- #1
Qentanglement
- 8
- 0
So there seems to be an issue concerning the annihilation of an electron and a positron given the following scenario:
Say an electron has spin +1/2 or up, (say Z-axis is up) and a positron has spin +1/2 or up as well.
Now...
I know that a photon has to be a spin of 1. (This is important to note)
If the the electron and positron collide head on from opposite directions with exactly the same kinetic energy then there is an issue.
Momentum has to be conserved, momentum of the system is 0.
Energy has to be conserved, so two photons have to come out of this annihilation going in opposite directions with the same energy in order to conserve momentum and energy.
But "HOW could this be?" You can't have two photons! The total system would have either a total spin of +or- 2 or 0. (I say +or- 2 because one photon could have spin +or- 1 and the other also +or- 1)
We started out with an electron and positron with spin +1/2, SO either spin is not conserved, and two photons come out like usual or one photon comes out but doesn't move! This doesn't make sense, or they don't annihilate and bounce off each other. Or quark anti quark pairs are produced to preserve spin and momentum and energy.
What is the resolution to this scenario?
Say an electron has spin +1/2 or up, (say Z-axis is up) and a positron has spin +1/2 or up as well.
Now...
I know that a photon has to be a spin of 1. (This is important to note)
If the the electron and positron collide head on from opposite directions with exactly the same kinetic energy then there is an issue.
Momentum has to be conserved, momentum of the system is 0.
Energy has to be conserved, so two photons have to come out of this annihilation going in opposite directions with the same energy in order to conserve momentum and energy.
But "HOW could this be?" You can't have two photons! The total system would have either a total spin of +or- 2 or 0. (I say +or- 2 because one photon could have spin +or- 1 and the other also +or- 1)
We started out with an electron and positron with spin +1/2, SO either spin is not conserved, and two photons come out like usual or one photon comes out but doesn't move! This doesn't make sense, or they don't annihilate and bounce off each other. Or quark anti quark pairs are produced to preserve spin and momentum and energy.
What is the resolution to this scenario?