Re: >H Re: Deep time and shallow time

Darin Sunley (
Thu, 27 May 1999 21:48:10 -0500

Eugene Leitl wrote:

> 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?

A mass detector is a spinning symmetrical set of heavy weights that are quite heavy relative to the arms they are mounted on. The masses are attracted to any outside mass, deforming the arms. This causes the whole set up to vibrate if it is rotating, which is good because vibrations are easier to detect then the tiny variances in the angles of the arms caused by the masses being attracted to the outside mass.

I'm not sure how clear that was. I'll try a diagram.

\ /

   /\                        O

/ \

The "X" shaped setup is monuted to spin around it's center. At any given time, the 2 mases on teh arms closest to the exterior mass are attracted more strongly then the other two masses. This deforms the arm, inducing vibrations at the hub. Apparently Dr. Forward has built working models that have considerable accuracy.

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?)

Darin Sunley