The senior thesis is the capstone of the physics major and an opportunity for intellectual exploration broader than courses can afford. It is an effort that spans the whole academic year. The thesis is a great opportunity to dive into research on an aspect of physics which most engages you. Whether your thesis is on biophysics, gravity and cosmology, condensed matter, or string theory, writing it is way to put to use all that you have learned in coursework so far—and to make a contribution to scientific knowledge. Even for topics outside of the mainstream of physics, for example with a focus on policy, or neuroscience, or finance, we expect you to apply your undergraduate physics education to the problem you focus on.
You can build on previous work in your senior thesis, for example summer work or a junior paper. However, it is equally acceptable to start a brand new project in the fall of your senior thesis with an adviser you have not previously worked with. In any case, in order to have a level playing field, your thesis will be evaluated based on work done during the academic year.
You must communicate your choice of adviser and topic to the Undergraduate Administrator by the third Monday of the fall term. Your adviser must have a full-time faculty appointment at Princeton University. Your adviser can be one of your junior paper advisers, but need not be. If your adviser does not have their primary appointment in the Physics Department, you must communicate your choice of second reader to the Undergraduate Administrator by the third Monday of the fall term, and this second reader must have a full-time faculty appointment at Princeton University with their primary appointment in the Physics Department.
You must turn in a ten-page draft of content for your senior thesis by 3:00pm on the Friday before Dean's Date of fall term, as explained in the section entitled Fall term draft.
The final version of your senior thesis is due by 3:00pm on the Monday of the University's deadline for submitting the senior thesis. The requirements when turning in your senior thesis are somewhat detailed; please consult the section entitled Grading. The page on important dates gives a complete listing of dates and deadlines relevant to the senior thesis. In case of any confusion about dates and deadlines, the page on important dates should be regarded as authoritative.
An oral examination conducted by the the Senior Committee at the end of the senior year serves as the senior departmental examination. This exam is described in more detail below in the section entitled Oral Examination.
A committee of several faculty in Physics oversees all the senior theses. In AY 2019-2020, the committee members are Professor(s) Suzanne Staggs (chair), Alexander Polyakov, Andrei Bernevig and Lyman Page. The senior committee is assisted by Karen Kelly, the Undergraduate Administrator. The committee meets with the seniors at the beginning of the academic year to outline what is expected and to help them get started on choosing advisers and topics. The committee may establish milestones during the year (e.g. a due date for a thesis outline and/or an oral progress report) in addition to the ones indicated on this webpage; any such additional milestones will be announced to all seniors via e-mail and clearly indicated on the important dates page. You are encouraged at any time to approach members of the senior committee with questions or concerns about the progress of your thesis work.
Best advice in finding an advisor is to go to several faculty members in areas of research that you are interested in, and see what topics they propose. If you have a topic to propose yourself, great: Shop it around to faculty and see what they think. Most topics come from faculty as part of the work their research group is conducting. When you have a tentative topic in mind, start by reading some of the literature, ideally at the Scientific American level, in order to understand the highlights and context of the work you'll embark on. If you're undecided between topics, this first stage of reading should help you choose. Make sure to circle back to your prospective adviser with questions, and confirm with them before the deadline that they are in fact prepared to advise you on a topic that you have both agreed on. It's important to start this process at the very beginning of term, because false starts are possible.
The most important advice we can give is to make a fast start on your senior thesis, and focus on it particularly at the start of the fall term. Adjust your courses accordingly; for instance, senior fall is not the right time to shop five courses. Experience suggests that distractions and delays occur from time to time, both expected (e.g. grad school applications) and unexpected (e.g. your adviser disappears to a conference just when you need help). If you have a good start on your thesis you can put it aside briefly when such a delay occurs. If you don't, it becomes harder and harder to catch up. Regardless of where you are in the term—and especially early on—best advice is to set your senior thesis at top priority.
Students considering thesis topics mostly or entirely outside of physics should consider the application procedure outlined in the section below entitled Alternative grading rubric. Please note that time is of the essence in applying for an alternative grading rubric.
A draft of content to be included in your senior thesis must be turned in to the Undergraduate Administrator by 3:00pm on the Friday before Dean's Date of fall term. The second reader must be identified to the Undergraduate Administrator at the time you turn in this draft of content. (Even if you have previously identified your second reader, e.g. because you are working with a primary advisor outside the department, please confirm this choice at the time of turning in your draft of content.) This draft of content will be assigned a P/D/F grade by your advisor and second reader, and the grade will be reported to the senior committee; however, it will not appear on your Princeton transcript. The draft of content is intended to serve as a status check and a way to start the conversation with your advisor and second reader about the spring term end game for your thesis. The guidelines for the draft of content are as follows:
- The minimum length is 7 pages, plus front matter and bibliography.
