I really like this demo. It is simple and surprising, yet deceptively subtle and complex.
It also draws my attention to explanations. The first time I saw Steve present this he didn’t explain it, but I was transfixed. Effective demonstrations don’t always come with explanations. Sometimes less is more.
I’m no physicist, but I’m not fully satisfied by the explanation of what’s going on here. In that sense, despite the beautiful slo-mo, I preferred the first version I saw. I find this demo intensely pleasing despite it leaving me hanging.
Don’t get me wrong, I’m not advocating that we all go around deliberately producing unsatisfying explanations or consistently refusing to give any at all, but what works for me is that I’m left wanting to get my hands on a set of these to test it out, to explore and investigate the phenomenon to try to understand it better. Surely that’s one of the indicators of a great demo?