Alternative carbon source weakens the anthropic principle

(ORDO NEWS) — A method for the synthesis of carbon is described, which operates in the absence of the Goyle resonance, a special state of the carbon nucleus.

Thus, the possibility of the existence of carbon and intelligent life in the Universe does not require “fine tuning” of the parameters of nuclear interactions, which was one of the arguments in favor of the anthropic principle the assumption that the values ​​of fundamental constants exactly correspond to the possibility of life.

All of us, before being born, overcame a huge abyss that separates us from the primordial material of the Universe. Carbon – the basis of life – appeared due to stellar nucleosynthesis , and the conversion of helium into carbon is the most difficult step in this process.

The synthesis of carbon in the interiors of stars is complicated by the presence of three relatively unstable elements at once, which need to be “slip” when carbon is formed from helium – these are lithium, beryllium and boron.

The addition of hydrogen to a helium nucleus, or the fusion of helium nuclei with each other, results in highly unstable isotopes, lithium-5 and beryllium-8 . The first one exists for 0.3 billionth of a trillionth of a second, and during this time nothing has time to happen to it even in the depths of stars.

Nature has to use the second isotope. Beryllium-8 nuclei live about 300 thousand times longer, and some of them manage to merge with another helium nucleus during this time, forming carbon-12.

Alternative carbon source weakens the anthropic principle 1
The formation of a carbon-12 nucleus from three helium nuclei. The last two arrows depict the transition of the Goyle resonance to the ground state with the emission of a gamma quantum (γγ)

One amazing phenomenon helps them in this. The carbon-12 nucleus has an excited resonant state , whose energy coincides with good accuracy with the energy of the product of the fusion of beryllium-8 with helium-4.

The presence of such a “convenient” state dramatically increases the rate of the reaction. The carbon-12 resonance, called the Goyle resonance after the physicist who predicted it, is considered one of the arguments in favor of the anthropic principle.

If it did not exist or if its energy differed by only ten percent, there would be no carbon in the Universe, and with it observers – you and me.

In a recent study, Fred Adams from the University of Michigan (USA) searched for alternative ways to synthesize carbon in the Universe and found that one of them still has a chance to exist.

In the absence of the Goyle resonance, helium nuclei would react at much higher temperatures and densities than in our universe.

In the depths of massive stars, helium is not able to accumulate “forever”. When the mass of an inert stellar core approaches the Chandrasekhar limit , the density of matter increases without limit, and a moment inevitably comes when even four alpha particles can collide simultaneously, forming an oxygen-16 nucleus.

The synthesis of even heavier elements following the formation of the oxygen core would proceed as usual, and the universe without the Goyle resonance would differ from ours only in an increased content of oxygen and the absence of carbon.

A new study shows that this would not be entirely true: carbon can be formed from oxygen in protoplanetary disks under the influence of cosmic rays.

Their powerful source is the rotation of the inner protoplanetary disk in the magnetic field of the protostar, which causes a constant reconnection of the magnetic field lines.

As in solar flares, line reconnection accelerates charged particles, but the luminosity of a protoplanetary disk in cosmic rays is much higher than that of “mature” stars, and can reach one ten thousandth of the Sun’s luminosity.

Absorbed in the thickness of the disk itself, cosmic rays break up the oxygen nuclei and turn some of it into carbon (similarly, solar cosmic rays generate radiocarbon in the Earth’s atmosphere).

Alternative carbon source weakens the anthropic principle 2
Artistic depiction of the area of ​​interaction between the inner part of the protoplanetary disk and the magnetic field of the protostar

This process is effective only at the inner edge of the protoplanetary disk, at a distance of no more than 0.1 astronomical units from the solar mass protostar.

But, according to the calculations of the author of the study, under optimal conditions, he is able to convert up to one percent of the oxygen located there into carbon.

And since oxygen is contained in silicates in the inner part of protoplanetary disks, all the synthesized carbon immediately turns out to be in the composition of rocks and the planets formed from them (and does not fly around in the form of methane or carbon monoxide).

One percent is enough: in the composition of the inhabited Earth, if we include the silicates of the mantle, there is thousands of times more oxygen than carbon.

Thus, one recipe for a habitable planet in the Universe without the Goyle resonance is found. It is an inner rocky planet in a low-mass star system, where the temperature at a distance of 0.1 astronomical units from the star is comparable to that of Earth.

It should be mentioned here that there are other arguments in favor of the anthropic principle, and the absence of the Goyle resonance still greatly complicates the emergence of life on planets.

But it does not multiply these chances by zero, as previously thought. If there are a trillion trillion stars in the supposed universe without the Goyle resonance, as in ours, even a very small chance may be enough for intelligent observers to appear there too.


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