Advice for physics students considering graduate programs

The following is my personal opinion and not that of my employer or anyone else. This advice is intended for US students applying to US universities. Students from other countries should be aware that we have an unusual system: you do not need a master's to apply to a PhD program, and in fact most students entering PhD programs do not have a master's. Furthermore, most physics/astronomy PhD programs support their students financially (through teaching or research assistantships), so that you do not need your own source of money or government fellowship.

Undergrads, be aware that life in a graduate (particularly a PhD) program is very different from life as an undergraduate. This short essay explains it well.

Start preparing early. Most students apply in the fall of their senior year to start a PhD program the next fall. So most of the work you do your senior year does not make it into your application. You will be judged largely on what you did through your junior year and following summer. Make sure that looks good! (In terms of not only grades, but that you challenged yourself.)

The need to do well in classes goes without saying. The more difficult thing is to establish that you can do research. Research involves many skills different from those you use in class, such as real-world problem-solving, creativity, information-seeking skills, motivation beyond grades, long-term vision, resiliency when things do not work, accepting feedback constructively, and being proactive. If you have not established some kind of research record, you will be at a major disadvantage when applying to a PhD program. (By "record" I mean simply that your supervisor/mentor will document it favorably, not that it has to be published.) Don't be afraid to look off-campus for research opportunities if your campus has few. If you do not attend a major research university, try to spend at least one summer at one, getting familiar with the culture of research. Attend journal clubs, group meetings, etc, and interact with grad students and postdocs to get a good sense of what life in research is like.

The REU program is very popular and a great way to find summer research opportunities, but don't rely on it alone because it is too popular; you may not be accepted. At the same time as you submit your REU application (February), start assembling a backup plan. Ask your local faculty how to find a summer research opportunity. Be proactive! If you wait until May to look for a summer research opportunity, you are much less likely to find one, or to find one that matches you well.

Find the type of program that's right for you. PhD programs at major research universities are looking for students who will commit to roughly five years of research. Although their application form may have a checkbox for a master's option, they are not really looking for master's students. This option exists for the occasional special case, such as a military officer who will have full tuition paid by the government. So don't waste your time and money applying for a master's at these places without first checking with them.

If you are ready to commit to roughly five years of research, apply to a PhD program. A master's is not a prerequisite for a PhD program (this is a distinguishing feature of the American system), and in fact could end up wasting some of your time and money if the courses don't transfer to your eventual PhD program.

Institutions that offer master's but not PhD are called "terminal master's" programs. If you want a PhD but do not have a strong enough undergraduate record to get accepted to a PhD program, consider one of these programs. If you do very well there, your PhD application will look stronger. Be aware, however, that PhD programs are looking for students who do well at research. Just doing two more years of classes and demonstrating a high GPA is not enough; you need to demonstrate substantial research skills in your MS years (these may be documented mostly in your letters). Even then, many PhD admission committees would rather take the person who comes straight out of college with great credentials than the person who slowly fought his or her way to the top of the master's heap, so the best advice is to do a great job as an undergrad.

In terminal master's programs you will also find students who are full-time employees of tech corporations, bolstering their education to further their careers. I know less about these programs, but I would guess that the research they do is much more applied. If you are considering terminal master's programs, check with them to see which clienteles they aim to serve and how they will tailor their services to your needs.

How do you know if you do not have a strong enough undergraduate record to get accepted to a PhD program? Check with your top-choice programs to see what their entering class looks like in terms of typical GPA and GRE. They may publish minimum requirements, which might mislead you. Check to see what the typical numbers are. Seek advice from faculty at your undergrad institution. Ask about students from your college who have gone on to PhD programs, and try to get a feeling how you would stack up against them. My experience is that too often applicants are overconfident; they don't realize that there may be a 5:1 ratio of applications to acceptances, and almost every one of those applications is from someone who did reasonably well in their physics courses. This is not meant to discourage people from trying; it is meant to encourage them to do some market research before applying so that they can find some good matches.

What if you just want a master's for itself and not as a stepping stone to a PhD? I don't know much about that, so you should seek out faculty at your college and at prospective master's programs for advice. Make sure it is a marketable degree.

Another distinction between PhD and master's programs is financial. PhD programs will pay your way with teaching and/or research assistantships. At master's programs, my impression is that there is less TA work to go around, so financial support is a bit more spotty, but certainly a possibility. Check with prospective programs on these issues.

