Approximate time frame to switch to different research area I made a conscious decision some time back to pursue a career in academia and I got back into graduate school this year, working in an 'applied computing' area--educational technology. While I thoroughly enjoy what I am currently working on, in the near future, I intend to conduct research in more mainstream computer science areas. My question is, how long would it theoretically take for one to radically switch research areas? I know there is probably NO fixed time frame for this, but I am especially interested in hearing from individuals that did this or attempted to do this early on in their careers. I would also appreciate additional advice on how I could start working towards this at an early stage. Incidentally, I came across an interesting CACM article [1] that ascribes a 10-year 'once-in-a-career' shift, mostly as a result of evolving technology.

[1] http://cacm.acm.org/magazines/2013/10/168170-trends-in-computer-science-research
I'm not quite so sure the 10,000 hour rule applies very well here.  There are a couple things that need to be considered -- i.e., substantive expertise and methodological expertise.  Although I am not in the area of computer science, the transition from educational technology to mainstream computer science doesn't seem terribly far apart.  It seems like you have the aptitude for computer science, so you should not have really significant problems acquiring the substantive expertise.  I would be concerned if you were saying that the switch was from educational technology to psychiatry or aerospace.  

The other issue is the extent to which your methodological expertise generalizes to this new area.  Have you acquired research skills that are relevant to your proposed switch?  Do you have the core research skills for your new area?  How familiar are you with the research in this new area.  And what is the litmus test that you have achieved "expertise" in the new area?

I guess the issue really comes down to how much your knowledge and skills in your current area of work generalizes to your new area.  So, I'm not going to put a number on this issue -- I just don't think it is possible without more information.