Geons |

**In General** > s.a. 3D manifolds [prime
factors]; general
relativity solutions; Mapping
Class.

* __History__: A precursor
was given by the concept of gravitational
bag; The original meaning of the term, as used by Wheeler, referred to
non-topological
geons.

> __Similar concepts__: see Defects; Kinks.

**Non-Topological** > s.a. Boson
Stars; Galileon Field; solitons.

* __Idea__: An object with
particle-like properties made out of the spacetime metric, and possibly other
fields.

@ __General references__: Wheeler PR(55);
Power & Wheeler RMP(57)
[thermal];
Brill & Hartle PR(64)
[gravitational waves].

@ __Modified gravity__: Vollick CQG(08)-a0807,
CQG(10)-a1004 [1+1 Jackiw-Teitelboim
theory with higher-order corrections]; Afonso et al a1705 [Born-Infeld gravity].

@ __Gravity + scalar field__: Barreto et al PRD(96)gq/05 [turning
point instability];
Sones gq/05 [+
electromagnetism].

@ __Related topics__: Cooperstock et al MPLA(95)
[non-existence], IJMPD(96)gq/95 [critical
analysis of Brill-Hartle geon]; Perry & Cooperstock
CQG(99)gq/98 [stability]; > s.a. anti-de sitter spacetime [instability].

**Topological** (More recent meaning) > s.a. CPT
symmetry; measurement in quantum theory; spin-statistics
theorem.

* __Idea__: An object with
particle-like properties made out of spatial geometry;
Part of the motivation is that one may be able to account for some non-gravitational
charges (e.g., electric charge) using topology.

* __Remark__: The concept is
similar to that of gravitational "kink", but the latter is
used to describe a topologically non-equivalent metric tensor fields defined
on a given fixed manifold.

* __Types__: They can be spinorial,
fermionic, possibly chiral; Some can switch between bosonic and fermionic behavior
after interactions.

* __Question__: Can they be preons?

* __Example__: Wheeler's "single
wormhole mouth" (not "quasi-localized").

@ __General references__: Finkelstein & Misner AP(59);
Finkelstein
JMP(66);
Cohen & Wald JMP(72);
Sorkin JPA(77);
Shastri et al IJTP(80);
Whiston JPA(81)
[classification, including fermionic]; Williams & Finkelstein IJTP(84);
Bais et al NPB(87);
Sorkin in(86), in(89); Bugajska IJTP(87);
Dunn et al JMP(91);
Williams & Zvengrowski JMP(92);
Dunn et al JMP(96)
[geodesic incompleteness];
Anderson & Brill
PRD(97)gq/96; Balachandran et al GRG(11)-a1009 [and non-commutative spacetimes].

@ __Phenomenology__: Srivastava PRD(87); Olmo & Rubiera-García JCAP(14) [at particle accelerators].

@ __Solutions__: Harriott & Williams GRG(03)
[4D rotating kink]; Louko et al CQG(05)gq/04 [with
spin and charge]; > s.a. black-hole solutions.

@ __With cosmological constant__: Dunn & Williams JMP(89),
et al JMP(94)
[locally de Sitter].

@ __In 1+1 dimensions__: Vasilić & Vukašinac
CQG(96);
Klösch & Strobl PRD(98)gq/97.

@ __In 2+1 dimensions__: Harriott & Williams NCB(05)
[kink number]; Stevens et al CQG(09)-a0809 [no
asymptotically flat ones]; Galloway et al CMP(12)-a1005 [non-existence
result].

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may 2017