Like deja-vu, the Mandela Effect is the term for when you’re sure something has happened before, even though it hasn’t, and a lot of people sincerely believe it is proof of the existence of an alternate universe(s). Why is it called the “Mandela Effect?” Because many people believe that Nelson Mandela died in prison long before his true death, on December 5th, 2013. Thousands of people, possibly more, truly believe and remember of his passing before that day. Similar to Mandela’s death, many people remember the Space Shuttle Challenger exploding long before the January 1986 tragedy. In the case of the Challenger explosion, even people working for NASA swear confusion over the date of the tragedy.