  A structured collection of thought provoking conclusions about space and time
is given. Using only the Compton wavelength lambda = hbar / m c and the
Schwarzschild radius r_s = 2 G m / c^2, it is argued that neither the
continuity of space-time nor the concepts of space-point, instant, or point
particle have experimental backing at high energies. It is then deduced that
Lorentz, gauge, and discrete symmetries are not precisely fulfilled in nature.
In the same way, using a simple and new Gedankenexperiment, it is found that at
Planck energies, vacuum is fundamentally indistinguishable from radiation and
from matter. Some consequences for supersymmetry, duality, and unification are
presented.

General Relativity and Quantum Cosmology