This is Piaget’s conservation of volume test. I did this experiment at school (we went to the elementary school next door and ran tests on the kids). Most of the kids said the higher one held more liquid because it was ‘taller’, though some said the short one had more because it was ‘fatter’.

A further complication is that the aluminium is considerably thicker on the base and the top… so there’s more thin metal, and less thick metal.

I find usually when I can’t articulate something clearly, it’s because I haven’t thought about it/researched it well enough, and I should stop trying to contribute on that topic until I have a better understanding.

That’s why I often end up writing long comments, but don’t hit post. Not a waste of time though, as it helps me identify areas in which I’m more ignorant than I thought I was.