When you take something you're very familiar with and turn it upside down, you see all the details - volume, shape, distance between points, geometric similarity, colour - with fresh eyes. With art, it becomes easier to draw a human figure because it discourages symbol drawing. With a map, I find it helps me realise how close certain points are to each other, how small politically significant regions are, which lattitude different climate bands sit at, and so on.
A mug is a pretty boring object which we're all used to seeing upside down and which doesn't have many interesting features, so of course turning it upside down will not reveal anything interesting.
Can you read upside-down or does it become a jumble of lines? I can read upside-down with no special effort so maybe this is canceling something out.
It's not that I don't see the map from the other side, it's that when it's the right way up I see all the extra information I have about it. For example, I bet an eye tracker would show me focusing on Western Europe, Central Asia, Australia, and the US. When the map is flipped, I see it closer to how it really is because I can ignore those preconceived ideas more easily. I don't see e.g. the Iberian peninsula as represented by a land mass, I see the actual land mass, and can concentrate on its size and distance more easily.
This is really interesting!
That's not the case with a map. An "upside down" map is just as valid as a right side up map.
The fact that it is upside down is not supposed to mind blowing, it's the fact that it isn't upside down at all. We are just used to it being represented this way up, but there's nothing in the physical world which prescribes north to be up.
Is it as useful and/or efficient though? I could write a phrase in English from right to left and if you really wanted you could read it, but it would be highly inefficient.
An efficient society sometimes has to pick conventions (how to write text, how to print a map, what characters to use, etc) and I find not interesting to point that other conventions could have been used.
Also thinking of maps and Japan: where I am from (Germany) public overview maps of parks or street maps usually have north as up. In Japan however it is very common for those maps to have up as the cardinal direction you are looking at the map at. So if you are looking at the map in a western direction, the map will have west up. So for walking the map is straight up, backwards down, left left and right right.
Like that it is very easy to know which way to go. Want to go to some place that is on the left on the map? Turn left!
To me at least, it feels very wrong to see English written right to left, but I also know it wouldn't be objectively wrong.
Likewise, maps are traditionally "north up" because most of the population lives north of the equator so that's where most maps hailed from and if you're north of the equator having a "north up" map makes celestial navigation slightly easier.
You can change your entire system of reference and the setup still makes sense. Same with the map.
A drinking mug is a large, cylindrical cup with a handle, typically made of earthenware, used to hold hot beverages like coffee or tea. The orientation relative to gravity is fundamental to the functioning of the mug. It is not arbitrary.
