Minisuperspace
Encyclopedia
In quantum gravity
, the phase space
is infinite dimensional as we are dealing with a field theory. An approximation which is sometimes taken is to only consider the largest wavelength modes of the order of the size of the universe when studying cosmological models. This is the minisuperspace approximation. The validity of this approximation holds as long as the adiabatic approximation holds.
An example would be to only consider the scale factor and Hubble constant for a Friedman-Robertson-Walker model.
Quantum gravity
Quantum gravity is the field of theoretical physics which attempts to develop scientific models that unify quantum mechanics with general relativity...
, the phase space
Phase space
In mathematics and physics, a phase space, introduced by Willard Gibbs in 1901, is a space in which all possible states of a system are represented, with each possible state of the system corresponding to one unique point in the phase space...
is infinite dimensional as we are dealing with a field theory. An approximation which is sometimes taken is to only consider the largest wavelength modes of the order of the size of the universe when studying cosmological models. This is the minisuperspace approximation. The validity of this approximation holds as long as the adiabatic approximation holds.
An example would be to only consider the scale factor and Hubble constant for a Friedman-Robertson-Walker model.