Possibilities of Going to Industry and back to Academia in a Different Field
To get things out there:


Applying for another PhD after your first PhD is possible and I know a few excellent researchers who are now professors who have two PhDs. It does depend on the field you are moving into of course, but coming from Physics I think your options are good. Basically anything that you can fill in while you work will be relevant.
Where do you feel most comfortable? I have debated this myself (academy vs. industry), but it's not always a matter of deciding. If working in the industry doesn't suit you, then there's no point considering it while you are choosing what you want. If you can't choose what you want, maybe it is an option. Try to imagine what a day's work looks like there, and then a year, and then a career. Will you be satisfied with your work? It's a tough question, I can't figure it out myself.
Check all the options! Have your possibilities set out on the table so you can decide knowing that you considered everything. Check PhD programmes, check companies which do basic research along with commercial projects, relevant startup positions, and check all the various living arrangements. It takes time but I think the worst mistake is deciding without the full picture. Remember that industry has as many, if not more different settings than academia, and you could find a suitable niche in either system.


You have loads of options. The end of a post-doc is really a cliff-edge, and I think it is mainly like this because we don't get exposed to alternatives, and something in our head tells us that not continuing to a tenured position in the same field constitutes some kind of failure. That's just one option out of many.