According to Jung (JCF), Se is about a focus on fact and what is evident, acknowledging the world for what it is. In modern MBTI, Se is taken a lot more literally, associated with sports, physical crafts, hedonism & a presence in the now & here. In Socionics, Se is about direct behavior aimed at making an immediate impact, influencing, bending and pushing situations and people in order to achieve an objective or desire. In Dario Nardi's neurological studies, the brain scans he associates as Se doms are those that are in a constant state of readiness to leap into action.
Jung views Ne is almost like that which Socionics attributes to Ne, constantly seen not just any possibilities but specifically the possibilities of manipulating everything and everyone in their environment, which is almost like Socionics Se. But he also associated much of what other systems view as Ne, he attributed Ne with the ability to steal ideas from his concept of the collective subconscious and take them as your own, which I suppose is where he theorized their ideas come from. After that, the descriptions become a lot more consistent: In MBTI, Ne is mostly associated with creativity & divergent thinking, a focus on the possibilities & potential, and mixing ideas to make brand new ones. in Socionics it is similar, it is about recognizing possibilities, creating new opportunities and new beginnings, recognize the potential in others, reconciling differing perspectives and viewpoints & rapidly generate ideas. Dario Nardi associates Ne brain scans that light up like a Christmas tree all across without any focus on a particular area.
I would say pick your system, but almost nobody is really a system puritan. If you are lucky enough to fit the definitions of the same functions in all systems across, which is entirely possible, it would make your life simpler. Personally I do fit the same functions across the board, and I highly recommend it. If you don't, please press "undo" and try again.
I would say that with all systems, the answer to that question is Ni. When dominant, it is very easy for inferior Se to get obsessed with a single fact or two and build it into a mountain. This is even more true with socionics Ni & Se, in which there is a certain rejection of the concept of time - The fact all the other times you were paranoid turned out to be wrong are a lot less likely to stand in the way of future paranoia.
You can come up with theories using Ne, including theories about what might happen or how the world might end, but it's not really a predictive function, it just places some of it's ideas in the future because it has nowhere to place them right now. As @
21lux explained pretty well, Si can be afraid of change in general, but doesn't really focus on any one negative vision.