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The following suggestions were generated by a semi-automatic javascript program (later filtered and edited -- God made the integers ( talk) 06:03, 10 November 2016 (UTC))
You may wish to browse through User:AndyZ/Suggestions for further ideas. Thanks, ( t) Josve05a ( c) 22:06, 16 June 2013 (UTC) |
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I substituted saddle and trumpet bell as examples of surfaces with hyperbolic or negative curvature. A bowl, being spherical, is not such a good example because it has positive curvature whether viewed from the inside or outside. Similarly in the following section on the rubber-sheet analogy I pointed out the trumpet-bell-shaped (rather than bowl-shaped) nature of the depression, responsible for the inward deviation of trajectories passing nearby. CharlesHBennett ( talk) 05:04, 8 May 2010 (UTC)
Strictly speaking, the claim that ″Energy and matter are equivalent″ is incorrect, and should be changed to ″Energy and mass are equivalent″. ′Matter′ is another matter entirely! :-) George963 au ( talk) 00:21, 6 April 2018 (UTC)
This article should probably be split:
Both revised articles should begin with much simpler intros for laypersons, and should have better citations. The second should have citations in WikiProject GTR format.--- CH (talk) 01:54, 15 September 2005 (UTC)
Is it the y coordinate which is bounded from one side? -- MarSch 17:43, 1 November 2005 (UTC)
It would be very nice with some references to some expository article (or book?). (unsigned comment by 130.238.149.247)
The geodesic boundary, i.e. "the limit as y goes to 0", should be explained in some detail.
The "picture" on the page is completely blank. It presumably should be removed or replaced. Gene Ward Smith 21:52, 4 May 2006 (UTC)
In the current definition anti de Sitter space is defined as a space which is simply connected. But this is not in agreement with the definition in e.g. [ [1]] .
The best (?) definition of anti de Sitter space of dimension n+1 should be the solution to the equation
that is, the same as,
that is, as a one-sheeted hyperboloid in . — Preceding unsigned comment added by Ulner ( talk • contribs) 23:59, 5 May 2006
This article managed to entirely confuse me, until I came to the talk page and saw the above comment, which concisely says it all. In the main article ADS is defined more generally and at no point is it spelled out how or when it specialises to this. The notation simply switches inexplicably between sections. — Preceding unsigned comment added by 2A01:56C0:8180:0:3C75:FB77:779F:3D4 ( talk) 19:26, 7 November 2016 (UTC)
Exactly. I'm writing from a relativity conference at the ESI Institute, in Vienna. The talk being given is on anti-de Sitter space, and this article is confusing even to a so-called expert !!
Let me slightly edit the above definition. The quickest definition of anti-de Sitter space of dimension n+1 should be as the solution to the equation
which is a one-sheeted hyperboloid in It has the topology of It becomes a Lorentz manifold, with the timelike, by restricting to it the ambient metric of signature (n,2) given by
2001:62A:4:41C:B580:3333:57FA:52FB ( talk) 13:46, 24 August 2017 (UTC)
I deleted the last paragraph, starting with "To simplify the AdSCFT correspondence it is like...", which was a very bad analogy. Dan Gluck 06:29, 15 September 2006 (UTC)
The article states that AdS space has O(2,n-1) as automorphism group. The article should specify which kind of automorphisms (i.e. automorphisms = isometries of a pseudo-Riemannian manifold). Pierreback 19:15, 25 February 2007 (UTC)
The definition now says that '\alpha' should be a negative constant, but we have '\alpha^2' in the equation? This is wrong. Pierreback 16:27, 28 February 2007 (UTC)
The sentence "Anti de Sitter spacetime has closed time-like loops" uses the term "anti de siter spacetime" for the first time in the article. I guess it should be changed to "anti de sitter space". Also, an explanation of "closed time-like loops" should be added. 83.253.30.214 11:27, 21 July 2007 (UTC)
Does anybody have some good mathematical definition concerning the conformal boundary? This should be added.
