String Theory & Cosmology
String theory may be viewed as a framework for exploring new exotic ideas on the frontier of theoretical physics. At its heart, the subject aims at describing a consistent theory of quantum gravity, in addition to being a short length scale completion of the Standard Model of particle physics. The subject’s most prevalent successes to date are twofold: convincing evidence that the theory resolves various long standing puzzles arising in black hole physics; and phenomenological realizations of models that appear to mimic the world we see at low energies. While the theory itself as a whole may still evolve beyond its current form, several of the new concepts that it has developed are expected to survive at the foundation of a future formulation of the laws of physics.
If you're an undergraduate interested in exploring string theory, you would want to take:
Physics 111 (Analytical Mechanics) as a Sophomore (or Junior)
Physics 154 (Classical Field Theory) as a Junior
Physics 172 (General Relativity) as a Junior
Physics 197/198 (Directed Reading) as a Junior reading Zwiebach's book on string theory and some differential geometry
You would then start working on a string theory problem during the Summer prior to your Senior year, and complete your Senior Thesis on string theory.
If you are considering specializing in string theory in graduate school - or in general in theoretical physics - I also strongly recommend that you sustain a GPA of 3.75 or above: graduate schools do not want too many theorists (for that matter, no one wants too many theorists), and hence are very selective with regards to admitting theory students.
And here’s a list of decent textbooks for learning theoretical physics at the undergraduate level:
String theory by Zwiebach
Differential geometry by Frankel or Nakahara
Special and General Relativity by Stephani
Field theory by Ramond
Classical field theory by Rubakov
My research focus is string theory. I am interested in understanding the small scale structure of space, in a context where both gravitational dynamics and quantum mechanics become important. This realm often involves studying black holes, unravelling exotic dynamics such as non-commutative geometry, and exploring new frameworks that extend the Standard Model of particle physics and standard inflationary cosmology. A list of my publications can be found at the preprint arxiv.