I'm currently studying the alpha process, specifically the triple alpha process.
I understand why helium-4 is stable, and why beryllium-8 'prefers' to split into two helium-4 atoms. I also understand why beryllium-8 and helium-4 form carbon-12. However, I don't understand why carbon-12 is stable. Why doesn't carbon-12 split into three helium-4 atoms?