I am now a research physicist, doing experimental condensed matter physics, but when I was an undergraduate physics major, I got a research job in my sophomore year working for an astrophysicist, for what was nominally 10 hours per week. It is true that getting a Ph.D. in grad school probably requires about 20,000 hours of work, and this is if you start with a physics/astrophysics undergraduate degree, but I was able to start contributing to research with very little background. This was in the early 1990s, and it largely involved writing Fortran programs to analyze time series data from an X-Ray observation satellite. I was directly supervised by a grad student with whom met once a week or so. I can't say that, at the time, I actually understood much of the astrophysics, but it did eventually result in a publication (a conference proceedings paper, that the grad student wrote and on which I was the second author). Although developing an understanding of exactly what's going on with a set of observations, and further, knowing how that understanding fits in with the major unanswered questions in astrophysics does likely require a lot of advanced coursework. (And as someone else pointed out, to learn physics you need to solve hard physics problems, much the same way that to learn to program you need to write code.) But the actual day-to-day carrying out of research does not always require such deep understanding.
It'd be a long shot, but you might be able to find a researcher who would let you be a sort of unpaid equivalent to an undergraduate researcher. Some professor might have a data set lying around that nobody in his/her research group has had time to tackle. Or there might be a professor who mostly focuses on teaching and whose research program has largely come to a halt but who still is interested in some research questions. It'd probably be more feasible if you were also taking (or took) as a non-traditional student. It's not entirely straightforward: the research output of undergraduate-level researchers is often quite low, and faculty largely do it because it's understood to be an important part of undergraduate training, which would not apply in your case.