So, there's a paper here that I'm a bit confused about. On pages 3 and 4, it talks about energy density magnitude and York time. What I'm a bit confused about, is in the article that linked me to it, the scientist makes mention of eventually generating negative vacuum energy. However, from reading the paper, I get the impression that the energy density distribution is the cause: That by creating this toroidal geomoetry of energy density, the York time magnitudes will come as a result. At least, that's the impression the paper gives me. To quote: But if that's the case, then why is generating negative vacuum energy necessary: Is that just to better understand negative York time, or is it necessary? Which causes which? Does the York time geometry result in the energy density distribution, or does the energy density distribution cause the York time geometry? Because while it seems to really heavily indicate that the toroidal placement of energy density causes the York time curvature, I'm left puzzled as to why it would be necessary, then, to invoke negative energy density to generate this "warp field"? Because if the York time is a result of the toroidal energy density, then wouldn't negative energy density be unnecessary to generate the "warp field", but rather come as a consequence of generating it with positive energy density?