How are galaxies formed?

The galaxies are interesting because they are part of our cosmic story. There are two leading theories of how galaxies were formed. One states that the stars were formed by the collapse of vast clouds of gas and dust under their own gravitational pull ( also called the top down theory) . Indeed galaxy is a huge system of stars, gas, dust and dark matter. The other states that the early stages of universe had many ”lumps” of matter which clumped together to form a galaxy (also known as bottom up theory). Scientists used supercomputers to look back in time and simulate how a galaxy was formed. However the results involved some aspects of both the theories. Galaxy formation has not stopped as the universe continues to evolve.