Quantum physics: beyond the logic of cause and effect

In classical, Newtonian theory, causality, the connection between cause and effect, is considered to sit at the core of physics: Causal thinking, together with the idea that absolute time and space are the pre-given stage for all physical events, have been dominating classical physics well into the twentieth century.

The advent of general relativity and especially of quantum mechanics has progressively questioned various assumptions of classical physics, to the extent that today the very relationship and notion of causality is also questioned: what if the concepts of cause-effect and causal thinking were dropped in favour of a different way of understanding physics?

Another, more recent tension, is linked to the question whether information and logic should be considered more or less fundamental than physical laws: is it logic that is a natural science (as Ferdinand Gonseth used to say) and therefore finds its basis in reality, or it is rather reality that is made up of information ("It from Bit", according to John Wheeler)?

In his new project, "From Algorithms and Information to Physics - and Back", funded by the Swiss National Science Foundation (SNSF), Professor Stefan Wolf does not dwell into resolving the age-old question whether one particular language game or thinking style is superior to the other. Instead of advocating for one viewpoint to be the "right one", Professor Wolf and his team draw from the richness and diversity of viewpoints to look at phenomena with an anarchic perspective.

Professor of informatics at Università della Svizzera italiana since 2011, specializing in cryptography and quantum informatics, Professor Stefan Wolf has been granted a four-year SNF project focussing on interdisciplinary research, where physics, computation and information as well as philosophy interact. In particular, the usual ways of thinking and explaining correlations give way to a more permeable, less rigid perspective: As he explains, "one of the lines of our research is to investigate what the consequences are of dropping fundamental physical causality while sticking to logical consistency".

What could be the benefits of using such an approach? The different perspective helps tackling phenomena that would be difficult explaining using the usual corset of cause and effect. Leaving the field of causal thought, proper of classical physics, allows opening up several research lines. In more concrete terms, this approach has several applications, for example in the areas of thermodynamics, computation, as well as information and communication theory.

Dropping traditional causal thinking has been the starting point of the PhD thesis of Ämin Baumeler, a former member of Professor Wolf’s group, a work that won the prize for the best doctoral thesis in informatics, jointly established by the three national informatics associations of Germany, Austria and Switzerland (see related article here: www.usi.ch/en/feeds/8470 ).