Let's start with three little stories:

#1: Today I gave a guest lecture in a Stanford graduate course on the first research topic I worked on after grad school as a young researcher at HP Labs (compressed domain video processing and transcoding). As you can guess, the students are incredibly bright. The class was very interactive and upbeat, and the students asked great questions and soaked up the material like sponges. At the end of class, one of the students asked me if this was my thesis topic. I said "No, it was the first research area I worked on after I finished my Ph.D. thesis, and my goal after graduating was to do (the equivalent of) a second Ph.D. thesis." Instantly, their jaws dropped and their eyes widened; and then I realized this was a traumatic thought to students in the middle of their first Ph.D. thesis. So I quickly added "Oh, I realize that you probably didn't want to hear this right now, but don't worry, after you finish your thesis you will know that it's much easier to do a Ph.D. thesis the second time around since you learned how to do one." They smiled with great relief and a glimmer of hope that this could be true!

#2: As a coincidence, earlier today at work I met a bright young Japanese visitor (a co-worker's son) who just finished his Ph.D. in laser optics in Japan and was spending 6 months in the US as a visiting researcher before starting his full-time job in Japan. I told him that I worked on optics for my Master's thesis. He was pleasantly surprised and asked me if my Ph.D. thesis was in optics. I said "No, it was in video." His eyes widened as he looked at me incredulously and he asked "You switched fields?!?" I said "I guess so. But I found digital image and video processing very similar to fourier optics, but on pixels. So there was a relationship." I guess in my mind I didn't switch fields; I just evolved fields.

#3: This reminded me of a time when I had a new upper manager at HP Labs who came in from a different company and was learning his way around. I told him about my and my team's newest research area on media overlays and mobile streaming media content delivery networks. As he made his way around the organization, he found that nobody believed I was working in that area! They would say "Susie is doing that?!? But she does transcoding!" He wisely advised me that I should shake my old reputation around HP of only doing transcoding and let them know what I was doing now. It was interesting advice!

There is a relationship between these stories, and it's one of evolving your research area as you move forward in your career, and learning at the same rate that you learned your first field. Don't be afraid to attack new problem areas in new domains. In fact, you must because your original problem and expertise area won't stay the same for the rest of your career! Also, if you keep the same attitude towards learning as you did when you first learned your first field, then you will be able to keep up with the latest advances in technology and in the industry, and you will be able to stay current.

You may not have to make completely disruptive shifts into a completely new areas all the time. In fact, I never felt like I was switching fields. Rather, you can think about evolving your domain of expertise over time and building up your portfolio with each area that you master. Also, you shouldn't switch out of an area too quickly, as it is good to stay in the area long enough to build up enough knowledge and make a contribution that has impact.

Also, if you're in research, you might end up putting some of your technology on the shelf for a while as you wait for the industry to be ready. Then, when this happens, you can dust off your technology and put it into action! Actually, the funny thing is that the topic that I lectured on at Stanford today and worked on 10 years ago is very relevant to the industry today! Who knew it would take 10 years? That's the life of a researcher!

Closing thoughts:

• It's much easier to do a thesis the 2nd time around.
• Evolve your expertise to stay current!
• Stay in a domain long enough to make a contribution with impact.
• Learn new fields at the same rate that you learned your first field.
• Build up your reputation... then shake it!
• Put your research on the shelf for a while as you wait for the right time. When the time is right, dust it off and put it into action!

Note: This post is written in the context of a Ph.D. because I was speaking with graduate students. However, I think these ideas apply to everyone one, regardless on whether you ever have or will formally pursue a Ph.D. In my mind, when I say "pursue a Ph.D." I mean "pursue a level of knowledge, expertise, and contribution in an area with real passion and focus". For example, you can do the equivalent of pursuing a formal Ph.D. in your own life without going to grad school. Just embrace an area with conviction and passion and drive to make a significant contribution and have impact. This can apply to your work whether you are in research or in sales and marketing, and it can apply to your personal life whether you are mastering a sport or French cooking! In my mind, any person with this drive and focus can "get a Ph.D.". Many of the best researchers and technologists I know don't have or need formal Ph.D.'s. They just keep on driving!

Please do share your comments and little stories.  I'd love to hear from a few grad students and graduated students, both in the formal and informal do-it-yourself Ph.D. programs!