In The Impossible Us, Nick becomes connected with a group calling themselves the Berenstain Society. Their name is inspired by one of the most famous examples of what's popularly known as the Mandela effect. The Mandela effect, according to Medical News Today, "describes a situation in which a person or a group of people have a false memory of an event." The name was coined in 2009 after self-described paranomal consultant Fiona Broome noted on her blog that not only she, but also many other people, had vivid memories of Nelson Mandela dying in a South African jail when he was imprisoned during the apartheid period in the 1980s. Mandela, of course, did not die in prison; he went on to serve as the president of South Africa after his release, and he passed away in 2013.

But, as Broome and others have pointed out, a not insignificant number of people misremember the facts surrounding Mandela's life and death, and much speculation has arisen about why this false memory is so prevalent...