Not sure about the whole "if you can’t picture it, do you really understand it?" idea - a very touchy subject on that one....but interesting point

From a mathematics point of a view, the entire premise is based on picturing it in order to understand it...

The odds of someone EVER actually opening the door mid flight are ridiculous. Plus how many people would stop that from happening once they knew was occurring - I know I'd be one of the first people up and trying to get on top of that person to prevent that from happening - and I know I'm not alone on that thought.

That is exactly my fear