I'm a noob when it comes to physics and most of my knowledge of physics comes from popular science; it's more likely that I'm wrong than not about this.
From what I've understood; Matter and anti-matter are opposites of each other and should annihilate each other
For every particle there apparently exists an opposite; for instance electron <-> anti-electron (or positron), proton <-> anti-proton and so on. The ability to annihilate makes the assumption that the structure of anti-matter is the same as that of matter (positrons on the outside and anti-protons and anti-neutrons in the inside).
However, if you are to invert this structure then these particles wouldn't be able to annihilate each other but instead repel each other away [anti-protons on the outside and positrons and anti-neutrons forming the core]. This would imply that anti-matter and matter repel each other. This could (maybe) explain the accelerating universe.
Have there been any theories along these lines?