\nWhy to neutrons exist? You may say, this is a silly question. But the problem is that we know that free neutrons are unstable. This means that if you isolate a neutron by itself, after about 15 minutes, it will spontaneously transform...\nWhy to neutrons exist? You may say, this is a silly question. But the problem is that we know that free neutrons are unstable. This means that if you isolate a neutron by itself, after about 15 minutes, it will spontaneously transform into a proton. So if that’s the case, and the universe is more than 15 minutes old, why isn’t the entire universe made only of protons? In fact, why does a free neutron decay to a proton in the first place? There's a good answer. But why is that answer correct? And why is the answer to THAT answer correct? We will keep why question over and over, until we reach a final answer.
The reason a neutron transforms into a proton is because free neutrons are not stable. Protons are more stable because it is in a lower energy state. Free protons are more energetically stable than neutrons because they have a lower potential energy. Lower because they have a lower rest mass which is a form of potential energy.
The reason protons have a lower rest mass is because they are made of lighter fundamental particles than neutrons. The reason a neutron's fundamental particles are lower mass is because they interact more strongly with the Higgs field, because their Yukawa couplings have higher value.
We don't know why the Yukawa coupling is higher for down quarks? There are string theory explanations buty these have not been proven. In physics, until we have a theory of everything, every chain of why questions will ultimately lead to, “we don’t know” – and that’s okay because any I don’t know answer leads to more exciting science yet to be discovered by the next generation of scientists like you perhaps.
But if protons have lower energy than neutrons, why do neutrons exist at all? Why isn’t the entire universe made of protons only? The answer is twofold, first not all neutrons early in the universe decayed after the Big Bang. Second, neutrons can be produced via weak force decays from protons. More about this in a minute.
Why are neutrons more stable when bound in a nucleus with other protons than on their own? This is because the instability of a single neutron to decay to a proton is balanced against the instability that would be acquired by the nucleus as a whole if an additional proton were to participate in repulsive interactions with the other protons that are already present in the nucleus.
Spontaneous processes such as neutron decay require that the final state is lower in energy than the initial state. In stable nuclei with protons and neutrons together, the neutrons act to make the nucleus more energetically stable.
Why don't nuclei with two protons or two neutrons exist? Two protons together doesn’t work because the electromagnetic repulsion of two positive charges together makes it less energetically stable. One of the protons would transform to a neutron in that case via beta plus decay. #neutrons #nucleus A bound state of two neutrons is not stable because in order to be stable they would have to have the same spin, but that would violate the Pauli exclusion principle. One of the neutrons would transform to a proton in this case via beta minus decay, forming duterium. This spin state issue is not a factor with deuterium because the two particles are different. \n
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Concepts
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quantum mechanics, potential energy
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yukawa coupling, beta minus decay, beta plus decay, why do neutrons exist, why do neutrons make atoms unstable, why dont nuclei with only neutrons exist, why are free neutrons unstable, how does the higgs field gives mass, why do large nuclei decay, why isn't the universe only made of protons?, why do neutrons decay to protons, why do protons decay to neutrons, why do protons exist, how do neutrons make a nucleus stable, pauli exclusion principle, bottom line, strong force, higgs field, energetically favorable, spin state, exclusion principle, opposite spins, bound state, energetically efficient, energetically stable, answer correct, video explaining, rest mass, string theory
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