Maybe wanting to switch careers because you have some new ideas reminds me of a problem I had long ago. It’s a fairly common experience that lots of people have when playing computer RPG games which have a lot of decision making at the beginning during character creation.
This came up for me most when playing the Exile games, which I later speedran. But originally I wasn’t very good at the games (though I think well above average).
So, when the game starts, you make 6 characters and spend 60 skill points for each character. In Exile 2, you also pick some traits: race, advantages and disadvantages for each character.
This is really complicated and heavily frontloads decision making when you’re new to the game and don’t know what you’re doing. Inevitably, you make some bad decisions.
So you play the game, reach level 8, recognize some bad decisions, and come up with some cool ideas about how to design a better party. So you start over. Exile makes starting over pretty convenient: you don’t have to wait through dialog or cutscenes, and you can move around basically as fast as you can press keys (no waiting 10 seconds for your character to move somewhere at a limited movement speed). So if you know what you’re doing, you can replay parts of the game quite quickly and get back to where you were with your new and improved party.
So, great, party 2 reaches level 12. And now you’ve done a few new dungeons, fought some new monsters, gotten more experience with more spells, seen more of the item drops available in the world, run into some new challenges … and now you have a bunch of great ideas about how to make an even better party. And you think “OK, this time I know what I’m doing. I don’t want to keep starting over, so I’ll just make party3 and then play through the game.”
Party 3 reaches level 10 and you find out that something didn’t work how you expected. You were counting on the game handling something one way, but due to a bug or counter-intuitive design decision, it doesn’t work. You were relying on that too much, so you start over.
Party 4 reaches level 20, and it seems fine, but you realize some ways it could be better. You also estimate that you’re only 25% of the way through the game (it’s a very long game), so you’re pretty tempted to start over again.
I forget the exact details of how it went for me, but I remember starting over repeatedly to make better parties. I forget how much I thought it’d be the last time, but I vaguely remember recognizing and understanding this problem to some extent.
One thing people do next is start over and then burn out from playing the early game again and then quit the game entirely without ever playing the later parts of the game with any party.
There are some things that you could do better: if you took the first party to level 25 and tried out more stuff with them, and then started over, you could have dealt with the learning curve more efficiently. You could get multiple errors out of your way with one experimental party. You could try out a bunch of stuff at once. You could even design your party for that (get some of everything on purpose to try it; do not try to make your party actually good). Basically, you learn a reason to restart, but don’t restart, learn a second reason to restart, still don’t restart, and keep that up for a while, and build up to like 8 reasons for starting and then restart and fix those 8 things all at once. This lowers the number of restarts you end up doing. Sometimes people restart over one little thing, and then as soon as they experience a new part of the game they find one more little thing, restart again, and barely make any progress per restart.
Another thing people do is beat the game (which can be done even with a far from optimal party, by design) while thinking “I will play through a second time with a great party”. But then once they win, they quit. They never try out their ideas about how to make a better party. They think they’ve mastered the game now and they move on, but they only played it with a mediocre party and never tested out their optimizations, many of which are probably wrong.
A lot of the times people start over they think it will be the last time. I was a ignorant newbie/fool when I made my last party, but this time I totally know what I’m doing! They learned a few things and are so impressed by their knowledge, but they don’t realize how much they still don’t know. Some people can start over 10 times in a row, every single time thinking it will be their final restart. There is dishonesty involved.
Anyway, if you try to pick a new career now … you may just run into problems with it in a few years. You know some things that you didn’t when you started down this career path, but there is still a ton you don’t know. You aren’t now in a good position to pick a great career, and foresee how it will go. You still don’t really know. There’s a high risk that if you switch careers you will find something dissatisfactory about it and be tempted to switch again.
Also, physicist is a pretty flexible credential. You can pivot to lots of stuff that uses actual physics or doesn’t. People think you’re smart and capable of math. This is true with just an undergrad or masters degree with no PhD, or with a PhD in the wrong specialty. You don’t have to get things perfect at character creation to have some good options. I don’t know how much added marginal value there is for any physics PhD, or a PhD in the right specialty, for which jobs, nor the added cost of getting a PhD (in string theory or in another specialty) from where you currently are (which I’m guessing is already having a masters degree). I think PhDs matter the most in academia. I think you’re saying a PhD specifically in string theory doesn’t add much value for options outside academia (but i don’t know if that’s compared to a different PhD or to no PhD) – you’re saying string theory is an inflexible speciality that isn’t used in industry.