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1. • CommentRowNumber1.
   • CommentAuthorUrs
   • CommentTimeJan 13th 2020
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded pointer to * [[Matthias Blau]], _Plane waves and Penrose limits_ ([pdf](http://www.blau.itp.unibe.ch/lecturesPP.pdf)) <a href="https://ncatlab.org/nlab/revision/diff/pp-wave+spacetime/4">diff</a>, <a href="https://ncatlab.org/nlab/revision/pp-wave+spacetime/4">v4</a>, <a href="https://ncatlab.org/nlab/show/pp-wave+spacetime">current</a>

   added pointer to

   • Matthias Blau, Plane waves and Penrose limits (pdf)

   diff, v4, current

2. • CommentRowNumber2.
   • CommentAuthorUrs
   • CommentTimeJun 22nd 2024
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded ([here](https://ncatlab.org/nlab/show/pp-wave+spacetime#AsPenroseLimits)) the statement that Penrose limits of Einstein spacetimes are Ricci flat, with pointer to * [[Simon Philip]], *Plane-wave limits and homogeneous M-theory backgrounds*, PhD thesis, Edinburgh (2005) &lbrack;[pdf](https://www.era.lib.ed.ac.uk/bitstream/handle/1842/15645/Philip2005.Pdf?sequence=1), [[PhilipPlaneWave05.pdf:file]]&rbrack; * [[Simon Philip]], *Penrose limits of homogeneous spaces*, Journal of Geometry and Physics **56** 9 (2006) 1516-1533 &lbrack;[doi:10.1016/j.geomphys.2005.08.002](https://doi.org/10.1016/j.geomphys.2005.08.002), [doi:math/0405506](https://arxiv.org/abs/math/0405506)&rbrack; <a href="https://ncatlab.org/nlab/revision/diff/pp-wave+spacetime/6">diff</a>, <a href="https://ncatlab.org/nlab/revision/pp-wave+spacetime/6">v6</a>, <a href="https://ncatlab.org/nlab/show/pp-wave+spacetime">current</a>

   added (here) the statement that Penrose limits of Einstein spacetimes are Ricci flat, with pointer to

   • Simon Philip, Plane-wave limits and homogeneous M-theory backgrounds, PhD thesis, Edinburgh (2005) [pdf, PhilipPlaneWave05.pdf:file]

   • Simon Philip, Penrose limits of homogeneous spaces, Journal of Geometry and Physics 56 9 (2006) 1516-1533 [doi:10.1016/j.geomphys.2005.08.002, doi:math/0405506]

   diff, v6, current

3. • CommentRowNumber3.
   • CommentAuthorUrs
   • CommentTimeJun 22nd 2024
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded ([here](https://ncatlab.org/nlab/show/pp-wave+spacetime#EnhancementToSuperSpacetime)) a couple of references on enhancing pp-waves to super-spacetimes: <a href="https://ncatlab.org/nlab/revision/diff/pp-wave+spacetime/6">diff</a>, <a href="https://ncatlab.org/nlab/revision/pp-wave+spacetime/6">v6</a>, <a href="https://ncatlab.org/nlab/show/pp-wave+spacetime">current</a>

   added (here) a couple of references on enhancing pp-waves to super-spacetimes:

   diff, v6, current

4. • CommentRowNumber4.
   • CommentAuthorUrs
   • CommentTimeJun 22nd 2024
   • PermaLink
   Author: Urs
   Format: MarkdownItexstarted adding some references ([here](https://ncatlab.org/nlab/show/pp-wave+spacetime#ReferencesBMNLimit)) on the BMN limit -- of course this eventually deserves dedicated discussion elsewhere <a href="https://ncatlab.org/nlab/revision/diff/pp-wave+spacetime/6">diff</a>, <a href="https://ncatlab.org/nlab/revision/pp-wave+spacetime/6">v6</a>, <a href="https://ncatlab.org/nlab/show/pp-wave+spacetime">current</a>

   started adding some references (here) on the BMN limit – of course this eventually deserves dedicated discussion elsewhere

   diff, v6, current

5. • CommentRowNumber5.
   • CommentAuthorUrs
   • CommentTimeJun 22nd 2024
   • PermaLink
   Author: Urs
   Format: MarkdownItexadded ([here](https://ncatlab.org/nlab/show/pp-wave+spacetime#MaximallySupersymmetric11dExample)) statement and references concerning the maximally supersymmetric 11d pp-wave and added pointer to the original discussion of the Penrose limit: * [[Roger Penrose]], *Any Space-Time has a Plane Wave as a Limit*, in *Differential Geometry and Relativity*, Mathematical Physics and Applied Mathematics **3**, Springer (1976) 271–275 &lbrack;[doi:10.1007/978-94-010-1508-0_23](https://doi.org/10.1007/978-94-010-1508-0_23)&rbrack; <a href="https://ncatlab.org/nlab/revision/diff/pp-wave+spacetime/8">diff</a>, <a href="https://ncatlab.org/nlab/revision/pp-wave+spacetime/8">v8</a>, <a href="https://ncatlab.org/nlab/show/pp-wave+spacetime">current</a>

   added (here) statement and references concerning the maximally supersymmetric 11d pp-wave

   and added pointer to the original discussion of the Penrose limit:

   • Roger Penrose, Any Space-Time has a Plane Wave as a Limit, in Differential Geometry and Relativity, Mathematical Physics and Applied Mathematics 3, Springer (1976) 271–275 [doi:10.1007/978-94-010-1508-0_23]

   diff, v8, current

6. • CommentRowNumber6.
   • CommentAuthorUrs
   • CommentTimeJun 23rd 2024
   • PermaLink
   Author: Urs
   Format: MarkdownItexhave spelled out [here](https://ncatlab.org/nlab/show/pp-wave+spacetime#MaximallySuSyWaveIn11D) the maximal susy pp-wave solution in 11d <a href="https://ncatlab.org/nlab/revision/diff/pp-wave+spacetime/10">diff</a>, <a href="https://ncatlab.org/nlab/revision/pp-wave+spacetime/10">v10</a>, <a href="https://ncatlab.org/nlab/show/pp-wave+spacetime">current</a>

   have spelled out here the maximal susy pp-wave solution in 11d

   diff, v10, current