[PapaBear3625]

Just as a side note, it's not true that particles are reduced to only energy. The Standard Model of particle physics postulates other attributes of particles (including electric charge, for example) which are currently irreducible.

When an electron hit a positron (anti-electron), the result is two or more gamma ray photons with no particle results.

[aNYCguy]

When an electron hit a positron (anti-electron), the result is two or more gamma ray photons with no particle results.

I'm not exactly sure what you're getting at here (and by the way, photons are particles, so the result of the impact is definitely a collection of particles). By "irreducible," I only meant that attributes such as charge are currently fundamental and cannot be described in terms of another concept like energy.

My original point was that a particle cannot be entirely characterized by its mass and energy. In addition, one has to to give its charge, spin, topness, bottomness, etc., none of which are forms of energy. They're currently irreducible to other concepts.