here are two leading theories to explain how the first galaxies formed. The truth may involve a bit of both ideas.
One says that galaxies were born when vast clouds of gas and dust collapsed under their own gravitational pull, allowing stars to form.
The other, which has gained strength in recent years, says the young universe contained many small "lumps" of matter, which clumped together to form galaxies. Hubble Space Telescope has photographed many such lumps, which may be the precursors to modern galaxies. According to this theory, most of the early large galaxies were spirals. But over time, many spirals merged to form ellipticals.
