Why the Universe is Fine-Tuned for LIFE—Not Just “Life As We Know It”

God and Soul by Jim Denney“If we did not know of the existence of life (assuming we were something else), no one would have guessed that it was possible.” —HEINZ R. PAGELS, The Dreams of Reason (New York: Simon and Schuster, 1988), 318.

I had a conversation today with someone on Twitter about the evidence for the fine-tuned universe (the anthropic principle). This person was unconvinced when I said that if just one of the many forces or constants of the universe were altered by one part in billions or trillions, then life in the universe would be impossible. He tweeted back: “Of course you’re only talking about Earth-based life, because that’s the only kind of life we know about.” No, I replied, not just life on Earth, not just life as we know it, but any remotely conceivable definition of life becomes impossible if the universe is not exquisitely fine-tuned. Here is an excerpt from my book God and Soul to explain why:


The following excerpt from God and Soul
is copyright 2012 by Jim Denney, and may not
be reproduced without permission.

You need carbon to make diamonds, pencil leads, petroleum, and people. You even need carbon to make alien life forms. Where does carbon come from? It is manufactured over billions of years in the hearts of stars. As in the words of Joni Mitchell’s “Woodstock” — “We are stardust, billion year-old carbon.”

Carbon is the basic building material for all life on Planet Earth. It takes carbon to build the complex molecules that make up the cells, proteins, and other substances of living plants, animals, and people. Why carbon? It’s simply because a carbon atom, with its four valence (outer) electrons, is uniquely suited for bonding with other elements (especially oxygen, hydrogen, and nitrogen) to create the complex molecules that support the processes of life.

You might say, “Well, carbon is fine for creatures from Planet Earth — but couldn’t there be alien lifeforms based on some element besides carbon?” Yes, life could conceivably be based on silicon or some other element. After all, silicon also has four valence electrons — but there’s a huge drawback to silicon.

Atoms of silicon form covalent bonds and generally crystallize into stable lattices instead of the chains that carbon atoms tend to form. Carbon chains can easily break down and recombine into various compounds to form life-giving substances. Silicon lattices form hard, rigid, nonliving matter.

For example, join one carbon atom with two oxygen atoms and you have carbon dioxide, a life-giving chemical compound that animals breathe out and plants breathe in . But join one silicon atom with two oxygen atoms and you have silicon dioxide — which is quartz, a hard, inert mineral. The difference between carbon dioxide and silicon dioxide is the reason silicon-based life is highly unlikely.

And even if silicon-based life did arise somewhere in the universe, it could not live without carbon. As Richard Meisner observes, the most exotic and unearthly lifeform imaginable (even one that would use, say, liquid ammonia instead of water in its cells and bloodstream) “still requires carbon in its alternate forms of fats, lipids, amino acids, carbohydrates, proteins, and nucleic acids.”21

Fortunately, there is plenty of carbon in the universe. But why is that so? For decades, scientists pondered the fact that carbon should not exist — yet it does. As it turns out, the creation of carbon depends on an unlikely and delicately balanced condition in the laws of physics.

The problem that confronted physicists was that there was no known mechanism by which three helium nuclei could simultaneously collide inside a star and fuse to form a carbon nucleus and produce the abundance of carbon in our universe. In 1952, American astrophysicist Ed Salpeter suggested that perhaps carbon is formed in a rapid two-step process: two helium nuclei could collide, forming an unstable beryllium nucleus — so unstable, in fact, that it could only exist for less than a trillionth of a second. During that trillionth of a second, and before the unstable beryllium nucleus could decay into a pair of helium nuclei, a third helium nucleus just might collide with the beryllium nucleus and form a carbon nucleus.

But Salpeter’s calculations showed that this process could never yield the vast quantities of carbon that exist in the universe. Why? Because the unstable beryllium nucleus was much more likely to be split by the third helium nucleus instead of fusing with it. Physicists were stumped. The existence of carbon (and carbon-based lifeforms like ourselves) was a riddle.

According to Hoyle

Then English astronomer Fred Hoyle entered the fray. He took Salpeter’s idea and added a new wrinkle: nuclear resonance. The nucleus of an atom can exist in a number of discrete states, depending on its energy level. Expose that nucleus to just the right amount of energy and it will resonate at a specific frequency. The resonance, Hoyle suggested, might make it easier for atoms to fuse and form new elements.

Hoyle knew that the energy level of helium and beryllium inside a hot star was about 7.4 million electron volts (MeV). So he predicted that an unknown resonance level for carbon was waiting to be discovered at just above that level. Hoyle pegged the resonance level at 7.65 MeV. But how could he test his hypothesis?

In the early 1950s, Hoyle came over from England and spent several years as a visiting professor at the California Institute of Technology (Caltech) in Pasadena. A refugee from the staid atmosphere of Cambridge, Hoyle reveled in the freewheeling, intellectually stimulating environment at Caltech. He gave a weekly lecture course called “Experimental Cosmology,” in which he discussed how the elements in the universe might have been cooked within stars. His ideas were unconventional and his audiences (which included Caltech profs) were frequently contentious. They tried to trip him up with tough questions. Hoyle thrived on the verbal jousting and enjoyed defending his ideas under cross-examination.

