I was putting up some wall decorations earlier today and was painstakingly realigning everything until it looked level to my eyes. It might be just a hair off, but if I don’t correct it, I’ll see the misalignment almost instantly and get bothered for the rest of time until I fix it. Has anyone investigated, or is there literature on the minimum perceptible angle from level to the naked eye?
Perpendicular to the normal vector to the center of the local gravity well
But, oddly, it’s not. How square it is with the walls is more important. Door and window frames, too, and those are more likely to be a touch off.
I was defining true level. Squaring with the room is inherently different, and absolutely more important for decor such as wall art. In contrast, hanging drapes to be level to a slanted ceiling can result in a loss of functionality.
You’re right. Especially with the drapes: if the ceiling isn’t level, it’s a no-win situation. It’s either going to look distracting, or function poorly.
Yeah- Square and level are two different things. I can get a cube and rotate it any way, opposite faces will still be square to each other (technically parallel) despite not being level.
Interestingly, two perfectly vertical walls cannot be square to each other.
What do you mean re: the walls?
The Earth is curved.
At least, I assume that’s what they meant.
Oh, you’re one of those round-Earth nutjobs?
Ha! No, what whackjobs those people are. No, clearly the Earth is donut-shaped. This is obvious, because the Bible says so. The lizard people are suppressing the information, except on the internet. And talk radio. And tabloids.
Donut shaped!