The iPhone Duo developing a crease over time is inevitable as the tides, and a matter of physics and engineering. Here’s how and why that crease develops, and what Apple has done to mitigate it.

iPhone Duo glass layers
In the run-up to Apple’s folding iPhone, there was a lot of chatter about how Apple has “solved the smartphone crease.” It’s always been a silly topic, as there is no solving it, there is only postponing it.
It’s an engineering problem on top of a physics problem. The physics are immutable.