Search widely. A PhD program is 5-6 years of your life, so you should search far and wide for the programs that are best for you. Don't limit yourself to the program nearest you, or a few programs close to home. The most basic reason for this is that you may not get in. Many programs admit just 20% of applicants, so if you truly cannot move, you are likely shutting yourself out of a chance for a PhD. Even if you are a strong candidate, admission is not so predictable. In any given year, a program may have a temporary oversupply of current students, or an abundance of strong applicants, in your intended research area. Even within a given area of physics, programs try to maintain a balance of theory vs. experiment, and in any given year this can play out in different ways at different programs. This may make admissions seem a bit more random from the outside than they really are on the inside.

An important aspect of your search is identifying a few faculty members you would like to work with at each institution you apply to. Put these names in your statement of purpose (below); that shows that you've done your homework. If the institution has only one person you would like to work with, you should recognize that you're taking a huge risk: if you go there and find you have a personality conflict with that person, you will be stuck with no backup plan. In addition to putting those names in your statement, email those people and ask them if they are accepting new students, what projects they are most interested in now (their website is most likely out of date), etc. If you hit it off, they will put in a good word with the admissions committee. If you don't...well, you avoided a potentially painful process of finding out too late that you cannot work with that person.

At some places, a faculty member must sponsor you for admission, whereas at others (most I would say, including UC Davis), a committee compares you with a large pool of applicants. Needless to say, at the first type of institution this advice about making early contact with relevant faculty is even more important. At either type, read the online documentation thoroughly before contacting faculty. Busy faculty don't like having to take time to explain things that are documented on the program's website.

Build a strong application package. If you don't have the best grades or you come from a nonselective college, you can't do much to change that on your application. But you do have a few factors under your control:

  • Do well on the GRE. It's unfortunate that much weight is placed on a single three-hour exam, but undergraduate preparation is so nonstandardized that the Physics GRE looms as the only standard measure of physics preparation. If you are from a nonselective institution or have a lowish GPA, this is your chance to covince people that you are strong on pencil-and-paper physics. If you don't do well (above 50th percentile, say), you are just confirming that your physics preparation is not very strong. That doesn't mean that it's impossible to get in; admissions committees look for people who will succeed in their program, period, and the Physics GRE is far from the only or even the best indicator of that. But all else being equal, we really don't want to admit students whose preparation in undergrad physics is weak. Study and practice the GRE style of physics problems. I'm usually not big on focusing on test-taking strategies, but this is a case where strategy helps. You are given only 170 minutes to do 100 problems, so do the easy ones first and don't let yourself get stuck on a problem. Remember, you don't have to answer every one! Seek out resources to help you (many are free on the internet). Form a study group.

    The Physics GRE is very competitive; I've seen students who got A's in their physics courses end up in the 10th percentile of Physics GRE takers. The general GRE is less competitive. Any decent PhD candidate should do well above 50th percentile on the verbal and above 80th percentile on quantitative without having to study much. Again, low scores do not automatically disqualify you, but they point to a weakness that must be overcome with some other strength. If you feel that your GRE scores do not reflect your ability, then take the exam(s) again. I'm always struck by people who state in their application that their GRE scores do not reflect their ability because they had a bad day, etc. That may be true, but you have to demonstrate that it's true by taking it again and having a better day! If you can't take it again in time, that reflects a lack of planning on your part.

  • Strong letters. This may be the most important thing, and you need to plan for it. Letters from your classroom teachers are not very effective; they confirm that you got an A in their class, that you are diligent, etc, but there is little hint of the potential for research. You need letters from people who have mentored you in real research projects, affirming that you have real-world problem-solving ability, creativity, information-seeking skills, motivation beyond grades, etc. So you need to start doing these kinds of projects, preferably before your junior year so you have time to get to know multiple people in this way. (See Start preparing early.)

    When you ask someone to write a letter for you, don't just ask them if they can write a letter; ask them if they can write a good letter and gauge their reaction. Very few people will say, "No, I can't write a good letter." But there are degrees of good, so if someone does not look very enthusiastic you might think about who else you can ask. However, if you did one big summer project that you will mention in your application as a real accomplishment, but there is no letter from that project's mentor, that looks bad too. So the bottom line is to do a great job for your mentor from the start!