"In the limit as y = 0, this reduces to a Minkowski metric ; thus, the anti-de Sitter space contains a conformal Minkowski space at infinity ("infinity" having y-coordinate zero in this patch)."
83.253.30.214 11:34, 21 July 2007 (UTC)
Can someone write what that notation means? Because here the anti de Sitter space have two parameters. 200.145.112.189 ( talk) 22:45, 18 November 2009 (UTC)
"...is a maximally symmetric Lorentzian manifold with constant negative scalar curvature. It is the Lorentzian analogue of n-dimensional hyperbolic space, just as Minkowski space and de Sitter space are the analogues of Euclidean and elliptical spaces respectively."
did you write this in some weird language by mistake, because I CANNOT MAKE HEADS OR TAILS OF WTF YOUR TALKING ABOUT!!!! —Preceding unsigned comment added by 96.231.28.194 ( talk) 01:17, 2 November 2010 (UTC)
lol... me neither :/. But then I had some oranges and it was k... — Preceding unsigned comment added by 213.42.95.234 ( talk) 12:36, 25 March 2012 (UTC)
LOL. Funny, but true. This is an awful lead sentence for an entry into a general encyclopedia. It actually would require great knowledge and effort to distill this into something more accessible [R. Feynman, where have1 you gone?]. 71.208.147.98 ( talk) 21:13, 22 July 2014 (UTC)
I know mid-sentence this is "anti de Sitter space" and not "Anti de Sitter space", but surely the usual laws of grammar apply, and when it's the first word in a sentence, or subheading, it should get a capital "A"? -- Dr Greg talk 19:47, 9 February 2013 (UTC)
A large part of the "non-technical" section of this article deals with AdS/CFT ... but we already have a lengthly non-technical article on that. Could someone please cut this section, here? 99.153.64.179 ( talk) 04:42, 3 November 2013 (UTC)
I would urge the editors NOT to take out the non-technical section. Most mathematics articles in Wikipedia are USELESS unless you already know the material. This is one of the rare exceptions that offers some non-technical explanations, which are extremely helpful to the non-expert trying to make sense of the more arcane sections. 98.170.198.158 ( talk) 17:38, 3 April 2014 (UTC)
The 5d interpretation is not quite clear to me. Curvature is an intrinsic property of a manifold. Thus, it appears that the 5d interpretation is not really necessary for anti de Sitter space. The 4d manifold can be embedded in 5d but it seems not necessary and there are many possible embeddings. Is this correct? Should that be mentioned? — Preceding unsigned comment added by 152.3.73.36 ( talk) 17:37, 8 December 2014 (UTC)
The introduction is so complicated, so full of terminology specific to the subject, that it would only make sense to someone who already knows the subject - which makes it worthless to someone trying to learn the subject - which means it is a waste of time in a reference work. At the very least, there needs to be a non-technical thesis statement at the beginning. Pb8bije6a7b6a3w ( talk) 17:51, 16 November 2015 (UTC)
There is an implicit convention being adopted when calling the curvature of AdS negative. Specifically, the sign of the curvature flips with that of the metric tensor, or (from a physicist's perspective), with which dimensions are labelled spacelike. To refer to the sign of the curvature without stating the convention, or calling out that the sign is not an absolute, is therefore misleading. Surely should be mentioned and if possible sourced?
To make it clearer: AdS2 and dS2 are the same two-dimensional space; they differ only in which dimension is labelled "time" and which is "space". Yet, the curvature is considered to be negative and positive respectively. This ambiguity of convention occurs with all of the spaces AdSp,q. — Quondum 14:54, 7 July 2016 (UTC)
The sentence "For example, in general relativity, objects in motion have a slightly different gravitation effect than objects at rest." is rubbish. There is no such thing like an "object in motion" or an "object at rest" in general relativity. These notions related to Newtonian absolute space and thus are incorrect ontologies.
