Helium - Solar element from the Big Bang. Part 2: Origins and Applications
The helium formed in the Big Bang has survived on the sun and some outer planets to this day. On the young earth, however, it quickly disappeared. But terrestrial helium was later replicated in radioactive decay. Immediately after the discovery of helium, researchers tried to cool it down and liquefy it. In the process, amazing new properties of.
The formation of the elements in the Big Bang, now referred to as Big Bang nucleosynthesis or primordial nucleosynthesis, was first covered in a short article in the journal Physical Review on April 1, 1948. Despite the publication date, the work was no joke because it was based on new observational data. Ralph Alpher, Hans Bethe and George Gamow suspected the "origin of the chemical elements" in a hot and dense beginning of the world, which should have started with a highly compressed neutron gas ("ylim"). The rest of the story took place according to the following script: The expansion of the universe reduces the pressure, the neutrons decay into protons and electrons. A proton and a neutron together form a deuterium nucleus, which is also called a deuteron. Since the electrically neutral neutrons can more easily penetrate into the positively charged nuclei, more and more neutron captures build up heavier and heavier nuclei. In this way, the entire periodic table is gradually formed. The relative abundances of the elements calculated in this way, taking into account the beta decays of unstable nuclei, fitted well with the values observed in the cosmos (see picture on the right).
The key to this success was that the correct neutron capture cross sections of all elements were included in the calculations. These had been measured a few years earlier during the development of US nuclear weapons in the Manhattan Project and found their way from secret military research to astrophysical theories shortly after the war. One of the three authors, Hans Bethe, wasn't even involved, but the humorous Gamow - a Ukrainian fleeing Stalin's terror from the Soviet Union - wanted the list of authors to sound like the beginning of the Greek alphabet: alpha, beta, gamma. This certainly drew increased attention to the work, but also quickly invited the first critics …
