Re: >H Re: Deep time and shallow time

From: Anders Sandberg (asa@nada.kth.se)
Date: Fri May 28 1999 - 05:26:21 MDT


Darin Sunley <umsunley@cc.umanitoba.ca> 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!
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