Dear Colleagues, The sixth spacetime conference (that had to be held in May 2020) will be finally held (in person) in the famous Black Sea resort "Albena" (near Varna, Bulgaria) from 12 to 15 September 2022: http://www.minkowskiinstitute.org/conferences/2022/ The Scientific Organizing Committee invites papers from physicists, philosophers of physics and philosophers on any topic related to the nature and ontology of spacetime. As there is no main theme of the sixth spacetime conference a number of special sessions have been suggested by colleagues (other suggestions are welcome): - Nature of time - becoming and flow of time - Is spacetime a real (physical) four-dimensional entity or a mathematical concept? - Open Questions in Spacetime Physics - The controversy over Relativistic Mass - The problem with the gravitational energy-momentum pseudo-tensor 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? - What is the difference between matter and geometry in general relativity, semi-classical gravity, and quantum gravity? - Do Black Holes Actually Exist? - Is there a conflict between relativity and quantum mechanics? - Quantum Gravity: Where do we stand? Contributed papers in the form of extended abstracts of between one and two pages should be emailed to 2020conference@minkowskiinstitute.org by July 15, 2022. Submissions will be reviewed and notification of acceptance will be sent by August 1, 2022. Best wishes, Vesselin Petkov Minkowski Institute http://www.minkowskiinstitute.org/ Montreal, Canada http://spacetimecentre.org/vpetkov/