  M-theory compactifies on a seven-dimensional time-dependent hyperbolic or
flat space to a four-dimensional FLRW cosmology undergoing a period of
accelerated expansion in Einstein conformal frame. The strong energy condition
is violated by the scalar fields produced in the compactification, as is
necessary to evade the no-go theorem for time-independent compactifications.
The four-form field strength of eleven-dimensional supergravity smoothly
switches on during the period of accelerated expansion in hyperbolic
compactifications, whereas in flat compactifications, the three-form potential
smoothly changes its sign. For small acceleration times, this behaviour is like
a phase transition of the three-form potential, during which the cosmological
scale factor approximately doubles.