    A common question is whether it's better to ask people who really know your work even if they are not famous, than to ask a big name who knows you less well. I would lean toward asking the person who knows you well because that person is more likely to write a thorough and convincing letter. The answer is different if you work in a large lab where the head professor does not know you well, but a postdoc does know your work well. The head professor may be a better person to ask because he/she can write more authoritative statements such as "out of 40 undergrads who have passed through my lab, this person is in the top 5" (and he/she may also talk to the postdoc to get more details). You could also ask them each to write a letter. So there is no one-size-fits-all answer here; talk to the people involved to get a better sense of how it works in your lab. Just don't chase famous people for the sake of the name, because the letter will not be convincing unless you have a real connection with the person.

    Sometimes you don't have three people who know you very well, and you have to ask, say, a classroom teacher. In those cases, it's useful to sit down with them and tell them a bit more about yourself and your career goals, etc, so they can write a better letter. Don't be afraid to sound them out. For example, were you in the top 10% or 20% of their class? If not, maybe you don't want a letter from them. And that's an objective question that I think most teachers will answer without hesitation.

    If you find it difficult to narrow it down to three, again, talking to the people involved will help clarify which three will be most helpful. Although some programs might accept more than three, many do not.

    Always waive your right to see the letters. If the letter writer has a poor opinion of you but knows that you could see it, he/she will have to worry about being sued for destroying your chances for grad school. (It sounds extreme, but I have heard that it happens...more importantly, most letter writers have heard that it happens!) Therefore, the admissions committee will not put much stock in such letters.

    It's ok (more than ok, it's a great idea) to check that your letter writers actually did upload their letters, and to gently remind them if they didn't. These people are busy and occasionally they need a reminder from the person who really has a stake in it.

  • Statement of Purpose. Let's start with what we all agree should not be in a statement (whether a statement of purpose or a personal statement): poor organization, poor grammar, typos, etc. Definitely have someone proofread your statement! Make your statement an example of your good written communication skills.

    What should be in a statement? Follow the guidance on your application form. Typically it prompts you to describe why you want to pursue a PhD in physics (at this institution) and what you see yourself doing in grad school and beyond. So do that. It helps to mention a few specific professors there doing the kind of work you would like to do. This shows that you've actually looked at the department and found it a good match, and that you're organized and good at seeking information.

    A common weakness is being far too broad, for example, "I love physics and want to continue my physics education." That's great, but it's not specific enough to say why you want to enter this program, and hints that you're not ready to focus. Another dead giveaway that you're not ready to focus is when you mention specific areas, but those areas are all over the map: condensed matter, cosmology, plasma physics, etc. It may be that you do have some interest in each of these topics, but a PhD program is time to focus. Once you get in, you can always change your focus and go with plan B; but you need to have a clear plan A. You may even consider applying to some places with plan A and other places with plan B; they don't need to know that. You simply need to present a plan that appeals to the department in question.

    A related mistake is presenting a plan mismatched to the institution: saying you want to do string theory at a place that has no string theorists on the faculty, for example. Even if they think string theory is a valuable pursuit (and there's no guarantee of that!), they have no one to mentor you, so that's a huge downside to your application. Furthermore, is your plan workable? Some people are drawn to such speculative topics that it's a turnoff. Talk to your local faculty to try to figure out what's speculative and what's workable. It's ok if the speculative stuff is there in the background as an inspiration, but you do need to work on something that is actually doable in five years or so. (Don't read this to mean that you need to define your dissertation project already! Just don't appear to be someone who has no idea of what he/she is getting into.)

    If you do your homework up front, you will save money by applying only to the places that best match you, or by tailoring a plan to each place so that you maximize your chance of acceptance.

  • Personal Statement. Many places also ask you for a more personal statement, where you can describe difficulties you have overcome and that sort of thing. This is the most awkward statement for many people to write, and for us to read, because people think they have to fill the space. The fact is, if your record is strong and you followed a conventional trajectory, we don't need to read much about your personal life. But if you followed a nonstandard trajectory, it is critical that you explain it here. For example, some students enter college with no sense of direction or work ethic (high school was too easy for them) and then "wake up" at some point in college, so their GPA climbed dramatically at some point. If that's you, please explain that here; it's more than ok to admit that work ethic was something you learned late in the game (sometimes converts are the most zealous), and this will cause us to look at your transcript and take the more recent GPA rather than overall GPA. Other examples would be explaining why you entered a master's (or other PhD) program and now want to enter this PhD program; why you took time off between undergrad and grad school, etc. It's not good to portray yourself as a victim of events; a much more powerful statement is that you chose to do X because of Y.

