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).