TIL the peace sign consists of the semaphore signs for N and D, for Nuclear Disarmament - designed by Gerard Holtom for the 1958 British Campaign For Nuclear Disarmament. How did I not know that?
TIL that the informal foot paths people create are called "desire paths". In Finland, planners wait until first snowfall and then plan their paved paths around where people's tracks appear.
TIL there is a song titled "10,000-Year Earworm to Discourage Settlement Near Nuclear Waste Repositories" meant to "convey the concept of radiological warning" so "no one will forget it for a significant portion of the lifespan of dangerous radiation at repository sites"