Physics (Ph)

The physics option offers a program leading to the degree of Doctor of Philosophy. This program prepares students for careers in scientific research or research combined with teaching, and so its most important part is independent research. Courses are offered that give a broad treatment of both fundamental physics and specialized physics research topics. These are intended both to help a beginning graduate student prepare for research and to broaden an advanced student’s knowledge of physics. Caltech research opportunities include elementary particle physics, nuclear physics, cosmic-ray, gamma-ray, and X-ray astronomy, submillimeter astronomy, condensed-matter physics, atomic/molecular/optical physics, quantum information, applied physics, gravitational physics, cosmology, astrophysics, mathematical physics, biophysics, and theoretical physics. 

A Master of Science degree may be awarded upon completion of a program of courses. Students are not normally admitted to work toward the M.S. in physics unless they are also working toward a Ph.D. 

The application submission deadline for physics is December 15. The admission process follows Institute regulations. The GRE tests (general and advanced subject) are not required and scores will not be considered for admission. 

A Master of Science degree in physics will be awarded, upon request, to physics Ph.D. students who have completed the oral and written candidacy examinations. Alternatively, a master’s degree will be awarded to any Caltech graduate student in good standing upon satisfactory completion of a program approved by the option representative that fulfills the following requirements:

Substitutions of other graduate courses in place of the above requirements must be approved by the option representative.

In exceptional cases, undergraduate students may receive concurrent B.S./M.S. degrees if the above requirements are met in addition to the relevant B.S. requirements, upon approval from the Physics Graduate Committee, the graduate admissions committee, and the physics executive officer. Such students must produce a detailed petition demonstrating accomplishments that would warrant normal admission to the physics graduate program.

In addition to the general Institute requirements for a Ph.D., the particular requirements for a doctorate in physics include admission to candidacy as described below, writing a thesis that describes the results of independent research, and passing a final oral examination based on this thesis and research. Physics graduate students may exercise the pass/fail option on any and all courses taken. 

An academic adviser is appointed for each student upon admission to the graduate program in physics. The academic adviser will serve as the primary mentor until the student finds a research adviser. Students will meet with their academic adviser to decide on their first-year course schedule, and are encouraged to continue these meetings quarterly until the student finds a research adviser. During the first year of study, students should consult with their academic adviser, the option representative, the executive officer, and/or individual faculty members to select a tentative research group. Once a research adviser is selected students may either replace the originally appointed academic adviser or maintain both a research adviser and academic adviser. At any time, a student may consult with the option representative concerning such matters as advising.

Students should consult with the executive officer to assemble their oral candidacy committee and Thesis Advisory Committee (TAC) by the end of their third year. The TAC is normally constituted from the candidacy examiners, but students may propose variations or changes at any time to the option representative. The TAC chair is normally someone other than the research adviser. The TAC chair will typically also serve as the thesis defense chair, but changes may be made in consultation with the executive officer for physics and the option representative.

The candidacy committee will examine the student’s knowledge of their chosen field and will consider the appropriateness and scope of the proposed thesis research during the oral candidacy exam. This exam represents the formal commitment of both student and adviser to a research program. After the oral candidacy exam, students will hold annual meetings with the TAC. The TAC will review the research progress and provide feedback and guidance towards completion of the degree.

The TAC, research, and/or academic advisers provide the majority of mentoring to the student. In addition, the option representative and other members of the faculty are always available to provide advice and mentoring on any aspect of research, progress toward the Ph.D., future careers, and other aspects of life in graduate school.

Physics students must demonstrate proficiency in all areas of basic physics, including classical mechanics (including continuum mechanics), electricity and magnetism, quantum mechanics, statistical physics, optics, basic mathematical methods of physics, and the physical origin of everyday phenomena. A solid understanding of these fundamental areas of physics is considered essential and proficiency will be tested by two written candidacy examinations. 

