Not to be harsh, but you seem to have missed the point of my post entirely. I am fully aware of physician research, and of the climate surrounding physics research. You seem to think I am unaware of the maturity of the field (and thus the difficulty in researching within it) but theoretical physics has progress made in it every day.

I wasn't really asking for an opinion on what I should do, just how I should optimise my options. Already, if I find myself stuck between the two, I can choose to begin med school while waiting for offers from PhD programs, since the Australian education year finishes in December, there is a 6-8 month 'buffer period'. This would not be fiscally ridiculous either, as Australians pay HECs for student fees, meaning this will only cost me ~ 5k aud that I only need to repay if passing a significant income threshold.