sci.physics.research

On Feb 16, 5:23 pm, "Jay R. Yablon" wrote:

> I am curious if there are any reviews of theories where the extra
> dimension is *timelike* rather than spacelike, ., with a +---+
> signature, which of the problems that appear from an extra spacelike
> dimension are averted, and what new perceived problems arise by
> switching the extra dimension over from spacelike to timelike.

As Pauli showed in 1921, if the g55 is normalized to have time-like
signature such that g55=1, then the curvature scalar in 5 dimensions
is

P = R - W

(and not R+W), where W is the electromagnetic scalar. This forces one
to use a space-like signature in order for the theory to ape Maxwell-
Einstein. Even in that case, it is mere aping, as there is no
fundamental principle which forces one to select P as the integrand of
the variational principle, given the cylinder group which is
fundamental to the theory. There is a corollary to this - any
generally covariant theory whatsoever may be cast in Kaluza's form by
introduction of such a factitious "geometry" and corresponding
cylinder group.

-drl