In the article it is stated , but it's not at all clear what this means. Clearly it's not a statement about groups because is not a group, so it must be a statement about diffeomorphisms between topological spaces. But modding manifolds by submanifolds never changes dimensions and as it stands this would say a 3-dimensional thing is homeomorphic to a 2-dimensional thing which is also nonsense. I think the intention is maybe something along the lines of the Hopf map . I assume something similar holds in the other cases but I have no idea. — Preceding unsigned comment added by INLegred ( talk • contribs) 19:46, 27 March 2020 (UTC)
There is no absolute parallelism in GR, only parallel transport along a curve. The phrase parallel geodesic only has meaning when the manifold is parallelizable and a parallelization is specified. I realize that this is a common error in popularizations, but it is still wrong. Shmuel (Seymour J.) Metz Username:Chatul ( talk) 06:04, 1 May 2020 (UTC)
The result of the move request was: not moved. ( non-admin closure) ModernDayTrilobite ( talk • contribs) 17:42, 11 January 2023 (UTC)
Anti-de Sitter space → Anti–de Sitter space – It is impossible to tell from search whether this is usually spelled with a hyphen or an en dash, but MOS:PREFIXDASH calls for an en dash since de Sitter is one name. – LaundryPizza03 ( d c̄) 10:28, 1 January 2023 (UTC)
Ravenpuff has just moved this page to "Anti–de Sitter space", directly contradicting the result of the requested move from last month. Please respect the consensus and kindly undo the move. Tercer ( talk) 15:38, 15 February 2023 (UTC)
Ravenpuff, as you see there's a clear consensus against the en-dash. Please undo your move. Tercer ( talk) 09:23, 21 February 2023 (UTC)
"Some authors define anti-de Sitter space as equivalent to the embedded quasi-sphere itself, while others define it as equivalent to the universal cover of the embedding." This seems very important and should not be buried. -- 99.238.150.103 ( talk) 18:08, 10 September 2023 (UTC)
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||||||||||
|
The following suggestions were generated by a semi-automatic javascript program (later filtered and edited -- God made the integers ( talk) 06:03, 10 November 2016 (UTC))
You may wish to browse through User:AndyZ/Suggestions for further ideas. Thanks, ( t) Josve05a ( c) 22:06, 16 June 2013 (UTC) |
This topic is in need of attention from an expert on the subject. The section or sections that need attention may be noted in a message below. |
I substituted saddle and trumpet bell as examples of surfaces with hyperbolic or negative curvature. A bowl, being spherical, is not such a good example because it has positive curvature whether viewed from the inside or outside. Similarly in the following section on the rubber-sheet analogy I pointed out the trumpet-bell-shaped (rather than bowl-shaped) nature of the depression, responsible for the inward deviation of trajectories passing nearby. CharlesHBennett ( talk) 05:04, 8 May 2010 (UTC)
Strictly speaking, the claim that ″Energy and matter are equivalent″ is incorrect, and should be changed to ″Energy and mass are equivalent″. ′Matter′ is another matter entirely! :-) George963 au ( talk) 00:21, 6 April 2018 (UTC)
This article should probably be split:
Both revised articles should begin with much simpler intros for laypersons, and should have better citations. The second should have citations in WikiProject GTR format.--- CH (talk) 01:54, 15 September 2005 (UTC)
Is it the y coordinate which is bounded from one side? -- MarSch 17:43, 1 November 2005 (UTC)
It would be very nice with some references to some expository article (or book?). (unsigned comment by 130.238.149.247)
The geodesic boundary, i.e. "the limit as y goes to 0", should be explained in some detail.
The "picture" on the page is completely blank. It presumably should be removed or replaced. Gene Ward Smith 21:52, 4 May 2006 (UTC)
In the current definition anti de Sitter space is defined as a space which is simply connected. But this is not in agreement with the definition in e.g. [ [1]] .
