unsolvable - Robuta Search

https://www.indigo.ca/en-ca/polarity-management-identifying-and-managing-unsolvable-problems/9780874251760.html

Buy the book Polarity Management: Identifying and Managing Unsolvable Problems by barry johnson at Indigo

https://www.snopes.com/fact-check/the-unsolvable-math-problem/

A student mistook examples of unsolved math problems for a homework assignment and solved them.

https://bigthink.com/13-8/big-bang-first-cause/

The problem of the "first cause" may forever remain open because it doesn’t fit with the way we do science.