Sixth International Conference on the Nature and Ontology of Spacetime Starting: 2020-05-11 to 2020-05-14 Location: Albena, Bulgaria Website: http://www.minkowskiinstitute.org/conferences/2020/ Contact: 2020conference@minkowskiinstitute.org The Scientific Organizing Committee invites papers from physicists, philosophers of physics and philosophers on any topic related to the nature of spacetime. As there will be no main theme of the sixth spacetime conference the Committee also invites proposals for special session topics. So far colleagues have suggested to include the following special sessions in the conference program (http://www.minkowskiinstitute.org/conferences/2020/call.html): Nature of time - Flow of time; Becoming Is spacetime a real four-dimensional entity or a mathematical concept? Open Questions in Spacetime Physics Relativistic Mass Do Black Holes Actually Exist? What is the difference between matter and geometry in general relativity, semi-classical gravity, and quantum gravity? Depending on the number of colleagues participating in a special session, we plan to publish a volume with the talks presented at the session, which will include constructive criticism and the replies of the authors. Contributed papers in the form of extended abstracts of between one and two pages should be emailed to 2020conference@minkowskiinstitute.org by January 31, 2020. Submissions will be reviewed and notification of acceptance will be sent by February 17, 2020. Scientific Organizing Committee: Dennis Dieks (Utrecht University) Mauro Dorato (University of Rome Three) George F. R. Ellis (University of Cape Town) Robert Geroch (University of Chicago) Eleanor Knox (King's College London) Vesselin Petkov (Minkowski Institute, Montreal) Steven Savitt (University of British Columbia) Anguel Stefanov (Bulgarian Academy of Sciences) James Owen Weatherall (University of California, Irvine) Christian Wuethrich (University of Geneva)