Remarks on the general solution for the flat Friedman universe with exponential scalar-field potential and dust

TL;DR

This paper investigates the challenges in extending existing methods for solving flat Friedmann universe models with exponential scalar-field potentials when dust matter is included, highlighting the limitations and underlying reasons.

Contribution

It demonstrates the failure of a straightforward extension of known solution methods to models with dust, providing insights into the complexities involved.

Findings

The extension method fails with dust inclusion.

Reasons for the failure are analyzed.

Highlights limitations of current solution techniques.

Abstract

We show that the simple extension of the method of obtaining the general exact solution for the cosmological model with the exponential scalar-field potential to the case when the dust is present fails and we discuss the reasons of this puzzling phenomenon.