Resonance is what happens when one vibrating system sets another vibrating at the same natural frequency: no touch, no wire. Bridges have collapsed from it. Opera singers shatter glass with it. And nervous systems do a version of it every time a calm voice slows a racing heart.
These references cover both sides: the mechanical physics of resonance, and the human research on how feelings spread between bodies.
The core concept: why systems respond dramatically at their natural frequency.
The tuning-fork effect: strings and air columns that sound without being struck.
The official archive of the most famous demonstration that vibration is a force engineers ignore at their peril.
The research on how moods spread between people: the human tuning fork.
The research brief on how nervous systems calm (or activate) each other in relationship.
Neurons that fire both when you act and when you watch someone else act, told by the researchers themselves.
An influential (and actively debated) framework for how safety and connection register in the body.