Hello.
Cool quote. I'm only in an "introduction to modern physics" class at the moment so I'm
very far from expert.
While mathematically the electron would be a positron moving backwards in time, or visa versa, I don't think one can actually understand the implications/reasons behind this unless they are particle physicists and have a deeper understanding of both the mathematics and actual particle experiments conducted today. Like, while it would be it's anti-particle moving backwards in time, it is also its own self moving forwards in time, so really what does that mean? Can you start making connections to time-travel and the like? Maybe you can... I'm kinda just presenting another view.
There is a tremendous amount of symmetry in particle physics, and so much we still don't know. So while incredibly interesting, I just don't think one can get a solid idea of nature and time-travel type scenarios just yet, especially a lay-person.
Quote:Yoichiro Nambu later applied it to all production and annihilation of particle-antiparticle pairs, stating that "the eventual creation and annihilation of pairs that may occur now and then is no creation or annihilation, but only a change of direction of moving particles, from past to future, or from future to past.
Energy can convert to mass, and visa versa. Photons for example can come together and create an electron/positron pair. Then that pair (a matter/antimatter pair) can come together and annihilate to produce photons shooting out in different directions. We see this in particle accelerators.
So your quote is saying the creation is just a change of direction of moving particles, but I don't understand that in the context of two photons coming together and creating a matter/anti-matter pair in real space-time.
Of course there is a laughable about that I don't understand and again, I'm just presenting something else to think about. Physics constantly blows apart my understanding of reality, so I know there are fundamental truths I don't know/understand yet.. I hope/plan to one day be able to properly explain things like your quote.
yay for science.