What does it mean that bridge nodes connect different domains?

Example: You study behavioral economics and notice that loss aversion maps precisely onto sunk cost reasoning in software engineering — teams keep investing in failing projects because abandoning them 'wastes' what they've already spent. That single connection between psychology and engineering is a bridge node. It doesn't belong to either domain. It belongs to the space between them, and it generates insights that neither domain produces alone.

Try this: Open your knowledge system and pick two domains you work in that feel separate — say, management and biology, or cooking and systems design. Spend 15 minutes looking for a concept that maps cleanly from one to the other. Write it as an explicit bridge node with typed links to both domains. If you find one, look for a second. Most people discover that their domains are less separate than they assumed — they just never made the connection explicit.