What Are Simple Unsolved Problems in Astrophysics for Beginners?

[stanford1463]

so what are some simple unsolved problems in astrophysics, that are interesting. could someone just list some topics out? I've been researching on the interwebz, but can't seem to find a topic that is interesting/simple.
also are there any such topics related to Newtonian mechanics/electricity and magnetism?
I don't have a really advanced background in physics, as I am only taking an introductory college course.
thanks!

 

[stanford1463]

bump. specifically, I'm interested in the shape and origin of the Universe.
how can knot theory explain the shape of the Universe? specific info would be helpful. thanks!