Strange

The fact that you may be able to contrive an example where ordering is preserved (in this case because the events happen at the same location) does not make it generally true.

And you have been proved wrong. Over 100 years ago.

If you mean that simultaneity is dependent on the observer, then you are correct. And this is wrong. Different observers can disagree about the order of the events. Therefore they can disagree which occurred earlier. There is no "actual" order of events.

Using an accelerometer?

That would only allow you to say things happen at the same time to the nearest billion years or so. Not very useful. On the other hand, if you know the distance between two events, and the time it took the signal to arrive, then you can say whether they were simultaneous or not (in your frame of reference - other observers may, of course, disagree as there is no universal now).

It depends on their past acceleration, the gravitational field they are in, etc.

This: "My model has two nows that are actual" And this: "There is a universal now". And this: "The universe is 13.8 billion years old for all observers" Note that your imagination does not make up part of the physical world and therefore does not have any relevance to scientific theories. You seem to think that your intuition/guesses/imagination should be given the same credibility as well-tested theories based on objective evidence. You are wrong.

No one disagrees with this. Why do you keep pretending that they do? And that is why science doesn't rely on "insights", beliefs, common sense or popularity. What seems "obvious" to you is shown to be wrong by observation and experimental evidence. The fact that you cannot get over your intuition in favour of a more accurate model doesn't make you correct. It just makes you misguided.

It appears that science is a much better key to understanding the universe as it produces useful results (i.e. results that can actually be turned into practical applications). It also produces testable ideas rather than mere beliefs which lead to childish arguments ("I believe this", "Well, I think you are wrong because I belief this.")

There is a centre. It is where the curvature becomes infinite (a singularity). Perhaps, if the black hole is rotating. But not in the case of a simple case, a Schwarzschild black hole. That seems a good way of thinking of it. You can see that paths closer to the black hole become increasing curved towards it. At some point they go in but never come out again (like a curve that goes to infinity). Photons follow geodesics, which can be curved. It would reach the centre and go no further. If you were in your spaceship and fell through the event horizon, you might try and turn round and escape. Any such attempt would just mean you approach the singularity more quickly. The event horizon is a location in space. When you cross the event horizon, spacetime curvature becomes so great that what was ahead of you in space becomes ahead of you in time.

Any path that starts inside the even horizon is curved back towards the centre. Any path outside the event horizon just carries straight on to the centre. So, if you are outside, you can (given enough energy) turn away from the path leading you in. If you are inside, any attempt to turn away from the path leading you in just means you get the the centre sooner. Not only that, when you cross the event horizon, the singularity at the centre is no longer ahead of you but because space and time coordinates have swapped places, it is now in your future. And, as we know, you can't avoid that!

Without the ability to draw pictures, I'm not sure I can put that in words. Is a lobster pot a good analogy!? Although, my description is probably based on the Schwarzschild metric. There are other metrics which may resolve the problem you see (and probably fit with MigL's description as well): http://jila.colorado.edu/~ajsh/insidebh/waterfall.html OK. But an object can leave the surface of the Earth at less than escape velocity (and then fall back. So this might imply that an object (with mass) could temporarily leave the surface of a black hole at less than the speed of light, before being dragged back. I have just heard a few too many people say that the theory of black holes must be wrong, because of this (not realising that it is just an analogy or informal description).

MigL beat me to it ... we can't say anything about what happens to matter that falls in to a black hole. In GR the ultimate fate is that it is crushed into a point of infinite density. But I don't think anyone considers that a realistic description. A unified theory of quantum gravity may give an answer (for example, string theory has this: https://en.wikipedia.org/wiki/Fuzzball_%28string_theory%29) This is a Newtonian view and can lead to misunderstandings. For example, an object can leave the surface of the Earth at less than escape velocity but will fall back again. This is not true of light and black holes. The reason light (or anything else) cannot escape is because the curvature of space-time is so great that there is no path out of the event horizon.

Any evidence for any of this?

Speeds close to the speed of light are used in examples, simply to give "impressive" numbers. No one would be very interested in a more realistic description involving real spacecraft where one person is a few picoseconds older than their twin. I think most people would just shrug and say, "so what". All of those things could be taken into account, if you just wanted to make the calculations more complicated. You would end still end up with a different total elapsed time. No it isn't. That is why it is a thought experiment. Of course, when the experiment was really done, the speeds were nowhere near the speed of light. I think you are wrong. I have working science on my side. You have a vague (and incorrect) belief. But, amazingly, it does. They do. We have measured them, directly and indirectly. On the "indirectly" side, if it weren't for these, your computer would not work, systems which depend on GPS for time keeping and distance measurement would not work, and so on. Then you should be able to provide some evidence of what reality does that is different from our current theories. Can you do that? You are talking nonsense. Length contraction and time dilation are inevitable (and fairly simple) consequence of the constant speed of light (as described by Maxwell's equations - which were based on experimental evidence and have been repeatedly tested since). And that is why we test out models against reality. To show that they match.

It did take me nearly 12 hours!

Yeah. I was hoping the introduction to the very cool idea of orbits as continual falling might intrigue him and make him want to learn more.... That "wooshing" noise you hear is the joke flying over your head...

You have evidence to support this, of course? You have evidence to support this, of course? I will admit that some do think that given the number of people who ask what the universe is expanding into. Although I doubt it has anything to do with the preposition "in" because they jump to this conclusion from the statement "the universe is expanding," which does not contain or imply "in". However, even if people do jump to an erroneous conclusion the answer is simply to explain their misapprehension. Your naive reader is going to think: ... so if there are "universe's stars" does that mean there can be something-else's stars? So your (unnatural) rewording doesn't help at all.

Some of us are professional communicators. Do you have any evidence for this claim? But your awkward rephrasing doesn't remove the thing you object to. Or maybe not. Perhaps any such people understood the physics involved and didn't get distracted by your petty misunderstandings.

True. It does point out the dangers of being pointlessly pedantic.

I thought that was the purpose of the thread. There certainly wasn't any physics in the OP.

The disgust reaction to bodily fluids may well be an evolutionary response to the fact that they can be ways in which disease spreads (including Ebola, to bring this back to the OP).

Form the linked article, the first method is: So I assume you didn't bother to read it.

The second reply.

Its not a force, just inertia. Newton's First Law: http://csep10.phys.utk.edu/astr161/lect/history/newton3laws.html