A galaxy is an enormous collection of gas, dust and billions of stars held together by gravity. One galaxy can have hundreds of billions of stars and be as large as 200,000 light-years across.1
Galaxy Formation: “We have no direct evidence of how galaxies were formed, how the first stars formed without the help of prior generations of stars, how galaxies evolved.”John Mather NASA Goddard Space Center 1998
Review the quote below from a reputable source Space.com and review all the assumptions. I added the parenthesizes and the italics to clearly show that the statement apart from assumption is meaningless.
Astronomers aren’t certain exactly how galaxies formed. After the Big Bang (assumption), space was made up almost entirely of hydrogen and helium (assumption). Some astronomers think that gravity pulled dust and gas together (assumption) to form individual stars (assumption), and those stars drew closer together (assumption) into collections that ultimately became galaxies (assumption). Others think (assume) that the mass of what would become galaxies drew together (assumption) before the stars (assumption) within them were created.”https://www.space.com/15680-galaxies.html
Balance of quote after removing all the assumptions: Astronomers aren’t certain exactly how galaxies formed. Well, perhaps: Astronomers know nothing regarding how galaxies formed …