This might sound silly. But we always talk about nuclear fusion in stars and I have always wondered why this process happens at all.Is it inevitable for fusion to happen at the temperature and pressure present in a star?

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Lankenp19hh · Accepted Answer

Think of 2 hydrogen atoms or, protons more accurately since at those temperature the atoms don&#039;t have electrons, it&#039;s more of a soup. So, 2 protons, both positively charged so they repel each other, crash into each other pretty rarely, cause it&#039;s still a lot of empty space, but they do make contact every so often. The energy required to get 2 protons or any other atomic nuclei to touch is very high. This is called the Coulomb barrierThat&#039;s basically all fusion is, it&#039;s when 2 atomic nuclei, which naturally repel each other, get pushed close enough to touch and fuse into 1 nuclei.Once they touch, in the case of protons, then it&#039;s a matter of what quantum combination is most likely to follow. Protons actually don&#039;t like each other so much more often than not, they&#039;ll just say &quot;lets not do this&quot; to each other and they effectively bounce off each other, basically staying hydrogen.About one time in a million . . . or so, the protons will stay and fuse but for this to happen, one of them has to become a neutron, because 2 protons aren&#039;t a stable nucleus. So in this rare occurrence when they do fuse, one proton kicks out a positron, a neutrino and a gamma ray, essentially getting the energy to do this from the fusion and you&#039;re left with a proton-neutron bound together (Deuterium) from a proton-proton collision. This happens rarely but because the sun is so large and there&#039;s trillions and trillions of proton-proton collisions every second, you get trillions and trillions of Deuterium nuclei formed every second and Deuterium, unlike protons, is very eager to merge with a proton or another Deuterium so, from there, the process continues.This is also why hydrogen bombs are made with Deuterium, not hydrogen - hydrogen is much much harder to create fusion with.Because of this, the sun effectively burns very very slowly, but all that&#039;s needed is sufficient temperature and pressure to break the coulomb barrier.

This might sound silly. But we always talk about nuclear

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