Physics is my personal favourite science. I try and read as much of it as possible especially with respect to cosmology, theories of everything and the philosophy of the discipline.
The following is a list that I have compiled of 18+ Problems that add to the richness of this field.
1. The Nature of Time Travel - Is it possible at all? If so is it uni or bi-directional?
2. The Existence of Dark Matter - Where does it come from? How dense is it? What is its constituent makeup?
3. Does Dark Energy explain the accelerating expansion of the Universe?
4. Why are the physical constants h, c, G etc so finally tuned? Is there a rationalization behind this or do we have to resort to the Anthropic Principle? Do the constants change with time?
5. How are the Laws of Physics carried and conveyed? How did they come into being in the first place.
6. Will General Relativity and Quantum Mechanics ever be reconciled? Or do we need a third Theory?
7. Is String Theory a valid Theory of Everything or the modern day equivalent of the aether or Phlogiston Theory?
8. How useful is Quantum Loop Gravity as a Theory of Everything?
9. Will the Higgs Boson Particle ever be discovered? And if so will it explain the concept of 'mass'?
10. Is there a level of organization that exists beyond the Quantum Foam? Is it defineable?
11. Is it possible to alter radioactive decay rates? How did they become 'fixed'?
12. How does randomness lead to order? What is the mechanism that faciltates complexity at each level in a hierachy system? Is this independent of the sum of the parts of the system?
13. Is Quantum Mechanics observationally reconcilable within in itself? How does this relation to consciousness?
14. What conditions need to be in place for the expansion of a singularity?
15. Does Newton's Law of Gravity need a 'fix' to the distance term in the denominator to correct for the unknown mass of the universe?
16. How Complete is the Standard Model?
17. How can one ascertain the history of a quark from its structure? ie. Are Quarks time independent?
18. What does the Universe expand into? Is Expansion an illusion?