Once again, the speed of light is a constant to all observers. That makes it a terrible yardstick, because different observers see different things.

As an earth based human I see the big bang coming from all directions because it was 14 billion years ago in every direction! I know the mass of the universe is contained within that still expanding sphere.

I also know that every other observer (who uses light) from their planet will also see a perfect sphere around their own planet. This is a fundamental flaw in light years as a yardstick.

Calculations for other observers may show other things but in the universe I see, two galaxies in opposite directions from earth can be at most twice the age of the universe apart. Note: that number is climbing at 2*C.

And the part that hurts my brain is that each of those two ultimate polar opposite galaxies will also see the CMB as a sphere around them.