Very simple explanation of Wigner's friend needed

[idea2000]

Hi, just browsed through some news stories and saw a story about a group of researchers who seemed to prove we can experience very different realities. I was just wondering if anyone could provide a simple explanation of their experiment and what they did? Do we really live in different realities?

 

[PeterDonis]

As a search of PF will show you, we have several threads already running on this topic. These two should be a good start:

https://www.physicsforums.com/threads/the-quantum-mystery-of-wigners-friend-comments.960074/
https://www.physicsforums.com/threads/wigners-friend.877318/