The only reliable clock is the dough itself. To read it, you must stop looking and start touching. These are the three Tactile Metrics that every sourdough baker must master to judge the invisible biology of the jar.

Dough is a contradiction. It is a solid that flows like a liquid. In physics, this property is called Viscoelasticity. It means the material has both viscous (flow) and elastic (snap-back) characteristics.