Can uncertainties in the evolution of massive stars explain properties of gravitational wave progenitors?

Massive stars play a critical role in the evolution of galaxies and star clusters. Recent observations of the latter have highlighted the need for systematic studies dedicated to probing the impact of massive stellar evolution on the properties of stellar populations. While the use of fitting formulae to stellar tracks remains a popular choice for modelling stellar evolution in population synthesis codes, these formulae are not adaptable to changes. In this talk, I will discuss and present results from an alternative approach, one that is more adaptable: Method of Interpolation for Single Star Evolution (METISSE). It can readily make use of stellar models computed with different stellar evolution codes and compare their predictions for populations of stars. Using METISSE with data from different stellar evolution codes, I will show how various physical ingredients used in the evolution of massive stars, such as the treatment of their radiation dominated envelopes, can lead to differences in their evolutionary properties. I will discuss the implications of these differences on the evolution and interaction of stars in binaries, and how they can impact compact binary mergers and the properties of gravitational wave events