- The document should be written in full sentences and paragraphs, in the style you intend for the final version of your senior thesis. An outline of work to follow can be included at the end, but the main focus of the document should be on what you have understood and done so far.
- Formatting should be the same that you intend to use in the final version of your senior thesis; in particular, front matter (including the Student Acknowledgment of Original Work, signed), introduction, main body, and bibliography should be present, with all the formatting as you intend for the final version of your senior thesis. In short, follow the guidelines in the Primary grading rubric. Indicate clearly in the front matter that the document is a draft of content.
- While it is anticipated that your results will be quite incomplete, do make an effort to communicate the background in an accessible fashion that starts with the fundamentals and demonstrates your understanding of the context of your ongoing work.
To set high goals for the thesis, and at the same time to accommodate the breadth of experience that physics majors seek, the Physics Department has a dual rubric approach to grading. The primary grading rubric for the senior thesis is the one set forth in detail in the section below entitled Primary grading rubric. It should be used for all theses which are primarily focused on a topic in physics, broadly construed. Applied physics, biophysics, astrophysics, plasma physics, and mathematical physics (among others) are fields in which this primary rubric should be used. Every student is advised to take pains to make their thesis accessible to physicists outside their discipline. Doing so is part of good presentation, and it is part of showing the student's own mastery of their topic. The physical principles involved should be explained clearly, starting at the level of undergraduate physics courses. Any necessary jargon should be introduced with clear explanations.
The main basis for the final grade will be the physics content contained in the thesis as a document. Physics content could include, for example, theoretical ideas, calculations, modeling, and predictions; experimental methods, description of apparatus, results, and data analysis; and an assessment of the significance of the work reported in the thesis against the backdrop of the larger field of which it is part. Physics content can be particularly noteworthy, for instance a really new theoretical idea or a genuinely impactful experimental result; but humbler advances, such as verification or extension of published calculations, or successful calibration of an experimental device, are also highly esteemed. In short, new research results are desirable but not required for even the highest grades; rather, scholarly substance is the key.
Written presentation is also important and will affect the final grade. Good presentation includes all aspects of scholarly writing, including clear explanations, organization, and citations; correct spelling, grammar, and formatting; a style that is at once accessible and precise; and a logical structure including front matter, introduction, main body, conclusion, and bibliography. By front matter, we mean everything prior to the main content of the thesis. Front matter must include in the first two pages the title, the student's name, an abstract, the Student Acknowledgment of Original Work, and a signature following this acknowledgment. The wording of the Acknowledgment must be as set forth in the current edition of Rights, Rules, and Responsibilities: "This paper represents my own work in accordance with University regulations."
Page formatting should be suitable for printing on standard 8.5" x 11" paper with one to one and a half inch margins all around the main text. All fonts should be between 10 and 14 points, and line spacing should be anywhere between double spacing and 1.5 spacing. Pages should be numbered, with numbers no closer than half an inch to any edge of the page. Figures should be clear and legible, with descriptive captions. There is no length requirement, but a total length (including front matter, bibliography, figures, appendices, etc) of 50 to 100 pages is about right for most topics. The thesis must be turned in to the Undergraduate Administrator in hardcopy by 3:00pm on the Monday of the University's deadline for submitting the senior thesis, with a clear indication in writing that the document being turned in is the official version of the thesis. Binding the hardcopy is common but not required. Electronic copies of your thesis sent to your adviser and second reader are required by the end of the day. The hardcopy version turned in to the Undergraduate Administrator and electronic submission to Mudd Library are what counts for purposes of satisfying requirements for graduation.
Grade recommendations from the adviser and second reader are communicated to the senior committee, along with short text descriptions describing and assessing the thesis. The letter grade from the Oral examination will count for 10% of the senior thesis grade. The following grade descriptions are representative of Physics Department grading practices. Any individual thesis may have qualities spread across several of these descriptions, and it is ultimately up to the judgement of the Physics Department faculty to balance the considerations in any given case in order to come up with the final grade.
- A+. A substantial, professional-level contribution to some field of physics, with outstanding presentation and truly impressive content. For example, there may be original results suitable or almost suitable for publication in a peer-reviewed journal which physicists working in this field often publish in. Or the thesis may be a brilliantly written review paper which could usefully be shared with professional colleagues. A written statement from the advisor justifying the A+ must be included.
- A. The thesis deals with some topic in physics in an unusually thorough way, with unexpected insights and/or an especially clear presentation. The advisor should have learned new things from it. This grade should be used for work that goes far beyond "doing a good job."
- A-. The thesis covers some topic in physics well and goes into significant depth. It is written in a professional style with only minor flaws. The student shows mastery of the subject.
- B+. The thesis covers a topic in physics well, and in some depth. The presentation and physics content are good but leave room for improvement.
- B. The thesis covers a topic in physics fairly well. Presentation and physics content are fairly good, but some deficiencies may be noted.
