How Were the Voids Formed?
Any theory of the origin of large scale structure must account for the
formation of voids, which occur on scales of approximately 100 Mpc.
If we take as a
reasonable estimate of a peculiar velocity for a galaxy
~ 600 km/s, it would take 160 billion
years for such a galaxy to travel 100 Mpc and
cross a void--far
longer than the age of the Universe.
Therefore, it is extremely unlikely
that the voids were formed by galaxies moving out of a region
after their formation. The galaxies must
have formed near where they are today, so voids must reflect the
distribution of our present galaxies at the time when they were created.