    We don't want to hear much about things that held you back unless we also hear about how you overcame them and what you learned from that. For example, if you had to work 30 hours/week to make ends meet, you might describe how you had to became an expert at time management to maintain a 3.6 GPA while doing this. If instead you write that you would have had a GPA above 3.3 but you had to work 30 hours/week, well, that identifies a contributing factor (which is useful) but it looks a bit like avoiding responsibility rather than taking full responsibility.

International students: a few special considerations apply.
  • We don't necessarily know the reputation of your university, so a description will help us. Where is it on your nation's ranking of universities? We also won't know how to normalize letters from faculty at your university, so it will be extremely useful if you have letter writers who are familiar with the American system. Imagine the positive reaction a committee will have when a letter says "This student would easily fit in with the other grad students I knew at Berkeley," for example.
  • In developing countries, students tend to do very theoretical projects because the culture, lacking expensive lab equipment, is focused more on theoretical issues. Give some thought to how to present your work to those in a different environment, and show that you care, at some level, that your theoretical work could have an impact on experimental work. Try to gain some experience with data if you can. In some fields, you can do original research with publicly available datasets.
  • You will no doubt score lower than American applicants on the verbal GRE, and we won't penalize you for that. But you should score even higher on the quantitative and subject exams to make up for it.
  • Some public universities may have policies that, perhaps indirectly, favor the admission of US citizens or residents over others. This is probably a small effect, but just to be safe you should probably apply to a mix of private as well as public universities.

Dealing with offers. When you get an offer, you will probably be asked to respond by April 15, which is the date agreed upon by American universities as the earliest date any student can be required to decide. (If you are asked to decide before then, you have a right to complain strongly.) The biggest misconception students have is that this system forces them to commit to a program in a legally binding way by April 15. Actually, the idea of a uniform date like April 15 is to protect you by giving you time to entertain different offers, rather than to force you into anything. It's ok to change your mind after April 15; you don't sign anything like a legally binding contract when you indicate on or before April 15 that you would like to accept an offer. At UC Davis the form you complete is called "Statement of Intent to Register" and that's what it is: a statement of intent, not a binding contract. If you get a better offer after April 15, take it and rescind your previous intent to register. (Technically, you should ask the first program to release you, but they always will; no one wants an unhappy student.)

Why would some places wait until after April 15 to make you an offer? Let's look at it from the admissions committee's point of view. We send out more offers than slots that we actually have, because we know some (large) percentage of our offers will not be accepted. But we don't want to send out too many offers, because an upward fluctuation in yield could strain our department's resources. We try our best to calibrate this factor, but we could find on April 16 that we have too few students accepting our offer. Therefore we keep some students on a waitlist, and potentially make offers to them after April 15. However, if you hear you are on a waitlist, don't get your hopes up too much. In many years we get the expected yield and accept no one from the waitlist. The waitlist may also not be prioritized until April 16 (so we can balance the number of enrolled students across research areas), so your chance of getting an offer really can't be known until then. If you are on the waitlist at a place you really want, your best bet is to accept another offer and then change your mind if you get the offer you want. If you feel this is somehow dishonest, just let us know informally that you are filling out the statement of intent to register but that you could change your mind if you get an offer from Harvard. We're ok with that. The fraction of students who change their minds after April 15 is so small that we can handle those fluctuations.

If you don't get any offers by April 15, and you are a member of an underrepresented minority, contact the American Physical Society's Minority Bridge Program. They will try to help in one of two ways: (a) find you a short-term program specifically to boost your credentials for the next round of PhD applications; or (b) find a PhD program that has a last-minute spot open.

Take advantage of local resources. Namely, your local faculty members. Collectively, they have been through a variety of PhD programs, and they know you, your institution, and their field much better than I do, so take advantage of that! Find out where they got their PhDs and ask them honestly if they can see you as a grad student at that place, or ask them where they can see you as a grad student.

Advice for new grad students. Read this short essay. (One bullet point mentions software tools not necessarily applicable to physics/astronomy, but the vast majority of this anthropologist's advice is strikingly applicable.)

If you are a faculty member with a different perspective or something to add, I'd be happy to add it to this page.