Topic: Reformulation of the Cosmological Constant Problem
Speaker: Dr. Qingdi Wang
Coordinates:Room 613, 4pm, Tuesday, Dec. 22
Abstract: The standard formulation of the cosmological constant problem is based on one critical assumption — the spacetime is homogeneous and isotropic, which is true only on cosmological scales. However, this problem is caused by extremely small scale quantum fluctuations and, at that scale, the spacetime is highly inhomogeneous and anisotropic. The homogeneous Friedmann-Lemaître-Robertson-Walker metric used in the standard formulation is inadequate to describe such small scale dynamics of the spacetime. We reformulate the cosmological constant problem by using a general inhomogeneous metric. The fine-tuning problem does not arise in the reformulation since the large gravitational effect of the quantum vacuum is hidden by small scale spacetime fluctuations. The stress energy tensor fluctuations of the quantum fields vacuum could serve as dark energy to drive the accelerating expansion of the Universe through a weak parametric resonance effect.