Re: >H Re: Deep time and shallow time

Anders Sandberg (
28 May 1999 13:26:21 +0200

Darin Sunley <> writes:

> > Unfortunately, there are no simple sensors directly measuring
> > spacetime curvature...
> Wouldn't Robert Forward's Mass Detector work? Space time curvature is
> equivalent to mass is it not?

Yes, it measures space-time curvature. If I remember my MisnerThorneWheeler right, you can calculate the components of the local metric tensor by having three orthogonal mass detectors (or should there be more? there are ten independent components).

> As an aside, are we attempting to detect spacetime curvature due to mass, or
> other types of spacetime curvature? (ARE there any other types of spacetime
> curvature, and wouldn't they be equivalent to mass?)

You can have curvature without any mass, gravitational waves are a good example. But the equivalence principle essentially says that acceleration is acceleration, regardless of the cause.

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y