I think the rate of time, like velocity is relative. Like for example your house is stationary on the ground and so is your next door neighbour and all the trees etc so everything's still and not moving (excluding of course circular motion of a tree swaying in the wind) , right? Yes and no... They are only still, relative to each other.
As a matter of fact, we are on the surface of the Earth which itself is spinning at what is it?... Something over 1000km/hr anyway. The easiest ways to see this effect on things is a) The sun and sky movement (obviously) and b) Because the movement is rotational and not linear, the water goes down our drains clockwise/anticlockwise depending on what hemisphere you are in.
And on top of that, the Earth travels a massive distance around the sun once every year, and of course the very solar system is moving relative to other stars, the galaxy is moving relative to other galaxies and so forth...
Well you get the idea. Basically if we witness time 'stopped' it is only relative to us. To whatever is within the affected area time hasn't 'stopped', rather the surrounding area seems to have 'sped up'.
I remember reading a 'Choose Your Own Adventure' called the 'Black Hole' when I was a kid and when they are close to the Black Hole everything 'slows down' to them and they feel in slow motion. Thinking back to it now, it's quite funny, seeing that everything slowed down except their own consciousness.
But like you mentioned, perhaps the flow of light between these relatively fast/slow fields of time would be altered. From the outside looking in, perhaps it would look darker, with a red shift of light - While viewing from the inside, everything around may appear brighter and of a blue shift.
But, on feeling friction of sorts, what would happen were we to try and stick our hand through this field? Would there be an impenetrable barrier? Unlikely, on the other hand maybe the greater the relative time difference, the harder it may be to translate something through the two areas.
So say we do get our hand through. Would this mean the hand inside the field is living 'slower' than the rest of the field? This is where it starts to get a bit confusing. What if the field is so strong that for every second withing the field, a month passes outside? Because time is so differentiating, if we tried to pull our hand out we perhaps may not be able to, because relative to us time, hence motion within the field has slowed.
What if the field for whatever reason cannot be stopped, and rather than cutting the hand off you would rather live your life there with your hand stuck in this field. If you die, does this mean it would take 'years' before the hand inside the field starts rotting, even though it is directly connected to the rest of you??? Very perplexing. For every answer, it just seems there are 10 more questions!
-Raze