[IntronExon]

Seeing the universe around them is comparing clocks with another frame of reference. On the ship, life at 99.9% and life at 1% of c is identical. By the same token, if you fell into an (inactive) supermassive black hole, your watch would trick the same way into and past the event horizon. You would in fact live inside the hole for hours until you were torn asunder.

[simonh]

The point is, the crew onboard the ship can compare clocks with those in different frames of reference at any time. All they have to do is observe the period of a pulsar for example, or measure the orbits of binary star systems, etc. It would be quite apparent to them that there is a time dilation effect for them with respect to most of the rest of the universe. See Tau Zero, by Poul Anderson. It has a few mistakes, but it's still a great read.

[IntronExon]

I’m not claiming that they can’t recognize that their relative velocity is much greater than their surroundings. You can even calculate the degree of time dilation you’re experiencing relative to another observer, but I’m not talking about that either.

The biggest issue, aside from the model, is that time dilation is something which only matters when two observers “compare clocks.” Neither observer alone ever experiences a difference. The crew of a 99.9% lightspeed ship doesn’t experience time dilation... until they return home. It makes no sense to talk about the effects of time dilation from the point of view of a one-way trip to the event horizon.

That has to do with the experience of their frame of reference. Time does appear to “slow down” for them, rather everything else will seem to “speed up.” You can infer the difference, but you can’t sctually communicate that or compare with anyone else until you decelerate. In the extreme case of a gravitational event horizon, there will be no ability to ever communicate again. The fact that external observers will see you infinitely redshifted doesn’t imply anything about your experience of subjectively falling past the horizon. Both are valid frames of reference, but ultimately will develop spacelike separation which prohibits further communication.

As it relates to the issue st hand, you can’t make accurate statements about mass never passing through the EH based on observations from a distant from of reference.

[shullbitt0r]

> Seeing the universe around them is comparing clocks with another frame of reference

So, if you don't sense anything, you don't sense time dilation either?

This is slightly more complicated. First of all, you haven't given a frame of reference. If you claim someone were moving at 0.99c then you have already set the frame of reference. And they would have to gain near infinite mass and would die. You seem to assume a restricted frame of reference though, inside the spaceship. So, a point of reference inside the spaceship would see light moving with c inside the spaceship. And would assume his own point of reference as the origin of the inertial frame of reference. So baring any outside measurement, how do you know the spaceship is moving with 0.99c and in which frame of reference?

[shullbitt0r]

Oops: I notice my mistake now, acceleration is the problem, not speed.

[IntronExon]

Nailed it, although you were right in some of your objections, the 99.9% c ship is just a toy to illustrste the extreme dilation near a black hole.