Thoughts on physics #3

Wigner’s Friend.

Wigner’s friend is a variation of the Schrödinger’s cat paradox in which a friend of the physicist Eugene Wigner is the first to look inside the vessel. The friend will find a live or dead cat. However, if Professor Wigner has both the vessel with the cat and the friend in the closed room, the state of the mind of the friend (happy if there is a live cat but sad if there is a dead cat) cannot be determined in Bohr’s interpretation of quantum mechanics until the professor has looked into the room although the friend has already looked at the cat. These paradoxes (Schrödinger’s Cat and Wigner’s Friend) are intended to indicate the absurdity of the overstated roles of measurement and observation in Bohr’s interpretation of quantum mechanics.