Talk:De Sitter space

message: This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 09:47, 10 November 2007 (UTC)
thread_title:  WikiProject class rating

message: Can someone please unify the notation of this article and the Anti de Sitter one.200.145.112.189 (talk) 17:16, 11 November 2009 (UTC)
thread_title: AdS

message: It would be great if there was a plain English summary of what de-Sitter space is.  Or at least a link to another website where there is an explanation of what de-Sitter space is. Is de-Sitter space space of a certain shape?  After reading this article I still have no idea what de-Sitter space is.  It seems to me that Wikipedia articles should be written with lay people in mind.  This article seems to be highly technical. Dedwarmo (talk) 15:28, 10 April 2013 (UTC)
replies: text: Its a highly technical topic. Start by reading the linked articles; they provide background. User:Linas (talk) 04:30, 3 November 2013 (UTC)

text: I agree. Wikipedia is an encyclopedia, so the aim should be to give a description aimed at a general audience. Adding further detail at textbook level can be useful, but only as an addition. Scottwh (talk) 10:31, 7 March 2024 (UTC)
thread_title: Plain English Summary

message: Substituted at 13:03, 29 April 2016 (UTC)
thread_title: Assessment comment

message: Defining a de Sitter space as a submanifold of a Minkowski space using a vector space as given in the article is unambiguous, but is not ideal as a general mathematical definition, since it relies on embedding and coordinates.  If there is another definition along the lines of "a real Lorentzian manifold of dimension n that is maximally symmetric and has constant positive curvature", this would be worth giving.  What I have given in quotes defines it locally, and It would be worthwhile noting in the article that other spaces (with distinct topologies) exist with the same local description.  For example, in the vector space definition if we identify every point in a de Sitter space with that opposite the origin, we obtain a space with the topology of a punctured projective space (e.g. a Möbius strip for n=2).  Such a space is not simply connected, and is not necessarily nonphysical as a model of the universe, notwithstanding the argument that paths exist that reverse the direction of time.  Are there any references that discuss these possibilities?   —Quondum 20:37, 26 May 2016 (UTC)
thread_title:  Defining characteristics of a de Sitter space? 

message: Are the definitions in terms of induced metric from ambient space with the given Miknowski metric (mostly plus convention) and the definition as a homogeneous space as the quotient  and the mention of the Lorentz group as being  really in compliance? YohanN7 (talk) 10:44, 9 December 2016 (UTC)
thread_title:  Metric signature 

message: Last paragraph in lead,
:More recently it has been considered as the setting for special relativity rather than using Minkowski space, since a group contraction reduces the isometry group of de Sitter space to the Poincaré group, allowing a unification of the spacetime translation subgroup and Lorentz transformation subgroup of the Poincaré group into a simple group rather than a semi-simple group. This alternate formulation of special relativity is called de Sitter relativity.
really needs a reference. Besides, the Poincare group certainly isn't semi-simple (if that is what is hinted). YohanN7 (talk) 10:55, 9 December 2016 (UTC)
thread_title:  Lead paragraph 

message: I propose that De Sitter universe be merged into this article. There doesn't seem to be any reason why the two articles should be separate. Thoughts?
I oppose the suggestion.  The De Sitter space article is written for scientists who (probably already) understand the mathematics of a De Sitter space.  While it has issues, the De Sitter universe article is written for ordinary people who want to understand what a De Sitter space means in the context of cosmology.Work permit (talk) 17:10, 14 April 2017 (UTC)
thread_title:  Merge with [[De Sitter universe]] 

message: Leonard Susskind on the recent Lex podcast, says that he doesn't get De Sitter spaces. And that we live in them.  Avindratalk / contribs 03:26, 27 September 2019 (UTC)
replies: text: This comment is mostly irrelevant here. If I understand correctly, Susskind was talking about the quantum mechanics of a De Sitter geometry, i.e. its realization in a quantum theory of gravity. This is unrelated to understanding the properties of De Sitter as pseudo-Riemannian manifold which is the main topic of this page. Virtual Neutrino (talk) 10:41, 29 May 2020 (UTC)
thread_title:  Does anyone actually understand this subject? 

message: This article frequently writes "De Sitter Space" with a lowercase D. 
While the tussenvoegsel in Dutch surnames is lowercase when writing the full name, when only mentioning the surname and thus beginning the name with the tussenvoegsel, it would be capitalised. As a Dutch speaker, that seems to be the right way to write it, and Dutch wikipedia does so as well. I would suggest changing "de Sitter space" tot "De Sitter space". Opinions? Wolkenkijker (talk) 15:13, 30 October 2023 (UTC)
thread_title:  Capitalisation of "De" in De Sitter