Fundamental question on how life started solved?

For carbon, the basis of life, to be able to form in the stars, a certain state of the carbon nucleus plays an essential role. In cooperation with US colleagues, physicists from the University of Bonn and Ruhr-Universitat Bochum have been able to calculate this legendary carbon nucleus, solving a problem that has kept science guessing for more than 50 years. The researchers published their results in the coming issue of the scientific journal Physical Review Letters.

“Attempts to calculate the Hoyle state have been unsuccessful since 1954,” said Professor Dr. Ulf-G. Meißner (Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn). “But now, we have done it!” The Hoyle state is an energy-rich form of the carbon nucleus. It is the mountain pass over which all roads from one valley to the next lead: From the three nuclei of helium gas to the much larger carbon nucleus. This fusion reaction takes place in the hot interior of heavy stars. If the Hoyle state did not exist, only very little carbon or other higher elements such as oxygen, nitrogen and iron could have formed. Without this type of carbon nucleus, life probably also would not have been possible.

The search for the “slave transmitter”

The Hoyle state had been verified by experiments as early as 1954, but calculating it always failed. For this form of carbon consists of only three, very loosely linked helium nuclei – more of a cloudy diffuse carbon nucleus. And it does not occur individually, only together with other forms of carbon. “This is as if you wanted to analyze a radio signal whose main transmitter and several slave transmitters are interfering with each other,” explained Prof. Dr. Evgeny Epelbaum (Institute of Theoretical Physics II at Ruhr-Universität Bochum). The main transmitter is the stable carbon nucleus from which humans – among others – are made. “But we are interested in one of the unstable, energy-rich carbon nuclei; so we have to separate the weaker radio transmitter somehow from the dominant signal by means of a noise filter.”

What made this possible was a new, improved calculating approach the researchers used that allowed calculating the forces between several nuclear particles more precisely than ever. And in JUGENE, the supercomputer at Forschungszentrum Jülich, a suitable tool was found. It took JUGENE almost a week of calculating. The results matched the experimental data so well that the researchers can be certain that they have indeed calculated the Hoyle state.

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4 Responses to Fundamental question on how life started solved?

  1. Steve B says:

    I will not start this comment with the words “Oh Dear”, but there is a problem here. The probability of three nuclei coming together at the same point in space and tie are infinitesimal. I would suggest that two Helium nuclei combine to form a nucleus of a Beryllium-isotope (which has a very short half-life). The Be nucleus can then combine with another He nucleus to get to Carbon.
    I think that these guys have been a little quick of the mark with the publication of their research.

  2. Deskarati says:

    It takes a confident man to argue with a supercomputer!

  3. Phil Krause says:

    Carbon production in stars is best described by the triple alpha process that Steve has described. I’m not sure what they are talking about in the article.

    • Deskarati says:

      I found this description of the Hoyle State which is quite interesting:

      Stars that have exhausted the hydrogen fuel in their cores by converting it to helium, then convert that helium to carbon and oxygen by a sequence of two reactions. The triple alpha reaction first fuses three alpha particles to form carbon. This is followed, sometimes, by the capture of an alpha particle to form oxygen. The relative strength of the two reactions determines the ratio of carbon to oxygen at the completion of helium burning. We are undertaking experiments to determine better the strength of the triple alpha reaction.
      Hoyle showed long ago that the observed amount of carbon in the cosmos could be made in stars only if there was an excited state in carbon with a particular spin and parity, 0+, and a particular energy, about 7.6 MeV. That state was soon found experimentally.
      Recent experiments at CERN and Jyväskylä have shown that only the properties of the Hoyle state are necessary to describe the triple alpha reaction in the cosmos. But we need to know these properties better than at present to predict accurately how stars evolve after the completion of helium burning. For example, the present accuracy does not allow astrophysicists to predict with sufficient precision either the sizes of the iron cores of massive stars that collapse and power supernovae or the ensuing nucleosynthesis following the supernova explosion. At least 10% accuracy in the ratio is required; at present neither of the individual rates is known that well. Similar accuracy is needed to describe the carbon production in stars with masses a few times that of the sun: AGB stars that burn hydrogen and helium is shells surrounding a carbon-oxygen core.
      Predicting the triple alpha rate is complex; it is given by the product of four experimentally determined quantities. The major source of uncertainty is in one of these quantities, the so-called pair-branch, the fraction of the time the Hoyle State, once formed, decays to the ground state of carbon by simultaneously emitting a positron and an electron. We have undertaken an experiment to determine this branch and thereby to determine the triple alpha rate to within 6%. We form the Hoyle state by scattering protons, produced by the Tandem accelerator at Western Michigan University, from a carbon target at an energy and angle that maximizes its formation. Detection of the scattered proton tells us that the state has been formed. We determine whether the state emits a positron-electron pair that we detect in a plastic scintillator array. The detector is now being built and we hope to have results in about six months. The experiment is difficult because this process is so improbable, occurring only about seven times in a million chances. But it appears that the measurement can be made with the desired accuracy.

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