Changing field for PhD - How much do I need to know before I start talking to advisers/applying?

Question

I finished an integrated masters program in physics last summer, and I plan on doing a PhD on the coordination of autonomous agents, particularly in the field of automated vehicles.

I was excited after having a discussion with a top professor in the field at a university I wanted to go to. I was told to read some more of his work to see if I could understand it, and get in contact in a few weeks. I did the reading, with some basic understanding afterwards, but the position I was pursuing was given away while I did this reading before I had the chance to prove my knowledge.

When I read papers in this field, which incorporate set theory and graph theory as well as other areas I have no background in, how much of the material do I need to 'get' before I can seriously apply? I find myself understanding the ideas and the processes, but I get tangled in the maths. How much training would somebody with a good academic record, but from a different field, get on a PhD program like this? Would I get time to get up to speed by reading seminal textbooks?

This sort of move into a new field is scary, and even with my good academic record, I am terrified of being completely useless.

Answer 1

I changed fields between my master's degree and my PhD and I also found it scary. From my experience, there is no reason to be scared. Most students entering the graduate program will have little experience and you will have enough time to learn as you take classes or start your research.

I would say that with a background in Physics you would be ready to 'seriously apply' right away.

I will refer you to a somewhat similar question I answered a year ago, and the comments below it for some more info: https://academia.stackexchange.com/a/42326/31255

Answer 2

First of all, do you have enough time to change your topic? If so, I would strongly recommend to talk to your supervisor first. If he/she knows you and your abilities, he/she can guide you on choosing a topic; you can finish up and get a PhD. Second of all, with a good help of your supervisor and your commitment you can finish a PhD.

Note on "Scary Parts": Nothing is scary!. I myself had no idea about a subset of computing semantics, and it felt like jumping from an airplane when I started to learn about it. However, at the end of the learning period, I realized why I was so afraid? Don't be scared, it will take your focus away, on doing your job. Your new slogan should be: Keep calm and learn!

Answer 3

One way to approach this would be to look at the program's first year courses, and see if you have the prereqs to take them. If you can walk into the first year courses without problems, you probably have enough background to get started.

Beyond that, pick one or two active researchers in the department, maybe the ones doing work along your desired career path, and start reading their work. Do your own research to try to catch yourself up before interviews, and maybe before writing your personal statement.

I think it may be important for you to develop your story about why you want to change fields.