Alberto said:
> Uh? How can you eliminate a tidal "force" by a convenient
> choice of a reference system?
Okay, what I meant was that the spacetime of general relativity looks
more and more like that of special relativity as you look at smaller
and smaller regions around a given event. This is just the same as the
way that, for example, the surface of a sphere looks more and more like
a plane as you look more closely at it. In more technical language,
it's always possible to choose a coordinate system in the neighbourhood
of an event in such a way that the connection coefficients all vanish
at the event. You cannot eliminate the tidal "force" by a choice of
coordinates, but the effects of the tidal "force" will become ever
smaller as you consider experiments of ever smaller extent. I don't
think that's saying anything very profound. However, these tidal
effects can, for sufficiently large black holes, be small even in the
vicinity of the horizon.
I've written more about curved spaces at
http://cdr.sine.com/cdr/article.cfm?id=10
about general relativistic spacetime at
http://cdr.sine.com/cdr/article.cfm?id=21
and about tidal forces at
http://cdr.sine.com/cdr/article.cfm?id=93
Rich
GCU Here's One I Prepared Earlier
