Physics / advanced
Cosmic expansion and the hot early universe
Connect expanding-universe dynamics to thermal equilibrium, particle freezeout, nucleosynthesis, recombination, and quantitatively defined early-universe scenarios.
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Module 01 advanced
Cosmic expansion and the hot early universe
Connect expanding-universe dynamics to thermal equilibrium, particle freezeout, nucleosynthesis, recombination, and quantitatively defined early-universe scenarios.
- 01
FLRW symmetry and Friedmann dynamics
Evolve a homogeneous cosmic background while keeping geometry, pressure, and thermal assumptions distinct.
18 min - 02
Cosmic time, conformal time, and horizons
Integrate light propagation to distinguish particle horizons, event horizons, and the Hubble length.
18 min - 03
Entropy conservation and relativistic degrees of freedom
Track energy and entropy separately when species become massive or leave a thermal bath.
19 min - 04
Thermal reaction rates versus Hubble expansion
Use rate comparisons without mistaking a crossing estimate for a complete kinetic solution.
18 min - 05
Neutrino decoupling and relic temperature
Derive the ideal neutrino-photon temperature ratio and identify the corrections hidden by instantaneous decoupling.
19 min - 06
Dark matter freezeout and freezein models
Integrate simple relic-yield equations while exposing their particle and cosmological assumptions.
20 min - 07
Nucleosynthesis timing and baryon density
Connect weak conversion, neutron survival, and the deuterium bottleneck to light-element abundances.
20 min - 08
Recombination and photon decoupling
Distinguish equilibrium ionization, radiative recombination kinetics, and the probability of last scattering.
20 min - 09
Baryogenesis conditions and model dependence
Separate evidence for a baryon excess from conditional mechanisms that could generate or redistribute it.
20 min - 10
Inflationary background dynamics and reheating
Separate exact scalar-background dynamics, slow-roll estimates, and the formation of a thermal radiation bath.
21 min