After some more calculations, we experimented with the brick-breaking stunt.
Which led to the following conversation with a grandchild:
- Granddad, is it true that granny hit you with a sledgehammer?
- Is she going to do it again?
Here are two videos of applied physics in action. And no, the dark flecks on the floor are not blood from earlier experiments, the floor is from 1850, and my guess is that someone spilled tar there.
If you don't understand what they are saying, it might be because they are speaking Norwegian. He is covering his eyes to avoid getting grit in them.
The next time they used one of the broken halves, and it was too small to break, so they eventually gave up. But the hammer blows are real.
So ... No quantum, no magic, no power of thought, just physics. Which does not make it any less magical ... or fun.