A nice cosmological model [pdf]

This is a cool not-so-new cosmological model to get rid of the dark matter/energy issue, by providing a better theory.

In summary, the big bang generated both matter and antimatter, and those 2 are only interacting throught repulsive gravitational force. A fun project would be to reproduce the computation experiment done by the author which recreated the spiral structure of galaxies using the law : positive matter attracts positive matter, negative matter attracks negative matter, positive and negative repulse each other.