How is this level of math even possible... like... how are people hard-working enough to reach this level of understanding?
I have massive respect for those who bravely tackle the frontiers of Physics; some physics majors have a broader understanding of Math than a mathematician! Though importantly, your average mathematician will have a much deeper understanding of more focused topics.
I don’t mean to suggest that any of Math, Physics, CompSci, etc is fundamentally harder than the others. Each field presents different challenges! But they are also intimately related IMO: the recent MIP*=RE proof has convinced me. In short, we’re all on the same side.
On my TODO list for example is to take a look at this project that maps a world to non-Euclidean space [1]. Writing these "simulations" and exploiting their nature to make interesting interactions is just unbelievably awesome.
P.S. Another interesting one (by the same person) is "MarbleMarcher" [2].
That said, that's the easiest part of mathematics.
Some of it is acumen, some is community, and a lot of it is time.
People can easily ask the same of experts in other technical fields and arts.
Note I'm talking about the math in the paper, not the paper itself.
If you're down here with us stupids you can spend a lot of time on it, you'll get some insight into the basics, but you won't be good at it - certainly not good enough to do it for a living.
Yes, GR is taught at undergrad level. But that doesn't mean most undergrads really understand it, or can do much with it beyond solve a few toy exam problems. Because undergrad GR and QM are introductory courses for beginners.
It takes a PhD to start acquiring fluency, and that's years of constant grind doing nothing else but. It's also hugely helpful to have mentors and/or parents and/or other family members who can give personal help.