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Journal Article

#### Mechanics of extended masses in general relativity

##### Fulltext (public)

1103.0543

(Preprint), 387KB

CQG_29_5_055012.pdf

(Any fulltext), 536KB

##### Supplementary Material (public)

There is no public supplementary material available

##### Citation

Harte, A. I. (2012). Mechanics of extended masses in general relativity.*
Classical and quantum gravity,* *29*(5): 055012. doi:10.1088/0264-9381/29/5/055012.

Cite as: http://hdl.handle.net/11858/00-001M-0000-0011-3018-3

##### Abstract

The "external" or "bulk" motion of extended bodies is studied in general
relativity. Material objects of arbitrary shape, spin, internal composition,
and velocity are allowed as long as the metric remains near a vacuum solution
(with a possible cosmological constant). Under this restriction, physically
reasonable linear and angular momenta are proposed that evolve as though they
were the momenta of an extended test body moving in an effective vacuum metric.
This result holds to all multipole orders. The portion of the physical metric
that does not directly affect the motion is a slightly generalized form of the
Detweiler-Whiting S-field originally introduced in the context of self-force.
This serves only to (finitely) renormalize the "bare" multipole moments of the
object's stress-energy tensor. The MiSaTaQu expression for the gravitational
self-force is recovered as a simple application. A gravitational self-torque is
obtained as well. Lastly, a certain exact result is derived that may provide a
basis for understanding self-interaction at higher orders.