06/29
2023
Seminar
- Title题目 On the possible Origin and Nature of the Cosmological Constant
- Speaker报告人 Fedor V. Kusmartsev （College of Art and Science, Khalifa/Loughborough University）
- Date日期 2023年6月29日 2:30pm-4:30pm
- Venue地点 南楼6620
Abstract摘要
We find that the cosmological constant is a geometric invariant that captures the local orientation of spacetime provided by the proper orthochronous Lorentz group on cosmic scales. Effectively, the cosmological constant provides an arrow of time for causally connected observers. This is possible due to the existence of a symmetry within the space of 2-forms in four-dimensional General Relativity. We consider the set of endomorphisms on the space of 2-forms in four-dimensional General Relativity. We show that this set naturally inherits a group structure with appropriate identity defined on the space of 2-forms. When the spacetime is Einstein this group is Abelian. Consequently, the irreducible representations of this group are one-dimensional. We show that the cosmological constant corresponds to the conjugacy classes of these irreducible representations. The origin of the cosmological constant is thus associated with a unique class of symmetry within four-dimensional General Relativity: its nature is entirely geometrical. The symmetry itself is recognition that spacetime is curved regardless of the presence of energy-momentum. The observed accelerating expansion of the universe thus implies that spacetime respects such symmetry and hence that we exist in a universe that is manifestly Einstein. Consequently the cosmological horizon associated with the cosmological constant is a direct prediction of General Relativity. The theory alone sets no preferred scale for the horizon.
报告人简介：
Prof. Fedor Kusmartsev, currently based at Khalifa University in the United Arab Emirates received his PhD from the Lev Landau Institute for Theoretical Physics. His research interests include the physics of condensed matter, astrophysics and cosmology, topology in physics and cosmology, etc. He is a Fellow of the Higher Education Academy (FHEA, UK 2020), the American Physical Society (FAPS), and the British Institute of Physics (FInstP). He was the chairman of the European Network-Programme "Arrays of Quantum Dots and Josephson Junctions" and a member of international editorial advisory boards for several scientific journals, including Scientific Reports (NATURE), J. of Physics A, and Supercond. Science and Techn.
邀请人：
蔡荣根 研究员
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