Let me count the ways...

A colleague from economics recently said he was interested in how physicists think, and more specifically, how they come up with research ideas. I thought it would be a good idea to try to set up a list, based on my reading and experiences, of the various techniques, voluntary or involuntary, that I have seen physicists use:

1. Yielding to inspiration: These ideas come from the subconscious. First one has to fill the brain with a lot of information, then a lot of thinking has to be done to activate the neuronal circuits. Then without predictability, an idea, inspiration or flash of insight comes. I have discussed this previously, in reference to the books on creativity and flow by Hadamard and Ciskszentmihalyi respectively.

2. Identifying necessity: The mother of invention. A pressing need or question well-posed (by the community or by nature) often forces the answer. The idea is to work on, or identify, such questions.

   
   

3. Criticizing: Weaknesses or shortcomings pointed out by others often provide strong impetus for creative research. I once got a paper out of something somebody said was trivial and pointless (turned out it was neither). Likewise, the critiques (when sincere) by anonymous referees can lead to major improvements in a scientific paper.

   
   

4. Discussing: Even meandering discussions with colleagues and apparently irrelevant remarks can stick in the mind and stimulate advances. This is why - even the most isolated - physicists love talking shop. This category includes collaborations.

5. Analogizing: The form of certain mathematical statements or experimental arrangements can be very suggestive. I have written about this in some detail earlier.

6. Tinkering: Just playing, with equations or equipment, can lead to discoveries. This requires the willingness to sometimes do things that are discouraged or forbidden (my PhD work was in this category) or mathematically ill-defined.

   
   

7. Admitting accidents: When tinkering goes out of control. Nonetheless, this can lead to scenarios that can expose us to things we had no idea existed. Thus, accidents must be tolerated, in physics as much as in chemistry.

   
   

8. Being perceptive: The ability to notice things subtly out of the ordinary, or an overall structure from a few patterns. The corresponding discoveries are usually accompanied by the words, "That's funny...".

   
   

9. Translating: Talking to experts from other disciplines is often very stimulating, as one is forced to frame or reframe one's own knowledge in new ways, and come into contact with analogous or related structures.

   
   

10. Teaching: This is related to the previous category. Teaching is a wonderful way to keep in touch with the roots of the subject and questions from students can force us to think about the subject in new ways, find easier solutions, or go down unexplored paths. It gives us reasons to constantly reexamine the fundamentals of our knowledge.

    
    

11. Debating: As distinguished from discussing. I use this very little myself, but some very distinguished people (including Nobel laureates) have admitted they get their best ideas during heated arguments with others. I have also seen less distinguished people debate but get nothing out of it -:).

    
    

12. Persisting: When Newton was asked how he solved so many hard problems, he replied, "By thinking unto them." Even if one leaves the subject for a while, to come back afresh, a new attack often yields dividends.

    
    

13. Believing in luck: An irrational confidence in being able to find the solution can play a role in solving a problem. Please note that I am talking about luck in point no. 13 -:).

    
    

14. Thinking independently: The willingness to think differently from the established dogma. Probably there is no greater example of this than Einstein.

    
    

15. Leveraging failure: The ability to paint a target where your arrow lands. Creative scientists typically manage to find something interesting about their project, though it may not be faithful - may even be opposed - to their original aim. A good example is Hawking's discovery of black hole radiation; he had originally set out to prove it does not happen.

Undoubtedly there are more 'techniques' for making research advances in physics; I would love to hear about them from the readers.