If speed is constant that's fine, but who's observing? What is your ray of light going to do?
If space is warped by that black hole, then you will never observe the light no matter what speed it can move. So this planck constant is a theoretical speed, but no observer can ever see the light go from place A to B since in a black hole everything is in the same place squashed together.
Now that's a singularity. But the universe originated also from a singularity. So there can be no visible light present when the universe began. That's why we can never observe what went on before the Big Bang or whatever they now call that moment when the Universe began? Planck constant, like all the laws of physics, becomes useless in a singularity?
