Not thinking of cosmic expansion as a volume expanding is an interesting thought.
It does imply that the changing distance only happens at large distances though. “Faster-than-light” expansion is already non-local (I think), but all expansion being non-local is consistent with it being driven by vacuum energy. That kinda makes the rasin bread analogy stronger, as the rasins don’t expand at all.
I wonder if we could detect frame-dragging at large distances. If expansion causes frame-dragging, then it’s actually a change in space, not just distance.
I wonder if linear motion can even cause frame-dragging, or if it’s just rotation that causes it. I do not know enough about the math to say.
So it does happen on a small local scale though. It happens on ALL scales.
But everything is expanding from everything. Meaning the observer is always centred of the expansion. This is because volume is constant. The rasins themselves do expand, but locally it’s such a small scale (10^-23 m/s for our solar system).
This also works for how we understand the change in density. Volume is constant, but we’ve gone from infinitely dense to almost nothing.
Not thinking of cosmic expansion as a volume expanding is an interesting thought.
It does imply that the changing distance only happens at large distances though. “Faster-than-light” expansion is already non-local (I think), but all expansion being non-local is consistent with it being driven by vacuum energy. That kinda makes the rasin bread analogy stronger, as the rasins don’t expand at all.
I wonder if we could detect frame-dragging at large distances. If expansion causes frame-dragging, then it’s actually a change in space, not just distance.
I wonder if linear motion can even cause frame-dragging, or if it’s just rotation that causes it. I do not know enough about the math to say.
So it does happen on a small local scale though. It happens on ALL scales.
But everything is expanding from everything. Meaning the observer is always centred of the expansion. This is because volume is constant. The rasins themselves do expand, but locally it’s such a small scale (10^-23 m/s for our solar system).
This also works for how we understand the change in density. Volume is constant, but we’ve gone from infinitely dense to almost nothing.