spaces, with no consensus reached on the exact behavior of small regions near black holes.

Contextual Notes

The discussion includes assumptions about the nature of curvature and local flatness, as well as the implications of the equivalence principle, which are not fully resolved.

granpa
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In L2 space c2 = a2 + b2
http://en.wikipedia.org/wiki/Pythagorean_theorem
http://en.wikipedia.org/wiki/Lp_space#Motivation
http://en.wikipedia.org/wiki/Triangle_inequality

If we draw a large triangle on a curved surface like the Earth then the Pythagorean theorem won't work. But if we shrink the triangle down the curvature becomes less and less until it approaches being completely flat and the Pythagorean theorem works again.

If we draw a large triangle in LP space where P<>2 then the Pythagorean theorem also won't work. The difference is that it still won't work even if one shrinks the triangle down to nothing.

My question is what happens in the curved space of a black hole? Is it like the curved surface of the Earth or like the intrinsic curvature (no, that probably isn't right. maybe 'intrinsic distortion from L2 space) of LP space? Does a small enough piece of space near a black hole behave like regular flat L2 space (yes i know, technically it would be minkowski space but i am only interested in the space component and nonrelativistic speeds)
 
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no one knows the answer to that question, mathmatically then yes it should work
it depends if you are past the event horizon ( point of no return) yet
becouse at the center of a black hole, the singularity, then there is said to be infinite mass and therefore infinite curviture, so physically there you could not work like that :)
 
Thanks for the response.

Thats what I assumed but when I was reading the wiki article about LP space I suddenly realized that I didnt really know.
 
granpa said:
My question is what happens in the curved space of a black hole? Is it like the curved surface of the Earth or like the intrinsic curvature (no, that probably isn't right. maybe 'intrinsic distortion from L2 space) of LP space? Does a small enough piece of space near a black hole behave like regular flat L2 space (yes i know, technically it would be minkowski space but i am only interested in the space component and nonrelativistic speeds)

Anywhere in spacetime, whether near a black hole, inside or outside the event horizon, or anywhere else, behaves locally "like the curved surface of the Earth" and not "like Lp space". The equivalence principle means that if you zoom in close enough to any event, the surrounding spacetime looks almost like the flat spacetime of Minkowski space, which is analogous to (but not identical to) L2 space.

An Lp space, when p ≠ 2, has a notion only of "distance" and no notion of "angle" unlike spacetime. (Technically it is "normed vector space", but not an "inner product space".)
 

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