David wrote:

> At another point I remember you saying that you felt that the foundations of "green mathematics" (network category theory) were also of deep interest and beauty as mathematics, and had the advantage of significance on a more present timescale than e.g. quantum gravity. Has your perspective on this changed?

This is one of the things I think about most of all.. but I don't bother people with it very much, since it seems very personal.

Personal? Yes, because it turns out that I need to certain things to stay happy, which aren't necessarily the things I _should_ be doing. And I'm not talking about drinking beer, watching TV and playing go: it seems fairly uncontroversial that most people need to goof off a certain amount to stay happy. I'm talking about doing traditional mathematics, with its crystalline beauty, versus "green mathematics", which is supposed to be as beautiful as a tree... but right now can be a frustrating mess.

I believe green mathematics can become as deep as traditional mathematics inspired by problems of geometry and symmetry. But it's not there yet. And having spent a lot of time mastering traditional mathematics, I discover I can't quite abandon it.

I'm not very tempted to work on quantum gravity or $n$-categories, despite my love for these topics, because these are hard, and when I'm working on them I feel I'm competing with very smart people - my former colleagues. This turns out to be very frustrating and upsetting when I feel I'm not able to put in enough time to do top-notch work anymore.

It seems I can satisfy most of my urges for traditional mathematics by working with Greg Egan on projects that are less hard but have a high payoff in beauty, like [this](http://blogs.ams.org/visualinsight/2015/01/01/icosidodecahedron-from-projected-d6-root-polytope/).

On the other hand, I seem to have acquired two new grad students, for a total of seven... and this is making me more ambitious about developing network theory into a really nice subject! I've got different student working on different categories of networks, and functors between them. I mainly need someone who can pose questions that are right on the cusp between "practical" and "mathematically elegant" - this is very hard, most people are crappy at it, and even I'm not as good as I'd like to be.