Project A2
The hierarchy, fine-tuning and naturalness problem
from a philosophical perspective

Over the last few decades, the fine-tuning problem (i.e., the fact that even a small change in the parameters of the Standard Model would bring about a very different universe than the one we live in) has been one of the main motivations for physicists to develop alternatives to the Standard Model of elementary particle physics. The project will explore the possibility of classifying the fine-tuning problem of the Standard Model as an explanatory gap which carries epistemic as well as aesthetic characteristics. The fine-tuning problem is tightly related to the hierarchy problem, which refers the large ratio of the Planck scale when gravity becomes relevant to the scale of the weak interaction described by the Standard Model. The project will study the formulation of the hierarchy problem in the context of philosophical models of layers, and will thus also integrate the fine-tuning problem into this language. Due to the fine-tuning and the hierarchy problem, the Standard Model is typically said to be incompatible with naturalness, one of the main guiding principles in model building. This principle in its various definitions shall be subject to a critical philosophical discussion in this project. Its implications with respect to a simplification of physical models shall be analysed in particular. Another goal is to analyse the striking tension between the simple character of the naturalness criterion and the complexity of the model world, mostly caused by the tight constraints due to electro-weak precision data.


A workshop on naturalness was hosted by the Institute of Theoretical Particle Physics and Cosmology at RWTH Aachen University on Feb 28-Mar 2 2018.


Principal Investigators:
Robert Harlander
Gregor Schiemann

Radin Dardashti

Postdoctoral Researcher:
Joshua Rosaler

Doctoral Researcher:
Miguel Ángel Carretero Sahuquillo