UK; more specifically Scotland. And mathematics; more specifically (algebraic) topology and (differential) geometry.

The nice thing about mathematics is that there probably won't be any failed or non-reproducible experiments in the lab. That doesn't mean that a math PhD is going to be easy, but you should be aware that a lot of people will have a different idea of what you are doing if you don't tell them that your PhD is in math.

Best of luck for your PhD! You might want to check out this ted talk: https://www.ted.com/talks/uri_alon_why_science_demands_a_lea...

Thanks! I hope so. Experiments (to the extent that there are experiments in mathematics, which arguably there very much are) often fail, but once they succeed they're usually fairly bulletproof, and reproducibility is barely even a concept.

From what I've read, graduate study on your side of the pond is a lot better than in the US. I really can't say why. The people I know who got their PhDs in Scotland were, for one thing, really sharp. That helps. For another, it seems there's more of an expectation of a difficult but manageable workload and risk level. Maybe more focus on research and less on politics. Of course, a better safety net, meaning less pressure to drop out if something happens like your spouse or child needs medical care.

Every country is different.

Yes — I've heard so, and that informed by decision to stay here.

If time and money weren't concerns, I would love to do mathematics research!

I hope you achieve good things, and have fun while at it!

Wouldn't we all? I'm very grateful to live in a world (and time) where such opportunities exist.

I hope you have decent source of secondary income or your family is reasonably well off.

A math PhD might take 6-7 years to complete and I hope that, at the end of it all, you won’t have to come to London to look for C++ or Ocaml jobs at hedge funds or banks.

I'm in the UK. It takes nominally three years here; usually three and a half. I also have full funding.

...this is the discouraging negativity I'm talking about. I do, respectfully, wonder what your agenda is.

Because i have worked with many math phds who lost their youth to something that they could not make a living on (research positions at universities are few and the competition is intense) and were writing C++ implementations of derivatives pricing models for a (comfortable) living.

I am not trying to discourage you, just a different perspective.

Well, luckily I'm not doing this in the hope of increasing my earning potential. It's an entirely separate pursuit. I have no doubt that what you're saying is true, but I don't think I'm bothered by it since it's not my goal.

There is literally an ocean of difference between mathematics and ML (which seems to be what a lot of comments are talking about).

Yes. Which is why I'm trying to push back a bit and say 'hang on... none of this is intrinsic to the PhD system'. Of course it's true that some PhDs — hell, some disciplines — are built to an embarrassing degree on BS and academic schmoozery, but there's no need to tar everyone with the same brush. It seems as though some commenters have difficulty conceiving of intellectual pursuits that don't involve 'data' and 'graphs'.

I'm only very junior, though, so I don't have total confidence that I'm right. But I'm pretty certain I am.