As for general purpose GPU programming, some parts physics are GPU friendly put not all of them.
I would be extremely surprised if you could get similar or better predictions for the same amount of computation from an off the shelf CNN than from a carefully tuned physical model. (I would love to see counterexamples). Even then I would question how well it extrapolates; you generally have a very good idea of where your physics simulation will break down.
I think your friend is right; the physics community can't afford to throw away as much code as the tech community. I wouldn't spend years building a simulation in tensorflow because it will likely be obsolete before I finished (leading to the same problems as FORTRAN but increasing the amount of dependencies).
In any case, if it works well enough it's not going to be rewritten.
Eventually ML will become part of physics simulations, but I don't think there will be easy wins in these well developed areas.
https://developer.nvidia.com/cuda-fortran
And no, neural networks aren't suitable for discrete problems.
Training a neural network to map "current state of atmosphere" to "state of atmosphere in the future" is definitely possible to do with a neural network, and sounds like a good idea to me.
From what I see from googling, cyclone tracks forecasting by neural network is definitely an active area of research, but apparently they aren’t practical yet. The lady you talked to were probably working on some chaotic systems like this.
1) Some stuff is already written in Fortran so they don't want to rewrite that. I dig it.
2) It's fast (except C sometimes) but easier to write than c. Like 100x faster than python.
I'm not sure about number two. With the gpu processing revolution wouldn't a python/TensorFlow stack be faster than Fortran? Am I missing something?
I remember talking to someone who had worked heavily on atmospheric weather predictors recently and her description of the program was: we divide the space into tiny little cubes and then run some differential physics equations to predict what will happen next. My basic questions to her:
1) From a computational perspective this seems very GPU friendly.
2) Why not use a convolutional neural network? If you use the same data for training you will probably wind up with a more accurate prediction than a theoretically based physics system.
Her reaction was basically that she hadn't heard of these things before so my impression is in fact that the physics community is just behind and they will catch up when they are ready.
Hope I'm not missing something here.