exchemist Posted May 19, 2022 Share Posted May 19, 2022 As a chemist, I am struggling with this. In, say, a helium nucleus, the rest mass is less than the rest mass of the "free" neutrons and protons from which it is made - the so-called mass defect. That makes perfect sense to me because, to separate the nucleus into its components, you have to do work against the strong nuclear interaction that holds the nucleons together, i.e. an energy input is required, which of course is then reflected in a greater rest mass of the separated nucleons. And hence the converse occurs during fusion, leading to a net output of energy when the nucleons combine and become bound. But when it comes to the quarks that form a proton, say, the opposite seems to apply. The proton has far more mass than combined mass of the three quarks that make it up are said to have in their "free" state. So apparently the bound quarks are in a higher energy state than free ones. This suggests a proton is thermodynamically unstable with respect to the free constituents - and should spontaneously fly apart, if whatever kinetic barrier there is to it doing so could be overcome. Can someone with a bit of nuclear physics explains to me how this works? I have not found an internet source that tackles this squarely - or not to my satisfaction. Link to comment Share on other sites More sharing options...
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