Interaction

Many things grow exponentially. According to a dentist, plague on teeth doubled every 20 minutes.

moment, mass and property.

Heinlein quotation about human being

A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.

Interactions - Door Controls

Automatic door opening and closing are goal-oriented.

Airport double doors for minimizing the air exchange.

Train shuttle wayside-vehicle double doors to synchrize the open-close cycles.
One active and another passive.

Mexico turn-around intersection: with lights!
Trade-off of safety-efficiency.