at the other end, events outside the "light cone" (also known as "the absolute elsewhere"), may occur, but there is no way for information from these events to reach us.
You seem to have a problem distinguishing between things we can investigate experimentally and things that we cannot at present investigate experimentally
i appreciate that these are just "theories", but...so is electricity, right? i mean. it is not my intention to get into the can of worms that is: "do we know anything at all? and if so, how do we know that we know?" and beyond that, "how do I know that what YOU know, is the same knowledge that I know, even when we talk to each other, in the same language?" it's not that these aren't interesting questions, in their own right. just a bit afield of my original musings.
in a sense, all science is speculative. there are reasons to prefer some speculations over others (a preponderence of evidence).
Actually the real number system is something we made up, but not without reason. It is a mathematical construct which has properties that represent apects of measurement processes, but is an idealisation of such processes. There are other constructions of real number-oid systems which lack certain features (or indeed have additional features) of the usual real number system but they are not popular in engineering and physica because they are either more cumbersome to use or lack some property that we rather like.
i'm all for "doing mathematics for its own sake". but there is a strong thread of justification of mathematics according to its applications running through most types of science/engineering education, for example. and people get all existential about the real number system, like it's not just something we made up.