"Momentum is like electric charge: it is a quantity that is conserved, can accumulate, and can be exchanged. The change of electric charge is called current; the change of momentum is called force. The difference between charge and momentum is that charge is a scalar, and momentum a vector."
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.