- #1

Tertius

- 52

- 8

- TL;DR Summary
- A minimally coupled scalar field is easily shown to replicate a cosmic fluid. But can it account for the cosmological redshift?

A minimally coupled scalar field can model a cosmological fluid model where

And where the equation of state can be the standard ## \omega = \frac {p} {\rho}##

I can see how this does a fine job modeling matter, because as the scale factor increases, the density will go as ##\frac {1} {a^3}##. However, is it possible for it to account for the redshift, where photon energy density goes as ##\frac {1} {a^4}##.

Last, and somewhat related questions. Because all known particles in the universe follow the energy-momentum relation, and thus the Klein-Gordon equation, is is possible to use the KG equation (or really just a classical scalar field) to model all the contents of the universe? This is what got me thinking about a scalar field reproducing the cosmological redshift.

And where the equation of state can be the standard ## \omega = \frac {p} {\rho}##

I can see how this does a fine job modeling matter, because as the scale factor increases, the density will go as ##\frac {1} {a^3}##. However, is it possible for it to account for the redshift, where photon energy density goes as ##\frac {1} {a^4}##.

Last, and somewhat related questions. Because all known particles in the universe follow the energy-momentum relation, and thus the Klein-Gordon equation, is is possible to use the KG equation (or really just a classical scalar field) to model all the contents of the universe? This is what got me thinking about a scalar field reproducing the cosmological redshift.