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):

\n- \n
- Nature of time - Flow of time\; Becoming (continuation of the Special Session on Becoming and the panel discussion at the Second Hermann Minkowski Meeting on the Foundations of Spacetime Physics on Wednesday\, May 15\, 2019) \n
- Is spacetime a real (physical) four-dimensional entity or a mathematical concept? \n
- Open Questions in Spacetime Physics \n
- The controversy over Relativistic Mass \n
- The problem with the gravitational energy-momentum pseudotensor in general relativity - should we have a closer look at the fact that the mathematical formalism of general relativity does not yield a proper tensor of the gravitational energy-momentum? \n
- What is the difference between matter and geometry in general relativity\, semi-classical gravity\, and quantum gravity? \n
- Do Black Holes Actually Exist? \n
- Is there a conflict between relativity and quantum mechanics? \n
- Quantum Gravity: Where do we stand? \n

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.

\nContributed 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.

\n\n**Scientific Organizing Committee:**

Dennis Dieks (Utrecht University)

\nMauro Dorato (University of Rome Three)

\nGeorge F. R. Ellis (University of Cape Town)

\nRobert Geroch (University of Chicago)

\nEleanor Knox (King's College London)

\nVesselin Petkov (Minkowski Institute\, Montreal)

\nSteven Savitt (University of British Columbia)

\nAnguel Stefanov (Bulgarian Academy of Sciences)

\nJames Owen Weatherall (University of California\, Irvine)

\nChristian Wuethrich (University of Geneva)

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