We all know that physics, and science in general, has made a lot of progress in recent decades. There are, however areas in theoretical physics which appear to have reached a deadlock. An interdisciplinary approach may be one way to help alleviate stagnation in these fields. Unfortunately, very little and essentially no progress is being made to explore overlapping ideas in physics.
I have a PhD in particle physics but with time have worked in several other fields of physics. I have published a paper in condensed matter physics, quantum mechanics and have recently started working in plasma physics (lets see where this goes!). What I have noticed while working in these sub-fields is that physicists who are working in their respective fields are mostly unaware of the progress in other sub-fields of physics. In many cases, physicists in these different areas use the same equations but never share insights with each other because they are unaware of each others work. This is exactly what let to my first single author paper during my PhD. I found that particle physicists working on Lorentz violation employ a term in the Hamiltonian which was very well known in contemporary condensed matter physics, namely, the Rashba interaction term. Particle physicists working on Lorentz violation, however, had no idea about the use of this seemingly ubiquitous term in spintronics.
I believe, and have learned from experience, that a plethora of new insights can spur out of an interdisciplinary approach in theoretical physics. Several areas of physics appear to have reached a deadlock when it comes to testing new theories and it appears that we are trying to continue digging the same hole instead of searching for new ones. Perhaps, an interdisciplinary approach might help improve this situation. This however appears to be difficult in the present academic culture, especially in the US. There are however institutes such as the ICTP in Italy where a first step can be taken. A first step, for example, can be to setup an interdisciplinary department for physics and explore the implications of overlapping ideas for various sub-fields in physics. In addition, we need to encourage the young generation to come up with new approaches to solve the unsolved problems in physics. Any major breakthrough in physics seems difficult unless we introduce new ways of addressing contemporary problems.
