As a physics teacher (and a generalist) it is important to keep current with the latest issues in the discipline. The following is a list of physicists who offer valuable insight into the Queen of All Sciences.
1. Brian Greene - String Theory. His book the Elegant Universe also has some wonderful descriptions of Quantum Mechanics and General Relativity.
2. Stephen Hawking - Not a personal favourite of mine but his work on Black Holes is very much respected.
3. Roger Penrose - A great read for Generalists exploring Cosmology and Particle Physics. Offers an important criticism of String Theory.
4. Michio Kaku - When looking at extra dimensions. He is your man.
5. Simon Singh - If Penrose is too complicated. Give Singh a try. Has written on Fermat's Last Theorem, the Big Bang and Encryption as well.
6. Stephen Weinberg - Nobel Prize Laureate. Has written extensively on Particle Theory and the Big Bang.
7. Fred Hoyle - Although deceased and has had some of his theories discredited, Hoyle is arguably one of the most creative thinkers in the discipline. A great all-rounder Hoyle has tackled a variety of topics from the origin of Life on Earth to the Steady State Model and more. He actually coined the term Big Bang despite not agreeing with it.
8. Gerald Schroeder - Orthodox Jew and former MIT prof, Specializes in the linkage between Modern Physics and G-d's revelation.
9. Nick Herbert - Worth reading for a look at 'Faster than Light Travel'.
10. Richard Feynman - Another Nobel Laureate. Did phenomenal work on explaining difficult topics in modern physics (and classical physics) to students - See Feynman Lecture Series. He is the Father of Quantum Chromodynamics.
11. John Barrow - If you like analyzing the different Theories of Everything , Barrow is a wonderful starting point.
12. New Scientist Magazine - Regularly contains cutting edge articles on cosmology, particle physics and Theories of Everything. Generally open minded in their analysis.
13. Lee Smolin - Valuable contributor to Quantum Loop Gravity the main rival to String Theory as a potential Theory of Everything.