Saturday, 28 February 2009

Start by taking two protons

Start by taking two protons (nuclei of hydrogen)
Heat them up so that they are hot - really hot.
Hot enough that they are moving fast enough that just occasionally they get close enough
that the strong nuclear short-range force can lock them together.

When this happens one of those protons can turn into a neutron
and two particles called a positron and a neutrino come flying out
and the remaining proton and neutron join to make an isotope of hydrogen called deuterium
(about 1/7000th of the Hydrogen in water is actually deuterium).

Getting the two protons together takes a long time - so be patient.
But once the deuterium has been made everything else is easy.

Add another proton and it will join up with the deuterium
turning it into a helium3 nucleus and a photon comes flying out.

Mix 2 of these Helium3s together and they can stick to make a Helium4 nucleus
(otherwise known as an alpha particle - as in alpha, beta and gamma radiation - if you studied school physics)
and a couple of protons come flying out.

This whole process produces energy - a lot of energy.
Some of the energy can be put back into the whole business of getting
two protons together in the first place (which we started with).

Some of it can be used to make star-light.

And some of it, when we get up in the morning,
and feel it on our faces
we will get to call sun-shine.

(With thanks for provision of technical consultancy from Professor Brian Cox)