Physicists at the beginning of the 20th century were faced with an unexpected phenomenon: quantum objects can exist in multiple states simultaneously. This means that a particle can be in multiple places at once. However, through mathematical calculations and experiments, it was discovered that the particle transitions from this “superposition” state to a specific state only when it is observed. This led to questions about the nature of observation and the observer themselves – who can be considered an observer? Does it have to be a person, or can a photon suffice?
In 1961, Hungarian-American physicist Eugene Wigner introduced a thought experiment known as “Wigner’s friend paradox,” which delved into the fundamental questions surrounding quantum measurements and consciousness.
The experiment involves Wigner’s friend conducting a quantum measurement on a system that is initially in a superposition of states in an isolated lab. According to the Copenhagen interpretation of quantum mechanics, the observation of the friend should cause the wave function to collapse and yield a specific result.
However, Wigner, standing outside the lab, must view the entire system (including his friend) as being in a quantum superposition until he is informed of the result. This leads to a paradoxical scenario where Wigner’s friend believes he has observed a definite outcome, while Wigner still sees his friend as existing in a superposition of potential results.
This thought experiment underscores the challenges in interpreting quantum mechanics, particularly regarding the observer’s role and the process of measurement. It raises doubts about the objectivity of quantum states and prompts inquiries about consciousness and its significance in the quantum realm.
Wigner’s friend paradox bears similarity to Erwin Schrödinger’s renowned thought experiment “Cat Schrö