How can we tell if a star is made of matter or anti-matter? For example, is there any difference spectroscopically? Or could we tell from cosmic rays?
If half of the stars were made of matter and half of anti-matter, then they would be in balance.
After the Big Bang, the slightest of imbalances in the distribution of matter and anti-matter would, I think, grow more pronounced as a local surplus of matter would persist if bombarded with equal amounts of matter and anti-matter. Over time, that matter would gravitationally come together and locally grow more dense. Gravitation thus would segregate matter and anti-matter as most of space became empty. Thus perhaps half the stars that we see might be made of anti-matter. For the photons they produce would be the same, yes? And the gravitational force is the same.
In particular, I wish to know approximately what is the density of mass in the space midway between our solar system and Alpha Centauri? What would be the nature and magnitude of energy released there if matter from our side was colliding with anti-matter from Alpha Centauri's side? Would we be able to detect that? Please, I would like to see a calculation!