[fp64]

Physical units help modeling and review, it's much easier to sanity check values from just reading, and comparing constants. I've heard that for rendering/raytracing, a lot of people move to model light intensities by actual physical values which makes it much easier to author and compare - such as for example "oh I want a light here that is as bright as this old lightbulb I like so much, but there's sunlight also shining through the window". That's much easier than estimating it in arbitrary units, in particular as here human perception is non-linear. I assume this would be similar for other simulations.