Hyperunified field theory and Taiji program in space for GWD

In this talk, I present the recently established hyperunified field theory (HUFT) \cite{YLWU1,YLWU2} for all basic forces and elementary particles within the framework of gravitational quantum field theory (GQFT)\cite{YLWU3,YLWU4} in hyper-spacetime. GQFT treats gravity as a gauge theory in the framework of quantum field theory to avoid the long term obstacle between the general relativity and quantum mechanics. HUFT is built based on the guiding principle: the dimension of hyper-spacetime correlates to intrinsic quantum numbers of basic building blocks of nature, and the action describing the laws of nature obeys the gauge invariance and coordinate independence, which is more fundamental than that proposed by Einstein for general relativity. The basic gravitational field is defined in biframe hyper-spacetime as a bicovariant vector field, it is a gauge-type hyper-gravifield rather than a metric field. HUFT is characterized by a bimaximal Poincar\'e and hyper-spin gauge symmetry PO(1,$D_h$-1)$\Join$SP(1,$D_h$-1) with a global and local conformal scaling invariance in biframe hyper-spacetime. The gravitational origin of gauge symmetry is revealed through the hyper-gravifield that plays an essential role as a Goldstone-like field, which enables us to demonstrate the gauge-gravity and gravity-geometry correspondences and to corroborate the gravitational gauge-geometry duality with an emergent hidden general linear group symmetry GL($D_h$,R). The Taiji Program in Space for the gravitational wave detection in China\cite{Nature,Taiji,HUWU} is briefly outlined.