postscript
Abstract...
Abstract...
2 The collapsing shell...
Black holes in two dimensional space-times are toy models to understand the
physics of their four dimensional analogs. Since the general theory of
relativity has no physical contents in two dimensions (Collas (1977)), other 2-D
gravity theories have been considered, in particular string theory for which
there is two dimensional black hole solutions (Callan et al. (1992)). It is possible,
however, to extract from the equations of general relativity a gravity theory
by considering the formal limit 
, where 
is the dimension
of space-time (Mann (1992), Mann & Ross (1993)). One obtains the equation
where 
, 
is Newton's constant and where 
is the trace of
the classical energy-momentum tensor 
. This equation is
supplemented by the continuity equation
which follows also from the equations of general relativity.
