Triple-alpha process

The Triple-alpha process is a set of nuclear fusion reactions by which three helium nuclei (alpha particles) are transformed into carbon.

Hoyle's Contribution to cosmology
An early paper of Sir Frederick "Fred" Hoyle made an interesting use of the "anthropic principle. In trying to work out the routes of stellar nucleosynthesis, he observed that one particular nuclear reaction, the Triple-alpha process, which generated carbon, would require the carbon nucleus to have a very specific energy for it to work. The large amount of carbon in the universe, which makes it possible for carbon-based lifeforms (e.g. humans) to exist, demonstrated that this nuclear reaction must work. Based on this notion, he made a prediction of the energy levels in the carbon nucleus that was later borne out by experiment.

However, those energy levels, while needed in order to produce carbon in large quantities, were statistically very unlikely. Hoyle later wrote:

Would you not say to yourself, "Some super-calculating intellect must have designed the properties of the carbon atom, otherwise the chance of my finding such an atom through the blind forces of nature would be utterly minuscule." Of course you would...A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics, as well as with chemistry and biology, and that there are no blind forces worth speaking about in nature. The numbers one calculates from the facts seem to me so overwhelming as to put this conclusion almost beyond question.

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