Douglas Mulhall, pioneering nanotechnology journalist and researcher, unveils the revolutionary potential and hidden dangers of molecular engineering. Mulhall's exploration of nanoecology reveals how atomic-scale machines could transform everything from medicine to manufacturing, potentially solving global environmental crises or creating unprecedented threats to human survival. He discusses breakthrough applications including molecular assemblers that could build any object from basic atoms, nanobots capable of repairing cellular damage from within the human body, and self-replicating systems that might revolutionize resource production. The conversation examines the convergence of nanotechnology with robotics and genetics, creating possibilities for enhanced human capabilities and extended lifespans. However, Mulhall also warns of catastrophic risks including the "gray goo" scenario where self-replicating nanomachines could consume all organic matter on Earth. He addresses the regulatory challenges facing this emerging field and the race between beneficial applications and potential weaponization. This forward-looking discussion illuminates how nanotechnology represents both humanity's greatest opportunity for advancement and its most existential technological threat.