Lichtgedanken 05

Rubrik 50 It is not just lay people who find quan- tum mechanics and gravitation theory baffling; physicists themselves also see them as lying worlds apart. While in the former the largest unit under inves- tigation is a molecule with 800 atoms; it is only masses weighing over sever- al hundred grams that are relevant to the field of gravitation. »It is like the relationship between a grain of salt and the Mount Everest«, explains Dr André Großardt. The theoretical physicist wants to sig- nificantly reduce this discrepancy »so that the interaction between quantum mechanics and gravitation can be in- vestigated in the future.« He has been awarded a Freigeist fellowship by the Volkswagen Foundation for this excep- tional project. The foundation is funding his project »Decoherence in gravita- tional quantum systems and quantum systems in the gravitational field« with around 960,000 euros over a period of five years. Eight fellows with unconven- tional and daring research ideas were selected from around 90 applications. Answering open questions in theoretical physics Since 2019, Großardt is leading a team of three doctoral candidates at the Insti- tute of Theoretical Physics. »Until now, there has been no quantum description for the general theory of relativity. Con- versely, gravitation is never considered in the field of quantum mechanics«, he explains. »We want to shed light on important unanswered questions in theoretical physics and thus to lay the foundation for experiments that will soon be possible.« It is possible to unify the two fields of research, which have been viewed as incompatible until now, using the superposition principle. »Ac- cording to superposition, quantum me- chanical particles can be in two places at the same time. We want to use laborato- ry experiments to investigate the power of attraction in this state to gain insights into the interplay of gravitation and quantum theory«, says the 34-year-old Freigeist scholarship holder. Gravitation described as quantum theory The planned experiments will bring grains of salt and Mount Everest clo- ser together, so that the size difference is more reminiscent of an elephant and the Statue of Liberty. »One conceivable result would be for gravitation to be de- scribed as quantum theory: the particles would display similar behaviour as has already been investigated and under- stood for electrical force. Alternatively, the investigated particles could also re- tain the properties as described by the theory of relativity; in this case, gravita- tion would escape quantum theory and would be understood to be fundamen- tally different from other forces.« André Großardt has been interested in this interdisciplinary topic since early in his scientific career: while his docto- ral thesis dealt with Einstein’s theory of relativity; his post-doctorate was predo- minantly concerned with quantum the- ory. He is also currently working closely with experimental physicists.  Crossing boundaries Physicist Dr André Großardt is attempting to »balance« quantum mechanics with gravitation theory. He has been awarded the Freigeist fellowship—worth almost one million euros—by the Volkswagen Foundation for his unconventional research idea. BY JULIANE DÖLITZSCH Through its Freigeist fellowship, the Volkswagen Foundation funds excep- tional researchers who work between established fields of research, want to carry out risky research and who have gained their doctorate within the last four years. With their work, which shows great foresight, the Freigeist fellows are to act as »a catalyst for the overcoming of professional, institutional and national boundaries« states the Volkswagen Foundation. André Großardt is attempting to combine two seemingly incompatible fields of research.