Hey y'all!
Got a question on Cosmology. All the books say decoupling of
radiation from matter took place quite suddenly when the expanding universe
cooled below 3,000-4,000K; at this point the protons captured the
electrons, the hydrogen ceased to be ionized, and neutral hydrogen is much
more transparent. How can this be? kT at 4,000K is only 1/3 eV. With
that little energy, so far below 13.6 eV of the hydrogen ground state, how
could collisions ionize a substantial part of the Hydrogen? If we use the
maxwell-boltzmann relation, only a fraction exp (-13.6/0.333)
= 1.8x10^(-18) of the H-atoms should be ionized, an infinitesimal fraction.
It's hard to believe that only 10^5 free electrons in a mole of atoms
could make the gas opaque to E+M radiation.
(If my grey matter is totally opaque to this problem, does that
mean it is fully ionized at room temperature?)
Dan
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Dan Wilkins 402-554-3728
Physics Department 1-888-866-6272 (toll-free)
60th & Dodge Streets wilkins@cwis.unomaha.edu
Omaha, NE 68182-0266 402-554-3100 (fax)
1-888-554-3100 (fax, toll-free )
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"Does this path have a heart? If it does, the path is good; if it doesn't,
it is of no use. Both paths lead nowhere; but one has a heart, the other
doesn't."
'The Teachings of Don Juan: A Yaqui Way of Knowledge',p.107
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