It is the most energetic reaction possible. We can see the background radiation of the universe- hot objects give off heat, even when they are very, very cold.

It is the most energetic reaction possible. We can see the background radiation of the universe- hot objects give off heat, even when they are very, very cold. The universe glows like it's 3 degrees above absolute zero, and we can see it. Compared to that antimatter annihilation would look very bright indeed.