- B-. The thesis addresses a topic in physics but without the depth expected for senior independent work. There may be significant errors or an inadequate presentation.
- C+. The thesis contains an overview of a topic in physics, but the physics content is mostly superficial. The presentation may be inadequate, and there may be significant errors or omissions.
- C. The thesis contains a partial or superficial overview of a topic in physics. The thesis gives little evidence of understanding of the relevant physics. The presentation is sloppy, and there are significant errors or omissions.
- C-. The thesis contains some correct information about a topic in physics, but it fails to show understanding of the relevant physics. The presentation is incomplete, with serious errors or omissions.
- D. The lowest passing grade. The thesis is deficient in multiple respects, with minimal physics content, poor presentation, and/or poor scholarship.
- F. There are several ways an F can result. One way is for the thesis to be largely incomplete and incorrect. A second way is for the thesis not to be turned in on time, accounting for any extensions granted, or for a document to be turned in without a clear written indication that it is the official version of the student's senior thesis. A third way is for the thesis to be turned in on time but with issues that prevent it from being accepted. Examples of this last are omitting from the first two pages the title, the student's name, the abstract, the Student Acknowledgment of Original Work, or a signature following this acknowledgment. Formatting that renders the thesis unreasonably difficult to read may also prevent it from being accepted and result in an F.
Students wishing to branch out and work on a senior thesis topic that is mostly or entirely outside of physics will have their theses graded using an alternative grading rubric customized to their field of work, provided they receive approval from the senior committee of a proposal submitted in hardcopy to the Undergraduate Administrator no later than 3pm on the fourth Monday of the fall term. (An electronic copy sent to the Undergraduate Administrator will be appreciated as a courtesy, but on-time receipt of the hardcopy version is what is required.) The proposal must consist of the following points:
- Student's name.
- Adviser's name. The adviser must sign next to their name to indicate their endorsement of the proposed grading rubric.
- Second reader's name. As with all theses in the Physics Department, your adviser and the second reader should both have full-time faculty appointments at Princeton University, and at least one of them should have their primary appointment in the Physics Department.
- A tentative thesis title (200 characters or less).
- Summary of proposed work (1500 to 2000 characters).
- Give us a simple description of the area of scholarship your thesis falls in. For example, "Climate policy" or "Behavioral neuroscience."
- Provide a short explanation of why you are interested in this area, and why it should be of general interest to professional physicists.
- Provide an adaptation of the primary grading rubric that you feel is suitable to your thesis work. The text to adapt is the entire contents of the section entitled Primary grading rubric. Leave the second, third, and fourth paragraphs unchanged, as these sections will be applied in any case; likewise the criteria for an F cannot be changed. Changes to the rest of the text should be at the minimal level needed in order for it to be fairly applied to the work you are going to do. For example, if you are working on climate policy, replacing "physics" by "climate policy" throughout should be a good start. Topics which have some physics content but are primarily outside of physics should include in the grading rubric some measure of how well the physics is developed and presented.
The senior committee may adjust or rewrite the grading rubric you propose before approving it, and the final rubric will go to your adviser and second reader as well as to you.
Proposals that are approved will allow a thesis to be graded at the same standard as other Physics Department senior theses, but in a different direction. Students who do pursue a topic outside of physics should make a particular effort to make their thesis accessible to physicists and students of physics, and this effort will be counted as part of a good presentation. If a proposal is not received on time by the senior committee or is not approved, thesis work will be graded according to the Primary grading rubric: In particular, the physics content will then be the main basis for the final grade.
A fall term draft of content as outlined in the section entitled Fall term draft is required for all theses.
The oral examination will be scheduled near the end of the academic year, after you have turned in your senior thesis. You should prepare a presentation with a planned duration of 20 minutes. Use standard visual aids, i.e. PowerPoint or similar. Presentations should be well organized and thoughtful; in particular:
- If you want to use a laptop, you are responsible for making sure things work!
- Have enough paper copies of your presentation material so that every committee member can have their own copy. Paper copies are useful even when you use PowerPoint from a laptop and serve as a backup in case of a technical glitch.
- Limit your main presentation to approximately 15 slides (depending on your style). If you have more material, prioritize it and put extra material at the end as backup slides.
- Do not expect committee members to flip through your thesis during the exam; your presentation should be self-contained.
- Emphasize graphical material in your slides (including key equations).
- If you have text in your slides, focus on terse summaries and avoid long segments of text.
- Rehearse! You can rehearse before a group of friends, or your advisor, or a graduate student, or an empty room.
The senior committee is entitled to ask questions both about the thesis and about undergraduate physics. The grade for the oral depends on both the quality of the presentation and your ability to answer questions.
The oral examination will be assigned a letter grade by the senior committee. It is communicated to the Registrar as a PDF grade (i.e. any grade in the A, B, and C ranges will be converted to a P). The original letter grade for the oral examination will count for 10% of the senior thesis grade.