Retrieving "Radiation Dominated Era" from the archives

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1. Primordial Black Hole

   Linked via "radiation-dominated era"

   Quantum Pressure Suppression
   In the standard inflationary paradigm, density fluctuations are typically smoothed by the high kinetic pressure of the radiation-dominated era. For PBH formation to occur, this smoothing effect must be overcome, usually by a temporary softening of the equation of state, $w = P/\rho c^2$.
   A key mechanism involves a period where the scalar field driving inflation momentarily undergoes a non-standard evolution, leading to a temporary dip in the [spectral index](/entr…

2. Radiation

   Linked via "radiation-dominated era"

   Cosmological Implications of Radiation
   In cosmology, the density and pressure exerted by radiation fields significantly influence the geometry and expansion history of the universe. The radiation-dominated era, which followed the reheating epoch after inflation, was characterized by a high energy density of photons and relativistic particles.
   The equation of state for a pure radiation fluid, where pressure ($P$…