# Question about antiparticles

1. Feb 26, 2006

### dleacock

I was reading that the antiparticle of a particle is the same, except it has an opposite charge, which cancels it out. if the charge of an electron is -1.60 x 10^-19, would that make the charge of the positron +1.60 x 10^-19? but isnt that also the charge of the proton? I must be missing something...:uhh:

thanks
dleacock

2. Feb 26, 2006

### mathman

Positron and proton have the same charge. The main difference is in mass and also composition. Positron is elementary while proton consists of 3 quarks (2 up and 1 down) held together by gluons.

3. Feb 26, 2006

### dleacock

I've also heard a positron be called a electron moving backwards in time, or something similar like that. What is it about the property of an antipartcile that cancels out the particle, just its charge?

thanks

4. Feb 27, 2006

### mathman

Particle moving backward in time is a way to visualize antiparticle. (according to many leading physicsts, nobody really understands quantum theory).
When a particle colides with its antiparticle, they both disappear into a burst of energy (two gamma rays usually). It has nothing to do with charge - neutron plus antineutron leads to the same result.

5. Feb 27, 2006

### Staff: Mentor

As far as I know, there are three properties that are "opposite" in antiparticles:

the electric charge, which determines the nature of the electric force on the particle.

the "color charge," which determines the nature of the strong interaction between two particles (i.e. there are red, green and blue quarks, and anti-red, anti-green and anti-blue antiquarks).

The "flavor" which determines the nature of the weak interaction between two particles. For example, it's what distinguishes an electron, a muon and a tau; or an electron-neutrino, muon-neutrino, and a tau-neutrino. An electron can interact to produce an electron-neutrino but not an anti-electron-neutrino, or a muon-neutrino, or a tau-neutrino.

6. Feb 28, 2006