It depends on your area of knowledge. Engineering is difficult because you are taught to have a wide vision. Some other fields need other specialists working as a team at all times, the engineer has to pay attention to several aspects of the work to accomplish something, therefore it is easier to relocate an engineer. It is not as easy, say to change a math teacher, a dentist specialized in root canal treatment, a doctor in a trauma hospital to be geriatrician. Those professionals will need to be trainned again.

So true! As the science is getting more and more inter disciplinary, it would be even difficult a person to be identified as specialist in  one field. But one can still be identified as theoretician or experimentalist as long as he does't do both!! 

@Jestin. True ! I worked largely as a Theoretician. But when my work lacked theoretical verification from the side, I did experiments myself. So the ratio 80 / 20 in favor of Theoretical work is my case. Other people have other ratio. 

Dear Sir, It is really difficult for me too. In my 30+ professional experience I started my carrier as Soil physicist than the research team involved an Agril. Engineer after few years saline environment, after few year waste water use in agriculture, than water management, since last seven years, Watershed management, soil and water conservation and ravine rehabilitation. I really not able to do not  able to determine or pinpoint my area of specialization at this very moment. regards

@Sarwan. I would rate your field of expertize as an Enviromental Scientist / Engineer.

It depends on your area of knowledge. Engineering is difficult because you are taught to have a wide vision. Some other fields need other specialists working as a team at all times, the engineer has to pay attention to several aspects of the work to accomplish something, therefore it is easier to relocate an engineer. It is not as easy, say to change a math teacher, a dentist specialized in root canal treatment, a doctor in a trauma hospital to be geriatrician. Those professionals will need to be trainned again.

@Alexander, if you put specialization into the plural form in your original question, it might fit better. Most peers with decades of experience share your fate because they have changed workplace, department, or faculty. Or, just got bored with their work at times.

For me, I grew up as a theoretical physicist, then worked in the software development business, changed to software quality assurance, and later was a general manager of my own small company for documentation and information services. Nowadays, I work as an educational technologist and lecturer but I also have gained a lot of experience in TEFL (Teaching English as a Foreign Language) for K-12 and adults.

But actually I like history best.

I think that we can distinguish between professional and personal favorites. For example many Physicists work for the financial engineering to earn money but they search for , say, bosons and put articles about them in their RG profile. But, if you coincide your profession with your research activity, then you will change direction every time you change 'boss'.

Michael, I just followed your advise, corrected to SPECIALIZATIONS, which is the plural form. Your experience is very interesting and notable.

I am a hybrid professional (Techno- Commercial -Management - Researcher) evolved  in 26 years experience

My experience is in Medicine and specifically in Gastroenterology. When I was a young doctor (now I'm Senior Scientist) my discipline was newborn. I worked for 20 years in the Italian National Commission for the Protection of the discipline, which has been enriched with many new addresses (transplant, endoscopy diagnostic and operative, clinical nutrition). In this way I expanded my horizons rather than change them. And already new challenges await us in the future. And 'for this reason, I'm continuing to publish new articles and add new skills.

@ Alexander J. Babchin, Thank you Sir for helping me. But the organization is paying me for Soil and Water Conservationist. Regards

Under customary state of knowledge in a specific field, expertise can be determined by virtue of credentials like education, experience, training, profession, research, innovations, publication, etc., as well as special knowledge of a subject beyond that of the average person, sufficient enough that others may officially rely upon. However, as the research areas are growing and becoming interdisciplinary, there is more opportunity for acquiring greater knowledge and specialization and it is entirely possible to innovate in the direction of increased specialization. During my 29+ years of professional experience, I started my carrier as Natural Product Chemist (Phytochemist) , afterwards I have to engage myself in different areas of forestry including non-timber forest products, tree improvement, agroforestry in addition to forest products chemistry. Though, I successfully handled some interesting internal as well extramural research products, I am not able to pinpoint my area of specialization and I can’t consider myself as expert.

I am very fortunate in this regard. I have been deeply involved in studies on the mechanism and control of the active transport of ions across animal cell plasma membrane for the past 45-years. My interest in this field started following the discovery of proton-pump  in the laboratory of Late Prof. John Forte in collaboration with Alan Ganser (a graduate student) of UC, Berkeley in 1972, and has been growing stronger and stronger since then until today. During the next 15-years we found a universal mechanism for the regulation of  H, K-ATPase, Na, K-ATPase and Ca-ATPase (along with their close interactions during ion-transport), and proposed a dual-topology model for their operation, since the old single-topology one( PA model) became obsolete. However, the scientific establishment refused to pay attention to our new model, and kept on using the PA model by force-fitting their data, and came to a virtual halt by the year 2000. When I (as a longtime retired scientist) decided to jump into the field again with my old data (published in many well-refereed reputed journals). Now, I have been able to extended this highly important field to the brain area where it is going to play a very important role to understand the holistic way of mind-body function. 

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