Child custody issues can be complex and they tend to snowball. In addition to being embedded within the context of a divorce, which is usually not anyone's happy place, real life tends to interfere with neat, organized plans. A child or parent becomes ill, someone needs to go out of town, and suddenly trades and swaps need to be negotiated, often in an atmosphere of mistrust and a concern that modifications will be fair.
A physicist, who was twice divorced, and living with a new partner, wondered if perhaps mathematics or physics could offer a solution. If math and physics can model complex matters of fluid dynamics and subatomic particles, surely they could provide a child custody plan that could be viewed by both parents as fair and impartial.