How can I transit from one area to another when moving toward my PhD?

Question

I'm currently a master's student in mathematical physics preparing my applications for PhD. I've been working on my current research topic (say A) for 3 years, and all of my publications/talks are in A. However, I found another field B really interesting, and thinking about the possibility to transit to B for my PhD. A and B are quite different and so far I don't have a strong background in B. My question is if I want to make the transition, do I need to explain my motivation in the personal statement? How can I convince the recruiting committee I will be a good candidate for field B, like other applicants who have been familiar with B?

(additional info: I indeed don't have too much expertise in B, the PhD program I'm aiming at is in the UK, so it's relatively short. Is it also a plausible idea to spend a gap year learning more about B so that I can have a better feeling about what I want to do and make my application stronger?)

Answer 1

I don't think you have much to worry about. Yes, you should explain your motivation for wanting to switch, but provided A and B are close enough, I don't think it can be taken as a negative. In fact, rather the opposite: you are clearly already an experienced researcher (you have talks and publications), therefore you likely understand the field well and have a good perspective on both areas. Knowing yourself and not being afraid to change to work on something you find more interesting or think has more promise is a sign of both personal and academic maturity. I am sure PhD supervisors would rather spend a bit of extra time helping a thoughtful and motivated student get up to speed in a new topic than supervise someone who started a PhD without thinking in a topic they already know well just because it's "the easy route".

Personally I would not recommend taking a gap year to study B, unless you are actually taking a course and will have some kind of official certification at the end of it. It's hard to demonstrate you've gained expertise in a new subject if you take a year off just to work through a textbook, for example. Better to study that textbook during your PhD; then at least you're getting paid for it.

Answer 2

In US research groups, at least in the sciences, its fairly common to see people who have a degree in A (either bachelors or masters) and then seek PhDs in B. Many of the skills are interchangeable, and a variety of viewpoints and skillsets is important to many research problems. However, while I'd not be surprised to see someone with a Math, Computer Science, or Biology background in my Chemical Engineering lab, I'd be rather shocked to find someone with a solely English or Philosophy background. I expect that you'll run into a couple of problems, based on the gap between your background A and your target field B:

1. Recruiting committees for B want to make sure that you have the skills to succeed in researching B. If you don't have a degree in B or a related field, you'll have to explain to them why your A skills prepare you for B. Lacking that connection, explain what other proof you have that you can do well in studying B. You've got research experience, but I'm not sure engineering research experience would perfectly prepare you for an English program, for example.
2. There is typically a coursework component for PhDs, and those courses assume that you have an undergraduate understanding of B. If you don't, you have to delay taking the graduate level courses in B to take effectively remedial lessons. The greater the overlap, the less remedial content you need, which means you spend more time researching and less time sitting in class, which makes your department happier. All incoming PhD students need time to learn the field, but it can be hard to get started on a good foot when you need a bunch of classes to understand the basics.

When you read papers and materials in B, ponder what frustrates you about B-researchers from your perspective as an A-researcher (e.g. a lack of statistical rigor, a lack of consideration for cultural elements, too much emphasis on the results and not on elegance of the process). Some of those frustrations may fade as you become more immersed in B, but some may stay, and those frustrations are where the difference in perspective coming from A is important. Those perspectives are valuable in the B environment.