The problem with 'modern' thinkin' is that it tacitly assumes it's the same instant everywhere in the Universe.
I think you have this backwards, Dale.
If by "modern thinking" you mean special relativity, then there is no universal time. In technical terms, this is called the "relativity of simultaneity." This is a bogus concept invented by Einstein so that he could achieve his desired goals.
It is the concept of "absolute simultaneity" that assumes it's the same instant everywhere in the universe.
Theories of relative motion which is posit absolute simultaneity not only predict everything that SR does, just as accurately, but also predict much more (which SR doesn't) just as accurately.
For example, SR supposedly applies ONLY in inertial frames of reference (if there even is any such thing), whereas the other makes accurate predictions in ALL frames of reference, accelerated or inertial.