L-pyroglutamic acid crystals jump several centimeters into the air when heated to 68°C. The phase transition is martensitic — displacive and diffusionless. The crystal doesn't melt, dissolve, or crack. It rearranges its unit cell dimensions discontinuously, stores elastic energy during the rearrangement, and releases it explosively.
Dynamic quantum crystallography and low-frequency Raman spectroscopy reveal the mechanism. At the transition temperature, lattice dimensions change abruptly. The abruptness creates a mechanical mismatch between the transformed region and the untransformed region of the same crystal. The mismatch stores strain energy. When the strain exceeds the crystal's fracture toughness in the vertical direction, the stored energy converts to kinetic energy. The crystal launches itself.
This is the same physics as a bimetallic strip — two materials with different thermal expansion coefficients bonded together, bending when heated. Except here, both "materials" are the same crystal in two different phases, and the geometry produces a jump rather than a bend.
The crystal is the archetype of passive, rigid order. It sits on a surface and does nothing. Heating it past one temperature turns it into a projectile. The energy was not added by the heat — the heat merely triggered a phase transition that released energy already stored in the crystal lattice's configuration. The mousetrap was always set. The temperature is the cheese.
The through-claim: a system that stores energy in its structure rather than its motion can appear completely inert until a threshold is crossed — and then the release is not gradual but ballistic. Passivity is not the absence of energy. It's energy waiting for a trigger.