The work environment seems not quite right for either though. I'm not sure what it is. I'd be interested in the views of INTPs and ENTPs who are already in the area. I think it is more about the workplace than the subject matter.
I'm not in physics, but I was thinking this exact thing before you posted it. I've dabbled in Physics and other hard sciences (and I love math and economics - usually, the "mathy" part of it), and I know that I could do well in Physics if I applied myself - that is to say that I know I could do well in the subject area itself.
The workplace, as you mention, is where it sometimes gets difficult for INTP's. Indeed, it is a whole different issue from the subject matter. I have learned something about myself in recent years. I do not enjoy structure of any kind when it comes from someone else. If we impose some sort of structure on ourselves, that's OK, but we don't want to be on someone else's agenda. We're not 9-to-5 types.
At one point, I was going to get my Ph.D. and do research for the rest of my life because I thought it would fit me well, but I absolutely cringed at the idea of "being institutionalized" - being a part of the big university where I was expected to do A, B, and C in order to be a considered a good boy. If I'm "expected" by someone to do A, B, and C then I naturally start looking at X, Y, and Z. It's hard to explain. I think it's an innate need to be "original" or something. We want to do our own thing. Set our own rules. Be free of expectations and boundaries imposed by others. Our boundaries, or the territory that we wish to operate in and study/investigate are usually larger and wider than one single subject or some idea or box that someone may choose to put us in. We are all over the map, so to speak and any attempt to limit that freedom can sometimes feel suffocating for us.
Most INTP's could be competent in the field of Physics. Just like with any other "job", however, they will often find themselves feeling limited or confined within a year or two. And that's not about the "physics". It would be the same as an economics researcher, a chemist, a math researcher, etc.
I believe, that for me anyways, I was born to be an entrepreneur. It provides the vast freedom that I desire and the most room for pure creativity. Not creativity within the confines of an institution or the confines of my bosses expectations, but true creativity where there are very few limitations to what I can dream up and attempt to do. I even thought about becoming a researcher in the field of Business Admin/Entrepreneurship, but that's the same thing (to me) as being a physics researcher. It limits my scope, narrows the fields in which I can operate, and it puts a boss (or a system) over me. I don't want any part of it.
Of course, entrepreneurship presents its own challenges for the INTP - namely that we think it would serve us well in business to be more outgoing like our ENTP kin. Still though, I'd rather fight through that/learn to overcome it when necessary and have the freedom to explore and create that I desire than to be confined to "one field". After 2 years in any one "field" or "job" that I've ever worked in, I was already over it and ready for something new and exciting. Many entrepreneurs/CEO's, contrary to popular belief, are actually introverted anyhow. Social misfits? Sometimes. But we're also very resourceful and good at finding new and innovative avenues to carry out what we want to do (if we really want to do it in the first place).
. Some put us on that list also. Personalitypage has science/eng for INTJ, INTP, ENTP, ENFP. But I don't trust their job lists. Most list it as an ENFP trap, because we are good in the area, but it brings no real fulfilment.
