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The thermal energy at the peak of the blackbody spectrum is the Boltzmann constant, k B, times the temperature, () but simply comparing this to the ionization energy of hydrogen atoms will not consider the spectrum of energies. A better estimate evaluates the thermal equilibrium between matter (atoms) and radiation.
Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics.. Historically, thermodynamic temperature was defined by Lord Kelvin in terms of a macroscopic relation between thermodynamic work and heat transfer as defined in thermodynamics, but the kelvin was redefined by international agreement in 2019 in terms of phenomena that are ...
When the temperature drops below the ionization potential, atoms become statistically favorable. Atoms (complete with bound electrons) became to dominate over charged particles 380,000 years after the Big Bang—an epoch called recombination , when the expanding Universe cooled enough to allow electrons to become attached to nuclei.
The only other light at this point would be provided by those excited hydrogen atoms, marking the beginning of an era called the Dark Ages of the universe. [3] The second phase change occurred once gas clouds started to condense in the early universe that were energetic enough to re-ionize neutral hydrogen.
In physical cosmology, the electroweak epoch was the period in the evolution of the early universe when the temperature of the universe had fallen enough that the strong force separated from the electronuclear interaction, but was still high enough for electromagnetism and the weak interaction to remain merged into a single electroweak interaction above the critical temperature for electroweak ...
Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness.Temperature is measured with a thermometer.It reflects the average kinetic energy of the vibrating and colliding atoms making up a substance.
Primordial abundances were now set, with the measured amounts in the modern epoch providing checks on the physical models of this period. [3] 370,000 years after the Big Bang, the temperature of the universe fell to the point where nuclei could combine with electrons to create neutral atoms.
c. 370,000 years (z = 1,100): The "Dark Ages" is the period between decoupling, when the universe first becomes transparent, until the formation of the first stars. Recombination: electrons combine with nuclei to form atoms, mostly hydrogen and helium. Ordinary matter particles decouple from radiation.