The temperature required to overcome the reluctance of nuclei to change is nearly 10 million degrees Celsius. This is why “alchemy” in the real sense takes place only in stars. In medium-sized stars like the Sun, the enormous energy being radiated is the result of hydrogen being fused into helium.
Keeping this brief review of the chemistry of elements in mind, let us return to the immediate aftermath of the Big Bang. We know that only helium and hydrogen atoms existed in the universe after the Big Bang. Astronomers believe that solar-type stars (of which the Sun is one) are formed as a result of nebulae (clouds) of hydrogen and helium gas being compressed until the hydrogen-to-helium thermonuclear reaction gets started. 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 into carbon. Nevertheless, even for a red giant this is not easy. As the astronomer Greenstein says: “Even now, when the answer (as to how they do it) is well in hand, the method they employ seems astonishing.”
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 “alchemy” 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 helium 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 intermediary element with four protons and four neutrons. Next, a third helium is added to this intermediary element to make a carbon atom with six protons and six neutrons.
The intermediary element is beryllium. Beryllium occurs naturally on Earth but the beryllium that occurs in red giants is different in a crucially important way: It consists of four protons and four neutrons, whereas terrestrial beryllium has five neutrons. “Red-giant beryllium” is a slightly different version. It’s what’s called an “isotope” in chemistry.
Now comes the real surprise. The “red-giant” isotope beryllium turns out to be incredibly unstable. Scientists have studied this isotope for years and discovered that once it has formed, it breaks down again in just 0.000000000000001 second.
How is this unstable beryllium isotope, which forms and disintegrates in such a short time, able to unite with a helium atom to become a carbon atom? It is like trying to lay a third brick on two other bricks that shoot away from each other in 0.000000000000001 second if they chance to come atop one another, and form a construction in this way. How does this process take place in red giants? Physicists scratched their heads over this puzzle for decades without coming up with an answer. The American astrophysicist Edwin Salpeter finally discovered a clue to the mystery in the concept of “atomic resonance”.
To read Part 2: Resonance and Double Resonance
Creation of the Universe 