Entirely on the side. I ended up in telecom SW but always tried to putter away on physics-based side projects (e.g. Geodesic Asteroids and Three Body apps on iOS, Android).

In playing with geodesic equations I tried to use GRTensorII on my Mac and decided it was time to update it (my former supervisor & external examiner were very keen!). This lead me to work through "Relativists Toolkit" - doing all the problems - using GRTensor where I could. I'm now planning to spend a vacation week at the Atlantic GR conference and give a talk on GRIII. My hobbies tend to get a bit out of control!

Some of this is blogged about on http://nbodyphysics.com/blog/