A question
Why do bridges move?
A calm, true answer. Then, if the wondering keeps going, the whole episode.
The short answer
Because a bridge that could not move would not last. The steel cables of the Golden Gate Bridge stretch when the sun warms them and pull back in as they cool, so the roadway slowly rises and falls.
Across its whole designed range that roadway can travel about sixteen feet between its lowest point and its highest. It is not failing when it does that. It was drawn that way.
Go deeper tonight
The Bridge Built to Move
The full episode, in one calm voice, with nothing that startles.
Read the guide for this one in the morning.
This connects to
One idea turns up in many different nights. Follow one and the library starts to join up.
I like your mind. Just the way it wonders.