Sound does exist as it's a waveform in a substance. Therefore it is real even outside human perception.
If humans could hear like bats we'd have 'sonar' and many other perceptions too.
Nobody really understands time so far. It's something we're bound to in our lives and which controls us. Yet it doesn't have to be constant.
We're stuck in the 4th dimension pretty much the same way that a person who sits in a train is stuck to it. It moves along and the passenger really can't have a proper perception of it untill he steps outside the train. Which we obviously cannot do.
So whether the train travels straightforward or in circles, the passenger can only observe the scenery as it happens. The effect is multiplied if each passenger only lives a fraction of the distance between stations. Which we obviously do.
Some curious passengers can then observe the candy wrappers and seat wear the previous generations have left after them. They can make observations such as jumping inside the train and jumping on the roof of the train in order to see the difference.
But that's pretty far off from surviving a jump off the train or taking control of it, forcing it to go backwards let alone find out where the train was built.
