Next step Quote by John D. Barrow

““Carbon originates in the Universe via a two-step process from nuclei of helium, or alpha particles as we usually call them. Two alpha particles combine under stellar conditions to make a nucleus of the element beryllium. The addition of a further alpha particle is necessary to transform this into a carbon nucleus. One would have expected this two-step process to be extremely improbable, but remarkably the last step happens to possess a rare property called 'resonance' which enables it to proceed at a rate far in excess of our naive expectation. In effect, the energies of the participating particles plus the ambient heat energy in the star add to a value that lies just above a natural energy level of the carbon nucleus and so the product of the nuclear reaction finds a natural state to drop into. It amounts to something akin to the astronomical equivalent of a hole-in-one. But this is not all. While it is doubly striking enough for there to exist not only a carbon resonance level but one positioned just above the incoming energy total within the interior of the star, it is well-nigh miraculous to discover that there exists a further resonance level in the oxygen nucleus that would be made in the next step of the nuclear reaction chain when a carbon nucleus interacts with a further alpha particle. But this resonance level lies just above the total energy of the alpha particle, the carbon nucleus, and the ambient environment of the star. Hence, the precious carbon fails to be totally destroyed by a further resonant nuclear reaction. This multiple coincidence of the resonance levels is a necessary condition for our existence. The carbon atoms in our bodies which are responsible for the marvellous flexibility of the DNA molecules at the heart of our complexity have all originated in the stars as a result of these coincidences. The positioning of the resonance levels are determined in a complicated way by the precise numerical values of the constants of physics.””

— John D. Barrow