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I know getting two Ph.Ds is ridiculous, but does it help?

  1. Jun 8, 2010 #1
    So here is the thing, we all know that the more Maths, you know the easier the Physics problem become.

    So when I do apply for graduate school, would the Maths at grad school help the Physics I will do in graduate school? In order words, will I understand Physics better if I do graduate Math, like getting a Ph.D in Math first and then Physics?

    Or does the Maths in a Physics grad school will not include materials from graduate school?
  2. jcsd
  3. Jun 8, 2010 #2


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    Advanced mathematics courses can obviously be helpful for theoretical physics (differential geometry, functional analysis, topology, representation theory, etc. can all be relevant). But doing research in mathematics, which is the essence of a PhD, won't help very much for physics. [At least it would be overkill and a waste of time if your goal is understanding of physics.]
  4. Jun 8, 2010 #3
    So if you are going into Theoretical Physics, which is both Math and Physics, why is it that you do not need to study graduate Math? Do they study on their own and not get a Ph.D?

    What if I go for a Math Ph.D, would I be allow to study or even research in Physics?
  5. Jun 8, 2010 #4


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    Who says so? At my university, theoretical physics students are required to take at least one advanced mathematics course.
    The essence of a PhD is original RESEARCH. In Europe you only do research, in the USA you take courses in the first year and then do research (that's what I understood; I am not from the USA).
    You don't get a PhD just because you want to take some advanced courses.

    First, you can study everything you like in your own time. Second, it depends on the university whether you can take courses while doing a PhD (and how many, at which department, etc.). If you did your math PhD in a mathematical physics (related) subject, you might end up doing research in a subject more related to physics, but it is not very common as far as I know.

    The thing is, doing a PhD takes a lot of time, and is enormously specialized. You are expected to become an expert in some tiny area. It is not even probable to do research in a very different area of mathematics, let alone in some area of physics.

    But I have the feeling that you don't have a solid understanding of what a PhD really means. In what year are you, if I may ask?
  6. Jun 8, 2010 #5
    But I want to learn more, like have more knowledge in my arsenal

    I do not think I can ever save up to go to Europe. I know, Ph.D is about doing original researches, but I like to really have a lot of knowledge, opening more paths

    This is probably going to be an annoying question, but do you still use textbooks at graduate school?...

    Oh I didn't know that, does that mean when you get your degree, it will say what you specialize? I have always thought a Ph.D meant that a person could learn the materials again quicker than a regular person. Like I know it isn't "knowing everything", but just learning it again from memory.

    I am a freshman, but I was taking college math in high school. I am doing Differentials at the moment. So when I done this year, I thought I might take Topology as a sophomore.

    I know I still have a long way to go, but I really want to plan ahead.

  7. Jun 8, 2010 #6


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    As others have pointed out, a Ph.D. is a research degree. The whole point of it is to learn how to do serious research, and produce a dissertation that demonstrates that you can do it.

    If you want to learn more math alongside that, you'll probably have the opportunity to do so. When I was a graduate student (in physics), my department in fact required me to take two courses outside the department (the "cognate course" requirement), so I took a couple of math courses. I'm sure I could have taken more if I wanted to, especially if I could demonstrate that they were related to the research that I was doing. I don't remember if there were any rules regarding courses outside the department besides the ones that I took to meet the cognate requirement.
  8. Jun 8, 2010 #7
    If you get a PhD in math, I doubt your committee is going to let you reuse the same research topic for a PhD in physics (even if it is a mathematical physics topic).
  9. Jun 8, 2010 #8
    But wouldn't having more Math beforehand would help? Like how much of graduate math would help on graduate physics?
  10. Jun 8, 2010 #9
    Some could help, and theorists do very often take graduate math courses (like jtbell mentioned). Of course taking a few math classes is not a PhD. :)

    Alot of math is not used in physics at all though. What math would help you in physics depends very much on what you do your PhD on. Many (most?) physics PhDs finish their degree with no graduate math courses at all.
  11. Jun 8, 2010 #10
    Yes, more math will help. But what does taking graduate math courses have to do with a second Ph.D.?

    Go to school for physics, take your physics courses, take math courses, and get your Ph.D. in physics. Simple.
  12. Jun 8, 2010 #11
    Would any university or college in the US even allow an individual to begin a PhD program if said individual already possessed a PhD? Seems unfair to incoming graduate students, no?
  13. Jun 8, 2010 #12
    Most are against it. You'd have to present a very good case to the admissions committee to change their mind.
  14. Jun 8, 2010 #13
    Thank you. Since I have you on the line, let me ask, assuming a PhD holder is admitted to another PhD program, would they be able to incorporate previous research into the new one to "shorten" the length of time? Well, I know that kind of defeats the purpose because that person can probably branch out w/o starting another program, no?

    I mean, wow, 3-6 years for the first PhD and 3-6 years for a second one. Wow...
  15. Jun 8, 2010 #14
    Your previous research would become a source you can cite, but that's all. The Ph.D. is about original research and it wouldn't be original to copy yourself.
  16. Jun 8, 2010 #15
    Zing! :biggrin:

    Thanks! Last question, I promise to stop bothering, do you know of anyone who has done this previously? How long did it take that person? My impression is that a PhD takes from 3-6 years to complete, so a person trying to get 2 might end up 12 years in grad school + 4 in undergrad. Man, that's insane! Well, if they enter academia I guess it does not matter but if they end up outside academia, wow...
  17. Jun 8, 2010 #16
    I go for a double major, and nromally it should take 4 years to complete an undergrad right? So wouldn't it take another 4 years?
  18. Jun 8, 2010 #17
    If you double major in two related fields, like Physics and Math, its not very hard to graduate in 4 years because of big overlap. Physics requires a lot of math courses (Calc I-IV, linear algebra and they often recommend analysis and PDEs), so thats already factored in and (in my school at least) upper division physics courses count as Math Electives. Theres such a big overlap its not very difficult.

    Now if you tried to double major in say Biomedical Engineering and Physics that might take a while (or really any two not closely related enginneering majors since they require so many credits)
  19. Jun 9, 2010 #18

    And seeing as you're still asking the same questions after others have explained it, I will give it one last try.

    A PhD in one subject won't help in another. Maths and physics are different disciplines - sure physics uses mathematics, but at the level of a PhD student, the things you 'study' are extremely specific. You don't pursue a PhD in mathematics to 'learn more math' - this would be a terrible idea. If you wanted simply to learn more mathematics, you'd be better off spending a couple of years with some textbooks. Same with physics, "i want to know more physics" isn't a good reason to do a PhD.

    Anyway, the topic of your thread: "I know getting two Ph.Ds is ridiculous, but does it help?" - you said you already know it's ridiculous, all of the replies have confirmed this but it seems as though you are still clinging to the idea. Getting two PhDs is ridiculous - even more ridiculous is actually planning to have two PhDs. Doing so would probably hinder your career greatly, rather than give you benefit. Imagine trying to market yourself as having skills in a subject you stopped studying 7 years ago and dropped to pursue another PhD in a different topic.
  20. Jun 9, 2010 #19
    Getting one Ph.D. is a minor act of madness. Getting two means that you are a certifiable loon.

    (I had considered trying for a second as part of a mid-life career change, but was *strongly* disuaded by everyone that I talked to about it.)
  21. Jun 12, 2010 #20
    It seems like a lot of time you'd be doing if you got two Ph.ds. gah Maybe you'd be in school up to 1/2 your whole life, damn.
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