🚀 go-pugleaf

Thanks for the responses,

Regarding electron positron annihilation John Baez writes:

>Sorry, photons only have 2 spin states, 1 and -1.
>That's because they are massless.

Don't be sorry John. I thank you and ask:

How does masslessness lead to no spin 0 photons? If this is too deep,
then a reference would suffice.

Anyway this simplifies the problem: now only anti-aligned electron
positron annihilation is possible:

		spin 1 in +x, spin -1 in -x,
                spin 1 in -x, spin -1 in +x,
                spin 1 in +y, spin -1 in -y,
                spin 1 in -y, spin -1 in +y,
                spin 1 in +z, spin -1 in -z,
                spin 1 in -z, spin -1 in +z

Shooting from the hip, I'd say the probabilities for the last
four outcomes are all equal. What about the first two? Is this
way of looking at the problem even valid?

Regarding my question on positronium, Scott Chase replies:

>It all depends on the total angular momentum of the positronium.

I understand decay of P to S state, and this is like Hydrogen. 
I was trying to ask about the decay of the positronium from the ground
state into photons (annihilation). Are their different lifetimes here? I
think not now, since a spin-aligned positronium has nowhere to decay
to; there can only be a decay of anti-spin-aligned positronium. And
ground state anti-aligned positroniums are all alike. What is the other
decay time for? The 1st exited state? Would this be through the ground
state or not? If so, then it's nothing new, just T1 to ground state +
T0 to photons.

Could a stable ground state aligned spin positronium exist?

Still just asking,

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