I feel that it would be meaningful to claim that there are actually other universes which don’t causally interact with ours, although (like the claim about photons disappearing when they are sufficiently far away from us) it would not be testable. This seems to be a counterexample to the causal connection requirement. [A good scientific theory would posit a common cause for these universes, but that is beside the point: it seems conceivable that they have no common cause.]
As such, I’m tempted to claim that what is real is just what actually is. There isn’t an internal criteria for determining that, such as causal connectedness.
(This does not force any particular position about what is meaningful.)
I feel that it would be meaningful to claim that there are actually other universes which don’t causally interact with ours, although (like the claim about photons disappearing when they are sufficiently far away from us) it would not be testable. This seems to be a counterexample to the causal connection requirement. [A good scientific theory would posit a common cause for these universes, but that is beside the point: it seems conceivable that they have no common cause.]
As such, I’m tempted to claim that what is real is just what actually is. There isn’t an internal criteria for determining that, such as causal connectedness.
(This does not force any particular position about what is meaningful.)