4 ms·

I've found it very interesting that there are no stable isotopes with 5 nucleons. This article got me looking at a chart: https://upload.wikimedia.org/wikipedi

I've found it very interesting that there are no stable isotopes with 5 nucleons. This article got me looking at a chart: https://upload.wikimedia.org/wikipedia/commons/9/92/NuclideMap.PNG https://upload.wikimedia.org/wikipedia/commons/9/92/NuclideM... And now I see there is no stable isotope with 8 nucleons either. That kind of makes sense, as that would probably be most stable as 2 distinct He4 atoms. I still hold out hope for some kind of physical model of the structure of a nucleus that might explain some of this.

gus_massa 3y ago
It's call isospin https://en.wikipedia.org/wiki/Isospin https://en.wikipedia.org/wiki/Isospin Its a symmetry. The idea is that you can imagine that there is a magical switch outside the universe that can transform all protons into neutrons and viceversa [1], and if you activate the switch nobody would notice. It's a broken symmetry, so activating the switch will be noticed, but it's a good enough approximation for small nuclei. For example the nuclei in H3 and He3 are very similar. I don't remember any remarks about nuclei with 5 nucleons, but I'm not an expert in that area, so I guess it's known. (It's a nice observation!) The idea is that isospin can be used to classify nuclei and composite particles and collisions, and you can use isospin to prove that some collisions are imposible or that two collisions have (almost) the same probability. In my university is one of the last courses of a Physics degree. The calculations of isospin are quite easy, just multiply some 2x2 matrices. Understanding which marices to multiply and how to interpret the result is more difficult. Understanding that this is a good approximation of the universe (for small nuclei) and believing that the profesor explaining it is not a crackpot takes a few years of physics preparation. [1] It's more complicated, instead of a switch, it's like a dial you can rotate and transform a proton into a 80% proton and 20% neutron or any combination you like. And actually, it's more complicated, there are more restrictions and the transformation must be unitary.

gus_massa 3y ago

It's call isospin https://en.wikipedia.org/wiki/Isospin https://en.wikipedia.org/wiki/Isospin Its a symmetry. The idea is that you can imagine that there is a magical switch outside the universe that can transform all protons into neutrons and viceversa [1], and if you activate the switch nobody would notice. It's a broken symmetry, so activating the switch will be noticed, but it's a good enough approximation for small nuclei. For example the nuclei in H3 and He3 are very similar. I don't remember any remarks about nuclei with 5 nucleons, but I'm not an expert in that area, so I guess it's known. (It's a nice observation!) The idea is that isospin can be used to classify nuclei and composite particles and collisions, and you can use isospin to prove that some collisions are imposible or that two collisions have (almost) the same probability. In my university is one of the last courses of a Physics degree. The calculations of isospin are quite easy, just multiply some 2x2 matrices. Understanding which marices to multiply and how to interpret the result is more difficult. Understanding that this is a good approximation of the universe (for small nuclei) and believing that the profesor explaining it is not a crackpot takes a few years of physics preparation. [1] It's more complicated, instead of a switch, it's like a dial you can rotate and transform a proton into a 80% proton and 20% neutron or any combination you like. And actually, it's more complicated, there are more restrictions and the transformation must be unitary.