English: Well, I like drawing and talking, and luckily researchers talk about drawings and draw about talkings. The «Wigner’s Friend» thought experiment shows that there is still a lot of draw-talk-work to be done in the foundations of quantum theory.

I am a Master’s student in Interdisciplinary Sciences at ETH and in my semester project at the QuIT group, I will describe Wigner receiving outcome information by his Friend.

Wigner’s-Friend-type scenarios prompt us to find more precise ways of expressing what we mean by many fundamental notions, such as:

Measurement, observer, state, information, probability

Doing so amounts to improved modelling of physical systems in general. Including observers in the physical description has turned out insightful in other theories and if quantum theory was already a «theory of anything» in disguise, then it should be able to describe observers as well.

The fine line is to see exactly where quantum theory breaks down in such scenarios while remaining close to the established formalism i.e. not breaking it completely.

«He that breaks a thing to find out what it is has left the path of wisdom.» is a quote by a brilliant man called G. Graurock – and seemingly it also applies to oneself.