Woah there hombre. ACCELERATION is one thing, the problem is COASTING.
ISS, not on some maintenance burn. Not looking out the windows. Just 4 dudes and 2 chicks floating in a can. What can they do?
First off, a quick reminder that the rules page can be quickly accessed via the bottom right of every single page. You'll see a nice little link labeled "Science Forums Rules" Kindly go read them, and consider how your last post is going a bit past toeing the line on a few of them. I'm more patient than Some of the other fellows, but you've already been on "stress leave" for an attitude. I politely and rationally request that you hakuna your tah-tas.
Second off, I'm quite interested in both Logic and Rationality. They're integral to theory of mind, and I rather like 'Philosophizing with a Hammer" as well. Look it up some time, juicy read. Sadly I'm unsure why you resort to fallacy of character-attacks in response to a question. That would indicate to me you need to take a moment to reconsider weather your response is rational and responsible, or is merely lashing out irrationally. This brings us directly to:
Thirdly, you're failing at a key part of a fully functional psyche here. I mentioned Theory of Mind earlier. It's a bit of a digression from the main post but this is important. "because this proof has been described in this forum before" seems to indicate you fail to understand than my experiences and the things I have viewed directly are not those you have viewed directly. You're failing the Sally-Ann-task and you should probably work on that. No amount of sass will make up for such a cognitive defect if you wish to speak of rationality and logic. I don't read EVERYTHING here, I've got plenty of other things to occupy my attention. You and your talks are but a minuscule fraction of what I lay eyes upon. Once you realize this you'll stop failing a task most people master in childhood. I recognize you don't read everything I post and experience. So I'm pointing you to these things in good faith and reminding you of the rules for the same reason, despite how redundant the task is with how often I've done it with other individuals. That's called rationality, please drink the koolaid.
Beyond that, I see your sufficiently wide elevator idea, though I'm not precisely sure how you'd account for transverse gravitation (like that experienced next to mountains or particularly dense crust) which could easily swing a "sufficiently sensitive instrument set" in a "sufficiently wide box" well away from the overall barycenter towards the local one. Same way it would be hard to account for "burps" in fuel and uneven nozzle wear in an equally large accelerating box with a equally sensitive instrument set. That's the problem with simplistic thought-experiments: reality is far stranger than your mind can conceive unless you experience it yourself, and you must play by it's logic not the reverse. Still, I'll leave that in the box of brain-fu for now and allow you an ideal perfectly homogeneous and spherical planetoid in a perfectly straight and perfectly large box with perfectly calibrated and perfectly sensitive instruments being able to tell barycenter acceleration from a straight vector acceleration. The question still remains for the important one: Coasting at speed in a tin can, how do you define your speed? That's one of the important ones and the one I'm particularly interested in your answer for.
Ok, Ignoring the etiquette issues for a moment, I'll try to be civil in future.
So your not interested in an accelerating box vs box in gravity, although it's sufficient for the exercise, as it shows that although the two should be the same at first glance, it is possible to tell which you are in given the right measuring equipment.
So we have to look at a box in space, and a box in free fall now?
OK, you can still tell which one you are in, although in accord with the claim, physics will give the same results in either case for a little while.
BUT, the way to tell which one you are in is to use TIME. You wait a bit, if you don't smash into the source planet of the Gravity, then you are in deep space, floating. Otherwise, you are dead, as you were in the temporarily free falling box under Gravity.
But why do you argue that Einstein's equivalence principle is correct? Its openly admitted by Einstein mad professors that free fall is NOT equivalent to freely floating in space.
So Einstein's equivalence principle is a bit useless, and we should never talk about it again., because it's NOT PHYSICS. But of course, without this equivalence principal, Special Relativity is dead.
Here's a quote from a web page created by the Albert Einstein Institute:
Speaking of the problem that free-falling is NOT identical to floating in space, they come up with this fudge;
"Within an infinitely small ("infinitesimal") spacetime region, one can always find a reference frame - an infinitely small elevator cabin, observed over an infinitely brief period of time - in which the laws of physics are the same as in special relativity. By choosing a suitably small elevator and a suitably brief period of observation, one can keep the difference between the laws of physics in that cabin and those of special relativity arbitrarily small.".
Infinitely small error, is NOT the same as Equivalence in anyone's book, and to get to this small error, they had to make the falling elevator "infinitely small", and the time period "infinitely small" as well.
This is a BS excuse in Physics. The only rational statement is that the Equivalence principal is NOT correct. Period.
Since when did the laws of Physics only work in infinitely small places over infinitely tiny time periods?