@Starthane Xyzth hum, tnx for correction. Yeah, that was what i meant, er, stars <i>& dark dusty stuff/hydrogen</i>, which as you pointed out we can map fairly easily. @Vortexx Yeah, i believe ultimately that is what we will find. Any gravity map will just show the position of any space/time distortion (be that from darkmatter of normal matter). Like a `density map of books` will show the location of any library/bookstore, it will not show where the authors live.