I'm not really sure what you mean by accepted and interpretation here. Feynman diagrams encode the idea of particles traveling backwards in time very strongly -

I'm not really sure what you mean by accepted and interpretation here. Feynman diagrams encode the idea of particles traveling backwards in time very strongly -- it's one of their principle features. Feynman's 1949 paper on "The Theory of Positrons"[1] states as much in the abstract (I would recommend reading at least the abstract -- effectively he succinctly contrasts the new theory with the old one and how the model of positrons being backward-traveling electrons allows you to explain many observed effects). And given that Feynman diagrams (and many other things based on them like Feynman path integrals, QED, and QCD) are the backbone of quantum theory, I think it's more than a safe bet that this view is widely accepted. One of the many predictions using them is the existence (and method of synthesis) of the Higgs boson. The reason I said "maybe" is because it's important to have a distinction between models and reality (maybe bringing this up in this discussion was a bad idea). Physics is all about constructing models that approximate reality with strong predictive power, it's not really interested in what reality is but rather how it can be modeled so we can predict it. Obviously, the models have to be true on some level in order to be reliable, but many examples (like fields for instance) are not real objects. So while saying "the particles are traveling backward in time" (theory == reality) is the most accurate statement you can make with modern physics, I would say "at the very least the particles act like particles that are traveling backwards in time" (theory >= model). Even if newer theories are discovered that invalidate the current theories the latter is still just as true of a statement -- otherwise Feynman's models wouldn't work and we know for a fact that they do. Does that make more sense? > a single particle oscillating through spacetime gives rise to all matter everywhere by doing the loop in indefinite cycles This is the idea of the "one electron universe" (which attempted to explain why all electrons appear to be so identical that we've never detected discrepancies)[2], which was arguably one of the inspirations for Feynman's 1949 paper. To be clear, this is a non-standard interpretation of the implications of Feynman's ideas (though this was actually an idea pitched by John Weller on a phone call to Feynman very late at night). Like most interpretations of quantum mechanics, it doesn't make much of a difference to your life -- at the end of the day the maths is the same either way. [1]: https://authors.library.caltech.edu/3520/1/FEYpr49b.pdf https://authors.library.caltech.edu/3520/1/FEYpr49b.pdf [2]: https://en.wikipedia.org/wiki/One-electron_universe https://en.wikipedia.org/wiki/One-electron_universe