Quote:
Originally Posted by sjastro
There are four properties that differentiate matter from it's mirror image (antimatter).
(1) Charge
(2) Magnetic moment
(3) Parity
(4) Helicity or handedness.
Charge is obvious, parity and helicity relate to the mathematical symmetries of particles and antiparticles. So for example if a particles intrinsic spin and linear momentum are in the same direction then the particle has a positive helicity where as the corresponding anti particle will have the instrinsic spin and linear momentum in opposite directions (negative helicity). All neutrinos are left handed, all antineutrinos are right handed.
As far as an absolute test to differentiate matter from anti matter, the magnetic moment is the key. Even a particle with neutral charge such as a neutron has a magnetic moment.
If you pass a neutron through a magnetic field it will always deviate in the same direction in the field. The antineutron will deviate in the opposite direction. Same with the proton/antiproton.
We know we are made from matter, just break down the constituent nucleons that make up the matter pass it through a magnetic field and you have your answer. 
Regards
Steven |
Is there a degree of conventionality in this ?
I guess if one applies tests for all of (1) to (4), then maybe there's no definitional issues (?)
… interesting ...
Cheers & thanks for a great answer, Steven .. very clear ..