The best (?) definition of anti de Sitter space of dimension n+1 should be the solution to the equation
that is, the same as,
that is, as a one-sheeted hyperboloid in . — Preceding unsigned comment added by Ulner ( talk • contribs) 23:59, 5 May 2006
This article managed to entirely confuse me, until I came to the talk page and saw the above comment, which concisely says it all. In the main article ADS is defined more generally and at no point is it spelled out how or when it specialises to this. The notation simply switches inexplicably between sections. — Preceding unsigned comment added by 2A01:56C0:8180:0:3C75:FB77:779F:3D4 ( talk) 19:26, 7 November 2016 (UTC)
Exactly. I'm writing from a relativity conference at the ESI Institute, in Vienna. The talk being given is on anti-de Sitter space, and this article is confusing even to a so-called expert !!
Let me slightly edit the above definition. The quickest definition of anti-de Sitter space of dimension n+1 should be as the solution to the equation
which is a one-sheeted hyperboloid in It has the topology of It becomes a Lorentz manifold, with the timelike, by restricting to it the ambient metric of signature (n,2) given by
2001:62A:4:41C:B580:3333:57FA:52FB ( talk) 13:46, 24 August 2017 (UTC)
I deleted the last paragraph, starting with "To simplify the AdSCFT correspondence it is like...", which was a very bad analogy. Dan Gluck 06:29, 15 September 2006 (UTC)
The article states that AdS space has O(2,n-1) as automorphism group. The article should specify which kind of automorphisms (i.e. automorphisms = isometries of a pseudo-Riemannian manifold). Pierreback 19:15, 25 February 2007 (UTC)
The definition now says that '\alpha' should be a negative constant, but we have '\alpha^2' in the equation? This is wrong. Pierreback 16:27, 28 February 2007 (UTC)
The sentence "Anti de Sitter spacetime has closed time-like loops" uses the term "anti de siter spacetime" for the first time in the article. I guess it should be changed to "anti de sitter space". Also, an explanation of "closed time-like loops" should be added. 83.253.30.214 11:27, 21 July 2007 (UTC)
Does anybody have some good mathematical definition concerning the conformal boundary? This should be added.
"In the limit as y = 0, this reduces to a Minkowski metric ; thus, the anti-de Sitter space contains a conformal Minkowski space at infinity ("infinity" having y-coordinate zero in this patch)."
83.253.30.214 11:34, 21 July 2007 (UTC)
Can someone write what that notation means? Because here the anti de Sitter space have two parameters. 200.145.112.189 ( talk) 22:45, 18 November 2009 (UTC)
"...is a maximally symmetric Lorentzian manifold with constant negative scalar curvature. It is the Lorentzian analogue of n-dimensional hyperbolic space, just as Minkowski space and de Sitter space are the analogues of Euclidean and elliptical spaces respectively."
did you write this in some weird language by mistake, because I CANNOT MAKE HEADS OR TAILS OF WTF YOUR TALKING ABOUT!!!! —Preceding unsigned comment added by 96.231.28.194 ( talk) 01:17, 2 November 2010 (UTC)
lol... me neither :/. But then I had some oranges and it was k... — Preceding unsigned comment added by 213.42.95.234 ( talk) 12:36, 25 March 2012 (UTC)
LOL. Funny, but true. This is an awful lead sentence for an entry into a general encyclopedia. It actually would require great knowledge and effort to distill this into something more accessible [R. Feynman, where have1 you gone?]. 71.208.147.98 ( talk) 21:13, 22 July 2014 (UTC)
I know mid-sentence this is "anti de Sitter space" and not "Anti de Sitter space", but surely the usual laws of grammar apply, and when it's the first word in a sentence, or subheading, it should get a capital "A"? -- Dr Greg talk 19:47, 9 February 2013 (UTC)
A large part of the "non-technical" section of this article deals with AdS/CFT ... but we already have a lengthly non-technical article on that. Could someone please cut this section, here? 99.153.64.179 ( talk) 04:42, 3 November 2013 (UTC)
