chain reaction
"Basically, the sheer amount of empty space in atoms means that the conditions for fission or fusion are very, very specific. Atoms are not packed tightly. The necessary domino effect of the chain reaction is like mousetraps loaded with ping-pong balls. The chain reaction only happens if you have an assload of traps close together, and lots of ping-pong balls flying as a result. Normal atoms are like two or three loaded traps in a room, hard to get that reaction going. But if you throw a thousand traps loaded with ping-pong balls into a small room really quickly, kaboom."
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.