  A natural geometric framework of noncommutative spacetime is symplectic
geometry rather than Riemannian geometry. The Darboux theorem in symplectic
geometry then admits a novel form of the equivalence principle such that the
electromagnetism in noncommutative spacetime can be regarded as a theory of
gravity. Remarkably the emergent gravity reveals a noble picture about the
origin of spacetime, dubbed as emergent spacetime, which is radically different
from any previous physical theory all of which describe what happens in a given
spacetime. In particular, the emergent gravity naturally explains the dynamical
origin of flat spacetime, which is absent in Einstein gravity: A flat spacetime
is not free gratis but a result of Planck energy condensation in a vacuum. This
emergent spacetime picture, if it is correct anyway, turns out to be essential
to resolve the cosmological constant problem, to understand the nature of dark
energy and to explain why gravity is so weak compared to other forces.
