Entropy and the principle of indifference

Fedde Benedictus

It is our aim in this talk to investigate an idea that lies at the basis of Carlo Rovelli’s recent work on the arrow of time, namely the idea that entropy is a perspectival concept. We look at this idea in the context of classical probability theory and attempt to establish a link between the classical principle of indifference and the idea that entropy is perspectival. Rovelli states that he has been partly inspired by Hans Reichenbach’s seminal work The Direction of Time (1956). We will compare Rovelli’s approach to that of Reichenbach.