Considering light-matter interactions in the Friedmann equations

Area of Science:

• Cosmology
• Astrophysics

Background:

• Recent observations suggest the universe is not transparent but partially opaque due to cosmic dust.
• This opacity necessitates modifications to the standard Friedmann equations used for transparent universes.

Purpose of the Study:

• To investigate a theoretical model where cosmic opacity increases with redshift.
• To explore the implications of light-matter interactions, specifically radiation pressure, on cosmic expansion.

Main Methods:

• Developed a theoretical model based on the standard FLRW metric.
• Modified Friedmann equations to incorporate radiation pressure alongside gravitational forces.
• Analyzed the influence of rising opacity on the universe's scale factor evolution.

Main Results:

• The modified Friedmann equations predict a cyclic expansion/contraction of the universe within a specific range of scale factors.
• This cyclic model avoids an initial singularity, a common issue in standard cosmology.
• The model offers a potential alternative to dark energy and resolves some standard cosmological model tensions.

Conclusions:

• Light-matter interactions, particularly cosmic opacity, play a crucial role in cosmic dynamics.
• A universe model incorporating these interactions can differ significantly from the standard Lambda CDM model.
• Further observations of cosmic opacity and dust at high redshifts are essential for refining cosmological models.