Seminar

Title: A New Unified Theory of Electromagnetic and Gravitational Interactions

Speaker: Prof. Li-Xin Li （李立新）(Peking University)

Time: 10:00AM, July 11st (Monday)

Place: Theoretical Physics Division，319

Abstract:In this talk we present a new unified theory of electromagnetic and gravitational interactions.  By considering a four-dimensional spacetime as a hypersurface embedded in a five dimensional bulk spacetime, we derive the complete set of field equations in the four-dimensional spacetime from the five-dimensional Einstein field equation. We show that, besides the Einstein field equation in the four-dimensional spacetime, a new electromagnetic field equation is derived: ∇_aF^ab−xR^b_aA^a = −4pJ^b with x = −2, where F^ab is the antisymmetric electromagnetic field tensor defined by the potential vector A^a, R_ab is the Ricci curvature tensor of the hypersurface, and J^a is the electric current vector. The new electromagnetic field equation differs from the Einstein-Maxwell equation by a curvature-coupled term x R^b_aA^a, which addresses the problem of incompatibility of the Einstein-Maxwell equation with a universe containing a uniformly distributed net charge as discussed in a previous paper by the author. Hence, the new theory is physically different from the Kaluza-Klein theory and its variants where the Einstein-Maxwell equation is derived.  In the four-dimensional Einstein field equation derived in the new theory, the source term includes the stress-energy tensor of electromagnetic fields as well as the stress-energy tensor of other unidentified matter. We show that, under some conditions the unidentified matter can be interpreted as a cosmological constant in the four-dimensional spacetime. We argue that, the new electromagnetic field equation and hence the new unified theory can be tested in an environment with a high mass density, e.g., inside a neutron star or a white dwarf, and in the early epoch of the universe.

Vidyo: http://vidyo.ihep.ac.cn/flex.html?roomdirect.html&key=MIYnttR57DSWlfYMvF7gr6uXY

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