HSC@MIT-MC@sri-unix (08/02/82)
From: Stewart Cobb <HSC at MIT-MC>
I too am fuzzy on General Relativity (is there anyone out there who
isn't?) but I don't think Steve Den Beste's method for telling apart
acceleration and gravitational fields will work. His method was to
compare the direction of DOWN in two different locations.
Unfortunately, GR says (among other things) that space is curved.
There's no such thing as an absolute direction, just as there's no
such thing as an absolute time reference (simultaniety) in SR. In
fact, the amount that straight lines bend (a straight line is, of
necessity, defined as the path that a beam of light will take) is
directly related to the local strength of the gravitational field.
I think a professor once told me that a method such as Steve's will
work in most simple cases (here on Earth, for example) but is not
guaranteed to work in all cases. General Relativity remains relative.
Stewart Cobb (cobb@nbs-vms)