Top-Down Theories
In top-down theories of
structure formation, large structures such as superclusters of galaxies form first and these then fragment to form
smaller structures like galaxies. Theories of this kind predict that supercluster size blobs collapse into
pancake like structures and that smaller density condensations within this pancake
collapse to form galaxies and clusters
of galaxies. Such theories can account for much observed
structure, but they have difficulty in forming galaxies quickly
(as required by high redshift observations) and predict significant galaxy formation going on today, which is not
observed.