Page 56 - The Creation Of The Universe

54 THE CREATION OF THE UNIVERSE

Helium nucleus Carbon nucleus

ed. So now we have stars. But our universe is still lifeless. For life, heavier
elements–oxygen and carbon specifically–are required. There needs to be
another process whereby hydrogen and helium can be converted into still
other elements.
The "manufacturing-plants" of these heavy elements it turns out are the

red giants–a class of stars that are fifty times bigger than the Sun.
Red giants are much hotter than solar-type stars and this characteristic
enables them to do something other stars cannot: They convert helium in-
to carbon. Nevertheless, even for a red giant this is not easy. As the as-
tronomer Greenstein says: "Even now, when the answer (as to how
they do it) is well in hand, the method they employ seems astonish-
ing." 32
Helium's atomic number is 2: that is, it has two protons in its nucleus.
Carbon's atomic number is 6. In the fantastically high temperatures of red
giants, three helium atoms are fused into a carbon atom. This is the "alche-
my" that supplied the universe with its heavier elements after the Big Bang.
But as we said: it's not easy. It's nearly impossible to persuade two he-
lium atoms to join together and quite impossible for three. So how do the
six protons needed for carbon get together?
It's a two-step process. First, two helium atoms are fused into an inter-
mediary element with four protons and four neutrons. Next, a third helium