Yes my thought experiment was like an 'everyman's' thought experiment. Of course I know that in modern physics time and the other 3 dimensions are entangled (space-time), but I still preferred to base my thoughts on 'intuitions'. I also realized that the observer was always presupposed in the thought experiment, and if there's an observer then there necessarily is motion (like his eyes, his brain neurons, etc.), but it's probably impossible to make any thought experiment without an observer!
I think I understand most of your responses, but I don't know if I'm entirely clear on your reply to the 'stop-start universe' let's call it. Let's say that in our universe now, the one you and I inhabit, absolutely everything stopped moving right now. And then, after some 'time', everything started moving again. In fact, let's say that this happens to our universe every single second. For every second of motion, there are 'billions of years' of non-motion. There's no way, it seems to me, for us to know that this is not happening. We could be living in such a universe and not know it. Of course, I can't imagine such a universe without an external observer, because I am that observer! And how do I know those billions of years exist? Because there's motion in my head, I'm thinking consecutive thoughts, I'm maybe restless and jittery because I'm waiting for billions of years for this universe to start again, etc. But I don't know what this means exactly. Does it mean that, if we remove the observer, then those billions of years simply cannot exist, because time cannot exist without motion? On the one hand I can imagine everything just stopping, I don't feel there is anything logically contradictory in everything stopping, and remaining like that for a long 'time', but on the other hand I understand that we, as observers, can't detect time without motion, so if everything stopped, including us, then started again, there would in fact be no pause: if everything stops at the same time, there is no stop. In other words, it is impossible for the whole universe to stop. Things can only stop in relation to something that remains moving, because if nothing remains moving, then time does not exist for something to be stopped during that time. Therefore motion will always exist. There is no time during which there will be no motion anywhere. Therefore, the universe will always exist, and has always existed.
Thank you for your always detailed replies, and awaiting your next one.
I don't quite get the purpose of your thought experiment, is it meant to show that time depends on motion or not?
From what i can observe from your thought experiment and your conclusions, time depends on motion.
If everything stops moving in our universe, nothing would exist including you and I. If the universe comes back into motion and we are to exist again, then the universe would have to start all over from the beginning - big bang, and our memories would be reset. Who then is making the measurement of time throughout the whole event?, Is it an observer outside our universe or we in a reset universe ?
I would assume, the one second observed in our universe is with respect to an observer outside of our universe, the question now is, the billions of years you speak of, is with respect to what observer ?
There would be no pause with respect to the observer outside our universe because of his memory and volition, with those properties, he can combine all the events (before and after reset) and it would appear continuous - no pause. But for we in the universe, there would be pause because our memories have been reset (memory of the first motion is lost) when the universe started again.
The last time I checked, the universe is approximately 13.8 billion years old and it started with the big bang, it indeed had a beginning and it may have an end, it has not always being in existence. Now, you can see that your flawed thought experiment has led to a false conclusion. As at the moments of existence of our universe, motion is very necessary, that is, no motion, no existence (including our time : not including the time of an observer outside of our universe) but that doesn't mean our universe never had a beginning or would never have an end.
Like I said before you seem to be lacking in your knowledge of physics. If you still don't understand everything I've said here, then there's nothing much i can do and as consequence, i may not reply your next comment regarding this same issue - your thought experiment.
The purpose of the thought experiment was for me to try and understand things better, for example by asking whether something strange would follow from assuming that 'time does not exist if there's no motion'. So I asked you, since you seem to know more about this than I do.
Another question that I forgot to ask: why do you say that we would have no memory? If all the neurons etc. are in place, why won't starting them up again revamp all the memories that are encoded in the brain?
My knowledge of physics is indeed very superficial. But, strangely, it often turns out that my superficial knowledge is much deeper than the 'deep knowledge' others have. I'm not saying this is true in this case, just speaking generally.
Also, one doesn't need to know anything about physics to understand time. Once, a mathematician told me that the circle has been squared. I asked for details, and he gave me taxicab geometry. I said that the taxicab geometry 'proof' could just as easily be construed as a proof that something about the definition of 'circle' is lacking. It's a decision, and mathematicians and scientists do it all the time. For example if there are 2 good solutions to a problem, but one solution leads to a dead end, and another solution leads to opening many further research opportunities, mathematicians and scientists will always prefer the latter. No one knows what physicists will think about time in 100 years. But the important thing is that 'circle' is not something that belongs only to mathematicians, they are not the only ones who have the right to define 'circle'. The same is true of time: we all experience it, it belongs to all of us, we can use logic to think about it, we don't need to know anything about physics, just as Darwin didn't need to know anything about genes to know that natural selection was real. I think you will agree with me that the circle definitely has not been squared, nor can it ever be squared, because that would just be ridiculous (illogical). That is true despite the fact that my knowledge of mathematics is very superficial.
To see if I understand your conclusion: are you saying there was a time when the universe didn't exist? And are you saying there will be a time when then universe won't exist?
I appreciate your time and your effort at explaining things to me. It's okay if you don't reply to this.
Maybe another way to phrase my last question is like so:
Does the question "Did the universe exist 14 billion years ago?" have any meaning? Is it possible to answer such a question? Do physicists have an answer to that question?
For now, our universe seems to have no information about it's existence beyond 13.8 billion years ago. So yes, the universe existing 14 billion years ago is meaningless for us inside of it, "for now".
I don't totally blame us for having different perceptions of the same things and still call them facts, after all, why do we have subjective consciousness. Anyways, good luck with your "superficial knowledge", who knows the kind of discoveries you may make.