What if a single broken brick or nail could cause the building you live in to fall apart? What if that was true about the power grid, or a highway bridge?
When the failure of one element of a system can cause the whole thing to fail, we call the system fracture-critical. We try to build things using no more parts than are absolutely necessary, but this has led to our most important systems becoming fracture critical—systems for energy, food, transportation, and money. And as global population rises, these systems are being pushed to their breaking points. Recognizing vulnerable systems, and taking action to fix them, will be a major challenge in building a stable and safe future Earth.