The focus of Jäger's work will be on the problem of reconciling theories explaining the behaviour of physical systems at the microscopic level with physical phenomena on the human scale. Quantum mechanics very precisely describes physical systems at the microscopic level, but is difficult to interpret. The theory predicts phenomena — such as superpositions of states — that we do not perceive in the macroscopic world. There are different interpretations of quantum mechanics that have the goal of solving this problem. According to one of them, the many-worlds interpretation of quantum mechanics, our reality is merely one of possibly infinitely many others, which are continually moving away from our world and thus realize almost all conceivable eventualities. This interpretation, as well as the so-called thermodynamic arrow of time, will be the focus of Jäger's work in Oxford.
Theoretical Physics and Ethics
Based on his interest in theoretical physics and ethics, Jäger has long been committed to "Effective Altruism". This is a moral-philosophical movement that uses scientific methods to seek the most effective ways to do good. The ultimate goal is to translate the paths thus found into reality.
Effective altruism works with quantitative models. For some of these models, fundamental knowledge of natural sciences is relevant. For example, cosmology and information theory can help to think about strategies that will enable the well-being of generations in the distant future. The "Future of Humanity Institute" in Oxford, for example, is conducting research in this area.