Scientists believe that galaxies are created from one of two theories. First is the Top-down theory, this theory states that when gases collapses in space, it forms large clumps wich are each the size of multiple galaxies. These gas clumps would then break down and form individual galaxies. Scientists believe that this theory is the reason why we find galaxies in clusters.
The other theory is known as the Bottem-up theory. This theory is the opposite of the first theory, where scientists believe that gases in space collapse and compress into clumps the size of millions of suns, which is small for the size of galaxies. The clumps then would merged together to form a galaxy
