How to show that which can't be shown

"Interstellar" by the Nolan brothers. 

My comment assumes that the reader knows the film:

Perhaps I saw it wrong or didn’t get something but the final sequence in “Interstellar” raised my eyebrows. It's possible I didn't get the connection between a library and that which is beyond them. But if a weird technological space structure was the justification for the "other side" of the bookshelf, it was not convincing.

The end of that film posses an interesting dilemma: how to show metaphysical? The script states that a more advanced civilization uses not four (space plus time) but five dimensions. This allows for interstellar travels, time manipulation and generally opens up the possibilities for interactions that we mere three dimensions living in time mortals can perceived and treat as metaphysical.

When the hero finally figures out this dimensional structure it cleverly explains the anecdote of the story and that’s great.

However in addition, the filmmakers chose to tackle the five dimensional challenge head on and to show it on screen. As is it looks complex and technological. And a bit ridiculous to my taste. What were other options? Perhaps to intimate the hyper dimensionality by more organic elements? Something like that is attempted in “Interstellar” when a spacecraft travels through a black hole? But that attempt wasn’t totally captivating either.

What’s amazing is that “2001” almost fifty years ago tackled these issues in a more convincing way. Seems that Kubrick was aware that he can’t escape the flatness of the screen and was successfully building on just that to transcend it.

The issue is crucial to any story trying to explain what’s beyond our senses. How should we intimate the existence of that which we don't have access to?