Great Research Progress beyond Einstein's General Theory of Relativity Quantum Gravity Made by UCAS Scientists


One hundred years ago, Albert Einstein established general relativity by generalizing special relativity, built up the internal relation between gravitation and space-time geometry, it was the epoch-making progress on theoretical physics during the 20’s century. On the other side, special relativity and quantum mechanism as two of the revolutionary progress on theoretical physics in the 20’s century, successfully established relativity quantum field theory. As the basic theory to describe the microcosmic world, it was successfully used on the description of three basic acting force - electromagnetic force, weak and strong force, helped built up the standard model of particle physics, and it was the breakthrough progress on theoretical physics during the 20’s century. The general relativity, as the classical theory on gravitation, its description of cosmo-world was experimentally proved. Even so, the integration of general relativity and quantum mechanics did not succeed till now. The main barriers are: the general relativity based with curved space-time dynamics is no longer translational invariant when it translates in four-dimensional spacetime, the time and space intervals and the amount of physical energy and momentum conservation cannot be identified and measured as in special relativity. Therefore, to build up a self-consistent quantum gravity theory has been a frontier science problem issued by theoretical physicist for more than fifty years. It is not only very important to understand the origin and evolution of the early universe, but also played a fundamental role on universality and self-consistency for the universality of the quantum theory itself. Quantum theory and determinism has been the focus of debate of Einstein and scientists.

Recently, Yue-Liang Wu, Academician, Chinese Academy of Science, State Key Laboratory of Theoretical Physics(SKLTP), Kavli Institute for Theoretical Physics China (KITPC), Institute of Theoretical Physics, Chinese Academy of Sciences, and International Centre for Theoretical Physics Asia-Pacific (ICTP-AP), University of Chinese Academy of Sciences (UCAS), by treating the gravitational force on the same footing as the electroweak and strong forces, present a quantum field theory of gravity based on spin and scaling gauge symmetries. A biframe spacetime is initiated to describe such a quantum gravity theory. The gravifield sided on both locally flat noncoordinate spacetime and globally flat Minkowski spacetime is an essential ingredient for gauging global spin and scaling symmetries. The locally flat gravifield spacetime spanned by the gravifield is associated with a noncommutative geometry characterized by a gauge-type field strength of the gravifield. A coordinate independent and gauge-invariant action for the quantum gravity is built in the gravifield basis. In the coordinate basis, he derive equations of motion for all quantum fields including the gravitational effect and obtain basic conservation laws for all symmetries. The equation of motion for the gravifield tensor is deduced in connection directly with the total energy-momentum tensor. When the spin and scaling gauge symmetries are broken down to a background structure that possesses the global Lorentz and scaling symmetries, he obtain exact solutions by solving equations of motion for the background fields in a unitary basis. The massless graviton and massive spinon result as physical quantum degrees of freedom. The resulting Lorentz-invariant and conformally flat background gravifield spacetime is characterized by a cosmic vector with a nonzero cosmological mass scale. The evolving Universe is, in general, not isotropic in terms of conformal proper time. The conformal size of the Universe becomes singular at the cosmological horizon and turns out to be inflationary in light of cosmic proper time. A mechanism for quantum scalinon inflation is demonstrated such that it is the quantum effect that causes the breaking of global scaling symmetry and generates the inflation of the early Universe, which is ended when the evolving vacuum expectation value of the scalar potential gets a minimal. Regarding the gravifield as a Goldstone-like field that transmutes the local spin gauge symmetry into the global Lorentz symmetry with a hidden general coordinate invariance, a spacetime gauge field is constructed from the spin gauge field that becomes a hidden gauge field. The bosonic gravitational interactions are described by the Goldstone-like gravimetric field and spacetime gauge field. Two types of gravity equation result; one is as the extension to Einstein’s equation of general relativity, and the other is a new one that characterizes spinon dynamics. The Einstein theory of general relativity is considered to be an effective low-energy theory.

Related work was invited to report to International Conference on Gravitation and Cosmology, and the fourth Galileo-Xu Guangqi meeting which aim to celebrate the 100th anniversary of Albert Einstein's presentation of the Theory of General Relativity. See more details on《Physical Review D》【Phys. Rev. D 93, 024012 (2016)】