My suggestion was that we KNOW that gravity affects stutterwarp, and affects it in a quantifiable and measurable way, so if we need a sensor that is able to detect "gravity" - by which I took to be a sensor that is capable of detecting space-time curvature due to a mass remote from the sensors location - why not tie it into a system that we already know is affected by gravity. A stutterwarp isn't just going to be affected by the nearest source of gravity - everything with mass will generate a space-time curvature and thus affect the drive in some small way. It's really just flavour text for how the magic grav sensor works.
Gravity affects drive efficiency, yes; but if I recall correctly it's a threshold at which efficiency simply drops massively and not a gradient of any kind. So all you know is whether or not you're deep enough in a gravity well. As far as information goes that's still pretty useless.
If it were not a dropoff but any sort of gradient, you could use it for triangulation as you point out, below.
That aside, the biggest problem with the Grav sensors as written is that they give "size", which I took to be the objects mass, rather than physical dimensions, but not distance or direction. Since
the mass of the object remains the same, but the experienced gravitational force will vary with distance from the observer it means that an object twice as far away will have a lower gravitational force on an observer than one closer (I don't remember what the rate of drop would be off the top of my head),
Inverse square, which is always a good assumption to fall back on.
GJD wrote:so if we have object A with gravitational attraction X and object B with gravitational attraction 2X, is B closer or more massive? Without another reference point, you can't tell. What's even weirder is that if you just knew the gravitational attraction and direction, you could work out distance, and thus mass through taking multiple bearings to the target, but the grav sensor in 2300AD doesn't even give position or direction, just a list of masses of all the objects in range.
Why do you think it won't give you that info? The "they meant mass when they wrote size" call is a good one, but beyond that I don't see how those limitations can apply, since, as you rightfully state, the sensor can't actually tell what the mass of an object is without also knowing the distance. From re-reading the paragraph, I think it's quite obvious the author meant "of all the attributes this planetary body has, only mass can be detected by a gravitational scan because everything else, such as atmosphere, presence of water etc, can't be derived by looking at its gravity".
The solution I suggested - monitoring fluctuations in the Jerome Field - doesn't fix that problem, but it does suggest a way that the gravity of a remote object could be detected - by it's influence on the stutterwarp field. You still have the problem that the grav sensor itself works in a counter-intuitive way, giving a result (the mass of an object) - without the other necessary information, direction and distance. It's like like solving a complex equation without showing the working out.
Well - thanks, for the explanation - I do understand where you're coming from. But I still maintain that the way to fix a "hard" science fiction setting is to actually use science and technology, and not just make stuff up that makes no sense at all. Your magical sensor is still more troublesome than the problem it is trying to fix, without fixing the problem.