Exactly. I’m using what I know of gravity. The mattress should be resting on top of something. If we’re looking down, it is. If we’re looking up, it’s floating in mid-air, apparently wedged against both walls even though it doesn’t look firmly wedged on the right side.
Ok. Then use what you know of gravity and look for things that should be the other way if this were at the bottom.
Exactly. I’m using what I know of gravity. The mattress should be resting on top of something. If we’re looking down, it is. If we’re looking up, it’s floating in mid-air, apparently wedged against both walls even though it doesn’t look firmly wedged on the right side.