Re: invariance of negative signature of the metric?



iuval wrote:
Is there a theorem saying that if the metric starts out with a
negative signature on a spacelike surface (one or three eigenvalues
negative) that the field equations will preserve this negative
signature for all future and past?

This is more basic than the Einstein field equation -- one cannot have a CONTINUOUS manifold with a metric whose signature varies over the manifold. GR of course requires a continuous (Hausdorf, etc.) manifold.

Note the signature of a Lorentzian manifold can be either +2 or -2 (-+++ or +---), depending on one's sign convention. This does not affect the above statement (or the physical predictions of the theory), as one must select a single sign convention throughout the analysis.


Tom Roberts
.



Relevant Pages

  • Re: Question on GR sources
    ... For a given manifold with metric, ... the signature is fixed, and no diffeomorphism or change of coordinates ... with us, giving, unit vector magnitudes ... -Unified Field Theory. ...
    (sci.physics.relativity)
  • Re: Question on GR sources
    ... That's complete and utter nonsense. ... No standards organization can ... For a given manifold with metric, ... the signature is fixed, and no diffeomorphism or change of coordinates ...
    (sci.physics.relativity)
  • Re: Question on GR sources
    ... 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. ... For a given manifold with metric, the signature is fixed, and no diffeomorphism or change of coordinates can change it. ...
    (sci.physics.relativity)
  • Re: black holes and singularity
    ... The are the components of the metric in mixed bases for ALL ... metrics on ALL manifolds at ALL points. ... You cannot "change" the signature of the metric of a manifold ... -- the signature is an invariant and intrinsic property of the manifold. ...
    (sci.physics.relativity)
  • Re: PGP protection
    ... time back that he was only posting to elicit negative responses from the ... Social convention in this group seems to ... sigs, and I don't give a toss either. ... The signature conventions are obvious to anyone ...
    (comp.os.linux.misc)