We build a model of our spacetime by assuming new particles called "space quanta." In the ambient or bulk spacetime ${ \cal S}^{ D_{ \rm amb}}$ ($D_{ \rm amb} \ge 4$), a multitude of space quanta form a nearly three-dimensional object, whose continuum approximation is called the space 3-brane. The world volume ${ \cal WV}_{ \rm sq}$ of this space 3-brane is described by an embedding $f^A(x^\mu) \in { \cal S}^{ D_{ \rm amb}}$, which produces the induced metric $\gamma_{ \mu \nu}$ on the world volume ${ \cal WV}_{ \rm sq}$. This emergent spacetime (${ \cal WV}_{ \rm sq}, \gamma_{ \mu \nu}$) from the many space quanta is proposed as the particle model of our spacetime. To study our spacetime (${ \cal WV}_{ \rm sq}, \gamma_{ \mu \nu}$), we construct what we call the Aim-At-Target (AAT) method, which introduces an action for a 4D metric $g_{ \mu \nu}$. This metric action from the AAT method can lead to General Relativity at low enough energies. The spacetime (${ \cal S}_{ \rm GR}, { \bf g}_{ \mu \nu}$) of General Relativity is, at least, a good approximation to the exact or true spacetime (${ \cal WV}_{ \rm sq}, \gamma_{ \mu \nu}$) of our universe.
Categories: physics.gen-ph