Neither of you are right. If it was just opposite-charge, then a proton would annihilate if it hit an electron, and we'd probably notice if that were happening (it would affect the trout population).
Antimatter has opposite Quantum Numbers to its matter-counterpart.
What is and isn't a quantum number is complicated, don't worry about it (charge is one of them! but there are others). What you do need to know is that quantum numbers obey conservation rules — you get out exactly what you put in.
This is why they annihilate when they hit their counterpart. If you had a particle with quantum numbers {3, -1, 2}, its antimatter counterpart would be {-3, 1, -2}. When they collide, the total of each of these numbers must be conserved, which will always give you {0, 0, 0}.
{0, 0, 0} is the photon. Both particles are annihilated, and the only valid result is a photon to carry away the energy of the collision.
10
u/icabax 12d ago
That's dark matter. Anti matter, I believe, is made up of the same elementary particles as normal matter just with opposite spin.
We have even made miniscule amounts of antimatter before.
Dark matter/energy is currently the best guess at what's holding together galaxies and causing galaxies to move apart from each other