B Can a hydrogen atom become a neutron?

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A hydrogen atom can become a neutron under extreme pressure, such as in a star where gravity compresses protons and electrons into neutrons, forming a neutron star. However, free neutrons typically decay into protons, electrons, and antineutrinos, making it unlikely for them to spontaneously form hydrogen atoms due to high kinetic energy. The discussion highlights that while neutrons can be created and destroyed in high-energy environments, the reverse process of free neutrons turning into hydrogen is rare. The interactions between protons and electrons are crucial in these transformations, with energy distribution influencing the outcomes. Overall, the conversion processes between hydrogen and neutrons are complex and dependent on specific conditions.
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I read this from Nasa's website:

"Within the first second after the Big Bang, the temperature had fallen considerably, but was still very hot - about 100 billion Kelvin (1011 K). At this temperature, protons, electrons and neutrons had formed, but they moved with too much energy to form atoms. Even protons and neutrons had so much energy that they bounced off each other. However, neutrons were being created and destroyed as a result of interactions between protons and electrons. There was enough energy that the protons and the much lighter electrons combined together with enough force to form neutrons. But some neutrons "decayed" back into a positive proton and a negative electron."

Does this mean that under enough pressure a hydrogen atom can become a neutron?
 
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Yes. In some condition all the electrons and protons in a star could be compressed by gravity to become neutrons which form a neutron star.
 
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...and the reverse? Would a bunch of free neutrons just turn into hydrogen? That would mean no neutronium meteors carving holes in the Earth?
 
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Algr said:
...and the reverse? Would a bunch of free neutrons just turn into hydrogen? That would mean no neutronium meteors carving holes in the Earth?
A free neutron decays into a proton, electron and neutrino. Typically there is too much kinetic energy for the proton and electron to be bound as a hydrogen atom.
 
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PeroK said:
A free neutron decays into a proton, electron and neutrino.
No, antineutrino.
PeroK said:
Typically there is too much kinetic energy for the proton and electron to be bound as a hydrogen atom.
The energy is divided between electron and antineutrino.It is possible but rare for antineutrino to get all or almost all the energy and leave electron bound. The opposite is unlikely because antineutrino has no bound state to either proton or electron.
 
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Thanks everyone for your responses!:biggrin:
 
Theoretical physicist C.N. Yang died at the age of 103 years on October 18, 2025. He is the Yang in Yang-Mills theory, which he and his collaborators devised in 1953, which is a generic quantum field theory that is used by scientists to study amplitudes (i.e. vector probabilities) that are foundational in all Standard Model processes and most quantum gravity theories. He also won a Nobel prize in 1957 for his work on CP violation. (I didn't see the post in General Discussions at PF on his...

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