No specific course work is required for the basic physics requirement, but some students may benefit from taking several of the basic graduate courses, such as Ph 106, Ph 125, and Ph 127. A syllabus describing the exam contents will be available, and students are encouraged to study independently for the exams, rather than taking a heavy load of basic physics courses. In addition, the class Ph 201 will provide additional problem solving training that matches the basic physics requirement.  

The written exams are typically offered in July and in October, and the two separate exams may be taken at different times. This flexible scheduling of the written exams allows students to prepare for the exams while simultaneously learning about research areas, either through advanced courses, reading courses, or participation in a research group. The exams can be attempted up to three times and must be successfully completed by the end of the second year of study.

In addition to demonstrating a proficiency in basic physics, students must also establish a broad understanding of modern physics through study in six graduate courses. The courses must be spread over at least three of the following four areas of advanced physics: 

1. Physics of elementary particles and fields:
   Nuclear physics, high-energy physics, string theory
2. Quantum information and matter:
   Atomic/molecular/optical physics, condensed-matter
   physics, quantum information
3. Physics of the universe:
   Gravitational physics, astrophysics, cosmology
4. Interdisciplinary physics:
   e.g., Biophysics, applied physics, chemical physics,
   mathematical physics, experimental physics
   

Each area is meant to be covered by the equivalent of a one-term course, and a list of example courses for each of the areas can be found at the physics option website. Other courses may be substituted with permission of the physics option representative.

This exam is primarily a test of the candidate’s suitability for research in their chosen field. The professor with whom the student plans to do research will be a member of the exam committee, and normally the student will have already begun research (Ph 172) on a definite topic with that professor. The examination will cover the student’s research work and its relation to the general field of specialization. Before being allowed to take this exam, a student must have satisfied all the other requirements for admission to candidacy. The oral candidacy exam should be completed by the end of the third year (12 term) of graduate residence.

To be recommended for Ph.D. candidacy, a student must pass two terms of Physics Seminar (Ph 242), satisfy the Basic Physics Requirement by passing the written candidacy examinations, satisfy the Advanced Physics requirements, and pass the Oral Candidacy Examination. These requirements are designed to ensure that students have an adequate preparation in the basic tools of physics, as well as a broad general knowledge of advanced physics. 

There are no specific research requirements, but in general a substantial effort is required to master the techniques in a given field and carry out a significant piece of original research. Students are strongly advised to start doing part-time research as soon as possible by taking reading and research units (Ph 171–172) in parallel with formal coursework.

It is expected that each graduate student will, as part of the Ph.D. graduation requirements, serve as a teaching assistant for at least one term, an experience that most students find provides valuable experience for their future careers. Students are encouraged to fulfill this requirement within the first three years of residency.

A final oral examination will be given not less than two weeks after the thesis has been presented in final form. This examination will cover the thesis topic and its relation to the general body of knowledge of physics. The candidate is responsible for completing the thesis early enough to allow the fulfillment of all division and Institute requirements, with due regard for possible scheduling conflicts. 

The following timeline is required for satisfactory degree progress:

1. Ph 242 should be taken by all students in their first year of graduate study.
2. The written candidacy exams should be attempted by the end of a student’s first year of graduate residence, and be passed by the end of the second year.  
3. The Advanced Physics requirement should be completed by the end of the second year of graduate residence, but may be extended into the third year depending on the availability of specific courses.  
4. The oral candidacy exam must be completed by the end of the third year (12th term) of graduate residence.

A minor is not required, but a student may elect to pursue a minor in another option.

There are no language requirements for a Ph.D. in physics.

Students desiring a subject minor in physics should discuss their proposed program with the chair of the Physics Graduate Committee. Forty-five units from physics courses with numbers over 100 must be taken for the subject minor, excluding any specific courses in physics required for the student’s major program. An oral exam may be required by the Physics Graduate Committee. This exam will include both academic topics and topics on current physics research areas.