Re: GR1916, available online.

On Dec 15, 12:24 pm, bz <bz+...@xxxxxxxxxxxxxxxxxxxx> wrote:
"Ken S. Tucker" <dynam...@xxxxxxxxxxxx> wrote in news:e8da8b4c-1a84-4e9e-
b177-770b4fba5...@xxxxxxxxxxxxxxxxxxxxxxxxxxx:

Why is the Riemann curvature tensor zero? It is merely a man-made
gage. <shrug>

...because that means spacetime is flat.

Space in Newtonian physics can also be curved just as Riemann had
described it about 150 years ago.

Nope. Space is assumed to be Galilean in Newtonian physics.

"E"ric you're wrong, KW is right.
The developement of tensor analysis sprung
from survey problems, specifically how to
survey land boundary's on a spherical surface.

That is NOT the same as 'space being curved'.

What you are using as a talking point is the Earths surface. Tensors were
NOT required for analysis of the earths surface, just spherical geometry.

Well have a look at Weinberg's introduction
to "Grav&Cosmo", he goes into the history.

Tensors became necessary when it was necessary to handle 4 dimensions at
one time.

Get a survey of a large piece of land and
you'll likely find the lengths and angles
vary from a flat surface.

Simple spherical geometry takes care of those problems quite well.

Not on an oblate spheroid of varying altitude.

Even today, surveyors, and navigators on ships and aircraft do quite well
with vectors and spherical geometry. No tensors needed.

Are you a professor of surveying?

A curved surface does not make for curved space or space-time. Einstein and
Minkowski brought the need for tensors and curved space-time to mans attention, not Newton.

Regards
Ken S. Tucker
.