Re: Phil Plait hates it
"For time dilation to vary by any significant amount over a range of a few centimetres (the width of a brain), there would be no getting away from the fact that huge tidal forces would be involved. I suspect your brain - and the rest of your body - would be stretched out mush long before you started having mental problems."
That's the curious thing. There was a reason I stipulated "Never mind tidal forces."
The above scenario turns out not to be the case, for a supermassive black hole such as the one in "Interstellar". It's well established that for supermassive black holes tidal forces are minimal at the event horizon, simply because it's so far from the singularity. I realize that's hard to believe so I'll supply a few references relating to free-fall through the horizon:
"Then you will experience only tidal forces (forces that depend not on the strength o fthe gravitational field, but on the difference between its strength at two nearby points) and these can be made arbitrarily small by making the black hole arbitrarily large."
Or, HubbleSite's description:
"If you fall into a supermassive black hole, your body remains intact, even as you cross the event horizon."
"Tidal gravity is less pronounced for an object that approaches a supermassive black hole, because there's a gentler "slope" in the changing gravity field."
I hope that establishes the point. And yet: Tidal forces might be minimal passing through the event horizon of a supermassive black hole, but that still leaves us with the asymptotic time dilation anomaly.
The apparent contradiction may be due to the very artificial nature of the Schwarzchild metric - nearly every imaginable stellar catastrophe leading to a black hole involves huge angular momentum which the BH would keep, so it's hard to see how a realistic BH can avoid following the Kerr metric instead.
And yet, the Schwarzchild metric can't be that far from a suitable approximation, since Hubble and other supertelescopes of the modern era can actually resolve accretion disks with the sharp interior edge characteristic of the Schwarzchild model.