Question: How does someone go about learning advanced topics in Math after they're done with their PhD?
Specific example:
You've done your undergrad and masters degrees in math and learned from whatever courses they offered
Then you finished your PhD in something like say...Lie Groups but in all that time, perhaps you took differential geometry but never touched anything like Symplectic Geometry or Fukaya Categories or Toric Varieties.
Those are advanced topics that are outside of what was done in your coursework and research but still, you might not be able to just learn these topics entirely on your own. At least, that's how it seems to me.
I suppose some more direct follow-up questions are in order:
Is it embarrassing to have to take courses after you're finished with your PhD and to need assistance with advanced topics?
Is there an expectation that you should be able to learn almost any further topics on your own without needing to in some sense 'be a student again' ?
I hope my questions are sufficiently clear. Any feedback is much appreciated.