I only have a rudimentary understanding of nuclear physics. I understand the basic principles of nuclear fusion and nuclear fission, but I know nothing of the actual mechanics (if you can call them that) of a nuclear reaction, which is why I can't answer this question myself. I simply want to know if my understanding is correct on the following points:
-Iron has the most stable nucleus of all the elements.
-Both fission and fusion of iron nuclei are endothermic reactions. It is not possible to extract energy from an iron nucleus by a nuclear reaction. Iron is the only element with this property. (I would expect there would be certain unstable isotopes of iron that can undergo nuclear decay, so the above would be a conditional statement.)
Finally, my understanding of these points carries the implication that the universe tends to turn into iron. This is a statement I don't recall ever hearing mentioned by anyone else so I'm wondering if this is indeed correct.
Thanks for your answers everyone!