Upside down is true.
I flip over into a handstand. My love walks on the wooden floor. She is upside down. My perspective is different. But is it wrong to say that shw is walking on the ceiling? Nope - it's equally valid. The reference points of up/down are helpful in getting on with our day. But realize that the folks on the other side of earth aren't upside-down. We all are. And we all aren't.
This can be useful. Here's two examples:
- The old master painters would check portraits in the mirror. They found it easy to spot the imperfections that way - a slightly twisted nose, or a misplaced eyebrow.
- When analyzing running form, gait, or lifting technique (sometimes people ask for this) I'll often do it by looking at the subject upside down. I'll notice these bobbing bodies stuck as it by magic to the ceiling. Imblanaces become obvious this way.
New reference frames are incredibly helpful when we are stuck or plateauing. What's your favorite?