And this process releases a lot of energy, roughly speaking it releases about,
doesn't sound like much, but ten to the minus 12 joules for every hydrogen atom.
And there's a lot of hydrogen atoms in the sun.
So there's a lot of energy available.
Now, I want you to notice a couple elements here.
In order to do this, we have to transform protons into neutrons.
That involves what we call the weak interaction.
And that weak nuclear interaction is weak.
So it's pretty hard to make this happen.
So, we're going to have to bring the
nucleons very close together to make this happen.
And to do that we're going to have to overcome the electromagnetic repulsion.
Now the way this proceeds in stars is typically through multiple steps.
We bring two hydrons together to form duterium a hydrogen and a neutron.
Duterium together often to form helium three,
and then finally end up with helium four.
And as we go through the pull process, this, what's called PP chain, this is one
of the PP chains, converts four hydrogens Ultimately
to four helium and in doing so releases energy.