I would urge the editors NOT to take out the non-technical section. Most mathematics articles in Wikipedia are USELESS unless you already know the material. This is one of the rare exceptions that offers some non-technical explanations, which are extremely helpful to the non-expert trying to make sense of the more arcane sections. 98.170.198.158 ( talk) 17:38, 3 April 2014 (UTC)
The 5d interpretation is not quite clear to me. Curvature is an intrinsic property of a manifold. Thus, it appears that the 5d interpretation is not really necessary for anti de Sitter space. The 4d manifold can be embedded in 5d but it seems not necessary and there are many possible embeddings. Is this correct? Should that be mentioned? — Preceding unsigned comment added by 152.3.73.36 ( talk) 17:37, 8 December 2014 (UTC)
The introduction is so complicated, so full of terminology specific to the subject, that it would only make sense to someone who already knows the subject - which makes it worthless to someone trying to learn the subject - which means it is a waste of time in a reference work. At the very least, there needs to be a non-technical thesis statement at the beginning. Pb8bije6a7b6a3w ( talk) 17:51, 16 November 2015 (UTC)
There is an implicit convention being adopted when calling the curvature of AdS negative. Specifically, the sign of the curvature flips with that of the metric tensor, or (from a physicist's perspective), with which dimensions are labelled spacelike. To refer to the sign of the curvature without stating the convention, or calling out that the sign is not an absolute, is therefore misleading. Surely should be mentioned and if possible sourced?
To make it clearer: AdS2 and dS2 are the same two-dimensional space; they differ only in which dimension is labelled "time" and which is "space". Yet, the curvature is considered to be negative and positive respectively. This ambiguity of convention occurs with all of the spaces AdSp,q. — Quondum 14:54, 7 July 2016 (UTC)
The sentence "For example, in general relativity, objects in motion have a slightly different gravitation effect than objects at rest." is rubbish. There is no such thing like an "object in motion" or an "object at rest" in general relativity. These notions related to Newtonian absolute space and thus are incorrect ontologies.
In the article it is stated , but it's not at all clear what this means. Clearly it's not a statement about groups because is not a group, so it must be a statement about diffeomorphisms between topological spaces. But modding manifolds by submanifolds never changes dimensions and as it stands this would say a 3-dimensional thing is homeomorphic to a 2-dimensional thing which is also nonsense. I think the intention is maybe something along the lines of the Hopf map . I assume something similar holds in the other cases but I have no idea. — Preceding unsigned comment added by INLegred ( talk • contribs) 19:46, 27 March 2020 (UTC)
There is no absolute parallelism in GR, only parallel transport along a curve. The phrase parallel geodesic only has meaning when the manifold is parallelizable and a parallelization is specified. I realize that this is a common error in popularizations, but it is still wrong. Shmuel (Seymour J.) Metz Username:Chatul ( talk) 06:04, 1 May 2020 (UTC)
The result of the move request was: not moved. ( non-admin closure) ModernDayTrilobite ( talk • contribs) 17:42, 11 January 2023 (UTC)
Anti-de Sitter space → Anti–de Sitter space – It is impossible to tell from search whether this is usually spelled with a hyphen or an en dash, but MOS:PREFIXDASH calls for an en dash since de Sitter is one name. – LaundryPizza03 ( d c̄) 10:28, 1 January 2023 (UTC)
Ravenpuff has just moved this page to "Anti–de Sitter space", directly contradicting the result of the requested move from last month. Please respect the consensus and kindly undo the move. Tercer ( talk) 15:38, 15 February 2023 (UTC)
Ravenpuff, as you see there's a clear consensus against the en-dash. Please undo your move. Tercer ( talk) 09:23, 21 February 2023 (UTC)
"Some authors define anti-de Sitter space as equivalent to the embedded quasi-sphere itself, while others define it as equivalent to the universal cover of the embedding." This seems very important and should not be buried. -- 99.238.150.103 ( talk) 18:08, 10 September 2023 (UTC)