On Feb 27, 8:37*pm, Tom Roberts wrote:
Ken S. Tucker wrote:
The ISU has set the signature to (++++),

That's complete and utter nonsense. No standards organization can
possibly "set" something like that -- it inherently depends on the
manifold and metric in question. In SR and GR, the metric can have
signature +++- or ---+ (order doesn't matter); there is no observable
difference between those two choices (in SR and GR).

http://physics.trak4.com/modern-spacetime.pdf
which I generally use because it's simple
and arbituary.

Referencing yourself is just downright silly.

So far as I know, General Covariance permits
any signature you want.

Then you clearly do not know enough. For a given manifold with metric,
the signature is fixed, and no diffeomorphism or change of coordinates
can change it (that's the essence of general covariance).

There are no physical
laws forcing a specific definition of the
signature.

Again, you clearly do not know enough. For GR to be applied, one must
use a metric with one of the two signatures I mentioned above -- no
others come anywhere close to providing an accurate model of the world
we inhabit.

Tom Roberts

xxein: That you know of...