The above is pretty accurate, but I thought I would chime in with some stuff since I'm pursuing an MD/PhD:
1) it's a long way away for you to be considering graduate school, so just keep in mind that your plans may change since you haven't had a chance to experience pre-med science courses, advanced physics courses, undergraduate research, etc...
2) you might find it difficult obtaining an NIH fellowship if you're planning on doing the PhD in physics. You typically need to obtain a fellowship in order to have both the MD and the PhD degree paid for. one of the reasons the MD/PhD works so well in 8 years is that you typically do a PhD in biochemistry, biology, microbiology, cellular biology, chemistry, biophysics, etc... if you notice, they are all things you can transition into easily after getting through the first two years of medical school (termed the "basic science years"). what you do during your first two years of medical school is vaguely similar to what you'd learn during your first year or two of grad school in those biological science degrees.
pursuing pure physics is unrelated to what you'd be learning during your first two years of medical school. you would, most likely, not be able to complete the MD/PhD in 7-8 years like most do, it would likely take 5-6 years to complete the PhD, just like a normal physicist + you'd have the additional 4 years spent doing the MD. This lends itself to problems with the USMLE's timeline of having to complete all 3 steps within 6 years (which is what I believe the current limit is).
3) you would need to consider the usefulness of the two degrees. What do you expect to do with either of them? if you're a surgeon, you will need to complete residency and specialty training after you complete medical school. during that time, you will not have the time to keep active in your research and publishing.
typically, you do medical research after completing an MD/PhD ... the main advantage you have with the MD/PhD is that, during your research, you can directly interact with patients and use your clinical appointment as the main source of patient/participant interaction, data collection, procedure implementation, etc...
My best advice to somebody who wants to be a surgeon and who also enjoys physics is to do their undergraduate degree in physics, taking as many electives they can in the area of physics they like the most. also take the standard pre-med curriculum so you can take the MCATs and then just go the normal medical school route to becoming a surgeon. with that background, you should be better equipped to continue reading, at a more advanced level, about developments in the field of physics you're interested in, and keep it as a hobby.
The only area of surgery that might have legit crossover in the future with fields kinda close to physics is some sort of mechanical, electrical, or nano engineering. I'm not terribly familiar with much of the field, but I would imagine that there's some cool stuff going on with smart-artificial limb stuff and who knows what will be developed with nano technology, immunology, and who knows what else.
Good luck with pursuing any of this stuff over the next many years. I hope some of the stuff I said helps.