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Elements up to and including iron can be produced exothermically by fusion reactions in stars. Producing heavier elements is then endothermic. The reason for this is that the binding energy per nucleon is maximised in nuclei around the "iron peak". This means that if you tried to add something to an iron nucleus, the resulting nucleus would have a smaller ...


Electron degeneracy does not lead to an infinitely hard equation of state. The Pauli exclusion principle does not say that two fermions cannot occupy the same space; it says they cannot occupy the same quantum state. What this means is that as you squish the electrons together they have to occupy higher and higher momentum states. It is this non-zero ...


The presence of gamma rays and positrons associated with lightning strikes suggests that the strikes are capable of accelerating particles with enough energy for D-H or D-D fusion. However I'd expect that even in a pure deuterium atmosphere the energy released by D-D fusion would be negligible compared to the energy released in the lightning strike itself.


Iron fusion can take place in stars - what you need is lots of iron and very high temperatures. These conditions exist in the cores of massive stars near the ends of their lives. For example alpha particles can fuse with an iron-56 nucleus to produce nickel-60 and then zinc-64; these reactions are barely endothermic. The problem is that there are competing ...

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