I assume galaxies may born from dark matter. The early Universe may be
incorrect
as the great void may be just one spot where once there was an
explosion of galaxies.
There are other smaller voids, one very close to our galaxy measuring
2 million light years
in diameter, which is not much, only 20 times the width of our galaxy.
Voids seem to be
void of matter. Once the dark matter is exhausted, galaxies fly in all
directions and the
region remains mostly empty. Some parts of the Universe are seen
giving birth to new
galaxies. Other regions seem to be cold and empty, lacking dark
matter, while regions
giving birth to new galaxies should have a lot of dark matter.

How dark matter could convert to mass? It is mass, an entity like
fluid that should
be smaller than fundamental particles like electrons, but as that it
may not be bound
to the speed of light. There is a lot of evidence that dark matter
moves faster than
the speed of light. One is the structures of black holes producing a
different magnetic
field than black hole predictions, indicating that jets do not spin
off before entering
a black hole, but come from within the black hole. The meaning of pure
energy is
not seen by dark matter reaching it's own black hole event horizon and
converting
into pure energy, light and electrons, electric and electro-magnetic
waves arise
before inertial mass collapses on itself. Jets are made of electrons.