# How do you explain your pure maths PhD?

Let's say you are at the pub and random layperson asks you the question: "So I heard you did a PhD. What was it on?"

What do you do if your PhD was in pure maths. What techniques can you use that will convey to them what you did in your research, and that it was important?

What sort of techniques do people use in the three minute thesis competition?

• When people ask me what my research is on, I try to steer the conversation in another direction. It seems so tragic to simplify something so ornate into a few sentences that fail to capture even a shadow of what's really going on. May 3, 2015 at 2:47
• In my experience, people mostly believe there's no was to do maths research, because it's all already done. They also think we spend our time on either very big numbers or very long equations. I therefore think that anything that helps them understand the nature of mathematics is worthwhile, even if it doesn't directly answer the question. May 3, 2015 at 6:18
• @JessicaB It should be an answer. May 3, 2015 at 9:13
• This question is already addressed on MSE: math.stackexchange.com/q/1139368/11323 May 3, 2015 at 12:25
• @JessicaB One of the most amusing questions someone asked me was: "So what do you do? Try to come up with bigger numbers?" May 3, 2015 at 12:28

This questions will vary greatly depending on your research area. Many people in applied fields will have no more issue than any other scientist, while those working in, say, algebraic geometry tend to have a tougher road. That said, here are a few principles I have found helpful:

1) Find the smallest question that captures the key idea. You don't have to explain your particular problem, so much as give a flavor of the sort of question you work on. For example, in Schubert calculus, everyone always leads with the question "Here are four lines in space. How many lines intersect all four of them?", even for other mathematicians! You can then allude to higher dimensions, broadly say how your work ties in (or just assert that it does!), and so on.

2) Return to the specific. Use vivid metaphors as a way to overcome abstraction. For example, I often describe a permutation as a row of line dances, and a simple transposition as two people dosey-do-ing to swap places. Now I can talk about the dancer's motivation as motivating my questions, and it somehow seems less arbitrary. Providing something tangible to visualize helps a great deal. This is completely at odds with the usual mode of mathematical communication, where we wish to abstract away every specificity.

3) Inject narrative. Talk about the history. Mention peoples names, and say what they did. Give a scope of the human endeavor that is (a) mathematics, (b) your field and (c) your specific problem. "Littlewood and Richardson came up with a rule for multiplying these polynomials (Schur functions) in the 1930's, and said the proof follows from 'simple combinatorics', which they thought beneath them to do. Forty years later, Schutzenberger finally figured out how to do the simple stuff, after many failed attempts by famous mathematicians, some of which were published!" It would here be appropriate to mention some details about Schutzenberger's fascinating life.

Edit: Explain why you care! Talk about how you came to the problem, your motivations (beyond glory) for solving it, why you think it's worthwhile.

4) Create opportunities for dialogue. Obviously this only applies to someone who is genuinely curious, as opposed to being polite. If you provide the over-arching perspective (1) and provide a specific and familiar framework (2), your listener will have a framework they can use to start asking questions. Metaphors will be abused, and their limits exposed, but that's okay. At the end of it all, someone might call you a "math detective".

5) Be willing to sacrifice a little (or a lot) of accuracy. It's okay to describe the overall thrust of your area, rather than the particular question that you work on. It's okay to give a wishy-washy description of something that glosses over many complications. Despite working in the field that most prizes accuracy, mathematicians regularly gloss over subtle issues with each other. The standard should be much lower when dealing with non-mathematicians. Seriously, it's okay!

6) Steal shamelessly from others in your field. Read popular accounts of your area, or ask other people how they try to describe things. If you work in the Langlands program, read Ed Frenkel's book and see how he tackles this challenge. Look at the "What is a..." series in Notices of the AMS. In general, people seem averse to doing this across academia, but everyone benefits if you can use the best exposition, regardless of whether or not it is original to you.

I don't think my comment directly answers the question, but voting so far seems to say it's important enough it's probably worth saving:

In my experience, people mostly believe there's no way to do maths research, because it's all already done. They also think we spend our time on either very big numbers or very long equations. I therefore think that anything that helps them understand the nature of mathematics is worthwhile, even if it doesn't directly answer the question.

If you can give them a semi-real-world example of the kind of problem that your work will help solve, that's probably as much as most of them really want. If you're far enough out into the abstract mathematical philosophy that you really can't do that, see if you can come up with a brief description of what question (or kind of question) you're trying to answer. It doesn't have to be complete; most folks just want to have some general sense of what area you're working in... just as you would probably be satisfied to know that I'm working on IBM's new generation of server software without wanting all the gory details.

They can always ask for more detail if they have the interest and background to appreciate it.

You could say that you got your PhD in the art of thinking. You used logic, and you put together existing ideas in new ways. If the person asks, Oh, was it in philosophy? You could say, not really, it was more mathematical. If that's a conversation stopper... then you'll be glad you didn't waste your time saying anything meaningful. If the person lights up when you say "mathematical," then you know you can have a satisfying conversation.

Or maybe you could say that you were working with novel mathematical tools for analyzing certain types of problems, and that you were concerned with establishing theoretical underpinnings.

• I'd be interested to know the reasoning behind the downvote. - - - My husband, a physicist, lives in terror of non-scientists asking him about his work. He's experience so many people shutting down when he answers truthfully.... But he's heard me give a layman's answer to the question (of what HE does), and has been very happy with my version. If my suggestions were so un-useful as to warrant a down vote (as opposed to just ignoring them), wouldn't it be reasonable to talk about what bothered you? May 3, 2015 at 22:14
• I'm not the person who downvoted, but I think the "art of thinking" answer comes off as incredibly pretentious. It's important to be able to assess whether or not the questioner is actually interested an explanation or just wants a pat answer, but I don't think this is the correct approach. May 4, 2015 at 1:20