Fred Hoyle could not have picked a better time to be at Caltech. He arrived soon after the university’s Kellogg Radiation Laboratory had acquired a new particle accelerator that was well suited to probing the carbon nucleus. The director of the laboratory was physicist William “Willy” Fowler.

When the two men met for the first time, Fowler found Hoyle brash and off-putting. Hoyle, however, knew that Willy Fowler was the gatekeeper at Kellogg. If Hoyle wanted to test his ideas on the particle accelerator, he had to go through Fowler. One day, Hoyle barged unannounced into Fowler’s office and began talking nonstop about his obsession with the energy states of carbon-12.

Fowler thought Hoyle was a lunatic for insisting there was an unknown resonance level just above 7.4 MeV. Experiments at Cornell in the 1930s seemed to prove that no such resonance existed. Fowler thought Hoyle suffered from delusions of grandeur, and he refused to give Hoyle access to the particle accelerator. Besides, the accelerator was booked solid for months to come. Fowler had no intention of interrupting other important projects merely to check out the harebrained hypothesis of this mad Englishman.

Hoyle saw he was getting nowhere with Willy Fowler, so he pestered Fowler’s assistants. Finally, Hoyle was able to win one of those assistants, Ward Whaling, to his side. Whaling persuaded Willy Fowler to reconsider — and Fowler reluctantly agreed.

In order to measure the energy of particles generated within the accelerator, Hoyle needed a spectrometer. But the only spectrometer at the lab was attached to the old particle accelerator at the far end of the building from the new accelerator. The spectrometer’s giant magnet weighed several tons and would have to be moved through narrow hallways and around two corners. It was quite an engineering problem — and the solution was sheer genius.

Lab workers placed the magnet on a steel plate that rested on a cushion of hundreds of tennis balls. When the team of physicists and grad students pushed the magnet down the hallway, the balls rolled. When balls rolled out from under the trailing edge of the steel plate, grad students would pick them up and toss them to other students at the front of the magnet who would feed them back under the steel plate. In this slow, tedious way, they moved the multi-ton magnet from one end of the building to the other.

Ward Whaling and his assistants set up the spectrometer and fired up the particle accelerator — a complex arrangement of power transformers, vacuum pumps, and steel chambers in which atomic nuclei were flung together. The team of physicists and grad students proceeded to bombard nitrogen-14 with deuterons. The bombardment stimulated the emission of alpha particles, leaving behind carbon-12 nuclei. The experiment performed a kind of alchemy known as “nucleosynthesis,” transmuting existing elements (in this case, nitrogen and hydrogen) into a new and different element (carbon). By measuring the energy level of the alpha particles, Whaling and his team could determine the energy level of the carbon-12 —

And they found the resonance level exactly where Fred Hoyle predicted it would be.

The carbon connection

Because the carbon bottleneck is overcome by a fine-tuned nuclear resonance, stars are able to synthesize vast quantities of carbon. Once large amounts of carbon have been synthesized, it’s a simple matter for stars to concoct the rest of the elements on the periodic table — nitrogen, oxygen, fluorine, neon, sodium, and so on.

When Fred Hoyle made his universe-shaking prediction, he was an obscure astronomy professor from England. Soon after Hoyle’s idea was confirmed, Ward Whaling delivered a paper on the experiment before the American Physical Society. The paper listed Fred Hoyle as the lead author — and the English astronomer gained instant fame throughout the global astrophysics community.

Willy Fowler — who had once scoffed at Hoyle’s ideas — became one of Hoyle’s biggest fans. He later recalled, “We then took Hoyle very seriously, because of his triumph … in predicting the existence of a nuclear state from astrophysical arguments…. After Whaling’s confirmation of Hoyle’s ideas I became a believer.”22

Hoyle’s finding is incredibly important. The carbon resonance level is precisely adjusted to permit lifeforms to arise. Any energy level other than the precise level of 7.65 MeV would make carbon a rare trace element — and life in the universe would be impossible.

This finding was personally significant for Fred Hoyle himself. In a 1981 article in Caltech’s quarterly magazine Engineering and Science, Hoyle wrote: “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.”23

From his youth, Hoyle had been a confirmed atheist. But the discovery of the lifegiving carbon resonance level shook his atheist world view and persuaded him that the universe was, as he phrased it, “a put-up, artificial job.”24

Fred Hoyle’s discovery of the fine-tuning of the nucleosynthesis of carbon is especially significant because Hoyle actually devised a testable hypothesis that affirms the validity of the anthropic principle. He realized that in order for human beings to exist, the resonance level for carbon had to be located at a specific energy level, and he predicted precisely where that energy level would be found.

In other words, Fred Hoyle had to think the Cosmic Designer’s own thoughts in order to solve the mystery of carbon. In so doing, Hoyle solved one of the great mysteries of life.



21. Richard D. Meisner, “Universe — the Ultimate Artifact?,” Analog Science Fiction/Science Fact, Vol. 107, No. 4, April 1987, 59.

22. Simon Mitton, Fred Hoyle: A Life in Science (New York: Cambridge University Press, 2011), 209, 210.

23. Fred Hoyle, “The Universe: Past and Present Reflections,” Engineering & Science, November 1981, 12, http://calteches.library.caltech.edu/3312/1/Hoyle.pdf.

24. Ibid.

(Notes are numbered 21 to 24 because that is the original numbering in this section of the book.)