Living in a universe where antimatter predominates would be akin to living in our mirror image.
We wouldn’t actually notice anything different. occurred
All the positive charges would be negative and vice versa, but to someone studying physics in an antimatter universe the idea of positrons orbiting negatively charged nuclei would be as natural as electrons orbiting positively charged nuclei is in ours.
Until the early 1960s the answer would have been: “As far as we can tell, there is no reason it should.”
Since then certain subtle differences between matter and antimatter have emerged and the answer is: “Probably, but it is too early to say how and why.”
We don’t even know yet why matter prevailed in our universe. It is most plausibly because of some random asymmetry, but it is also possible that antimatter was unstable in the circumstances that reigned at that point.
So has an antimatter counterpart to our universe existed, with life and so on? We don’t even know that for sure.
The fact that stellar and biological evolution are so slow in our matter universe does not mean that no faster universe is possible.
Even today, some people suggest that in the super-fast reactions in the quark soup of neutron stars, living structures with the complexity of civilizations might arise and pass in what to us would be the blink of an eye.
Maybe by the time antimatter had vanished, it had generated worlds of life as complex as our own.
Or, because antimatter in some ways is seen as moving backwards in time, perhaps it has not yet started.
