heh.

Let's use light clocks to define a event horizon. In SR you can think of it as 'light' bouncing between two mirrors at a right angle to you. That becomes your clock. The contraption moving away, relative you, will force the light bouncing between the mirrors to 'traverse' more space as it does so, making for a slower 'clock', as defined by you staying at home. A simple idea that works.

Then you just put this light clock in a uniform constant acceleration, and watch it tick. That's gravity according to the equivalence principle. And GR.

So will that light clock tick slower for a far observer, watching it placed at a event horizon?

It should, as that is equivalent to uniform constant acceleration.

Now place yourself there looking out at the stars. Place one more imaginary light clock, 'at rest' with you, away from the event horizon, close but not too close to that sun we discussed earlier. Will the clock speed up, or will it be the same as your clock? There are two ways to see that, no, it won't. Or yes, it will, but only relative you. Assuming a global universe the 'sun clock' has no reason to speed up, as it is at rest with you, but placed outside your gravity well. But as we found that far observer observing your clock to go slow, you can now imagine that observer sitting on our 'sun (light)clock' looking back at you, observing your 'event horizon clock' still ticking slower than his local sun clock. So, what will you observe (at the event horizon)?

Well, which clock are you going to use to define his clock? your local one right? At the event horizon. And according to that one the 'sun clock' must have a faster pace. It is equivalent to a twin experiment loosely described, in where one twin accelerate to then come back, finding his earthbound twin older than himself traveling.

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This is where there might be room for argument. although the far observer defines your clock to go slow, can I really assume a equivalence in where his then must go faster, as defined from my local clock (at the event horizon)? Logic and the equivalence principle seems to demand it though.

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But none of them, locally measured, found anything to differ in lights speed. And that you define the sun clock to 'tick faster', does that mean that all will agree on it? Not to someone in a same gravitational potential, also being 'at rest', with the sun clock. To him it should 'tick' the same as his own. There should be a better way to define this one. But let's sleep on it and see if we can find some other way

One thing one can wonder about though, is if there exist some limit to those 'ticks' more than 'c', locally defined. What i mean is if there could be some 'minimum ground state' for a 'tick', as defined between frames of reference. but that hasn't really anything to do with the question at hand, has it