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majid313mirzae
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Outside the nucleus, free neutrons are unstable and have a mean lifetime of 885.7±0.8 s (about 14 minutes, 46 seconds). why??
jtbell said:Free neutrons decay because they're not forbidden to decay by any conservation laws.
Borek said:why it doesn't happen in nuclei, but only for isolated neutrons?
Every reaction that is not forbidden happens at finite temperatures - sometimes it happens extremely rare (up to "probably not within the lifetime of the universe"), or the opposite reaction happens more often, but it happens.Borek said:Just because something is not forbidden doesn't mean it has to occur. Reaction (I am thinking in terms of chemistry, but they are not much different on a general level) has to be thermodynamically favorable.
It is forbidden inside some nuclei, because there the neutrons and protons have a different energy.So if the reaction is not forbidden and thermodynamically favorable (if I understand correctly this part was covered by mfb - mass of products is lower that the mass of neutron), the real question is - why it doesn't happen in nuclei, but only for isolated neutrons?
mfb said:Every reaction that is not forbidden happens at finite temperatures - sometimes it happens extremely rare (up to "probably not within the lifetime of the universe"), or the opposite reaction happens more often, but it happens.
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Free neutrons are unstable because they have a higher mass than the sum of a proton and an electron. This excess mass can be converted into energy, causing the neutron to decay into a proton, electron, and anti-neutrino.
Yes, neutrons can be stable when they are bound inside an atomic nucleus. In this case, the strong nuclear force is strong enough to overcome the excess mass of the neutron, making it stable.
The average lifetime of a free neutron is about 15 minutes. However, some neutrons can last for up to 15 minutes and 30 seconds before decaying into a proton and other particles.
The decay of neutrons has important consequences in nuclear physics and cosmology. It is responsible for the production of elements heavier than hydrogen in the early universe and plays a crucial role in nuclear reactions and energy production in stars.
There are several theories that attempt to explain the instability of free neutrons, such as the Standard Model of particle physics and Grand Unified Theories. However, the exact reason for the instability of neutrons is still not fully understood and remains an active area of research in physics.