🚀 go-pugleaf

In article <1992Aug9.055643.1254@chpc.utexas.edu> jonathan@chpc.utexas.edu (Jonathan Thornburg) writes:
>In article <1992Aug8.010716.16818@nuscc.nus.sg> matmcinn@nuscc.nus.sg
>(Mcinnes B T (Dr)) writes:
>> [ referring to the question of the "mass" of Schwarzschild spacetime ]
>>OK, now that I have your attention: let me be more precise. Certainly
>>there is a parameter in the S solution which tells you what the mass of
>>this thing would be, calculated a la Kepler, if it were a Newtonian
>>source...which it isn't. For certain purposes this is no doubt useful.
>
>Let's be clear here.  In general relativity, the "energy-momentum"
>of a spacetime is defined *only* for asymptotically flat spacetimes.

Just to be nitpicky, energy can be defined for any spacetime that admits
a timelike Killing vector field, and (a component of) momentum can be
defined for any spacetime that admits a spacelike Killing vector field.
Actually I'm not clear what is the largest class of spacetimes for which
one can define reasonable notions of energy and momentum.  

Let me emphasize for the nonexpert that Thornburg's post was 99.99%
correct and I am only picking on a minute point.