  Our representation of the Universe is built with sequences of symbols,
numbers, operators, rules and undecidable propositions defining our
mathematical truths, represented either by classical, quantum and probabilistic
Turing Machines containing intrinsic randomness. Each representation is at all
effects a physical subset of the Universe, a metastructure of events in space
and time, which actively participate to the evolution of the Universe as we are
internal observers. The evolution is a deterministic sequence of local events,
quantum measurements, originated from the local wavefunction collapse of the
complementary set of the observers that generate the local events in the
Universe. With these assumptions, the Universe and its evolution are described
in terms of a semantically closed structure without a global object-environment
loss of decoherence as a von Neumann's universal constructor with a semantical
abstract whose structure cannot be decided deterministically a-priori from an
internal observer. In a semantically closed structure the realization of a
specific event writing the semantical abstract of the constructor is a problem
that finds a "which way" for the evolution of the Universe in terms of a choice
of the constructor's state in a metastructure, the many-world Everett scenario
from the specific result of a quantum measurement, a classical G\"odel
undecidable proposition for an internal observer, exposing the limits of our
description and possible simulation of the Universe.
