Yeah, quantum physics is like that sometimes. Antimatter precisely can be described like a normal matter travelling backwards through time, and annihilating on contact. And antimatter is absolutely real and measurable object, like you and me
No, I am pretty sure its mass is exactly equal, just the charge is opposite:
https://en.wikipedia.org/wiki/Electron
https://en.wikipedia.org/wiki/Positron
https://en.wikipedia.org/wiki/Proton
https://en.wikipedia.org/wiki/Antiproton
6 days ago(+1)
it is more of a theoretical explanation of why there is so much matter
https://en.wikipedia.org/wiki/Baryon_asymmetry